10,135 research outputs found
Driven Intrinsic Localized Modes in a Coupled Pendulum Array
Intrinsic localized modes (ILMs), also called discrete breathers, are
directly generated via modulational instability in an array of coupled
pendulums. These ILMs can be stabilized over a range of driver frequencies and
amplitudes. They are characterized by a pi-phase difference between their
center and wings. At higher driver frequencies, these ILMs are observed to
disintegrate via a pulsating instability, and the mechanism of this breather
instability is investigated.Comment: 5 pages, 6 figure
Fabrication of antenna-coupled KID array for Cosmic Microwave Background detection
Kinetic Inductance Detectors (KIDs) have become an attractive alternative to
traditional bolometers in the sub-mm and mm observing community due to their
innate frequency multiplexing capabilities and simple lithographic processes.
These advantages make KIDs a viable option for the detectors
needed for the upcoming Cosmic Microwave Background - Stage 4 (CMB-S4)
experiment. We have fabricated antenna-coupled MKID array in the 150GHz band
optimized for CMB detection. Our design uses a twin slot antenna coupled to
inverted microstrip made from a superconducting Nb/Al bilayer and SiN,
which is then coupled to an Al KID grown on high resistivity Si. We present the
fabrication process and measurements of SiN microstrip resonators.Comment: 7 pages, 9 figures, submitted to Journal of Low Temperature Physic
Systematic study of proton-neutron pairing correlations in the nuclear shell model
A shell-model study of proton-neutron pairing in shell nuclei using a
parametrized hamiltonian that includes deformation and spin-orbit effects as
well as isoscalar and isovector pairing is reported. By working in a
shell-model framework we are able to assess the role of the various modes of
proton-neutron pairing in the presence of nuclear deformation without violating
symmetries. Results are presented for Ti, Ti, Ti, V
and Cr to assess how proton-neutron pair correlations emerge under
different scenarios. We also study how the presence of a one-body spin-obit
interaction affects the contribution of the various pairing modes.Comment: 12 pages, 16 figure
Exchange bias effect and intragranular magnetoresistance in Nd$_{0.84}Sr_{0.16}CoO_3
Electrical transport properties as a function of magnetic field and time have
been investigated in polycrystalline, Nd_{0.84}Sr_{0.16}CoO_3. A strong
exchange bias (EB) effect is observed associated with the fairly large
intragranular magnetoresistance (MR). The EB effect observed in the MR curve is
compared with the EB effect manifested in magnetic hysteresis loop. Training
effect, described as the decrease of EB effect when the sample is successively
field-cycled at a particular temperature, has been observed in the shift of the
MR curve. Training effect could be analysed by the successful models. The EB
effect, MR and a considerable time dependence in MR are attributed to the
intrinsic nanostructure giving rise to the varieties of magnetic interfaces in
the grain interior
In-situ integrated processing and characterization of thin films of high temperature superconductors, dielectrics and semiconductors by MOCVD
In this strategy of depositing the basic building blocks of superconductors, semiconductors, and dielectric having common elements, researchers deposited superconducting films of Y-Ba-Cu-O, semiconductor films of Cu2O, and dielectric films of BaF2 and Y2O3 by metal oxide chemical vapor deposition (MOCVD). By switching source materials entering the chamber, and by using direct writting capability, complex device structures like three-terminal hybrid semiconductors/superconductors transistors can be fabricated. The Y-Ba-Cu-O superconducting thin films on BaF2/YSZ substrates show a T(sub c) of 80 K and are textured with most of the grains having their c-axis or a-axis perpendicular to the substrate. Electrical characteristics as well as structural characteristics of superconductors and related materials obtained by x-ray defraction, electron microscopy, and energy dispersive x-ray analysis are discussed
In-situ integrated processing and characterization of thin films of high temperature superconductors, dielectrics and semiconductors by MOCVD
In this strategy of depositing the basic building blocks of superconductors, semiconductors, and dielectrics having common elements, researchers deposited superconducting films of Y-Ba-Cu-O, semiconductor films of Cu2O, and dielectric films of BaF2 and Y2O3 by metal oxide chemical vapor deposition (MOCVD). By switching source materials entering the chamber, and by using direct writing capability, complex device structures like three terminal hybrid semiconductor/superconductor transistors can be fabricated. The Y-Ba-Cu-O superconducting thin films on BaF2/YSZ substrates show a T(sub c) of 80 K and are textured with most of the grains having their c-axis or a-axis perpendicular to the substrate. Electrical characteristics as well as structural characteristics of superconductors and related materials obtained by x-ray deffraction, electron microscopy, and energy dispersive x-ray analysis are discussed
On the optical properties of Ag^{+15} ion-beam irradiated TiO_{2} and SnO_{2} thin films
The effects of 200-MeV Ag^{+15} ion irradiation on the optical properties of
TiO_{2} and SnO_{2} thin films prepared by using the RF magnetron sputtering
technique were investigated. These films were characterized by using UV-vis
spectroscopy, and with increasing irradiation fluence, the transmittance for
the TiO_{2} films was observed to increase systematically while that for
SnO_{2} was observed to decrease. Absorption spectra of the irradiated samples
showed minor changes in the indirect bandgap from 3.44 to 3.59 eV with
increasing irradiation fluence for TiO_{2} while significant changes in the
direct bandgap from 3.92 to 3.6 eV were observed for SnO_{2}. The observed
modifications in the optical properties of both the TiO_{2} and the SnO_{2}
systems with irradiation can be attributed to controlled structural
disorder/defects in the system.Comment: 6 pages, ICAMD-201
Arduino based Dual Axis Smart Solar Tracker
Solar energy is rapidly advancing as an important means of renewable energy resource. It is radiant light and heat from the Sun that is harnessed using a range of ever-evolving technologies such as solar heating, photovoltaic, solar thermal energy, solar architecture, molten salt power plants and artificial photosynthesis. Trackers direct solar panels or modules toward the sun. These devices change their orientation throughout the day to follow the sun's path to maximize energy capture. The use of solar trackers can increase electricity production by around a third, and some claim by as much as 40% in some regions, compared with modules at a fixed angle. In any solar application, the conversion efficiency is improved when the modules are continually adjusted to the optimum angle as the sun traverses the sky. This paper presents the designing of a solar tracking system which is based on Arduino UNO and which provides movement of solar panel in the direction of maximum sun light incident. As a result of which we get more efficient system which is compact, low cost as well as easy to use
A Compact Millimeter-Wavelength Fourier-Transform Spectrometer
We have constructed a Fourier-transform spectrometer (FTS) operating between
50 and 330 GHz with minimum volume (355 x260 x64 mm) and weight (13 lbs) while
maximizing optical throughput (100 sr) and optimizing the
spectral resolution (4 GHz). This FTS is designed as a polarizing
Martin-Puplett interferometer with unobstructed input and output in which both
input polarizations undergo interference. The instrument construction is simple
with mirrors milled on the box walls and one motorized stage as the single
moving element. We characterize the performance of the FTS, compare the
measurements to an optical simulation, and discuss features that relate to
details of the FTS design. The simulation is also used to determine the
tolerance of optical alignments for the required specifications. We detail the
FTS mechanical design and provide the control software as well as the analysis
code online.Comment: Submitted to Applied Optics. [Copyright 2019 Optical Society of
America]. Users may use, reuse, and build upon the article, or use the
article for text or data mining, so long as such uses are for non-commercial
purposes and appropriate attribution is maintained. All other rights are
reserve
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