Cognitive radio is a viable technology for the next generation of wireless communications. The ability to sense the electromagnetic spectrum and to enable vacant bands to other users has been investigated in the past ...
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ISBN:
(纸本)9781479946037
Cognitive radio is a viable technology for the next generation of wireless communications. The ability to sense the electromagnetic spectrum and to enable vacant bands to other users has been investigated in the past years. One important issue is the use of an efficient spectrum sensing algorithm to monitor the frequency band occupancy. Usually, the effects of fading are overseen in the analysis of those algorithms. This paper aims to evaluate the performance of a spectrum sensing algorithm based on Jarque-Bera test. Rayleigh fading is considered in this paper. Preliminary simulation results are provided, to demonstrate the potential of the proposed strategy.
This paper investigates a power shunt filter composed by four standard h-bridge converters, acting in four-wire system. Compared with the usual four-wire shunt filters, the proposed converter permits reducing the dc-l...
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ISBN:
(纸本)9781479940318
This paper investigates a power shunt filter composed by four standard h-bridge converters, acting in four-wire system. Compared with the usual four-wire shunt filters, the proposed converter permits reducing the dc-link voltages, the harmonic distortion or the switching frequency. Suitable control strategies to adjust the filter currents as well as the three dc-link voltages are presented. The PWM strategy is designed to command the converter according to the reference voltage provided by the controllers. Simulation and experimental results are presented.
This paper shows the use of PBL (Problem-Based Learning) technique as a key to learning VoIP in courses like electricalengineering and computer Networks in conjunction with open source and the public domain software ...
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ISBN:
(纸本)9789897580215
This paper shows the use of PBL (Problem-Based Learning) technique as a key to learning VoIP in courses like electricalengineering and computer Networks in conjunction with open source and the public domain software called Asterisk which was used to create the scenario of the experiment and the problems presented to the students. In order to make the validation, the experiment was applied to students of Bachelor in electricalengineering and in Communication Technology System, undergraduate courses at the Federal Institute of Education, science and Technology of Paraíba - IFPB, in the Telephony subject, with promising results. The Asterisk software was presented as a useful and flexible tool for constructing scenarios and problems for the teaching of VoIP technologies and the used approach resulted as effective for improving the attainment of the defined learning objectives.
This paper presents a single-phase AC-AC converter based on Modular Multilevel Cascade Converter (MMCC) with Double-Star Chopper-Cells (DSCC). This structure is composed by three DSCC-legs, the middle leg is shared, a...
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This paper presents a single-phase AC-AC converter based on Modular Multilevel Cascade Converter (MMCC) with Double-Star Chopper-Cells (DSCC). This structure is composed by three DSCC-legs, the middle leg is shared, and also it does not present a common DC-link capacitor. It is suitable for regenerative low-power AC-AC conversion. The voltage-balancing control is presented to regulate the floating DC capacitor voltages. Furthermore, a grid current and terminal load voltage control is presented to correct the Power Factor (PF) and to ensure sinusoidal waveforms. Details about a designed 16-SM prototype are also presented. The experimental results allow validating the control strategies and the effectiveness of the proposed structure.
In this paper, three unidirectional single-phase rectifiers are proposed. Each converter is composed of two non-controlled legs and two controlled legs. Modelling and control strategy of the system, including a synchr...
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ISBN:
(纸本)9781479940318
In this paper, three unidirectional single-phase rectifiers are proposed. Each converter is composed of two non-controlled legs and two controlled legs. Modelling and control strategy of the system, including a synchronization method, are proposed. In the synchronization method, the grid current is synchronized with the generated voltage ensuring a sinusoidal grid current without zero-crossover distortions. Analysis of harmonic distortion and semiconductor losses are presented. Simulation and experimental results are shown for validation purposes.
In this paper the characteristics radiation of overhead power lines glass insulators is investigated. Two feeding possibilities are used to analyze the radiation effects. The first feeding point is placed on the cap o...
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In this paper the characteristics radiation of overhead power lines glass insulators is investigated. Two feeding possibilities are used to analyze the radiation effects. The first feeding point is placed on the cap of the insulator and the second one is connected to the pin. The reflection coefficient (S 11 ) for two insulators covering the band of 30 MHz to 1 GHz was measured. The measurements were performed on insulators with different conservation states: one has a metal frame in good condition and the other one has both cap and pin parts rusted. The measured results show bands with good impedance matching (30 MHz to 200 MHz). The cleaned insulator reached S 11 = -18.7 dB at 127 MHz while -10.87 dB at 121.2 MHz was obtained for the rusty insulator. These spectral bands can be used in the analysis of insulator's conservation state and its interference characteristics.
This paper presents a comparison between two different technologies of acquisition systems (BrainNet36 and Emotiv Epoc) for an Independent-BCI based on Steady-State Visual Evoked Potential (SSVEP). Two stimuli separat...
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This paper presents a comparison between two different technologies of acquisition systems (BrainNet36 and Emotiv Epoc) for an Independent-BCI based on Steady-State Visual Evoked Potential (SSVEP). Two stimuli separated by a viewing angle
This paper presents the evaluation of seven techniques of feature extraction (PSD, F-Test, EMD, MCE, CCA, LASSO and MSI) for gaze-target detections in a SSVEP-based BCI. Two type of technologies for visual stimulation...
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This paper presents the evaluation of seven techniques of feature extraction (PSD, F-Test, EMD, MCE, CCA, LASSO and MSI) for gaze-target detections in a SSVEP-based BCI. Two type of technologies for visual stimulation were used (LCD and LEDs). Five differents windows lengths (1, 2, 4, 5 and 10 s) were used and seven volunteers participated in this study. The highest accuracy obtained in all cases was 93.57% using LEDs and the highest ITR was 36.90 bits/min for LCD. The technique based on MSI shows the highest success rate in both cases (LCD or LED) and is even more noticeable when the window size is increased.
This paper presents the comparation of three different feature extraction techniques based on the Empirical Mode Decomposition (EMD) for a SSVEP-BCI. This approach based on the characterization of the signal by EMD, i...
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ISBN:
(纸本)9781479924004
This paper presents the comparation of three different feature extraction techniques based on the Empirical Mode Decomposition (EMD) for a SSVEP-BCI. This approach based on the characterization of the signal by EMD, is proposed as a novel alternative to other techniques and it was demonstrated that it exceeds both in accuracy rate and Information Transfer Rate (ITR). The experiments were performed in an offline way, and seven volunteers participated of the study. The stimulis were generated both by LCD and LEDs. The frequencies used were 8, 11, 13 and 15 Hz. The results here reported such represent the average of the seven participants, achieving a success rate of 81% and ITR of 23.32 bits/min of the total set of cases analyzed. It is further confirmed that the highest success rates and ITRs were obtained for stimulation by LEDs.
This paper presents an AC drive system based on six-phase machine with three neutrals. The machine side converter has nine power legs and can be connected to the grid through one single DC-link or three isolated DC-li...
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This paper presents an AC drive system based on six-phase machine with three neutrals. The machine side converter has nine power legs and can be connected to the grid through one single DC-link or three isolated DC-links. Compared with the conventional back-to-back AC six-phase machine drive system, the proposed drive system permits reducing the DC-link voltages, eliminating step-up transformer, and the voltage at the grid side converter has higher amplitude than that of the machine side, reducing the transmission I 2 R losses. The system model and PWM strategy are presented and experimental results demonstrate the feasibility of the system.
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