2,242 research outputs found
Unique Appearance of Lamellar Cleavage Patterns on Fracture Surfaces of Ti-Based Amorphous Matrix Composite
In order to improve mechanical properties of Ti-based amorphous matrix composites basically composed of ductile beta-Ti dendrites and brittle amorphous matrix by overcoming their inherent brittle nature, their fracture mechanisms should be verified in relation with microstructure, stress intensity factor level, and crack growth rate. In this study, thus, detailed fractographic observations including the unique appearance of lamellar cleavage patterns, which has not been reported in previous studies on conventional metals and alloys, were conducted. According to fractographic results, lamellar cleavage patterns were formed by repeated interruptions of crack propagation on {100} cleavage planes by difference between dendrite orientation and loading direction. Ductile-to-brittle transition phenomenon (ductile dimpled fracture -> lamellar cleavage fracture -> ordinary cleavage fracture in dendrite areas, and vein pattern -> smooth pattern in amorphous matrix areas) occurred with increasing crack growth rate was also plausibly explained by the concept of time required for crack growth as well as dendrite orientation.open1122sciescopu
Low-temperature ion beam mixing of Pt and Si markers in Ge
The mixing of Pt and Si marker atoms in Ge during 750-keV Xe irradiation was measured at temperatures between 6 and 500 K. The low-temperature measurements show that the mixing parameter for Pt is nearly twice that for Si. This result is in strong contradiction to the collisional theory of ion beam mixing. A weak temperature dependence in the mixing is found for both markers
Tree indiscernibilities, revisited
We give definitions that distinguish between two notions of indiscernibility
for a set \{a_\eta \mid \eta \in \W\} that saw original use in \cite{sh90},
which we name \textit{\s-} and \textit{\n-indiscernibility}. Using these
definitions and detailed proofs, we prove \s- and \n-modeling theorems and
give applications of these theorems. In particular, we verify a step in the
argument that TP is equivalent to TP or TP that has not seen
explication in the literature. In the Appendix, we exposit the proofs of
\citep[{App. 2.6, 2.7}]{sh90}, expanding on the details.Comment: submitte
High resolution angle resolved photoemission studies on quasi-particle dynamics in graphite
We obtained the spectral function of the graphite H point using high
resolution angle resolved photoelectron spectroscopy (ARPES). The extracted
width of the spectral function (inverse of the photo-hole lifetime) near the H
point is approximately proportional to the energy as expected from the linearly
increasing density of states (DOS) near the Fermi energy. This is well
accounted by our electron-phonon coupling theory considering the peculiar
electronic DOS near the Fermi level. And we also investigated the temperature
dependence of the peak widths both experimentally and theoretically. The upper
bound for the electron-phonon coupling parameter is ~0.23, nearly the same
value as previously reported at the K point. Our analysis of temperature
dependent ARPES data at K shows that the energy of phonon mode of graphite has
much higher energy scale than 125K which is dominant in electron-phonon
coupling.Comment: 9 pages, 8 figures, accepted for publication in Phys. Rev.
Attosecond counter-rotating-wave effect in xenon driven by strong fields
We investigate the subfemtosecond dynamics of a highly excited xenon atom coherently driven by a strong control field at which the Rabi frequency of the system is comparable to the frequency of a driving laser. The widely used rotating-wave approximation breaks down at such fields, resulting in features such as the counter-rotating-wave (CRW) effect. We present a time-resolved observation of the CRW effect in the highly excited 4d-1np xenon using attosecond transient absorption spectroscopy. Time-dependent many-body theory confirms the observation and explains the various features of the absorption spectrum seen in experiment. ?2017 American Physical Society.111Ysciescopu
Quantum linear amplifier enhanced by photon subtraction and addition
A deterministic quantum amplifier inevitably adds noise to an amplified
signal due to the uncertainty principle in quantum physics. We here investigate
how a quantum-noise-limited amplifier can be improved by additionally employing
the photon subtraction, the photon addition, and a coherent superposition of
the two, thereby making a probabilistic, heralded, quantum amplifier. We show
that these operations can enhance the performance in amplifying a coherent
state in terms of intensity gain, fidelity, and phase uncertainty. In
particular, the photon subtraction turns out to be optimal for the fidelity and
the phase concentration among these elementary operations, while the photon
addition also provides a significant reduction in the phase uncertainty with
the largest gain effect.Comment: published version, 7 pages, 9 figure
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