460 research outputs found
Adiabatic tracking for photo- and magneto-association of Bose-Einstein condensates with Kerr nonlinearities
We develop the method of adiabatic tracking for photo- and
magneto-association of Bose-Einstein atomic condensates with models that
include Kerr type nonlinearities. We show that the inclusion of these terms can
produce qualitatively important modifications in the adiabatic dynamics, like
the appearance of bifurcations, in which the trajectory that is being tracked
loses its stability. As a consequence the adiabatic theorem does not apply and
the adiabatic transfer can be strongly degraded. This degradation can be
compensated by using fields that are strong enough compared with the values of
the Kerr terms. The main result is that, despite these potentially detrimental
features, there is always a choice of the detuning that leads to an efficient
adiabatic tracking, even for relatively weak fields
New powerful outburst of the unusual young star V1318 Cyg S (LkH{\alpha} 225)
Young double star V1318 Cyg, which is associated with a small isolated
star-forming region around HAeBe star BD+40o4124, has very unusual photometric
and spectral behavior. We present results of photometric and spectroscopic
observations in the optical range. We carried out BVRI CCD photometric
observations of V1318 Cyg from 2015 Sept. to 2017 July. For the same period we
acquired medium- and low-resolution spectra. Observations were performed with
the 2.6 m telescope. We analyze the historical light curve for V1318 Cyg and
demonstrate that the southern component, V1318 Cyg S, after being rather bright
in the 1970s (V14 mag) started to lower its brightness and in 1990
became practically invisible in the optical. After its reappearance in the
second half of the 1990s the star started to become very slowly brighter.
Between 2006 and 2010 V1318 Cyg S started brightening more quickly, and in 2015
had become brighter by more than five magnitudes in visible light. Since this
time V1318 Cyg S has remained at this maximum. Its spectrum shows little
variability and consists of a mixture of emission and absorption lines, which
has allowed for estimates of its spectral type as early Ae, with obvious
evidence of matter outflow. We derive its current A(V) 7.2 and L = 750
L(sun) thus confirming that V1318 Cyg S should belong to the Herbig Ae stars,
making it, along with BD+40o4124 and V1686 Cyg, the third luminous young star
in the group. It is very probable that we observe V1318 Cyg S near the pole and
that the inclination of its dense and slow ( 100 km/s) outflow is low.
The unusual variability and other features of V1318 Cyg S make it difficult to
classify this star among known types of eruptive young stars. It could be an
extreme, higher-mass example of an EXor, or an object of intermediate class
between EXors and FUors, like V1647 Ori.Comment: 9 pages, 7 figure
Bistability and chaos at low-level of quanta
We study nonlinear phenomena of bistability and chaos at a level of few
quanta. For this purpose we consider a single-mode dissipative oscillator with
strong Kerr nonlinearity with respect to dissipation rate driven by a
monochromatic force as well as by a train of Gaussian pulses. The quantum
effects and decoherence in oscillatory mode are investigated on the framework
of the purity of states and the Wigner functions calculated from the master
equation. We demonstrate the quantum chaotic regime by means of a comparison
between the contour plots of the Wigner functions and the strange attractors on
the classical Poincar\'e section. Considering bistability at low-limit of
quanta, we analyze what is the minimal level of excitation numbers at which the
bistable regime of the system is displayed? We also discuss the formation of
oscillatory chaotic regime by varying oscillatory excitation numbers at ranges
of few quanta. We demonstrate quantum-interference phenomena that are assisted
hysteresis-cycle behavior and quantum chaos for the oscillator driven by the
train of Gaussian pulses as well as we establish the border of
classical-quantum correspondence for chaotic regimes in the case of strong
nonlinearities.Comment: 10 pages, 14 figure
Expansions of the solutions of the biconfluent Heun equation in terms of incomplete Beta and Gamma functions
Starting from equations obeyed by functions involving the first or the second
derivatives of the biconfluent Heun function, we construct two expansions of
the solutions of the biconfluent Heun equation in terms of incomplete Beta
functions. The first series applies single Beta functions as expansion
functions, while the second one involves a combination of two Beta functions.
The coefficients of expansions obey four- and five-term recurrence relations,
respectively. It is shown that the proposed technique is potent to produce
series solutions in terms of other special functions. Two examples of such
expansions in terms of the incomplete Gamma functions are presente
Empowering Cultural Heritage through Digitalization Strategies and Metaverse Implementation
The digitalization of cultural organizations and the adoption of metaverse tools represent a transformative leap towards safeguarding and promoting the nation's rich cultural
heritage. By embracing digital technologies, these organizations
can transcend physical boundaries and engage a global audience,
preserving national art, history, and traditions for generations to
come. The importance of digitalization lies in enhancing
audience accessibility, enabling virtual experiences, and
facilitating cross-cultural exchange. Metaverse implementation
opens doors to immersive virtual exhibitions, interactive
storytelling, and dynamic cultural spaces. Through strategic
partnerships and innovative content creation, cultural
organizations can unlock new avenues for education, research,
and revenue generatio
Dissipative Chaos in Quantum Distributions
We discuss some problems of dissipative chaos for open quantum systems in the
framework of semiclassical and quantum distributions. For this goal, we propose
a driven nonlinear oscillator with time-dependent coefficients, i.e. with
time-dependent Kerr-nonlinearity and time-modulated driving field. This model
showing both regular and chaotic dynamics in the classical limit is realized in
several experimental schemes. Quantum dissipative chaos is analyzed on the base
of numerical method of quantum trajectories. Three quantities are studied: the
Wigner function of oscillatory mode from the point of view of quantum-assemble
theory and both semiclassical Poincare section and quantum Poincare section
calculated on a single quantum trajectory. The comparatively analysis of these
distributions for various operational chaotic regimes of the models is
performed, as well as scaling invariance in dissipative chaos and quantum
interference effects assisted by chaos are discussed.Comment: 17 pages, 3 figures, proceeding of Modern Optics And Photonic
Quantum interference and sub-Poissonian statistics for time-modulated driven dissipative nonlinear oscillator
We show that quantum-interference phenomena can be realized for the
dissipative nonlinear systems exhibiting hysteresis-cycle behavior and quantum
chaos. Such results are obtained for a driven dissipative nonlinear oscillator
with time-dependent parameters and take place for the regimes of long time
intervals exceeding dissipation time and for macroscopic levels of oscillatory
excitation numbers. Two schemas of time modulation: (i) periodic variation of
the strength of the {\chi}(3) nonlinearity; (ii) periodic modulation of the
amplitude of the driving force, are considered. These effects are obtained
within the framework of phase-space quantum distributions. It is demonstrated
that the Wigner functions of oscillatory mode in both bistable and chaotic
regimes acquire negative values and interference patterns in parts of
phase-space due to appropriately time-modulation of the oscillatory nonlinear
dynamics. It is also shown that the time-modulation of the oscillatory
parameters essentially improves the degree of sub-Poissonian statistics of
excitation numbers
Roll-to-roll printed silver nanowires for increased stability of flexible ITO-free organic solar cell modules
We report the stability test results of ITO-free OPV modules using roll-to-roll printed silver nanowire networks as front electrode.</p
HFRR test method with stainless steel specimens for gasoline fuels
Reducing CO2 emission is a major challenge for the automotive industry. The different fuels (E10, E100, M15 etc.) that are used for gasoline systems not only influence the CO2 emission but also significantly influence the friction and wear behavior and subsequently the lifetime of powertrain components. The effect is much higher when biofuels are used. The characterization of tribological properties of gasoline fuels is necessary for a robust design which allows for permanent control of performance. The High Frequency Reciprocating Rig (HFRR) test concept according to ISO 12156 is the standard test method for evaluating the lubricity of diesel fuels. Up to now, no standard for gasoline fuels is known. The standardized HFRR test method uses 100Cr6 test specimens which are stable in contact with diesel fuel, but, unlike the stainless steel components used in gasoline fuel injection systems, is prone to corrosion in a gasoline environment typically containing a certain amount of water. This paper aims to develop a lubricity test method with stainless steel for gasoline fuels and reports first results for various fuel compositions
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