Search results for "Volt"
showing 10 items of 2187 documents
Readout of the UFFO Slewing Mirror Telescope to detect UV/optical photons from Gamma-Ray Bursts
2013
The Slewing Mirror Telescope (SMT) was proposed for rapid response to prompt UV/optical photons from Gamma-Ray Bursts (GRBs). The SMT is a key component of the Ultra-Fast Flash Observatory (UFFO)-pathfinder, which will be launched aboard the Lomonosov spacecraft at the end of 2013. The SMT utilizes a motorized mirror that slews rapidly forward to its target within a second after triggering by an X-ray coded mask camera, which makes unnecessary a reorientation of the entire spacecraft. Subsequent measurement of the UV/optical is accomplished by a 10 cm aperture Ritchey-Chretien telescope and the focal plane detector of Intensified Charge-Coupled Device (ICCD). The ICCD is sensitive to UV/opt…
Cooper-pair resonances and subgap Coulomb blockade in a superconducting single-electron transistor
2003
We have fabricated and measured superconducting single-electron transistors with Al leads and Nb islands. At bias voltages below the gap of Nb we observe clear signatures of resonant tunneling of Cooper pairs, and of Coulomb blockade of the subgap currents due to linewidth broadening of the energy levels in the superconducting density of states of Nb. The experimental results are in good agreement with numerical simulations.
Observation of thermally excited charge transport modes in a superconducting single-electron transistor
1997
Experiments on a superconducting single-electron transistor are reported. A new structure in the current-voltage characteristics at subgap voltages was observed when temperature was not too low as compared to the superconducting transition temperature Tc of the sample. The strength of the anomalies increases exponentially with temperature. The dominating features arise from matching of singularities in the density of states on two sides of a tunnel junction, and from the Josephson-quasiparticle cycle. Thermal excitations are essential for the former process, and they also make the latter process possible at low voltages.
Performances of a three-phase five-level cascaded H-bridge inverter with phase shifted B-spline based modulation techniques
2017
This paper presents a novel study of the performances of a five-level three-phase Cascaded H-Bridge Multilevel Inverter with Phase Shifted B-Spline based modulation techniques. The study has been focused on the use of B-Spline functions as carrier signals in order to evaluate the performances of the converter in terms of harmonic content on the output voltage. In the first step of this analysis the THD% has been taken into account to compare the voltage waveforms. Interesting results have been found on the fundamental amplitude of the phase and line voltage. Moreover, harmonic spectra has been compared to evaluate the different harmonic distribution in the voltage waveforms. In this work th…
Harmonic reduction in CHB 13-level inverters by PAM fundamental-frequency strategy
2019
In this paper cascaded H-bridges (CHB) 13-level inverters are considered and a particular pulse amplitude modulation (PAM) strategy is introduced to mitigate or eliminate many harmonic components on the output voltage, in order to obtain low Total Harmonic Distortion (THD) factor. This procedure defines different dc voltage sources and sets of six switching angles, depending on an integer parameter $q$ belonging to the close interval $I=[11, 15]$ . The obtained THD doesn't depend on modulation index $m$ . The control of $m$ is made by changing the dc voltage sources that depend linearly on m, while the switching angles remain constant. An investigation about the role of the $q$ parameter on…
Numerical investigation of one‐dimensional tunnel junction arrays at temperatures above the Coulomb blockade regime
1996
Arrays of tunnel junctions provide simple thermometric parameters in the limit where thermal excitations dominate over charging effects. We present numerical simulations for calculating the current versus voltage characteristics of an arbitrary one‐dimensional array at arbitrary temperatures on the premise of the ‘‘orthodox theory.’’ The purpose of the computer simulations is to investigate the suitability of tunnel junction arrays for thermometry at low temperatures when the analytical formulas do not hold and, specifically, to see the effect of background charges in this regime.
Full Wave Solution for Intel CPU With a Heat Sink for EMC Investigations
2010
A CPU with a heat sink (e.g. Intel Pentium 4 and Intel Pentium dual core) is a challenging problem for EMC analysis. A Very Large Scale Integrated (VLSI) device was modelled using the Finite Element Method (FEM) frequency domain solver to obtain a 3D full wave solution. The electromagnetic (EM) radiation emitted from these high power microelectronic circuits connected to a heat sink was found to have resonant frequencies around 2.4 GHz and 5 GHz with reflection coefficients less than -19 dB and -8 dB respectively. These resonant frequencies are very close to the operating frequency of both IEEE and Bluetooth wireless communication systems. This paper proposes a new benchmark model based on …
Charge measurement of dust particles on photovoltaic module
2013
Photovoltaic (PV) systems are one of the most promising renewable energy sources in the world, and hence it is important to explore the factors that affect the working / operational efficiency of this source. Many factors can affect the efficiency of the solar cells such as: dust accumulation on the surface of the arrays; cell material; shading; tilt angle of the cells; orientation of the PV modules and cell temperatures. This research is focused on the analyzing the effect of charged dust particles on the PV module performance. A number of studies have demonstrated the effect of dust accumulation on the PV modules' performance. But the relation between the amounts of charge of the dust par…
THE LIMITING EFFICIENCY OF FOUR-BAND CELLS REVISITED
2014
The limiting theoretical efficiency of four-band solar cells is revisited. In previous work, researchers have looked at the theoretical efficiency of four band cells where the smallest of the three sub-band gaps is closest to the valence band and the largest closest to the conduction band. In this work, limits are calculated also for other possible band configurations. In multi-band cells, photon selectivity can be assured by adjusting the band widths. The present work shows that previous authors have put too rigid constraints on the band structure to achieve spectral selectivity. Relieving these constraints gives a considerably higher limiting efficiency for cells with band width restricti…
Gap solitons in nonlinear electrical transmission lines
2005
We study theoretically and numerically the properties of monochromatic waves in a nonlinear electrical transmission line,whose capacitance has a periodic spatial variation.ln the continuum limit and weak amplitude limit we reduce the characteristic equations of this system to NLS equation. We find analytical solutions for the voltage envelope, which propagate with frequency in the gap induced by the capacitance periodicity. Our numerical experiments show that, when the input voltage increases, the transmissivity in the gap increases and the voltage envelope approaches the stationnary shape predicted by theory.