Search results for "Modula"
showing 10 items of 1481 documents
Modulador acusto-óptico en amplitud de fibra óptica basado en ondas acústicas de flexión
2014
Se reporta un estudio experimental de la operación de un modulador acusto-óptico (MAO) de fibra óptica basado en la interacción acusto-óptica producida por ondas acústicas de flexión estacionarias. Concentramos nuestra atención en los efectos de reducir el diámetro en la fibra óptica como mecanismo para optimizar la respuesta espectral del MAO. Como caso particular reportamos un modulador de 70 ¹m de diametro con una alta profundidad de modulación (60 %), bajas perdidas por inserción (1.3 dB) y un ancho ancho de banda a 3 dB de 40 nm que opera en el rango de los megahertz. Los resultados obtenidos demuestran que el incluir fibras estrechadas se puede considerar como un grado extra de libert…
Novel multipactor studies in RF satellite payloads: Single-carrier digital modulated signals and ferrite materials
2017
In this work it is reviewed the most novel advances in the multipactor RF breakdown risk assessment devoted to RF satellite microwave passive devices employed in space telecommunication systems. On one side, it is studied the effect of transmitting a single-carrier digital modulated signal in the multipactor RF voltage threshold in a coaxial line. On the other hand, an analysis of the multipactor phenomenon in a parallel-plate waveguide containing a magnetized ferrite slab it is presented.
Contributed Review: Review of thermal methods for space charge measurement.
2016
The space charge accumulation phenomenon has garnered great interest over the last two decades because of the increased use of direct current in high voltage electrical systems. In this context, a significant relevance has been achieved by the thermal methods, used for solid dielectrics. This paper presents a review of this non-destructive measurement system used for the measurement of space charge. The thermal pulse method, the thermal step method, and the laser intensity modulation method are described. For each configuration, the principle of operation, the thicknesses analyzed, and the spatial resolution are described, reporting also the main related applications
Comparison of Single Event Transients Generated at Four Pulsed-Laser Test Facilities-NRL, IMS, EADS, JPL
2012
Four pulsed-laser single-event effects systems, differing in wavelength and pulse width, were used to generate single event transients in a large-area silicon photodiode and an operational amplifier (LM124) to determine how transient amplitude and charge collection varied among the different systems. The optical wavelength and the focused spot size are the primary factors influencing the resultant charge density profile. In the large-area photodiode the transients can be distorted by high charge-injection densities that occur for tightly focused, higher energy optical pulses. When the incident laser-pulse energies are corrected for reflection losses and photon efficiency, with collection de…
Experimental Investigation of Efficiency Map for an Inverter-Fed Surface-Mount Permanent Magnet Synchronous Motor
2019
Losses in inverter-fed permanent magnet motors are underestimated by using analytical or numerical approach since additional losses due to extra harmonics of the frequency converter are normally skipped. Further, losses in switches and passive components of the converter and the effect of switching frequencies cannot be numerically taken into consideration. Loss-minimizing control and proper efficiency analysis of inverter-fed permanent magnet motors cannot be achieved if an efficiency map is built based on a numerical investigation of the motors alone. This works first reviews losses in a surface-mount permanent magnet synchronous motor (SPMSM) and frequency converters. The efficiency map …
Description of intermodulation generation of nonlinear responses beyond the validity of the power series expansion
2021
Weakly nonlinear responses are commonly described by a power series expansion. However, intermodulation distortion products that cannot be described by a power series have been observed in a variety of physical systems. As the power series description is only applicable within its radius of convergence, we choose an alternative approach based on Fourier coefficients to describe intermodulation levels beyond the convergence of the power series. The description over a wide power range allows us to make a decision about models and to determine previously inaccessible model parameters. We apply the approach to data obtained from the characterization of the nonlinear dielectric susceptibility of…
High sensitivity characterization of the nonlinear electric susceptibility of a glass ceramic in the microwave range
2019
The nonlinear electric susceptibility of a glass ceramic is characterized in the microwave range by measuring intermodulation of two high-power signals. To achieve the necessary sensitivity for dielectric nonlinearities, the setup ensures that the measured intermodulation can be ascribed to the material under test while all other intermodulation sources are suppressed. This is achieved by coupling three dielectric resonators in a cut-off waveguide. The third order nonlinearity of the glass ceramic is found to be χ3/er = (1.6 ± 0.8) × 10−15 m2/V2 at 950 MHz. The magnitude is comparable to the previously measured high-end sintered ceramics. The power of the intermodulation signal as a functio…
Atmosphere-Space Interactions Monitor, Instrument and First Results
2019
The Atmosphere-Space Interaction Monitor (ASIM) is an observatory mounted outside the Columbus module on the International Space Station. It has been operational since April 13th, 2018. It contains two instruments: The Modular X- and Gamma-ray Sensor (MXGS) and The Modular Multispectral Imaging Array (MMIA). The objective of ASIM is to monitor thunderstorms and auroras, including lightning discharges, especially discharges upwards above thunderstorms. This paper presents the instrument package and some first results.
Hierarchical networks of food exchange in the black garden ant Lasius niger
2020
In most eusocial insects, the division of labour results in relatively few individuals foraging for the entire colony. Thus, the survival of the colony depends on its efficiency in meeting the nutritional needs of all its members. Here, we characterise the network topology of a eusocial insect to understand the role and centrality of each caste in this network during the process of food dissemination. We constructed trophallaxis networks from 34 food-exchange experiments in black garden ants (Lasius niger). We tested the influence of brood and colony size on (i) global indices at the network level (i.e. efficiency, resilience, centralisation and modularity) and (ii) individual values (i.e. …
Modularity as a source of new morphological variation in the mandible of hybrid mice.
2012
Abstract Background Hybridization is often seen as a process dampening phenotypic differences accumulated between diverging evolutionary units. For a complex trait comprising several relatively independent modules, hybridization may however simply generate new phenotypes, by combining into a new mosaic modules inherited from each parental groups and parts intermediate with respect to the parental groups. We tested this hypothesis by studying mandible size and shape in a set of first and second generation hybrids resulting from inbred wild-derived laboratory strains documenting two subspecies of house mice, Musmusculus domesticus and Musmusculus musculus. Phenotypic variation of the mandible…