Theory of Quark-Gluon Plasma and Phase Transition

Nonperturbative picture of strong interacting quark-gluon plasma is given based on the systematic Field Correlator Method. Equation of state, phase transition in density-temperature plane is derived and compared to lattice data as well as subsequent thermodynamical quantities of QGP.Comment: 6 pages,5 figures; talk given at "13th Lomonosov Conference on Elementary Particle Physics", Moscow, August 23 -- 29, 2007; new reference adde

Self-inhibiting thermal conduction in high-beta, whistler-unstable plasma

A heat flux in a high-$\beta$ plasma with low collisionality triggers the whistler instability. Quasilinear theory predicts saturation of the instability in a marginal state characterized by a heat flux that is fully controlled by electron scattering off magnetic perturbations. This marginal heat flux does not depend on the temperature gradient and scales as $1/\beta$. We confirm this theoretical prediction by performing numerical particle-in-cell simulations of the instability. We further calculate the saturation level of magnetic perturbations and the electron scattering rate as functions of $\beta$ and the temperature gradient to identify the saturation mechanism as quasilinear. Suppression of the heat flux is caused by oblique whistlers with magnetic-energy density distributed over a wide range of propagation angles. This result can be applied to high-$\beta$ astrophysical plasmas, such as the intracluster medium, where thermal conduction at sharp temperature gradients along magnetic-field lines can be significantly suppressed. We provide a convenient expression for the amount of suppression of the heat flux relative to the classical Spitzer value as a function of the temperature gradient and $\beta$. For a turbulent plasma, the additional independent suppression by the mirror instability is capable of producing large total suppression factors (several tens in galaxy clusters) in regions with strong temperature gradients.Comment: accepted to JP

Polarization of Sunyaev-Zeldovich signal due to electron pressure anisotropy in galaxy clusters

We describe polarization of the Sunyaev-Zel'dovich (SZ) effect associated with electron pressure anisotropy likely present in the intracluster medium (ICM). The ICM is an astrophysical example of a weakly collisional plasma where the Larmor frequencies of charged particles greatly exceed their collision frequencies. This permits formation of pressure anisotropies, driven by evolving magnetic fields via adiabatic invariance, or by heat fluxes. SZ polarization arises in the process of Compton scattering of the cosmic microwave background (CMB) photons off the thermal ICM electrons due to the difference in the characteristic thermal velocities of the electrons along two mutually orthogonal directions in the sky plane. The signal scales linearly with the optical depth of the region containing large-scale correlated anisotropy, and with the degree of anisotropy itself. It has the same spectral dependence as the polarization induced by cluster motion with respect to the CMB frame (kinematic SZ effect polarization), but can be distinguished by its spatial pattern. { For the illustrative case of a galaxy cluster with a cold front, where electron transport is mediated by Coulomb collisions, we estimate the CMB polarization degree at the level of 10$^{-8}$ ($\sim 10$ nK). An increase of the effective electron collisionality due to plasma instabilities will reduce the effect. Such polarization, therefore, may be an independent probe of the electron collisionality in the ICM, which is one of the key properties of a high-$\beta$ weakly collisional plasma from the point of view of both astrophysics and plasma theory.Comment: 13 pages, 5 figures, accepted for publication in MNRA

On integration of the Kowalevski gyrostat and the Clebsch problems

For the Kowalevski gyrostat change of variables similar to that of the Kowalevski top is done. We establish one to one correspondence between the Kowalevski gyrostat and the Clebsch system and demonstrate that Kowalevski variables for the gyrostat practically coincide with elliptic coordinates on sphere for the Clebsch case. Equivalence of considered integrable systems allows to construct two Lax matrices for the gyrostat using known rational and elliptic Lax matrices for the Clebsch model. Associated with these matrices solutions of the Clebsch system and, therefore, of the Kowalevski gyrostat problem are discussed. The Kotter solution of the Clebsch system in modern notation is presented in detail.Comment: LaTeX, 24 page

Intelligent OFDM telecommunication system. Part 3. Anti-eavesdropping and anti-jamming properties of system, based on many-parameter wavelet and Golay transforms

In this paper, we aim to investigate the superiority and practicability of many-parameter Fourier transforms (MPFT) from the physical layer security (PHY-LS) perspective. We propose novel Intelligent OFDM-telecommunication system (Intelligent-OFDM-TCS), based on MPFT. New system uses inverse MPFT for modulation at the transmitter and direct MPFT for demodulation at the receiver. The purpose of employing the MPFTs is to improve the PHY-LS of wireless transmissions against to the wide-band anti-jamming communication. Each MPFT depends on finite set of independent parameters (angles), which could be changed independently one from another. When parameters are changed, multi-parametric transform is also changed taking form of a set known (and unknown) orthogonal (or unitary) transforms. We implement the following performances as bit error rate (BER), symbol error rate (SER), the Shannon-Wyner secrecy capacity (SWSC) for novel Intelligent-MPWT-OFDM-TCS. Previous research has shown that the conventional OFDM TCS based on discrete Fourier transform (DFT) has unsatisfactory characteristics in BER, SWSC and in anti-eavesdropping communications. We study Intelligent-MPWT-OFDM-TCS to find out optimal values of angle parameters of MPFT optimized BER, SWSC, anti-eavesdropping effects. Simulation results show that the proposed Intelligent OFDM-TCS have better performances than the conventional OFDM system based on DFT against eavesdropping. © 2019 IOP Publishing Ltd. All rights reserved

Many factor mimo-filters

Исследуется эффективность модифицированных многофакторных (би-, три- и четырех-латеральных) MIMO-фильтров для серых, цветных и гиперспектральных изображений. Обычные билатеральные фильтры осуществляют взвешенное усреднение соседних пикселей. Веса включают две компоненты: пространственную и радиометрическую. Первая компонента учитывает геометрическое расстояние между центральным пикселем маски и его локальными соседями. Второй компонент учитывает радиометрическое расстояние между центральным пикселем маски и его локальными соседями. В этом классическом алгоритме центральный пиксель маски играет определяющую роль в конечном результате фильтрации. Если он искажен, то и результат фильтрации будет искаженным. Этот факт определяет первую модификацию: центральный пиксель заменяется его любой сглаженной версией, полученной на основе соседних пикселей. Вторая модификация использует матрично-значные веса. Они включают четыре компоненты: пространственную, радиометрическую, межканальную и радиометрическую межканальную. Четвертый вес учитывает радиометрическое расстояние между центральным пикселем и межканальными соседними пикселями

Suppression of local heat flux in a turbulent magnetized intracluster medium

X-ray observations of hot gas in galaxy clusters often show steeper temperature gradients across cold fronts -- contact discontinuities, driven by the differential gas motions. These sharp (a few kpc wide) surface brightness/temperature discontinuities would be quickly smeared out by the electron thermal conduction in unmagnetized plasma, suggesting significant suppression of the heat flow across the discontinuities. In fact, the character of the gas flow near cold fronts is favorable for suppression of conduction by aligning magnetic field lines along the discontinuities. We argue that a similar mechanism is operating in the bulk of the gas. Generic 3D random isotropic and incompressible motions increase the temperature gradients (in some places) and at the same time suppress the local conduction by aligning the magnetic field lines perpendicular to the local temperature gradient. We show that the suppression of the effective conductivity in the bulk of the gas can be linked to the increase of the frozen magnetic field energy density. On average the rate of decay of the temperature fluctuations $\mathrm{d}\langle \delta T^2 \rangle /\mathrm{d}t$ decreases as $\langle B^2 \rangle ^{-1/5}$.Comment: 13 pages, 10 figures, published in MNRA

Fréchet mimo-filters

Медианная фильтрация получила широкое распространение при обработке скалярных изображений в качестве методов фильтрации, сохраняющих перепады яркости. Главная идея медианной фильтрации состоит в том, что центральный пиксель сканирующей маски заменяется медианой всех пикселей, содержащихся в маске. В этой работе идея расширяется на векторно-значные изображения. Расширение основывается на том факте, что медиана является также точкой, которая минимизирует сумму расстояний между ней и всеми скалярными пикселями внутри маски. Точкой Фреше конечного множества векторно-значных пикселей в некотором метрическом пространстве (с заданной метрикой) является такой вектор, сумма расстояний до которого от всех векторных пикселей (находящихся внутри маски) имеет минимальное значение. В данной статье понятие точки Фреше расширяется до обобщенной медианы Фреше, в которой используется агрегация расстояний, а не их сумма. Более того, при обобщении используются не классические расстояния, а их агрегационные обобщения. Обобщенные медианы Фреше используются для построения новых медианных MIMO-фильтров

Quantum tops as examples of commuting differential operators

We study the quantum analogs of tops on Lie algebras $so(4)$ and $e(3)$ represented by differential operators.Comment: 24 p