3,121 research outputs found
Introduction on atomic layer deposition for high-k dielectric & high mobility oxide semiconductor thin film transistors
Amorphous oxide semiconductors have been widely studied for the potential use in flat panel displays such as active matrix liquid crystal display (LCD) and Organic light emitting diodes (OLEDs). Since reporting amorphous InGaZnO semiconductor thin film transistor (TFT) in 2003 & 2004, many multi-component oxide semiconductors have been intensively investigated and developed by reactive sputtering method. Very recently, the sputtered InGaZnO TFTs are already adopted in mass-production to fabricate AMOLED TVs. However, there remain several problems such as high mobility & stability issues. Also, virtual and argument reality (VR, AR) applications are rapidly emerging in display markets but the main issues are high resolution and low-voltage driving technologies.
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To the Edge of M87 and Beyond: Spectroscopy of Intracluster Globular Clusters and Ultra Compact Dwarfs in the Virgo Cluster
We present the results from a wide-field spectroscopic survey of globular
clusters (GCs) in the Virgo Cluster. We obtain spectra for 201 GCs and 55
ultracompact dwarfs (UCDs) using the Hectospec on the Multiple Mirror
Telescope, and derive their radial velocities. We identify 46 genuine
intracluster GCs (IGCs), not associated with any Virgo galaxies, using the 3D
GMM test on the spatial and radial velocity distribution.They are located at
the projected distance 200 kpc R 500 kpc from the center
of M87. The radial velocity distribution of these IGCs shows two peaks, one at
= 1023 km s associated with the Virgo main body, and another
at = 36 km s associated with the infalling structure. The
velocity dispersion of the IGCs in the Virgo main body is 314 km s, which is smoothly connected to the velocity dispersion
profile of M87 GCs, but much lower than that of dwarf galaxies in the same
survey field, 608 km s. The UCDs are more
centrally concentrated on massive galaxies, M87, M86, and M84. The radial
velocity dispersion of the UCD system is much smaller than that of dwarf
galaxies. Our results confirm the large-scale distribution of Virgo IGCs
indicated by previous photometric surveys. The color distribution of the
confirmed IGCs shows a bimodality similar to that of M87 GCs. This indicates
that most IGCs are stripped off from dwarf galaxies and some from massive
galaxies in the Virgo.Comment: 19 pages, 20 figures, 8 tables, accepted for publication in Ap
Tomographic Alcock-Paczynski Test with Redshift-Space Correlation Function: Evidence for the Dark Energy Equation of State Parameter w>-1
The apparent shape of galaxy clustering depends on the adopted cosmology used
to convert observed redshift to comoving distance, the relation, as it
changes the line elements along and across the line of sight differently. The
Alcock-Paczy\'nski (AP) test exploits this property to constrain the expansion
history of the universe. We present an extensive review of past studies on the
AP test. We adopt an extended AP test method introduced by Park et al. (2019),
which uses the full shape of redshift-space two-point correlation function (CF)
as the standard shape, and apply it to the SDSS DR7, BOSS, and eBOSS LRG
samples covering the redshift range up to .We calibrate the test against
the nonlinear cosmology-dependent systematic evolution of the CF shape using
the Multiverse simulations. We focus on examining whether or not the flat
CDM `concordance' model is consistent with observation. We constrain
the flat CDM model to have and
from our AP test alone, which is
significantly tighter than the constraints from the BAO or SNe I methods by
a factor of 3 - 6. When the AP test result is combined with the recent BAO and
SNe I results, we obtain and
. This puts a strong tension with the flat
CDM model with at level. Consistency with is
obtained only when the Planck CMB observation is combined. It remains to see if
this tension between observations of galaxy distribution at low redshifts and
CMB anisotropy at the decoupling epoch becomes greater in the future studies
and leads us to a new paradigm of cosmology.Comment: 21 pages, 11 figures, accepted by Ap
Increasing the Durability of Piezoelectric Impact-based Micro Wind Generator in Real Application
AbstractThe purpose of this study is to increase the durability of piezoelectric impact-based micro wind generator (PIMWG) in real application. Using new PIMWG design, numerical simulation, and experimental comparison analysis, we improved the durability of PIMWGs in real application. The experimental results show that the optimized PIMWG generated 2.4 mW (RMS value), and it did not crack within 40h. In this study, we improved the durability of PIMWGs for real application
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