34 research outputs found
On the statistical mechanics of an adiabatic ensemble
Different descriptions of an adiabatic process based on statistical thermodynamics and statistical mechanics are discussed. Equality of the so-called adiabatic and isolated susceptibilities and its generalization as well as adiabatic invariants are essentially used to describe adiabatic processes in the framework of quantum and classical statistical mechanics. It is shown that distribution function in adiabatic ensemble differs from a quasi-equilibrium canonical form provided the heat capacity of the system is not constant in adiabatic process.Обговорюються різноманітні підходи до опису адіабатичних процесів на основі термодинаміки та статистичної механіки. Для опису адіабатичних процесів в рамках класичної та квантової статистичної механіки використовуються рівняння для так званих адіабатичної та ізольованої сприйнятностей і їх узагальнення, а також адіабатичні інваріанти. Показано, що функція розподілу в адіабатичному ансамблі відрізняється від квазірівноважної канонічної форми при умові, що теплоємність системи при адіабатичному процесі є змінно
Boundary Condition Effect On Photoacoustic Response Of Absorbing Liquid To Modulation Of Laser Intensity
The photoacoustic (PA) pressure response of the absorbing liquid (water, ethanol) with free and confined surface to laser pulse with modulated intensity is studied. Modulation amplitude of the PA signal demonstrates non-monotonous behavior during laser pulse action which can be explained as interference between thermo-acoustic and vaporization mechanisms of pressure generation. The phase behavior of modulated part of PA signal also gives important information on processes in the irradiated matter. Doppler photoacoustic monitoring (DPM) is used to determine surface movement during laser irradiation (wavelength – 2.94 um, pulse duration ~ 200-300 ns, fluence ~ 0.3-1.6 J/cm2). In the case of free surface this movement is possible into the upward and downward directions while for the constrained irradiated surface only one movement is supposed. This supposition is in agreement with the experiment. However the total behavior of PA response is more complicated due to probably vapor cavity formation between liquid and solid surfaces. In particular, despite the imposed constraint PA response behavior resembles the free surface case
Explosive Boiling of Transparent Liquids on Absorbing Targets Heated by Short Laser Pulses
Explosive boiling induced by sub-nanosecond laser pulses is theoretically analyzed in the case of transparent liquids on metal targets. In this case the variation of boiling start times due to inhomogeneous distribution of laser intensity through the irradiation spot can be reduced up to laser pulse duration and registered explosive boiling pressure signals become less distorted. The results are compared with experimental investigations of photoacoustic (PA) signals induced in metal target under transparent liquid layer irradiated by laser pulses of about 100 ps duration and wavelength 532 nm
On the theory of superconductivity in ferromagnetic superconductors with triplet pairing
We point out that ferromagnetic superconductors with triplet pairing and
strong spin-orbit coupling are even in the simplest case at least two-band
superconductors. The Gor'kov type formalism for such superconductors is
developed and the Ginzburg-Landau equations are derived. The dependence of the
critical temperature on the concentration of ordinary point-like impurities is
found. Its nonuniversality could serve as a qualitative measure of the two-band
character of ferromagnetic superconductors. The problem of the upper critical
field determination is also discussed.Comment: 8 pages, no figure; important changes with respect to the previous
versions due to the correction of a mistake: in this new version, a more
general form is considered for the order parameter (the two-components of the
order parameter were considered before as equal, which is in general not
true) ; submitted to Physical Review
Is the Luttinger liquid a new state of matter?
We are demonstrating that the Luttinger model with short range interaction
can be treated as a type of Fermi liquid. In line with the main dogma of
Landau's theory one can define a fermion excitation renormalized by interaction
and show that in terms of these fermions any excited state of the system is
described by free particles. The fermions are a mixture of renormalized right
and left electrons. The electric charge and chirality of the Landau
quasi-particle is discussed.Comment: paper 10 pages. This version of the paper will be published in
Foundations of Physic
Damping of phase fluctuations in superfluid Bose gases
Using Popov's hydrodynamic approach we derive an effective Euclidean action
for the long-wavelength phase fluctuations of superfluid Bose gases in D
dimensions. We then use this action to calculate the damping of phase
fluctuations at zero temperature as a function of D. For D >1 and wavevectors |
k | << 2 mc (where m is the mass of the bosons and c is the sound velocity) we
find that the damping in units of the phonon energy E_k = c | k | is to leading
order gamma_k / E_k = A_D (k_0^D / 2 pi rho) (| k | / k_0)^{2 D -2}, where rho
is the boson density and k_0 =2 mc is the inverse healing length. For D -> 1
the numerical coefficient A_D vanishes and the damping is proportional to an
additional power of |k | /k_0; a self-consistent calculation yields in this
case gamma_k / E_k = 1.32 (k_0 / 2 pi rho)^{1/2} |k | / k_0. In one dimension,
we also calculate the entire spectral function of phase fluctuations.Comment: 6 pages, 4 figures, published versio
Zero-bias conductance peak splitting due to multiband effect in tunneling spectroscopy
We study how the multiplicity of the Fermi surface affects the zero-bias peak
in conductance spectra of tunneling spectroscopy. As case studies, we consider
models for organic superconductors -(BEDT-TTF)Cu(NCS) and
(TMTSF)ClO. We find that multiplicity of the Fermi surfaces can lead to
a splitting of the zero-bias conductance peak (ZBCP). We propose that the
presence/absence of the ZBCP splitting is used as a probe to distinguish the
pairing symmetry in -(BEDT-TTF)Cu(NCS).Comment: 7 pages, 7 figure
RESPONSE OF RADIATION-INDUCED EVAPORATION TO THERMAL AND HYDRODYNAMIC PERTURBATIONS
On analyse la réponse linéaire du procédé stationnaire de l'évaporation pour des liquides qui absorbent l'irradiation intense. On examine des perturbations thermiques et hydrodynamiques. En cas de perturbations thermiques qui sont conditionnées par des modulations harmoniques de l'intensité absorbante, la réponse de la pression qui a lieu au cours du procédé de l'évaporation découvre la conduite de résonance par rapport à la fréquence de la modulation. Les perturbations hydrodynamiques mènent à la modulation spatiale de la pression du recul qui joue un rôle essentiel dans le problème de la stabilité de la surface évaporante. Une équation dispersive pour des ondes de surface (ripplons) du liquide évaporant d'une manière intense est reçue.A linear response of the steady-state evaporation process is investigated for liquids absorbing intense radiation. Thermal and hydrodynamic perturbations are considered. In the case of the thermal perturbations due to intensity modulation the vaporization pressure response shows a resonant behaviour with respect to the modulation frequency. The hydrodynamics (ripplon-like) perturbation results in differential pressure recoil which plays an essential role in the stability problem of evaporating liquid surface. Dispersion relation is obtained for ripplons in rapidly evaporating liquids
МУЗЫКАЛЬНЫЕ ПРОИЗВЕДЕНИЯ НА ЗАНЯТИЯХ ПО ИНОСТРАННОМУ ЯЗЫКУ
The paper reviews scientific works on using musical pieces at English lessons in primary and secondary schools, which reveals the popularity of such methods among scientists and teachers. The relevance of the study is related to the adoption and realization of the Federal Law “On Education in the Russian Federation”, which prescribes enriching pedagogical practice with inclusive methods and technologies contributing to the effectiveness and comfort of the educational process. It is noted that principles and conclusions formulated in the relevant literature from the end of the last century have many similarities. In most of the analyzed works, attention is paid to the same positive aspects typical of using musical pieces within the learning process: expanding the students’ mental outlook; increasing the comfort level of the educational environment; encouraging children to study; developing their communication skills. It is emphasized that the differences are commonly limited to small-scale observations and recommendations, along with an appeal to a new teaching material (previously unused musical pieces). The authors conclude that using songs in foreign language lessons should not be considered as an “educational panacea” or the main teaching method. It is recommended to develop listening skills via traditional exercises that have been tested for many decades.Рассмотрены научные труды, связанные с использованием музыкальных произведений в ходе обучения английскому языку в начальной и средней школе, что отражает популярность подобных методов в научно-педагогической среде. Актуальность исследования связана с принятием и вступлением в силу ФЗ «Об образовании в Российской Федерации», предписывающего обогащать педагогическую практику инклюзивными методами и технологиями, способствующими результативности и комфортности учебно-воспитательного процесса. Обнаружено сходство базовых принципов и выводов, формулируемых в соответствующей литературе с конца прошлого столетия. В большинстве проанализированных трудов уделяется внимание одним и тем же положительным моментам, характерным для использования музыкальных произведений в процессе обучения: расширению кругозора школьников; повышению уровня комфортности образовательной среды; стимулированию детей к учебе; развитию навыков, связанных с общением. Отмечается, что различия, как правило, ограничиваются наблюдениями и рекомендациями частного характера, а также обращением к новому учебному материалу (ранее не использованным музыкальным произведениям). Авторы приходят к выводу, что использование песен на уроках иностранного языка не стоит воспринимать как «образовательную панацею» или главный метод обучения. Навыки аудирования рекомендуется развивать с помощью традиционных упражнений, проверенных многими десятилетиями
МУЗЫКАЛЬНЫЕ ПРОИЗВЕДЕНИЯ НА ЗАНЯТИЯХ ПО ИНОСТРАННОМУ ЯЗЫКУ
The paper reviews scientific works on using musical pieces at English lessons in primary and secondary schools, which reveals the popularity of such methods among scientists and teachers. The relevance of the study is related to the adoption and realization of the Federal Law “On Education in the Russian Federation”, which prescribes enriching pedagogical practice with inclusive methods and technologies contributing to the effectiveness and comfort of the educational process. It is noted that principles and conclusions formulated in the relevant literature from the end of the last century have many similarities. In most of the analyzed works, attention is paid to the same positive aspects typical of using musical pieces within the learning process: expanding the students’ mental outlook; increasing the comfort level of the educational environment; encouraging children to study; developing their communication skills. It is emphasized that the differences are commonly limited to small-scale observations and recommendations, along with an appeal to a new teaching material (previously unused musical pieces). The authors conclude that using songs in foreign language lessons should not be considered as an “educational panacea” or the main teaching method. It is recommended to develop listening skills via traditional exercises that have been tested for many decades.Рассмотрены научные труды, связанные с использованием музыкальных произведений в ходе обучения английскому языку в начальной и средней школе, что отражает популярность подобных методов в научно-педагогической среде. Актуальность исследования связана с принятием и вступлением в силу ФЗ «Об образовании в Российской Федерации», предписывающего обогащать педагогическую практику инклюзивными методами и технологиями, способствующими результативности и комфортности учебно-воспитательного процесса. Обнаружено сходство базовых принципов и выводов, формулируемых в соответствующей литературе с конца прошлого столетия. В большинстве проанализированных трудов уделяется внимание одним и тем же положительным моментам, характерным для использования музыкальных произведений в процессе обучения: расширению кругозора школьников; повышению уровня комфортности образовательной среды; стимулированию детей к учебе; развитию навыков, связанных с общением. Отмечается, что различия, как правило, ограничиваются наблюдениями и рекомендациями частного характера, а также обращением к новому учебному материалу (ранее не использованным музыкальным произведениям). Авторы приходят к выводу, что использование песен на уроках иностранного языка не стоит воспринимать как «образовательную панацею» или главный метод обучения. Навыки аудирования рекомендуется развивать с помощью традиционных упражнений, проверенных многими десятилетиями