1,436 research outputs found
Kinetic equation for hydrogen-induced direct phase transformations in Y2Fe17 magnetic alloy
Model for evolution of the hydrogen-induced direct phase transformation in Y2Fe17 magnetic alloy has been proposed. It is shown that evolution process of hydrogen-induced direct phase transformation in Y2Fe17 type hard magnetic alloy is controlled by diffusion process of Fe atoms in low temperatures interval of 330β750 oC. On the base of Kolmogorov and Lyubov kinetic theory has been obtained kinetic equation that well described the isothermal kinetic diagram for this type transformation in Y2Fe17 alloy.ΠΡΠ΅Π΄Π»ΠΎΠΆΠ΅Π½Π° ΠΌΠΎΠ΄Π΅Π»Ρ Π΄Π»Ρ ΡΠ°Π·Π²ΠΈΡΠΈΡ ΠΈΠ½Π΄ΡΡΠΈΡΠΎΠ²Π°Π½Π½ΠΎΠ³ΠΎ Π²ΠΎΠ΄ΠΎΡΠΎΠ΄ΠΎΠΌ ΠΏΡΡΠΌΠΎΠ³ΠΎ ΡΠ°Π·ΠΎΠ²ΠΎΠ³ΠΎ ΠΏΡΠ΅Π²ΡΠ°ΡΠ΅Π½ΠΈΡ Π² ΠΌΠ°Π³Π½ΠΈΡΠΎΡΠ²Π΅ΡΠ΄ΠΎΠΌ ΡΠΏΠ»Π°Π²Π΅ ΡΠΈΠΏΠ° Y2Fe17. ΠΠΎΠΊΠ°Π·Π°Π½ΠΎ ΡΡΠΎ ΠΏΡΠΎΡΠ΅ΡΡ ΡΠ°Π·Π²ΠΈΡΠΈΡ ΠΈΠ½Π΄ΡΡΠΈΡΠΎΠ²Π°Π½Π½ΠΎΠ³ΠΎ Π²ΠΎΠ΄ΠΎΡΠΎΠ΄ΠΎΠΌ ΠΏΡΡΠΌΠΎΠ³ΠΎ ΡΠ°Π·ΠΎΠ²ΠΎΠ³ΠΎ ΠΏΡΠ΅Π²ΡΠ°ΡΠ΅Π½ΠΈΡ Π² ΠΌΠ°Π³Π½ΠΈΡΠΎΡΠ²Π΅ΡΠ΄ΠΎΠΌ ΡΠΏΠ»Π°Π²Π΅ ΡΠΈΠΏΠ° Y2Fe17 Π² Π½ΠΈΠ·ΠΊΠΎΡΠ΅ΠΌΠΏΠ΅ΡΠ°ΡΡΡΠ½ΠΎΠΌ ΠΈΠ½ΡΠ΅ΡΠ²Π°Π»Π΅ 330β750 oC ΠΊΠΎΠ½ΡΡΠΎΠ»ΠΈΡΡΠ΅ΡΡΡ ΠΏΡΠΎΡΠ΅ΡΡΠ°ΠΌΠΈ Π΄ΠΈΡΡΡΠ·ΠΈΠΈ Π°ΡΠΎΠΌΠΎΠ² Fe. ΠΠ° ΠΎΡΠ½ΠΎΠ²Π΅ ΠΊΠΈΠ½Π΅ΡΠΈΡΠ΅ΡΠΊΠΎΠΉ ΡΠ΅ΠΎΡΠΈΠΈ ΡΠ°Π·ΠΎΠ²ΡΡ
ΠΏΡΠ΅Π²ΡΠ°ΡΠ΅Π½ΠΈΠΉ ΠΠΎΠ»ΠΌΠΎΠ³ΠΎΡΠΎΠ²Π° ΠΈ ΠΡΠ±ΠΎΠ²Π° ΠΏΠΎΠ»ΡΡΠ΅Π½ΠΎ ΠΊΠΈΠ½Π΅ΡΠΈΡΠ΅ΡΠΊΠΎΠ΅ ΡΡΠ°Π²Π½Π΅Π½ΠΈΠ΅, Ρ
ΠΎΡΠΎΡΠΎ ΠΎΠΏΠΈΡΡΠ²Π°ΡΡΠ΅Π΅ ΠΈΠ·ΠΎΡΠ΅ΡΠΌΠΈΡΠ΅ΡΠΊΡΡ ΠΊΠΈΠ½Π΅ΡΠΈΡΠ΅ΡΠΊΡΡ Π΄ΠΈΠ°Π³ΡΠ°ΠΌΠΌΡ Π΄Π»Ρ ΠΏΡΠ΅Π²ΡΠ°ΡΠ΅Π½ΠΈΡ ΡΠ°ΠΊΠΎΠ³ΠΎ ΡΠΈΠΏΠ° Π² ΡΠΏΠ»Π°Π²Π΅ ΡΠΈΠΏΠ° Y2Fe17
Ordinary reduction of K3 surfaces
Let X be a K3 surface over a number field K. We prove that there exists a
finite algebraic field extension L/K such that X has ordinary reduction at
every non-archimedean place of L outside a density zero set of places.Comment: 7 page
A New Limit on the Antiproton Lifetime
Measurements of the cosmic ray pbar/p ratio are compared to predictions from
an inhomogeneous disk-diffusion model of pbar production and propagation within
the Galaxy, combined with a calculation of the modulation of the interstellar
cosmic ray spectra as the particles propagate through the heliosphere to the
Earth. The predictions agree with the observed pbar/p spectrum. Adding a finite
pbar lifetime to the model, we obtain the limit tau_pbar > 0.8 Myr (90 % C.L.).Comment: 13 pages, 3 encapsulated Postscript figures, uses AASTeX; accepted by
Astrophysical Journal; minor change
Luttinger-liquid-like transport in long InSb nanowires
Long nanowires of degenerate semiconductor InSb in asbestos matrix (wire
diameter is around 50 \AA, length 0.1 - 1 mm) were prepared. Electrical
conduction of these nanowires is studied over a temperature range 1.5 - 350 K.
It is found that a zero-field electrical conduction is a power function of the
temperature with the typical exponent .
Current-voltage characteristics of such nanowires are found to be nonlinear and
at sufficiently low temperatures follows the power law . It
is shown that the electrical conduction of these nanowires cannot be accounted
for in terms of ordinary single-electron theories and exhibits features
expected for impure Luttinger liquid. For a simple approximation of impure LL
as a pure one broken into drops by weak links, the estimated weak-link density
is around per cm.Comment: 5 pages, 2 figure
Diffusion and Transport Coefficients in Synthetic Opals
Opals are structures composed of the closed packing of spheres in the size
range of nano-to-micro meter. They are sintered to create small necks at the
points of contact. We have solved the diffusion problem in such structures. The
relation between the diffusion coefficient and the termal and electrical
conductivity makes possible to estimate the transport coefficients of opal
structures. We estimate this changes as function of the neck size and the
mean-free path of the carriers. The theory presented is also applicable to the
diffusion problem in other periodic structures.Comment: Submitted to PR
Properties of quasi-periodic pulsations in solar flares from a single active region
We investigate the properties of a set of solar flares originating from a
single active region (AR) that exhibit QPPs, and look for signs of the QPP
periods relating to AR properties. The AR studied, best known as NOAA 12192,
was unusually long-lived and produced 181 flares. Data from the GOES, EVE,
Fermi, Vernov and NoRH observatories were used to determine if QPPs were
present in the flares. For the soft X-ray GOES and EVE data, the time
derivative of the signal was used. Power spectra of the time series data
(without any form of detrending) were inspected, and flares with a peak above
the 95% confidence level in the spectrum were labelled as having candidate
QPPs. The confidence levels were determined taking account of uncertainties and
the possible presence of red noise. AR properties were determined using HMI
line of sight magnetograms. A total of 37 flares (20% of the sample) show good
evidence of having QPPs, and some of the pulsations can be seen in data from
multiple instruments and in different wavebands. The QPP periods show a weak
correlation with the flare amplitude and duration, but this may be due to an
observational bias. A stronger correlation was found between the QPP period and
duration of the QPP signal, which can be partially but not entirely explained
by observational constraints. No correlations were found with the AR area,
bipole separation, or average magnetic field strength. The fact that a
substantial fraction of the flare sample showed evidence of QPPs using a strict
detection method with minimal processing of the data demonstrates that these
QPPs are a real phenomenon, which cannot be explained by the presence of red
noise or the superposition of multiple unrelated flares. The lack of
correlation between the QPP periods and AR properties implies that the
small-scale structure of the AR is important, and/or that different QPP
mechanisms act in different cases.Comment: 23 pages, 57 figures. Accepted for publication by Astronomy &
Astrophysic
Compositional Verification for Autonomous Systems with Deep Learning Components
As autonomy becomes prevalent in many applications, ranging from
recommendation systems to fully autonomous vehicles, there is an increased need
to provide safety guarantees for such systems. The problem is difficult, as
these are large, complex systems which operate in uncertain environments,
requiring data-driven machine-learning components. However, learning techniques
such as Deep Neural Networks, widely used today, are inherently unpredictable
and lack the theoretical foundations to provide strong assurance guarantees. We
present a compositional approach for the scalable, formal verification of
autonomous systems that contain Deep Neural Network components. The approach
uses assume-guarantee reasoning whereby {\em contracts}, encoding the
input-output behavior of individual components, allow the designer to model and
incorporate the behavior of the learning-enabled components working
side-by-side with the other components. We illustrate the approach on an
example taken from the autonomous vehicles domain
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