Реферат: We obtain a new phantom black plane solution in 4D of the Einstein-Maxwell theory coupled with a cosmological constant. We analyse their basic properties, as well as its causal structure, and obtain the extensive and intensive thermodynamic variables, as well as the specific heat and the first law. Through the specific heat and the so-called geometric methods, we analyse in detail their thermodynamic properties, the extreme and phase transition limits, as well as the local and global stabilities of the system. The normal case is shown with an extreme limit and the phantom one with a phase transition only for null mass, which is physically inaccessible. The systems present local and global stabilities for certain values of the entropy density with respect to the electric charge, for the canonical and grand canonical ensembles.
Экспериментальные исследования теплофизических свойств Шубаркольского угля
Автор(ы): Жумагулов М. Г.*
Объем документа: С. 100-107
МРНТИ: 29.03.21
Ключевые слова: теплофизические свойства Шубаркольского угля*методы квазистационарного теплового режима*тепловой эффект реакции коксования*
Реферат: Статья содержит данные по экспериментальному изучению теплофизических свойств Шубаркольского угля методом квазистационарного теплового режима. Представлены полученные температурные зависимости теплоемкости и теплопроводности угля, а также тепловой эффект реакции коксования. Приведен также сравнительный анализ с аналогами углей Кузбаса. Полученые теплофизические свойства необходимы для исследования возможности коксования шубаркольского угля, а также представленная методика исследования применима для определения теплофизических свойств любых сыпучих материалов.
Моделирование процесса формования керамических изделий
Автор(ы): Жапбасбаев У. К.*Рамазанова Г. И.*Саттинова З. К.*Шабдирова А. А.*
Реферат: Приводятся результаты моделирования процесса формования керамических изделий методом горячего литья. Математическая модель описывает движение и теплообмен жидкого термопластичного шликера оксида бериллия с учетом изменения агрегатного состояния. Получены поля скорости и температуры в процессе формования в фильерах плоской и круглой полости. Показано распределение теплового потока на стенке формообразующей полости. Установлено повышение плотности шликера при переходе из жидкого в вязкопластическое и твердопластичное состоянии.
Numerical study of established thermo-mechanical state of rods of limited length, with the presence of local heat flows, temperatures, heat insulation and heat transfer
Автор(ы): Tashenova Zh. M.*Zhumadillaeva A. K.*Nurlybaeva E. N.*Kudaykulov A. K.*
Объем документа: С. 2395-2397
МРНТИ: 30.19.33
Ключевые слова: закон сохранения энергии*минимизация тепловой энергии*разрешающая система линейных алгебраических уравнений*поле распределения температур*стержни*
Реферат: The paper considers two end clamped rods of limited length of constant or variable cross section. Some closed local surfaces of the rod are heat-insulated. On some surfaces, heat flows of various intensity and varying coordinate are led. Through some local surfaces, heat transfer takes place with their environment. Herewith, the coefficients of heat-transfer and environment temperature can be functions of coordinates. In some sections of the rod, temperatures of changing coordinate can be defined as well. The distribution law of temperature, movement, and constituting deformations and tension along the length of rod under study are determined. The value of arising compressive force is calculated. Solution of the problem will be in two stages. In the first stage, minimizing the functionality of complete heat energy over the discrete nodal values of temperature, the resolving system of equations is made. Solving this system, the field of temperature distribution along the length of the rod is determined. The magnitude of arising compressive force is determined.
Global and local smoothness of the Hilbert transforms
Автор(ы): (Дьяченко М. И.*Нурсултанов Е. Д.*Тихонов С. Ю.*
Реферат: We study the smoothness properties of the Hilbert transform in terms of the smoothness of the function itself. We prove global and local analogues of Privalov\'s theorem. The sharpness of these results is shown.
Necessary and sufficient conditions for boundedness of the Hardy-type operator from a weighted Lebesgue space to a Morrey-type space
Автор(ы): Burenkov V. I.*Oinarov R.*
Объем документа: С. 1-19
МРНТИ: 27.25.17
Ключевые слова: оператор Харди*весовые пространства Лебега*пространство Моррия*
Реферат: Necessary and sufficient conditions on functions u and w are established ensuring boundedness of the multi-dimensional Hardy-type operator H from a weighted Lebeg space L(R) to a local Morrey-type space for a wide range of the numerical parameters p, q.
Color center accumulation in LiF crystals under irradiation with MeV ions: Optical spectroscopy and modeling
Реферат: Lithium fluoride crystals irradiated at room temperature with energetic 14N and 84Kr ions were studied by absorption and luminescence spectroscopy. Dependence of the average F-center concentration on the fluence was found to be different for the lighter and the heavier projectiles. In particular, the maximal concentration of the F centers reached a notably higher value in the case of irradiation with 14N than that for 84 Kr ions. This result is compared with our model of track overlapping and defect accumulation. The luminescence studies allowed distinguishing F3+ and F2 centers, having very similar absorption spectra. The luminescence corresponding to both centers was observed starting from the minimal fluencies. It means that the aggregation processes take place in single tracks in agreement with our model, which predicts the coagulation radius of about five lattice parameters. Anion vacancies va+, having higher mobility than F centers, should play an important role in the aggregation.
LiF crystals irradiated with 150 MeV Kr ions: Peculiarities of color center creation and thermal annealing
Реферат: Color centers in LiF crystals are studied under irradiation at room temperature with 150 MeV Kr ions in the fluence (Ф) range of 10-10ions/cm2 with a beam current density of 10, 50, and 100 nA/cm2, corresponding to flux of 4.46*10, 2.23*10 and 4.46*10ions/(cm2 s), respectively. At Ф>=3*10 ions/cm2 besides F and Fn centers also charged F+3 centers are created. Thermal annealing of irradiated LiF crystals with Ф>=10 ions/cm2 at 400 K leads to a decrease of F centers (due to annihilation with H centers) and an enhancement of complex Fn color centers (neutral and charged) due to interaction with thermally activated anion vacancies. Annealing LiF crystals at higher temperature (T>=400 K) leads to a decrease both of F centers and Fn centers. In the annealing process up to 480 K the F2 and F+[3] centers are dominating until their reduction above 590 K. At temperatures above 740 K mainly small Li and trace element (Mg, Na) colloids are present in the absorption spectrum. The role of anion vacancies on color center creation and annealing is discussed.
First-principles modeling of the H color centers in MgF2 crystals
Ключевые слова: расчеты Н центров окраски кристаллов*неэмпирические расчеты*электронная структура заряда*атомная геометрия заряда*распределение плотности заряда*принцип моделирования H центров окраски*
Реферат: MgF2 with a rutile structure is important wide-gap optical material with numerous applications. We present and discuss the results of calculations for basic hole defects interstitial F atoms (called also the colour H centers). This study is based on the large scale ab initio DFT calculations using hybrid B3PW exchange-correlation functional as implemented into CRYSTAL computer code. The electronic structure, atomic geometry, charge density distribution are calculated and compared with similar defects in CaF2 fluorite. It is shown that the H centers oriented nearly parallel to the (110) axis are energetically more favourable than those oriented along the (001) axis, in agreement with experiment.
Radiation transformation of the oxygen-containing impurity in LiF crystals doped with different polyvalent cations
Автор(ы): Даулетбекова А.*(Лисицына Л. А.*(Корепанов В.*(Лисицын В.*(Трефилова Л.*Касымканова Р. Н.*
Реферат: Time-resolved spectroscopy and infrared spectroscopy were used to investigate radiation transformation of the oxygen-hydrogen impurity in LiF crystals doped with oxides of different metals Li, W, Ti and Fe with the ab-sorbed dose range of 10-10Gy in the time interval of 10{-9}-10{-1}s and in the temperature interval of 15-300 K.