Search results for "NETWORKING"
showing 10 items of 1776 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-…
Design approach for high efficiency NFC systems with magnetic shielding materials
2020
The performance of a Near Field Communication (NFC) antenna may be diminished when it is placed close to any conductive surface such as a metallic case or a battery. This degradation is caused due to the stray magnetic field created by the eddy currents induced on the surface, which is opposite to the intended field generated by the NFC antenna. One of the first solutions that come to mind to designers when facing this problem is the use of high permeability magnetic shielding based on sintered ferrite sheets. This is a good approach but something that is not generally taken into account is that these materials introduce an additional inductance to the NFC antenna. If the permeability of th…
Measurement of the surface resistivity and electrical conductivity of carbon nanotube sheets using the resonant post-method
2016
Abstract The dielectric post-resonant measurement method is extended to characterize the conduction properties of carbon nanotube sheets in the GHz frequency range ( 3 GHz f 20 GHz ) without the need for external contacts or the necessity of carbon coating. Three low-loss reference dielectrics ( TiO 2 , BaTi 4 O 9 , Teflon) with known dielectric properties are used. Conductivity values of various metals (steel, lead, brass, aluminium, copper) of the order 106–107 S/m were measured to show the suitability of the method. The electrical conductivity of the carbon nanotube sheets could be determined to approximately 1.7·105 S/m.
Spin-crossover complex encapsulation within a magnetic metal-organic framework.
2016
The solid-state incorporation of a mononuclear iron(III) complex within the pores of a magnetic 3D metal–organic framework (MOF) in a single crystal to single crystal process leads to the formation of a new hybrid material showing both a guest-dependent long-range magnetic ordering and a spin-crossover (SCO) behaviour.
Free spectral range enlargement by selective suppression of optical modes in photonic crystal L7 microcavities
2015
We show an enlargement in the free spectral range (FSR) of the emission spectra of a L7 photonic crystal microcavity (PCM). The FSR enlargement is achieved by the selective modal suppression of the second cavity mode. The selective suppression is made by introducing two nano-inclusions in specific sites within the defect region that forms the cavity. We have demonstrated the suppression of the second mode of the L7-PCM, and a significant increase in the FSR of the fundamental mode. The method provides an alternative to engineer the modal structure of a photonic crystal microcavity. The large FSR-value might improve the emission properties of light sources based on photonic crystal structure…
Transmission Attenuation Power Ratio Analysis of Flexible Electromagnetic Absorber Sheets Combined with a Metal Layer.
2018
Electromagnetic noise absorber sheets have become a solution for solving complex electromagnetic interference (EMI) problems due to their high magnetic losses. This contribution is focused on characterizing a novel structure that is based on an absorber film with a metal layer attached on its top side. Two different absorber compositions were combined with Al and Cu metal layers in order to study the improvement on the performance of these structures, depending on the complex permeability, absorber film thickness, and type of metal. The transmission attenuation power ratio of the absorber films is analyzed and compared to the performance of absorber and metal structures. The measurement pro…
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…
A new dynamic identification technique: application to the evaluation of the equivalent strut for infilled frames
2003
A new time domain identification technique for systems under Gaussian white noise input is presented, requiring for its application the measurement of the system response but no information about input intensity. The technique proposed is based on the statistic moment equations derived by using a special class of mathematical models named "potential models". These models allow one to determine fundamental properties of the response statistics, making it possible to identify stiffness and dissipation features of a structural system, and also to determine the excitation input. The technique proposed is here applied to the identification of the strut equivalent to the infill of a single story-…
Intelligent Multi-Start Methods
2018
Heuristic search procedures aimed at finding globally optimal solutions to hard combinatorial optimization problems usually require some type of diversification to overcome local optimality. One way to achieve diversification is to re-start the procedure from a new solution once a region has been explored, which constitutes a multi-start procedure. In this chapter we describe the best known multi-start methods for solving optimization problems. We also describe their connections with other metaheuristic methodologies. We propose classifying these methods in terms of their use of randomization, memory and degree of rebuild. We also present a computational comparison of these methods on solvi…
On Equivalent Random Traffic method extension
2011
The key result of the paper is the Equivalent Random Traffic (ERT) method extension for estimation of the throughput for schemes with traffic splitting. The excellent accuracy (relative error is less than 1%) is shown in numerical example. A numerical algorithm is given — how to estimate the throughput for schemes at traffic splitting and merging. The paper also contains new Erlang-B formula algorithm for non-integer number of channels based on parabolic approximation.