Neutrino Quantum Kinetics

We present a formulation of the quantum kinetic equations (QKEs) which govern the evolution of neutrino flavor at high density and temperature. Here, the QKEs are derived from the ground up, using fundamental neutrino interactions and quantum field theory. We show that the resulting QKEs describe coherent flavor evolution with an effective mass when inelastic scattering is negligible. The QKEs also contain a collision term. This term can reduce to the collision term in the Boltzmann equation when scattering is dominant and the neutrino effective masses and density matrices become diagonal in the interaction basis. We also find that the QKE's include equations of motion for a new dynamical quantity related to neutrino spin. This quantity decouples from the equations of motion for the density matrices at low densities or in isotropic conditions. However, the spin equations of motion allow for the possibility of coherent transformation between neutrinos and antineutrinos at high densities and in the presence of anisotropy. Although the requisite conditions for this exist in the core collapse supernova and compact object merger environments, it is likely that only a self consistent incorporation of the QKEs in a sufficiently realistic model could establish whether or not significant neutrino-antineutrino conversion occurs.Comment: Revised version, published in Physical Review

A New Spin on Neutrino Quantum Kinetics

Recent studies have demonstrated that in anisotropic environments a coherent spin-flip term arises in the Quantum Kinetic Equations (QKEs) which govern the evolution of neutrino flavor and spin in hot and dense media. This term can mediate neutrino-antineutrino transformation for Majorana neutrinos and active-sterile transformation for Dirac neutrinos. We discuss the physical origin of the coherent spin-flip term and provide explicit expressions for the QKEs in a two-flavor model with spherical geometry. In this context, we demonstrate that coherent neutrino spin transformation depends on the absolute neutrino mass and Majorana phases.Comment: 11 pages, 3 figures, Major changes compared to v1, accepted for publication in Physics Letters

Neutrino scattering and flavor transformation in supernovae

We argue that the small fraction of neutrinos that undergo direction-changing scattering outside of the neutrinosphere could have significant influence on neutrino flavor transformation in core-collapse supernova environments. We show that the standard treatment for collective neutrino flavor transformation is adequate at late times, but could be inadequate in the crucial shock revival/explosion epoch of core-collapse supernovae, where the potentials that govern neutrino flavor evolution are affected by the scattered neutrinos. Taking account of this effect, and the way it couples to entropy and composition, will require a new paradigm in supernova modeling.Comment: 5 pages, 3 figure

Halo Modification of a Supernova Neutronization Neutrino Burst

We give the first self-consistent calculation of the effect of the scattered neutrino halo on flavor evolution in supernovae. Our example case is an O-Ne-Mg core collapse supernova neutronization neutrino burst. We find that the addition of the halo neutrinos produces qualitative and quantitative changes in the final flavor states of neutrinos. We also find that the halo neutrinos produce a novel distortion of the neutrino flavor swap. Our results provide strong motivation for tackling the full multidimensional and composition-dependent aspects of this problem in the future.Comment: 14 pages, 13 figures, 1 tabl

Large Eddy simulation of a supersonic coaxial helium-air jet

International audienceThe experiment of A. D. Cutler et al. (NASA Langley Research Center) was modeled, in which a round cold helium jet issued into a co-flow air stream. Both flows were nominally at Mach number 1.8 with convective Mach number equal to 0.7. This test provides high accuracy measurements of Pitot pressure, mass fraction, longitudinal velocity and its root mean square. Presented computations were carried out with the use of in-house code zFlare developed in TsAGI. Two sets of multiblock hexahedral grids were constructed, one for RANS computations and the other for LES. Computational domain reproduces the supplying channels, nozzles and the initial region of the jet. LES computational domain spans a full circle in azimuthal direction, while RANS implies axial symmetry. Due to the presence of near-wall domains, the approach adopted for LES was actually hybrid SST-DDES model. SLA modification was enabled to accelerate the development of the mixing layers. Steady RANS computations were conducted with SST and q-ω turbulence models using relaxation method. Time-averaged fields of Pitot pressure, Mach number, longitudinal velocity component and mass fraction were extracted and compared with the experiment

Ecological and economic significance of the Middle Don sand arenas

The research purpose is a comprehensive assessment of the Middle part of the Don river sand massifs soil and hydrological conditions. The research objects are the sandy massifs of the Middle Don on an area of 527 thousand hectares. The sand arenas water balance dynamics for the period from November to March and for the period from April to October has been revealed. It has been established that atmospheric precipitation is the main source of river water supply. The basis of river systems flood filling are clay soils that form an intra-soil runoff. The low water period level is supported by sandy soils. A decrease in the density of plant formations contributes to an increase in groundwater supply. The total underground runoff reaches 599 million m3 from the sandy massifs of the Middle Don. The volume and dynamics of the moisture movement in the soil depend on the system of sandy areas use. Therefore, the load on sandy arenas should be regulated. Pasture farming should remain the dominant form of sand use. An effective method of sandy arenas afforestation is the planting of pine plantations according to the savanna type

ДИЛЕММА ЦЕЛЕЙ ВЫСШЕГО ОБРАЗОВАНИЯ В ФИЛОСОФСКОМ ИЗМЕРЕНИИ

The reform of education is the subject of numerous discussions. However, scientifically based proposals have been developed only on a few issues. Subject of the analysis is the purposes of higher education that change their orientation in modern conditions. Article purpose is to reveal the reasons of contradictory character of the modern higher education purposes.Methodology and methods. The appeal to philosophical judgment of the purposes of modern higher education is considered on the basis of national education systems comparison with using of comparative and phenomenological approach; methods of the structural analysis and a philosophical reflection are used.Results. The author reveals common problems in statement of the purposes of modern higher education designed at the different levels. The purposes are designed without multilevel system activity of higher education institutes, in conditions of quickly extending and fragmented knowledge which is giving rise to new concepts, meanings and statements, but complicating statement of accurately definite purposes. The analysis of this problem leads to conclusion it is need to combine the global purposes of the higher education and the operational purposes of the concrete organizations entering this system.Practical implication. Results of research can be applied for development courses on philosophy of education and for management in the sphere of education.Цель. Реформа образования служит предметом многочисленных дискуссий ее сторонников и противников. Однако научно обоснованные предложения разработаны лишь по немногим вопросам. Предмет анализа – цели высшего образования, изменяющие свою направленность в современных условиях. Цель статьи – выявить причины противоречивого характера целей современного высшего образования.Методология и методы. Обращение к философскому осмыслению целей современного высшего образования рассматривается на основе сопоставления национальных систем образования с использованием компаративистского и социально-феноменологического подхода; используются методы структурного анализа и философской рефлексии.Результаты. Опираясь на указанные подходы и методы, автор выявляет общие проблемы постановки целей современного высшего образования, конструируемых на разных уровнях. Цели конструируются без учета многоуровневой системной деятельности институтов высшего образования, в условиях быстро расширяющегося и фрагментируемого знания, рождающего новые понятия, смыслы и утверждения, но затрудняющих постановку четко определенных целей. Анализ данной проблемы приводит к выводу необходимости сочетания глобальных целей высшего образования и операциональных целей конкретных организаций, входящих в эту систему.Область применения результатов. Результаты исследования могут быть применены при создании учебных курсов по философии образования, в сфере управления образованием

Digitalization of state environmental management: Legal aspects

This article discusses the features of the digital transformation of the following state functions: information support in the field of environmental protection, state accounting in the field of environmental protection, regulation in the field of environmental protection (in terms of the use of the best available technologies), state environmental supervision, and administration of fees for negative environmental impact (NVOS). It is proved that the data of the state register of objects of negative impact, formed as a result of the state accounting of objects that have a negative impact on the environment, the implementation of state environmental supervision, and the administration of fees for NWOS should become the basis for making environmentally significant decisions. To expand the scope of use of this information, it is proposed to ensure the interoperability of the state register data. In addition, the authors come to the conclusion that digitalization of technological rationing based on the best available technologies (hereinafter also BAT) is associated with the use of such technologies as data turnover regulation, experimental legal regimes (regulatory sandboxes) and assessment of the compliance of the applied technology with the best available technology. Moreover, when implementing state environmental supervision, inspections should be planned based on the hazard category of objects of negative impact and when conducting inspections, remote control methods should be used. It is also essential to introduce electronic test sheets for self-checking enterprises. Finally, the digitalization of calculating and collecting fees for NVOS should ensure the smooth functioning of calculating fees by the payer in digital format and control over the correctness of calculation and collection by the supervisory authority

Complex numerical-experimental investigations of combustion in model high-speed combustor ducts

International audienceFast technologies for numerical simulation of high-speed flows in ducts, developed in TsAGI, are described. The examples are presented of the application of experimental data, obtained at T-131 wind tunnel, for validation of the developed numerical technologies: 1) validation of 2.5D and 3D calculations of flow in the elliptic combustor with hydrogen supersonic combustion that was studied within HEXAFLY-INT international project; 2) validation of 2D and 2.5D calculations of flow in high-speed model combustor duct with step-like expansion. Preparation of new series of experiments, oriented on validation of turbulent combustion models, is described