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Electronics, Volume 8, Issue 7 (July 2019)

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Open AccessArticle
A Context-Aware Route Finding Algorithm for Self-Driving Tourists Using Ontology
Electronics 2019, 8(7), 808; https://doi.org/10.3390/electronics8070808 (registering DOI)
Received: 9 May 2019 / Revised: 17 June 2019 / Accepted: 28 June 2019 / Published: 19 July 2019
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Abstract
This study proposed a context-aware ontology-based route finding algorithm for self-driving tourists. In this algorithm, two ontologies—namely drivers’ experiences and required tourist services—were used according to tourist requirements. Trips were classified into business and touristic. The algorithm was then compared with Google Maps [...] Read more.
This study proposed a context-aware ontology-based route finding algorithm for self-driving tourists. In this algorithm, two ontologies—namely drivers’ experiences and required tourist services—were used according to tourist requirements. Trips were classified into business and touristic. The algorithm was then compared with Google Maps in terms of travel time and travel length for evaluation. The results showed that the proposed algorithm performed similarly to Google Maps in some cases of business trips and better in other cases, with a maximum 10-min travel time difference. In touristic trips, the capabilities of the proposed algorithm were far better than those of Google Maps. Full article
(This article belongs to the Section Computer Science & Engineering)
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Open AccessArticle
FT-GAN: Face Transformation with Key Points Alignment for Pose-Invariant Face Recognition
Electronics 2019, 8(7), 807; https://doi.org/10.3390/electronics8070807
Received: 22 May 2019 / Revised: 4 July 2019 / Accepted: 17 July 2019 / Published: 19 July 2019
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Abstract
Face recognition has been comprehensively studied. However, face recognition in the wild still suffers from unconstrained face directions. Frontal face synthesis is a popular solution, but some facial features are missed after synthesis. This paper presents a novel method for pose-invariant face recognition. [...] Read more.
Face recognition has been comprehensively studied. However, face recognition in the wild still suffers from unconstrained face directions. Frontal face synthesis is a popular solution, but some facial features are missed after synthesis. This paper presents a novel method for pose-invariant face recognition. It is based on face transformation with key points alignment based on generative adversarial networks (FT-GAN). In this method, we introduce CycleGAN for pixel transformation to achieve coarse face transformation results, and these results are refined by key point alignment. In this way, frontal face synthesis is modeled as a two-task process. The results of comprehensive experiments show the effectiveness of FT-GAN. Full article
(This article belongs to the Special Issue Multidimensional Digital Signal Processing)
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Open AccessArticle
Continuous and Stable Cross-Eye Jamming via a Circular Retrodirective Array
Electronics 2019, 8(7), 806; https://doi.org/10.3390/electronics8070806
Received: 27 May 2019 / Revised: 15 July 2019 / Accepted: 17 July 2019 / Published: 19 July 2019
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Abstract
Cross-eye jamming is an angular deception jamming technique against monopulse radar. Multiple-element retrodirective cross-eye jamming (MRCJ) as an improved method, uses a retrodirective antenna array with multiple antenna elements in a cross-eye jammer and can obtain better jamming performance. However, the practical MRCJ [...] Read more.
Cross-eye jamming is an angular deception jamming technique against monopulse radar. Multiple-element retrodirective cross-eye jamming (MRCJ) as an improved method, uses a retrodirective antenna array with multiple antenna elements in a cross-eye jammer and can obtain better jamming performance. However, the practical MRCJ system employing a linear antenna array becomes ineffective when the threat radar appears in the antenna array’s end-fire direction. To meet multiple threats from different directions and provide continuous jamming, MRCJ employing a circular antenna array (C-MRCJ) is proposed after defining the modulation direction of system parameters. Optimal configuration of C-MRCJ providing stable jamming performance is discussed. The number of the jammer loops is analyzed under considerable jamming performance and moderate hardware cost. Full article
(This article belongs to the Section Microwave and Wireless Communications)
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Open AccessArticle
Improvement in SNR by Adaptive Range Gates for RCS Measurements in the THz Region
Electronics 2019, 8(7), 805; https://doi.org/10.3390/electronics8070805
Received: 14 May 2019 / Revised: 27 June 2019 / Accepted: 15 July 2019 / Published: 18 July 2019
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Abstract
One of the major concerns in radar cross-section (RCS) measurements is the isolation of the target echo from unwanted spurious signals. Generally, the method of software range gate is applied to extract useful data. However, this method may not work to expectations, especially [...] Read more.
One of the major concerns in radar cross-section (RCS) measurements is the isolation of the target echo from unwanted spurious signals. Generally, the method of software range gate is applied to extract useful data. However, this method may not work to expectations, especially for targets with a large length-width ratio. This is because the effective target zone is dependent on the aspect angle. The implementation of conventional fixed range gates will introduce an uneven clutter signal that leads to a decline in signal-to-noise ratio. The influence of this uneven clutter signal becomes increasingly severe in the terahertz band, where the wavelength is short and the illumination power is weak. In this work, the concept of adaptive range gates was adopted to extract a target echo of higher accuracy. The dimension of the range gate was determined by the angle-dependent radial projection of the target. In order to evaluate the performance of the proposed method, both experimental measurements and numerical simulations were conducted. Noticeable improvements in the signal-to-noise ratio at certain angles were observed. Full article
(This article belongs to the Special Issue Terahertz Technology and Its Applications)
Open AccessArticle
Prototyping of an All-pMOS-Based Cross-Coupled Voltage Multiplier in Single-Well CMOS Technology for Energy Harvesting Utilizing a Gastric Acid Battery
Electronics 2019, 8(7), 804; https://doi.org/10.3390/electronics8070804
Received: 1 June 2019 / Revised: 10 July 2019 / Accepted: 13 July 2019 / Published: 18 July 2019
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Abstract
A gastric acid battery and its charge storage in a capacitor are a simple and safe method to provide a power source to an ingestible device. For that method, the electromotive force of the battery should be boosted for storing a large amount [...] Read more.
A gastric acid battery and its charge storage in a capacitor are a simple and safe method to provide a power source to an ingestible device. For that method, the electromotive force of the battery should be boosted for storing a large amount of energy. In this study, we have proposed an all-p-channel metal-oxide semiconductor (pMOS)-based cross-coupled voltage multiplier (CCVM) utilizing single-well CMOS technology to achieve a voltage boosting higher than from a conventional complementary MOS (CMOS) CCVM. We prototyped a custom integrated circuit (IC) implemented with the above CCVMs and a ring oscillator as a clock source. The characterization experiment demonstrated that our proposed pMOS-based CCVM can boost the input voltage higher because it avoids the body effect problem resulting from an n-channel MOS transistor. This circuit was also demonstrated to significantly reduce the circuit area on the IC, which is advantageous as it reduces the chip size or provides an area for other functional circuits. This simple circuit structure based on mature and low-cost technologies matches well with disposal applications such as an ingestible device. We believe that this pMOS-based CCVM has the potential to become a useful energy harvesting circuit for ingestible devices. Full article
(This article belongs to the Special Issue Energy Efficient Circuit Design Techniques for Low Power Systems)
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Open AccessArticle
Efficient Implementation of 2D and 3D Sparse Deconvolutional Neural Networks with a Uniform Architecture on FPGAs
Electronics 2019, 8(7), 803; https://doi.org/10.3390/electronics8070803
Received: 29 May 2019 / Revised: 6 July 2019 / Accepted: 9 July 2019 / Published: 18 July 2019
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Abstract
Three-dimensional (3D) deconvolution is widely used in many computer vision applications. However, most previous works have only focused on accelerating two-dimensional (2D) deconvolutional neural networks (DCNNs) on Field-Programmable Gate Arrays (FPGAs), while the acceleration of 3D DCNNs has not been well studied in [...] Read more.
Three-dimensional (3D) deconvolution is widely used in many computer vision applications. However, most previous works have only focused on accelerating two-dimensional (2D) deconvolutional neural networks (DCNNs) on Field-Programmable Gate Arrays (FPGAs), while the acceleration of 3D DCNNs has not been well studied in depth as they have higher computational complexity and sparsity than 2D DCNNs. In this paper, we focus on the acceleration of both 2D and 3D sparse DCNNs on FPGAs by proposing efficient schemes for mapping 2D and 3D sparse DCNNs on a uniform architecture. Firstly, a pruning method is used to prune unimportant network connections and increase the sparsity of weights. After being pruned, the number of parameters of DCNNs is reduced significantly without accuracy loss. Secondly, the remaining non-zero weights are encoded in coordinate (COO) format, reducing the memory demands of parameters. Finally, to demonstrate the effectiveness of our work, we implement our accelerator design on the Xilinx VC709 evaluation platform for four real-life 2D and 3D DCNNs. After the first two steps, the storage required of DCNNs is reduced up to 3.9×. Results show that the performance of our method on the accelerator outperforms that of the our prior work by 2.5× to 3.6× in latency. Full article
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Open AccessArticle
A n-out-of-n Sharing Digital Image Scheme by Using Color Palette
Electronics 2019, 8(7), 802; https://doi.org/10.3390/electronics8070802
Received: 15 April 2019 / Revised: 12 July 2019 / Accepted: 13 July 2019 / Published: 17 July 2019
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Abstract
A secret image sharing (SIS) scheme inserts a secret message into shadow images in a way that if shadow images are combined in a specific way, the secret image can be recovered. A 2-out-of-2 sharing digital image scheme (SDIS) adopts a color palette [...] Read more.
A secret image sharing (SIS) scheme inserts a secret message into shadow images in a way that if shadow images are combined in a specific way, the secret image can be recovered. A 2-out-of-2 sharing digital image scheme (SDIS) adopts a color palette to share a digital color secret image into two shadow images, and the secret image can be recovered from two shadow images, while any one shadow image has no information about the secret image. This 2-out-of-2 SDIS may keep the shadow size small because by using a color palette, and thus has advantage of reducing storage. However, the previous works on SDIS are just 2-out-of-2 scheme and have limited functions. In this paper, we take the lead to study a general n-out-of-n SDIS which can be applied on more than two shadow. The proposed SDIS is implemented on the basis of 2-out-of-2 SDIS. Our main contribution has the higher contrast of binary meaningful shadow and the larger region in color shadows revealing cover image when compared with previous 2-out-of-2 SDISs. Meanwhile, our SDIS is resistant to colluder attack. Full article
(This article belongs to the Special Issue Signal Processing and Analysis of Electrical Circuit)
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Open AccessArticle
An Intelligent Air Quality Sensing System for Open-Skin Wound Monitoring
Electronics 2019, 8(7), 801; https://doi.org/10.3390/electronics8070801
Received: 16 May 2019 / Revised: 27 June 2019 / Accepted: 8 July 2019 / Published: 17 July 2019
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Abstract
There are many factors that may have a significant effect on the skin wound healing process. The environment is one of them. Although different previous research woks have highlighted the role of environmental elements such as humidity, temperature, dust, etc., in the process [...] Read more.
There are many factors that may have a significant effect on the skin wound healing process. The environment is one of them. Although different previous research woks have highlighted the role of environmental elements such as humidity, temperature, dust, etc., in the process of skin wound healing, there is no predefined method available to identify the favourable or adverse environment conditions that seriously affect (positively or negatively) the skin wound healing process. In the current research work, an IoT-based approach is used to design an AQSS (Air Quality Sensing System) using sensors for the acquisition of real-time environment data, and the SVM (Support Vector Machine) classifier is applied to classify environments into one of the two categories, i.e., “favourable”, and “unfavourable”. The proposed system is also supported with an Android application to provide an easy-to-use interface. The proposed system provides an easy and simple means for patients to evaluate the environmental parameters and monitor their effects in the process of open skin wound healing. Full article
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Open AccessArticle
Effectiveness Assessment of a Nanocrystalline Sleeve Ferrite Core Compared with Ceramic Cores for Reducing Conducted EMI
Electronics 2019, 8(7), 800; https://doi.org/10.3390/electronics8070800
Received: 21 June 2019 / Revised: 12 July 2019 / Accepted: 15 July 2019 / Published: 17 July 2019
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Abstract
The interconnection of different electronic devices or systems through cables is becoming more difficult due to the hard restrictions related to electromagnetic compatibility (EMC) in order to comply with requirements. Therefore, the use of EMC components is a good solution to manage the [...] Read more.
The interconnection of different electronic devices or systems through cables is becoming more difficult due to the hard restrictions related to electromagnetic compatibility (EMC) in order to comply with requirements. Therefore, the use of EMC components is a good solution to manage the problems associated with the filtering of electromagnetic interference (EMI) in cables and to pass the compliance test. In this sense, sleeve ferrite cores become a very interesting solution since they can be set around a wire and, hence, they provide an effective solution against EMI without having to redesign the electronic circuit. This contribution is focused on the characterization of the performance of a sleeve ferrite core based on a novel nanocrystalline (NC) novel material for EMI suppression and comparing it to the most conventional ceramic ferrite cores such as MnZn and NiZn. The research highlights the suitability of an NC novel component in terms of its magnetic properties to reduce EMI within the conducted emissions range. This range is generally defined by the International Special Committee on Radio Interference (CISPR) test standards frequency band that covers from 150 kHz up to 30 MHz (108 MHz in the case of CISPR 25). First, this study presents a description of the main parameters that define the behavior of NC and ceramic cores and, secondly, by analyzing the data obtained from experimental procedures, it is possible to directly determine the insertion loss parameter. Hence, this characterization procedure is used to obtain the performance of NC material compared to the conventional sleeve ferrite core compositions employed to filter the interferences in this problematic frequency range. As can be deduced from the results obtained, an NC sleeve ferrite core provides the best performance in terms of EMI filtering within a significant frequency range between 100 kHz and 100 MHz. Full article
(This article belongs to the Section Microwave and Wireless Communications)
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Open AccessArticle
Model-Based Optimization of an LLC-Resonant DC-DC Converter
Electronics 2019, 8(7), 799; https://doi.org/10.3390/electronics8070799
Received: 10 June 2019 / Revised: 13 July 2019 / Accepted: 14 July 2019 / Published: 17 July 2019
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Abstract
The study presented in the paper is to guarantee the performance of the LLC DC-DC converter using model-based optimization. The primary scope of the study is to maintain the output parameters regardless of the variation of the values of the circuit elements. In [...] Read more.
The study presented in the paper is to guarantee the performance of the LLC DC-DC converter using model-based optimization. The primary scope of the study is to maintain the output parameters regardless of the variation of the values of the circuit elements. In engineering practice, it is known that any schematic element cannot be reproduced with an absolute accuracy of features. In addition, its main parameters change during operation due to changes in operating temperature, aging, operating modes and so on. Optimization procedures are a tool for finding the most appropriate values for circuit elements, with selected constraints, target functions and operating modes. In electronic converters, these are most often: minimal loss, maximum efficiency, the critical-aperiodic transition process, realization of certain dynamics, appropriate modes of operation and so on. The results obtained show that using the proposed approach produces more robustness to disturbances and tolerances, with improved dynamics and faster transient processes. On the other hand, the value of the circuit elements is smaller, and reliable operation of the protection and automatic regulation systems is achieved. Full article
(This article belongs to the Section Power Electronics)
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Open AccessArticle
Single-Switch LED Post-Regulator Based on a Modified Class-E Resonant Converter with Voltage Clamp
Electronics 2019, 8(7), 798; https://doi.org/10.3390/electronics8070798
Received: 25 June 2019 / Revised: 12 July 2019 / Accepted: 15 July 2019 / Published: 16 July 2019
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Abstract
The strict restrictions imposed both by mandatory regulations and by the recommendations contained in current standards have led to the fact that most commercially available LED ballasts nowadays use two-stage topologies. The first stage is intended to comply with the harmonics standards and [...] Read more.
The strict restrictions imposed both by mandatory regulations and by the recommendations contained in current standards have led to the fact that most commercially available LED ballasts nowadays use two-stage topologies. The first stage is intended to comply with the harmonics standards and the second stage is used to control the LED current and reduce the low frequency ripple. In this work, a new DC–DC resonant converter topology is presented. This topology is derived from a modified Class-E resonant inverter by adding a clamping diode. This diode achieves a double goal: it limits the maximum switch voltage and works as a power recirculating path. This way, the proposed topology behaves as a loss-less impedance placed in series with the LED thus allowing to control the output power. This converter maintains the extremely small switching losses inherent to the Class-E inverter while reducing the voltage stress across the switch. This work presents a simplified design methodology based on the fundamental approach. This methodology was used to design and build a DC–DC post-regulator for a 40 W LED lamp. The results obtained with the laboratory prototype show that this circuit can be used to stabilize and dim the LED current while maintaining very small losses. The measured efficiency was 95.7% at nominal power and above 90% when dimmed down to 25%. Full article
(This article belongs to the Special Issue Latest Developments in LED Drivers)
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Open AccessArticle
Near-Field Immunity Test Method for Fast Radiated Immunity Test Debugging of Automotive Electronics
Electronics 2019, 8(7), 797; https://doi.org/10.3390/electronics8070797
Received: 21 June 2019 / Revised: 12 July 2019 / Accepted: 13 July 2019 / Published: 16 July 2019
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Abstract
This study presents a near-field immunity test (NFIT) method for the fast debugging of radiated susceptibility of industrial devices. The proposed approach is based on the development of an NFIT setup which comprises of developed near-field electric and magnetic field probes and device [...] Read more.
This study presents a near-field immunity test (NFIT) method for the fast debugging of radiated susceptibility of industrial devices. The proposed approach is based on the development of an NFIT setup which comprises of developed near-field electric and magnetic field probes and device under test (DUT). The developed small-size and handy near-field testing probes inject the high electric (up to 1000 V/m) and magnetic (up to 2.4 A/m) fields on the DUT in the radar pulse ranges (1.2 to 1.4 GHz and 2.7 to 3.1 GHz) with the lower fed input power (up to 15 W) from the power amplifier in the developed NFIT setup. The proof of concept is validated with the successful near-field immunity debugging of an electric power steering (EPS) device used in the automotive industry with the developed NFIT setup. The radiated susceptibility debugging test results of developed NFIT method and conventional method of ISO 11452-2 test setup turned out to be close to each other for the tested DUT in immunity performance. The proposed procedure has advantages of industry usefulness with fast, handy, and cost-effective radiated immunity debugging of the DUT without the requirement of large antenna, high-power amplifiers, optical DUT connecting harness, and an anechoic chamber as needed in ISO 11452-2 standard setup for the debugging analysis. Full article
(This article belongs to the Section Microwave and Wireless Communications)
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Open AccessFeature PaperArticle
Maximum Transmit Power for UE in an LTE Small Cell Uplink
Electronics 2019, 8(7), 796; https://doi.org/10.3390/electronics8070796
Received: 19 May 2019 / Revised: 11 July 2019 / Accepted: 15 July 2019 / Published: 16 July 2019
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Abstract
To furnish the network with small cells, it is vital to consider parameters like cell size, interference in the network, and deployment strategies to maximize the network’s performance gains expected from small cells. With a small cell network, it is critical to analyze [...] Read more.
To furnish the network with small cells, it is vital to consider parameters like cell size, interference in the network, and deployment strategies to maximize the network’s performance gains expected from small cells. With a small cell network, it is critical to analyze the impact of the uplink power control parameters on the network’s performance. In particular, the maximum transmit power (Pmax) for user equipment (UE) needs to be revisited for small cells, since it is a major contributor towards interference. In this work, the network performance was evaluated for different Pmax values for the small cell uplink. Various deployment scenarios for furnishing the existing macro layer in LTE networks with small cells were considered. The Pmax limit for a small cell uplink was evaluated for both homogenous small cell and heterogeneous networks (HetNet). The numerical results showed that it would be appropriate to adopt Pmax = 18 dBm in uniformly distributed small cells rather than Pmax = 23 dBm, as in macro environments. The choice of Pmax = 18 dBm was further validated for three HetNet deployment scenarios. A decrease of 0.52 dBm and an increase of 0.03 dBm and 3.29 dBm in the proposed Pmax = 18 dBm were observed for the three HetNet deployments, respectively. Furthermore, we propose that the fractional power control mode can be employed instead of the full compensation mode in small cell uplinks. Full article
(This article belongs to the Special Issue Recent Technical Developments in Energy-Efficient 5G Mobile Cells)
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Open AccessFeature PaperArticle
A Multi-Inductor H Bridge Fault Current Limiter
Electronics 2019, 8(7), 795; https://doi.org/10.3390/electronics8070795
Received: 18 May 2019 / Revised: 28 June 2019 / Accepted: 12 July 2019 / Published: 16 July 2019
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Abstract
Current power systems will suffer from increasing pressure as a result of an upsurge in demand and will experience an ever-growing penetration of distributed power generation, which are factors that will contribute to a higher of incidence fault current levels. Fault current limiters [...] Read more.
Current power systems will suffer from increasing pressure as a result of an upsurge in demand and will experience an ever-growing penetration of distributed power generation, which are factors that will contribute to a higher of incidence fault current levels. Fault current limiters (FCLs) are key power electronic devices. They are able to limit the prospective fault current without completely disconnecting in cases in which a fault occurs, for instance, in a power transmission grid. This paper proposes a new type of FCL capable of fault current limiting in two steps. In this way, the FCLs’ power electronic switches experience significantly less stress and their overall performance will significantly increase. The proposed device is essentially a controllable H bridge type fault current limiter (HBFCL) that is comprised of two variable inductances, which operate to reduce current of main switch in the first stage of current limiting. In the next step, the main switch can limit the fault current while it becomes open. Simulation studies are carried out using MATLAB and its prototype setup is built and tested. The comparison of experimental and simulation results indicates that the proposed HBFCL is a promising solution to address protection issues. Full article
(This article belongs to the Special Issue Industrial Applications of Power Electronics)
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Open AccessArticle
Expressing Personalities of Conversational Agents through Visual and Verbal Feedback
Electronics 2019, 8(7), 794; https://doi.org/10.3390/electronics8070794
Received: 3 June 2019 / Revised: 2 July 2019 / Accepted: 6 July 2019 / Published: 16 July 2019
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Abstract
As the uses of conversational agents increase, the affective and social abilities of agents become important with their functional abilities. Agents that lack affective abilities could frustrate users during interaction. This study applied personality to implement the natural feedback of conversational agents referring [...] Read more.
As the uses of conversational agents increase, the affective and social abilities of agents become important with their functional abilities. Agents that lack affective abilities could frustrate users during interaction. This study applied personality to implement the natural feedback of conversational agents referring to the concept of affective computing. Two types of feedback were used to express conversational agents’ personality: (1) visual feedback and (2) verbal cues. For visual feedback, participants (N = 45) watched visual feedback with different colors and motions. For verbal cues, participants (N = 60) heard different conditions of agents’ voices with different scripts. The results indicated that the motions of visual feedback were more significant than colors. Fast motions could express distinct and positive personalities. Different verbal cues were perceived as different personalities. The perceptions of personalities differed according to the vocal gender. This study provided design implications for personality expressions applicable to diverse interfaces. Full article
(This article belongs to the Special Issue Electronics and Dynamic Open Innovation)
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Open AccessArticle
Embedded Flight Control Based on Adaptive Sliding Mode Strategy for a Quadrotor Micro Air Vehicle
Electronics 2019, 8(7), 793; https://doi.org/10.3390/electronics8070793
Received: 14 June 2019 / Revised: 5 July 2019 / Accepted: 8 July 2019 / Published: 16 July 2019
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Abstract
The design of an embedded flight controller for a quadrotor micro air vehicle, which is subject to uncertainties and perturbations, is addressed. In order to obtain robustness against bounded uncertainties and disturbances, an adaptive sliding mode controller is proposed. The control adaptive gains [...] Read more.
The design of an embedded flight controller for a quadrotor micro air vehicle, which is subject to uncertainties and perturbations, is addressed. In order to obtain robustness against bounded uncertainties and disturbances, an adaptive sliding mode controller is proposed. The control adaptive gains allow using only necessary control to satisfy the task, reducing the chattering effect and at the same time reject external perturbations. Furthermore, a stability analysis of the closed-loop system is given. Finally, simulations and experimental results carried out on a commercial micro air vehicle demonstrate the feasibility and advantages of the proposed flight controller. Full article
(This article belongs to the Special Issue Motion Planning and Control for Robotics)
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Open AccessArticle
A Study of the Sulfidation Behavior on Palladium-Coated Copper Wire with a Flash-Gold Layer (PCA) after Wire Bonding
Electronics 2019, 8(7), 792; https://doi.org/10.3390/electronics8070792
Received: 9 May 2019 / Revised: 4 July 2019 / Accepted: 15 July 2019 / Published: 15 July 2019
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Abstract
Palladium-coated copper wire with a flash-gold layer (PCA) is an oxidation-resistant fine wire that simultaneously has the properties of palladium-coated copper wire (PCC) and gold-coated copper wire. This research used an extreme sulfidation test to compare corrosion resistance between the PCC and PCA [...] Read more.
Palladium-coated copper wire with a flash-gold layer (PCA) is an oxidation-resistant fine wire that simultaneously has the properties of palladium-coated copper wire (PCC) and gold-coated copper wire. This research used an extreme sulfidation test to compare corrosion resistance between the PCC and PCA wires. In addition to closely examining the morphology of the wires, the internal matrix after the sulfidation test is also discussed. In doing so, the PCA wire was bonded onto the aluminum pads and the sulfidation test was conducted. Then, we observed its morphology and elemental distribution and found that the flash-gold layer of the PCA wire effectively enhanced resistance to sulfidation corrosion. Because the copper ball had an alloying effect on the ball bonding, it produced different shapes of sulfide after the sulfidation test. The degree of corrosion on the wedge bond was different because of the presence or absence of the coated layer. In contrast, the flash-gold layer of the PCA wire enhanced the bonding force and retained low resistance characteristics after the sulfidation test. Full article
(This article belongs to the Section Microelectronics and Optoelectronics)
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Open AccessReview
Shunt Active Power Filter: A Review on Phase Synchronization Control Techniques
Electronics 2019, 8(7), 791; https://doi.org/10.3390/electronics8070791
Received: 4 May 2019 / Revised: 9 July 2019 / Accepted: 13 July 2019 / Published: 15 July 2019
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Abstract
Owing to the destructive impacts of harmonic currents, the topic of reducing their impacts on power system has attracted tremendous research interests. In this regard, a shunt active power filter (SAPF) is recognized to be the most reliable instrument. It performs by first [...] Read more.
Owing to the destructive impacts of harmonic currents, the topic of reducing their impacts on power system has attracted tremendous research interests. In this regard, a shunt active power filter (SAPF) is recognized to be the most reliable instrument. It performs by first detecting the harmonic currents that are present in a harmonic-contaminated power system, and subsequently generates and injects corrective mitigation current back into the power system to cancel out all the detected harmonic currents. This means that other than the ability to generate corrective mitigation current itself, it is actually more important to make sure that the SAPF is able to operate in phase with the operating power system, so that the mitigation current can correctly be injected. Hence, proper synchronization technique needs to be integrated when designing the control algorithms of SAPF. This paper critically discusses and analyzes various types of existing phase synchronization techniques which have been applied to manage operation of SAPF; in terms of features, working principle, implementation and performance. The analysis provided can potentially serve as a guideline and provision of information on selecting the most suitable technique for synchronizing SAPF with the connected power system. Full article
(This article belongs to the Section Power Electronics)
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Open AccessArticle
Electrically Compact SRR-Loaded Metamaterial Inspired Quad Band Antenna for Bluetooth/WiFi/WLAN/WiMAX System
Electronics 2019, 8(7), 790; https://doi.org/10.3390/electronics8070790
Received: 27 May 2019 / Accepted: 5 June 2019 / Published: 15 July 2019
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Abstract
In this paper, we reveal a concept of low-profile Split Ring Resonator loaded metamaterial inspired antenna for Bluetooth/WiFi/WLAN/WiMAX communication systems. The antenna’s overall dimensions are 30 × 31 mm2 where two metamaterial unit cells are placed parallel to each other and a [...] Read more.
In this paper, we reveal a concept of low-profile Split Ring Resonator loaded metamaterial inspired antenna for Bluetooth/WiFi/WLAN/WiMAX communication systems. The antenna’s overall dimensions are 30 × 31 mm2 where two metamaterial unit cells are placed parallel to each other and a zig-zag feed line is connected with the SubMiniature version A connector. The defected ground technique was used to improve the antenna’s operational bandwidth. The computer simulation technology Microwave Studio was used to design and perform the numerical investigation, and the antenna was fabricated on FR-4 dielectric material. The Agilent N5227A VNA and anechoic chamber-based Satimo Star Lab were used to measure the antenna’s scattering parameters, voltage standing wave ratio, gain, efficiency and radiation patterns. The proposed metamaterial antenna had 200 MHz (2.40–2.60 GHz) and 390 MHz (3.40–3.79 GHz) overall bandwidth, which are similar to the simulated data. The measured results were applicable for Bluetooth (2.40–2.485 GHz), WiFi (2.4 GHz), WLAN (2.40–2.49 GHz and 3.65–3.69 GHz), and WiMAX (3.40–3.79 GHz) applications. The antenna’s average gain was 1.50 dBi, with the maximum and minimum gains of 2.25 dBi and 0.88 dBi, respectively, in addition to omnidirectional radiation patterns at operating bands. Full article
(This article belongs to the Section Microwave and Wireless Communications)
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Open AccessFeature PaperArticle
Task Scheduling to Constrain Peak Current Consumption in Wearable Healthcare Sensors
Electronics 2019, 8(7), 789; https://doi.org/10.3390/electronics8070789
Received: 30 May 2019 / Revised: 10 July 2019 / Accepted: 12 July 2019 / Published: 15 July 2019
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Abstract
Small embedded systems, in our case wearable healthcare devices, have significant engineering challenges to reduce their power consumption for longer battery life, while at the same time supporting ever-increasing processing requirements for more intelligent applications. Research has primarily focused on achieving lower power [...] Read more.
Small embedded systems, in our case wearable healthcare devices, have significant engineering challenges to reduce their power consumption for longer battery life, while at the same time supporting ever-increasing processing requirements for more intelligent applications. Research has primarily focused on achieving lower power operation through hardware designs and intelligent methods of scheduling software tasks, all with the objective of minimizing the overall consumed electrical power. However, such an approach inevitably creates points in time where software tasks and peripherals coincide to draw large peaks of electrical current, creating short-term electrical stress for the battery and power regulators, and adding to electromagnetic interference emissions. This position paper proposes that the power profile of an embedded device using a real-time operating system (RTOS) will significantly benefit if the task scheduler is modified to be informed of the electrical current profile required for each task. This enables the task scheduler to schedule tasks that require large amounts of current to be spread over time, thus constraining the peak current that the system will draw. We propose a solution to inform the task scheduler of a tasks’ power profile, and we discuss our application scenario, which clearly benefited from the proposal. Full article
(This article belongs to the Special Issue Low-power Wearable Healthcare Sensors)
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Open AccessEditorial
Visible Light Communication and Positioning: Present and Future
Electronics 2019, 8(7), 788; https://doi.org/10.3390/electronics8070788
Received: 25 June 2019 / Accepted: 11 July 2019 / Published: 15 July 2019
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Abstract
Future wireless communication may extend its spectrum to visible light due to its potential large bandwidth [...] Full article
(This article belongs to the Special Issue Visible Light Communication and Positioning)
Open AccessArticle
Nickel Particle-Based Compact Flexible Antenna for Modern Communication Systems
Electronics 2019, 8(7), 787; https://doi.org/10.3390/electronics8070787
Received: 3 May 2019 / Revised: 12 June 2019 / Accepted: 12 June 2019 / Published: 15 July 2019
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Abstract
A flexible antenna is a significant part of the new generation of wireless communication systems. Conventional antennas are typically fabricated on available FR-4 and RT/Duroid dielectric materials, where the dielectric constant cannot be selected arbitrarily and the degrees of freedom in designing the [...] Read more.
A flexible antenna is a significant part of the new generation of wireless communication systems. Conventional antennas are typically fabricated on available FR-4 and RT/Duroid dielectric materials, where the dielectric constant cannot be selected arbitrarily and the degrees of freedom in designing the antenna are limited, whereas our flexible substrate offers moderate dielectric values by changing the concentration of the raw materials. Synthesised nickel particle-based flexible nickel aluminate (NiAl2O4) is utilized as a substrate material to make an effective antenna for microwave applications. The nickel aluminate substrate was made with 42% concentration of nickel, and has a dielectric constant of 4.979 and a thickness of 1 mm. The fabricated flexible antenna shows measured bandwidth from 6.50–8.85 GHz. On the other hand, the maximum measured gain and efficiency was 4.75 dBi and 91%, respectively. Finally, that antenna has directional radiation patterns and the presented antenna has a novelty where the nickel aluminate substrate was used for the first time. Thus the compactness of the antenna and its performance with a flexible nature makes it a worthy one to be used in the C-band application. Full article
(This article belongs to the Section Microwave and Wireless Communications)
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Open AccessLetter
Elimination of Motion-Induced Phase Based on Double-Time Switching Scheme for SAA FMCW Radar
Electronics 2019, 8(7), 786; https://doi.org/10.3390/electronics8070786
Received: 1 June 2019 / Revised: 4 July 2019 / Accepted: 12 July 2019 / Published: 14 July 2019
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Abstract
Due to the low cost and straightforward structure, the switch antenna array (SAA) frequency modulated continuous wave (FMCW) radar has been widely applied in many fields. However, the motion-induced phase always leads to inaccurate direction estimation of moving targets. Here, we proposed an [...] Read more.
Due to the low cost and straightforward structure, the switch antenna array (SAA) frequency modulated continuous wave (FMCW) radar has been widely applied in many fields. However, the motion-induced phase always leads to inaccurate direction estimation of moving targets. Here, we proposed an elimination method of the motion-induced phase for the SAA FMCW radar. A double-time switching scheme (DTSS) is used for the reception of echo signals. Elimination of motion-induced phase is completed without estimating velocity, which can avoid the ambiguous velocity estimation problem. Additionally, the direction estimation of the moving target can be obtained by directly using a conventional digital beam forming (DBF) algorithm. The validity of the proposed method has been proved by the simulated and experimental results. Full article
(This article belongs to the Special Issue Radar Sensor for Motion Sensing and Automobile)
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Open AccessArticle
A Surface-Potential-Based Analytical I-V Model of Full-Depletion Single-Gate SOI MOSFETs
Electronics 2019, 8(7), 785; https://doi.org/10.3390/electronics8070785
Received: 10 May 2019 / Revised: 5 June 2019 / Accepted: 12 June 2019 / Published: 14 July 2019
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Abstract
A surface-potential-based analytical I-V model of single-gate (SG) silicon-on-insulator (SOI) MOSFETs in full-depletion (FD) mode is proposed and compared with numerical data and Khandelwal’s experimental results. An explicit calculation scheme of surface potential, processing high computation accuracy and efficiency, is demonstrated [...] Read more.
A surface-potential-based analytical I-V model of single-gate (SG) silicon-on-insulator (SOI) MOSFETs in full-depletion (FD) mode is proposed and compared with numerical data and Khandelwal’s experimental results. An explicit calculation scheme of surface potential, processing high computation accuracy and efficiency, is demonstrated according to the derivation of the coupling relation between surface potential and back-channel potential. The maximum absolute error decreases into 10−7 V scale, and computation efficiency is improved substantially compared with numerical iteration. Depending on the surface potential, the drain current is derived in closed-form and validated by Khandelwal’s experimental data. High computation accuracy and efficiency suggest that this analytical I-V model displays great promise for SOI device optimizations and circuit simulations. Full article
(This article belongs to the Section Semiconductors and Quantum)
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Open AccessArticle
Smartphone-Based Context Flow Recognition for Outdoor Parking System with Machine Learning Approaches
Electronics 2019, 8(7), 784; https://doi.org/10.3390/electronics8070784
Received: 18 April 2019 / Revised: 22 May 2019 / Accepted: 11 June 2019 / Published: 13 July 2019
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Abstract
Outdoor parking systems are one of the most crucial needs in a smart city to find vacant parking spaces in outdoor environments, such as roadsides, university campuses, and so on. In a typical outdoor parking system, the detection of a vehicle entering and [...] Read more.
Outdoor parking systems are one of the most crucial needs in a smart city to find vacant parking spaces in outdoor environments, such as roadsides, university campuses, and so on. In a typical outdoor parking system, the detection of a vehicle entering and leaving the parking zone is a major step. At present, there are numerous external sensor-based and camera-based parking systems available to detect the entrance and leaving of vehicles. Camera-based parking systems rely on sophisticated camera set-ups, while sensor-based parking systems require the installation of sensors at the parking spots or vehicles’ sides. Due to such complication, the deployment and maintenance costs of the existing parking systems are very high. Furthermore, the need for additional hardware and network capacity increases the cost and complexity, which makes it difficult to use for large deployment. This paper proposes an approach for outdoor parking utilizing only smartphone integrated sensors that do not require manpower support nor additional sensor installation. The proposed algorithm first receives sensor signals from the driver’s phone, performs pre-processing to recognize the context of drivers, which is followed by context flow recognition. The final result is obtained from context flow recognition which provides the output of whether the driver is parking or unparking. The proposed approach is validated with a set of comprehensive experiments. The performance of the proposed method is favorable as it uses only the smartphone’s internal sensors to recognize whether the cars are entering or leaving the parking area. Full article
(This article belongs to the Section Artificial Intelligence)
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Open AccessReview
A Survey on Deep Learning in Image Polarity Detection: Balancing Generalization Performances and Computational Costs
Electronics 2019, 8(7), 783; https://doi.org/10.3390/electronics8070783
Received: 19 June 2019 / Revised: 8 July 2019 / Accepted: 9 July 2019 / Published: 12 July 2019
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Abstract
Deep convolutional neural networks (CNNs) provide an effective tool to extract complex information from images. In the area of image polarity detection, CNNs are customarily utilized in combination with transfer learning techniques to tackle a major problem: the unavailability of large sets of [...] Read more.
Deep convolutional neural networks (CNNs) provide an effective tool to extract complex information from images. In the area of image polarity detection, CNNs are customarily utilized in combination with transfer learning techniques to tackle a major problem: the unavailability of large sets of labeled data. Thus, polarity predictors in general exploit a pre-trained CNN as the feature extractor that in turn feeds a classification unit. While the latter unit is trained from scratch, the pre-trained CNN is subject to fine-tuning. As a result, the specific CNN architecture employed as the feature extractor strongly affects the overall performance of the model. This paper analyses state-of-the-art literature on image polarity detection and identifies the most reliable CNN architectures. Moreover, the paper provides an experimental protocol that should allow assessing the role played by the baseline architecture in the polarity detection task. Performance is evaluated in terms of both generalization abilities and computational complexity. The latter attribute becomes critical as polarity predictors, in the era of social networks, might need to be updated within hours or even minutes. In this regard, the paper gives practical hints on the advantages and disadvantages of the examined architectures both in terms of generalization and computational cost. Full article
(This article belongs to the Section Artificial Intelligence)
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Open AccessArticle
Development of a Punch-O-Meter for Sport Karate Training
Electronics 2019, 8(7), 782; https://doi.org/10.3390/electronics8070782
Received: 30 May 2019 / Revised: 8 July 2019 / Accepted: 9 July 2019 / Published: 12 July 2019
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Abstract
In karate sparring (kumite), punches are used more than kicks to score points. Among these punches, gyaku tsuki is a very commonly used punch. The objective of the punch is to hit the target at a medium range in a very [...] Read more.
In karate sparring (kumite), punches are used more than kicks to score points. Among these punches, gyaku tsuki is a very commonly used punch. The objective of the punch is to hit the target at a medium range in a very short time, producing a maximum force. In this study, we proposed the development of a novel standalone Punch-O-Meter system to measure the speed and the force generated by a punch. Full article
(This article belongs to the Section Computer Science & Engineering)
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Open AccessCommunication
Fast Telemetry and Communication Scheme Based on Doppler Diversity Reception under Large Dynamic Doppler for Hypersonic Vehicles
Electronics 2019, 8(7), 781; https://doi.org/10.3390/electronics8070781
Received: 13 June 2019 / Revised: 6 July 2019 / Accepted: 8 July 2019 / Published: 12 July 2019
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Abstract
Large dynamic Doppler caused by high-speed flight of hypersonic vehicles brings a great challenge to acquisition, tracking and correct demodulation of telemetry and communication signals. Different from receiving schemes of existing telemetry and communications, a novel communication method based on Doppler diversity reception [...] Read more.
Large dynamic Doppler caused by high-speed flight of hypersonic vehicles brings a great challenge to acquisition, tracking and correct demodulation of telemetry and communication signals. Different from receiving schemes of existing telemetry and communications, a novel communication method based on Doppler diversity reception for hypersonic vehicles was proposed in this study. Firstly, the proposed method offers a coarse acquisition of Doppler frequency offset and its rate-of-change by fast-coarse acquisition method, and then decreases the large Doppler frequency offset into a certain range through compensation. Finally, signals with residual Doppler frequency offset are processed directly by Doppler diversity reception method without a complicated tracing method. Different from the traditional receiving scheme with acquisition and tracking module, the proposed scheme lowers requirements on acquisition accuracy and neglects the accurate tracking module, thus shortening telemetry and communication time significantly for hypersonic vehicles. Simulation results demonstrate that the proposed method can achieve satisfactory performance when the residual Doppler is no higher than 1 kHz with normalized Doppler frequency offset and when the normalized artificial frequency shift is 0.01 and 0.4 respectively. Full article
(This article belongs to the Section Microwave and Wireless Communications)
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Open AccessArticle
Pedestrian Detection with Lidar Point Clouds Based on Single Template Matching
Electronics 2019, 8(7), 780; https://doi.org/10.3390/electronics8070780
Received: 7 June 2019 / Revised: 5 July 2019 / Accepted: 8 July 2019 / Published: 11 July 2019
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Abstract
In the field of intelligent transportation systems, pedestrian detection has become a problem that is urgently in need of a solution. Effective pedestrian detection reduces accidents and protects pedestrians from injuries. A pedestrian-detection algorithm, namely, single template matching with kernel density estimation clustering [...] Read more.
In the field of intelligent transportation systems, pedestrian detection has become a problem that is urgently in need of a solution. Effective pedestrian detection reduces accidents and protects pedestrians from injuries. A pedestrian-detection algorithm, namely, single template matching with kernel density estimation clustering (STM-KDE), is proposed in this paper. First, the KDE-based clustering method is utilized to extract candidate pedestrians in point clouds. Next, the coordinates of the point clouds are transformed into the pedestrians’ local coordinate system and projection images are generated. Locally adaptive regression kernel features are extracted from the projection image and matched with the template features by using cosine similarity, based on which pedestrians are distinguished from other columnar objects. Finally, comparative experiments using KITTI datasets are conducted to verify pedestrian-detection performance. Compared with the STM with radially bounded nearest neighbor (STM-RBNN) algorithm and the KDE-based pedestrian-detection algorithm, the proposed algorithm can segment gathering pedestrians and distinguish them from other columnar objects in real scenarios. Full article
(This article belongs to the Section Electrical and Autonomous Vehicles)
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Open AccessArticle
Analysis of Counting Bloom Filters Used for Count Thresholding
Electronics 2019, 8(7), 779; https://doi.org/10.3390/electronics8070779
Received: 7 June 2019 / Revised: 7 July 2019 / Accepted: 9 July 2019 / Published: 11 July 2019
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Abstract
A bloom filter is an extremely useful tool applicable to various fields of electronics and computers; it enables highly efficient search of extremely large data sets with no false negatives but a possibly small number of false positives. A counting bloom filter is [...] Read more.
A bloom filter is an extremely useful tool applicable to various fields of electronics and computers; it enables highly efficient search of extremely large data sets with no false negatives but a possibly small number of false positives. A counting bloom filter is a variant of a bloom filter that is typically used to permit deletions as well as additions of elements to a target data set. However, it is also sometimes useful to use a counting bloom filter as an approximate counting mechanism that can be used, for example, to determine when a specific web page has been referenced more than a specific number of times or when a memory address is a “hot” address. This paper derives, for the first time, highly accurate approximate false positive probabilities and optimal numbers of hash functions for counting bloom filters used in count thresholding applications. The analysis is confirmed by comparisons to existing theoretical results, which show an error, with respect to exact analysis, of less than 0.48% for typical parameter values. Full article
(This article belongs to the Section Computer Science & Engineering)
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