22,968 research outputs found
Characterization of High Temperature Optocoupler for Power Electronic Systems
High-temperature devices have been rapidly increas due to the implementation of new technologies like silicon carbide, high-temperature ceramic, and others. Functionality under elevated temperatures can reduce signal integrity reducing the reliability of power electronic systems. This study presents an ongoing research effort to develop a high-temperature package for optocouplers to operate at higher temperature compared with commercial devices. Low temperature co-fired ceramic (LTCC) was used as the substrate. Bare die commercial LED and photodetectors were attached to the substrate and tested for functionality. Preliminary results show enhanced performance at elevated temperatures compared to a commercial optocoupler device
Abundance Analyses of Field RV Stars, V: DS Aquarii, UY Arae, TW Camelopardis, BT Librae, U Moncerotis, TT Ophiuchi, and RV Tauri
Abundance analyses are presented and discussed for eight RV Tauri variables.
The RV B star UY Ara shows the abundance anomalies seen in other RV B stars,
namely elements that condense into grains at high temperature are underabundant
but elements of low condensation temperature are much less underabundant. This
pattern is ascribed to a separation of dust from gas with accretion of gas but
not dust by the atmosphere. Abundances for two RV C stars with earlier results
for other RV C stars show that these intrinsically metal-poor stars do not show
effects of dust-gas separation. Analyses of five RV A stars show that these
cooler stars are very largely unaffected by dust-gas separation. It is proposed
that the deeper convective envelope of cooler stars dilutes anomalies resulting
from dust-gas separation - the dusty wind off the RV Tauri variable or a dusty
circumbinary disk - are reviewed and observational tests are suggested.Comment: 42 pages, 6 figures, 8 tables, this may be listed as ApJ in pres
Global constraints on anomalous triple gauge couplings in effective field theory approach
We present a combined analysis of LHC Higgs data (signal strengths) together
with LEP-2 WW production measurements. To characterize possible deviations from
the Standard Model (SM) predictions, we employ the framework of an Effective
Field Theory (EFT) where the SM is extended by higher-dimensional operators
suppressed by the mass scale of new physics . The analysis is
performed consistently at the order in the EFT expansion keeping
all the relevant operators. While the two data sets suffer from flat
directions, together they impose stringent model-independent constraints on the
anomalous triple gauge couplings. As a side product, we provide the results of
the combined fit in different EFT bases.Comment: 7 pages. v2: References and clarifications adde
Matrix Product States, Random Matrix Theory and the Principle of Maximum Entropy
Using random matrix techniques and the theory of Matrix Product States we
show that reduced density matrices of quantum spin chains have generically
maximum entropy.Comment: 11 pages, 4 figure
Natural Gauge and Gravitational Coupling Unification and the Superpartner Masses
The possibility to achieve unification at the string scale in the context of
the simplest supersymmetric grand unified theory is investigated. We find
conservative upper bounds on the superpartner masses consistent with the
unification of gauge and gravitational couplings, M_{\tilde G} < 5 TeV and
M_{\tilde f} < 3 \times 10^7 GeV, for the superparticles with spin one-half and
zero, respectively. These bounds hint towards the possibility that this
supersymmetric scenario could be tested at future colliders, and in particular,
at the forthcoming LHC.Comment: 8 pages, 4 figures, version accepted in Physics Letters
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