Search results for " Electrical & Electronic"
showing 10 items of 487 documents
Design of a 1 kW output power Folded Waveguide TWT operating in ka-band
2019
A Ka-band Serpentine Folded Waveguide Travelling Wave Tube (TWT) has been designed. The imposed design parameters values in terms of high power, high load, wide bandwidth, low weight, along with a structure manufactured with planar technique or by means of a micro milling process, have been obtained. Small signal simulations have been carried out with an in-house software for interaction impedance evaluation. The commercial electromagnetic simulation code CST Suite has been used for dispersion diagram prediction. An optimization of the one-dimensional software, normally used for large-signal simulation in coupled cavity TWTs (“Computer Program for Analysis of Coupled-cavity Travelling-wave-…
The Magnetic Properties of Electrical Pulses Delivered by Deep-Brain Stimulation Systems
2020
The aim of this article is to analyze the magnetic field properties for both the monopolar and bipolar electrode configurations of deep-brain stimulation electrodes using 3-D magnetic field measurements and to investigate if the magnetic measurements enable a localization of the electrode as a proof of concept. Therefore, a simplified head phantom with an integrated deep-brain stimulation electrode was created to measure the magnetic flux densities in all the three dimensions with a fluxgate magnetometer over a sensor trajectory of measuring points inside the magnetically shielded chamber. The magnitude of the magnetic flux density for monopolar stimulation and bipolar stimulation is in the…
Suppression of stimulated Raman scattering in optical fibres by power-controlled multifrequency pumping
1999
International audience; We present a method for suppressing the stimulated Raman scattering process induced by a multifrequency pump field propagating in a normally dispersive single-mode fibre. The suppression process is completely achieved by suitably choosing the frequency separation between the pumps, as well as the power distribution among the frequency components of the pump field. The experimental spectra show the effectiveness of this suppression process for a dual-frequency pumping configuration.
GigaHertz to TeraHertz Ultrashort Pulse Sources at 1555 nm
2006
We experimentally study the generation of ultrashort pulses through multiple four wave-mixing in optical fibers. Well-separated transform-limited Gaussian pulses are generated at repetition rates ranging from 20 GHz to 1 THz around 1555 nm.
Remote voltage synchronization for wireless Partial Discharge diagnostics
2016
The main objective of this paper is the assessment of the exact phase angle displacement of each Partial Discharge, PD, pulse with respect to the voltage reference waveform. Such problem also referred to as ‘synchronization’ is relevant when the cable is not accessible and the PD measure is carried out in wireless mode. It is well known, that the angle phase shift, due to the propagation phenomenon on the transmission line, can be calculated knowing the line type and length and typical operating conditions of the transmission line. The setup comprises a customized electronic device, the “Phase check”, a server to collect remote measurements and a Look up table to provide corrections to the …
High frequency microwave signal generation using dual-wavelength emission of cascaded DFB fiber lasers with wavelength spacing tunability
2010
[EN] A dual wavelength fiber laser source based on two cascaded phase-shifted fiber Bragg gratings is presented The gratings are written in an erbium-doped fiber each configuring the cavity of a distributed feedback fiber laser The spacing between lasing modes is controlled dynamically by the use of piezoelectric actuators A continuous tuning range of 5-724 pm of the wavelength difference which is equivalent to a photodetected 072-92 GHz range is obtained Efficient generation from the L to the W microwave and millimeter bands has been achieved by heterodyne photodetection of the dual-wavelength optical signal (C) 2010 Elsevier BV All rights reserved
Non-linear inductor modelling for a DC/DC buck converter
2017
The paper is focused on the modelling of an inductor to exploit its non-linear behaviour in the roll-off region when it is employed in a DC/DC converter. The model is set up on the basis of experimental data measured in operating conditions, which are fitted to a polynomial curve describing the inductance variations. The analysis of the buck converter, performed by including the proposed model, is validated by experimental tests.
Feedback Biasing Based Adjustable Gain Ultrasound Preamplifier for CMUTs in 45nm CMOS
2018
As CMOS technology is scaled down, supply voltages are decreasing and intrinsic gain of the nanoscale CMOS transistors is dropping while the threshold voltages of transistors are remaining relatively constant. In such scaled down nanoscale CMOS technologies, conventional vertical stacking architectures (for example. cascode architectures) for high-gain becomes no more attractive. In this paper we present the analysis and design of a feedback biasing based adjustable gain ultrasound preamplifier which is capable of amplifying signals from 15 MHz to 45 MHz from Capacitive Micromachined Ultrasound Transducers (CMUTs) in 45nm CMOS technology for medical ultrasound imaging applications. From the…
Predictive dead time controller for GaN-based boost converters
2017
A dynamic dead time controller is presented, specifically intended to operate in synchronous boost converters based on GaN field-effect transistor switches. These transistors have a reduced stored charge with respect to silicon metal–oxide–semiconductor field-effect transistors with similar breakdown voltage and series resistance, and can operate at higher frequencies with reduced switching losses. On the other hand, the voltage drop in reverse conduction is typically more than doubled with respect to silicon devices resulting in relevant power losses during the free-wheeling phases. Therefore, dynamic control of dead time can be profitably applied even in converters operating in the tens o…
A Simplified Analytical Approach for Optimal Planning of Distributed Generation in Electrical Distribution Networks
2019
DG-integrated distribution system planning is an imperative issue since the installing of distributed generations (DGs) has many effects on the network operation characteristics, which might cause significant impacts on the system performance. One of the most important characteristics that mostly varies because of the installation of DG units is the power losses. The parameters affecting the value of the power losses are number, location, capacity, and power factor of the DG units. In this paper, a new analytical approach is proposed for optimally installing DGs to minimize power loss in distribution networks. Different parameters of DG are considered and evaluated in order to achieve a hig…