i-ETC : ISEL Academic Journal of Electronics Telecommunications and Computers
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54 research outputs found
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Automated reactive thermal evaporation system for transparent conductive coatings
Full text linkThis work presents fully automated plasma-enhanced reactive thermal evaporation system (rf-PERTE) that can be used for the deposition of transparent metal oxide films with high reproducibility of their electrical and optical properties. The developed hardware/software platform enables the full control over the critical deposition conditions such as mass flow of oxygen, process pressure, current flowing through crucible and rf-power. For indium oxide films on glass substrates a resistivity of 9×10-4 Ω-cm and a transmittance of 90% in the visible spectral range were achieved without substrate heating. The system is also suitable for the deposition of transparent conducting coatings in a wide range of plastic substrates, for applications in the field of flexible sensors or solar cells. In particular, we have successfully deposited indium oxide on PEN (polyethylene naphthalate) sheets with electrical and optical properties approaching the ones of the films deposited on glass substrates
Benchtop SS-OCT – layout and performance evaluation
Full text link Abstract1— Optical coherence tomography (OCT) is a non-invasive biomedical imaging technique that provides high speed and high resolution three dimensional and cross sectional images of biological samples, in vivo and in situ. OCT applications targeting small animals is believed to bring developments in medical techniques, instruments, diagnosis and therapies for a number of human diseases as always have been the case of animal experimentation. With the swept source OCT (SS-OCT) system presented in this work, we were able to achieve performance parameters that meet the requirements to image the retina of small animals. Performance characteristics include 105 dB for system sensitivity, a roll-off below 1 dB/mm over 3 mm depth and an axial resolution of 8 μm. We describe the layout and acquisition/processing solutions towards fast imaging of in vivo samples
Intelligent Sensors for Real-Time Hazard Detection and Visual Indication on Highways
Full text linkTraffic collisions, in particular high speed car accidents often result in huge damages, long traffic queues and loss of human lives. In this work we present an intelligent modular system that monitors traffic in highways and alerts drivers of sudden stops, in poor visual conditions. The system is composed of several identical modules, to be placed in the middle of a highway’s lane, that sense the lights and communicate their presence and velocity to their neighbor modules via RF. With such information, the nearby modules estimate the velocity of the passing cars. When the module ahead detects a car passing at a much slower speed than what was previously estimated, it alerts the other modules, so they produce a visual indication for the oncoming drivers, preventing accidents. The system operates autonomously using solar energy harvesting
EYE GAZE TRACKING SYSTEM FOR ADAPTED HUMAN-COMPUTER INTERFACE
No full textThis work describes the implementation of an eye gaze tracking system for a natural user interface, based only on non-intrusive devices, like Intel RealSense camera. Through image processing, the implemented system is able to convert face elements to the corresponding focus point on the computer screen. Tests show promising results
Automatic Acoustic Scene Classification
Full text linkThis paper presents a baseline system for automatic acoustic scene classification based on the audio signals alone. The proposed method is derived from classic, content-based, music classification approaches, and consists in a feature extraction phase followed by two dimensionality reduction steps (PCA and LDA) and a classification phase done using a k nearest-neighbors algorithm.This paper also reports on how our system performed in the context of the DCASE 2016 challenge, for the acoustic scene classification task
Project Wireless Sensor Network Architecture for Tunnel Monitoring
Full text linkAbstract: This paper presents an architecture for wireless sensor networks (WSN) operating in the 2.4GHz RF band for implementation in environments of small tunnels. The study begins with an objective description of the RF architecture and with the implementation of a RSSI analysis in real scenarios. The designed modules are using directional and omnidirectional antennas for each test scenario. In initial experiment is included a test on the 433Mhz band. The developed WSN architecture provides a higher degree of reliability at environments with denser structures (tunnels) and enables the use of directional and omnidirectional antennas for better signal behavior considering the structure of environment to propagation
DEMUX OPERATION IN TANDEM AMORPHOUS SI-C DEVICES A two stage active circuit
Full text linkCharacteristics of tunable wavelength filters based on a-SiC:H multilayered stacked cells are studied both theoretically and experimentally. Curves of gain vs. wavelength illustrate the optical filter characteristics. A capacitive active band-pass filter model supports experimental data. Results show that the use of a double pi’n/pin a-SiC:H heterostructure as active capacitive filters depends on the wavelength and modulated frequency of the trigger light and on the wavelength of the additional optical bias. The devices combine three indispensable functions of transceivers, amplification, detection and wavelength filtering. Experimental and simulated results show the device combines the properties of active short-pass and long-pass filter sections into a capacitive active band-pass filter
MULTI-STAGE MIXED FREQUENCY-TIME SIMULATOR FOR BANDPASS SAMPLING RECEIVER FRONT-ENDS
Full text linkThis paper address the implementation of a mixed-domain simulator for first-order band-pass sampling receivers, which is based on an initial frequency-domain signal treatment followed by a time-domain simulation scheme. One of the proposed applications for this type of receivers is to perform the spectrum sensing feature, which is required in actual and future cognitive radio approaches. Some details about the multi-stage modelling strategy will be given focusing in each specific component of the receiver, wherein it is considered a mixed frequency-time signal treatment. Moreover, it will be summarized the main features of the implemented simulator, as well as potential improvements. Finally, several simulation examples obtained with the implemented simulator will be shown, in which are included the impact of a CW signal excitation in a received modulated signal and a multi-carrier signal reception scenario
Design Methologies for Integrated Inductor-Based Soft-Switching DC DC Converters
Full text linkThis paper presents a study on resonant converter topologies targeted for CMOS integration. Design methodologies to optimize efficiency for the integration of Quasi-Resonant and Quasi-Square-Wave converters are proposed. A power loss model is used to optimize the design parameters of the power stage, including the driver circuits, and also to conclude about CMOS technology limitations. Based on this discussion, and taking as reference a 0.35μm CMOS process, two converters are designed to validate the proposal: a Quasi Resonant boost converter operating at 100MHz and a Quasi-Square-Wave buck converter operating at 70MHz. Simulation results confirm the feasibility of these topologies for monolithic integration
SIMULATING LONG TERM EVOLUTION SELF-OPTIMIZING BASED NETWORKS
Full text linkWith the first 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) networks being deployed more complexity is added to current existing cellular mobile networks and more capital (CAPEX) and operational (OPEX) effort will be needed. In addition, the rising demand of users for new services and higher data rates demands more efficiency from operators. For this matter, 3GPP Release 8 as introduced the Self-Organizing Network (SON) concept, a set of self-configuration, self-optimizing and self-healing functions that allow the automation of labor-intensive tasks, reducing operational and capital costs. While requirements on cutting operational expenditure remain, operators still remain skeptical with the efficiency of these functions. In this paper, Physical Cell Identity (PCI) conflict detection and resolution, Automatic Neighbor Relation (ANR) and automatic Handover Parameter Optimization (HPO) functions are proposed as part of a simulator for LTE SON based networks. Based on user defined inputs, these functions allow operators to closely predict and gather optimal policy input values for SON algorithms, while maintaining desirable network performance. Based on a real network scenario, results show simulator’s clear benefit when compared with other proposals