Oscillation of solar radio emission at coronal acoustic cut-off frequency

Recent SECCHI COR2 observations on board STEREO-A spacecraft have detected density structures at a distance of 2.5--15~R propagating with periodicity of about 90~minutes. The observations show that the density structures probably formed in the lower corona. We used the large Ukrainian radio telescope URAN-2 to observe type IV radio bursts in the frequency range of 8--32~MHz during the time interval of 08:15--11:00~UT on August 1, 2011. Radio emission in this frequency range originated at the distance of 1.5--2.5 R according to the Baumbach-Allen density model of the solar corona. Morlet wavelet analysis showed the periodicity of 80~min in radio emission intensity at all frequencies, which demonstrates that there are quasi-periodic variations of coronal density at all heights. The observed periodicity corresponds to the acoustic cut-off frequency of stratified corona at a temperature of 1~MK. We suggest that continuous perturbations of the coronal base in the form of jets/explosive events generate acoustic pulses, which propagate upwards and leave the wake behind oscillating at the coronal cut-off frequency. This wake may transform into recurrent shocks due to the density decrease with height, which leads to the observed periodicity in the radio emission. The recurrent shocks may trigger quasi-periodic magnetic reconnection in helmet streamers, where the opposite field lines merge and consequently may generate periodic density structures observed in the solar wind.Comment: 10 pages, 6 figures, accepted in A&

The marginally stable Bethe lattice spin glass revisited

Bethe lattice spins glasses are supposed to be marginally stable, i.e. their equilibrium probability distribution changes discontinuously when we add an external perturbation. So far the problem of a spin glass on a Bethe lattice has been studied only using an approximation where marginally stability is not present, which is wrong in the spin glass phase. Because of some technical difficulties, attempts at deriving a marginally stable solution have been confined to some perturbative regimes, high connectivity lattices or temperature close to the critical temperature. Using the cavity method, we propose a general non-perturbative approach to the Bethe lattice spin glass problem using approximations that should be hopeful consistent with marginal stability.Comment: 23 pages Revised version, hopefully clearer that the first one: six pages longe

A unified stability property in spin glasses

Gibbs' measures in the Sherrington-Kirkpatrick type models satisfy two asymptotic stability properties, the Aizenman-Contucci stochastic stability and the Ghirlanda-Guerra identities, which play a fundamental role in our current understanding of these models. In this paper we show that one can combine these two properties very naturally into one unified stability property

Логістична підтримка в період війскових дій

Панченко А. С. Логістична підтримка в період війскових дій / А. С. Панченко / Авіація, промисловість, суспільство : матеріали ІІІ Міжнар. наук.-практ. конф. (м. Кременчук, 12 трав. 2022 р.) / МВС України, Харків. нац. ун-т внутр. справ, Кременчуц. льотний коледж, Наук. парк «Наука та безпека». – Харків : ХНУВС, 2022. – С. 887-888.Зазначено, що логістичні центри України повинні координувати діяльність та консультувати підприємств вантажоперевізників відносно безпечних маршрутів руху територією України з максимальною оптимізацією провізного процесу; відстежувати динаміку переміщення товарних запасів, витрати палива; здійснювати заходи щодо вирішення проблем організації вантажно- розвантажувальних робіт у тих чи інших місцях. Отмечено, что логистические центры должны координировать деятельность и консультировать предприятия грузоперевозчиков относительно безопасных маршрутов движения по территории Украины с максимальной оптимизацией провозного процесса; отслеживать динамику перемещения товарных запасов, расход топлива; осуществлять мероприятия по решению проблем организации погрузочно-разгрузочных работ в тех или иных местах. It was noted that logistics centers should coordinate the activities and advise the enterprises of cargo carriers regarding safe routes of movement through the territory of Ukraine with the maximum optimization of the transportation process; track the dynamics of the movement of inventory, fuel consumption; take measures to solve the problems of organizing loading and unloading operations in certain places

ДОСЛІДЖЕННЯ РЕЖИМІВ РОБОТИ ТЕПЛОВОЗА ЧМЕ3 НА ІМІТАЦІЙНІЙ МОДЕЛІ

Introduction. Fuel consumption by diesel locomotive during operation depends significantly on many factors, among which the main is the mode of driving a train. Purpose. Research on the mathematical model of the modes of driving a train on the site of Kharkiv-Merefa with the purpose of the main oscillograms of the operation of the locomotive on the site. Methodology. A mathematical model of the operation of the main units of the locomotive CHME3 in the Matlab environment was developed. The model of the diesel engine is based on the calculated indicator diagram of its operation, which is approximated by a continuous dependence. The control panel operates on a system of conditions, the purpose of which is to maintain the set speed. Results. In the course of the simulation, statistical data were obtained on the fuel consumption of the diesel locomotive when it operated on a section with a train of constant mass. Based on the data obtained, a three-dimensional surface is constructed showing the dependence of the fuel consumption on the time of the site's exploration and the maximum speed on the site. Practical value. The dependence obtained can be used to optimize the driving behavior of trains along a section. The apparent dependence of fuel consumption on the driver's behavior is the basis for the further development of automatic locomotive speed control systems.Розроблено імітаційну модель тепловоза ЧМЕ3, шо складається з дизеля з регулятором кількості обертів колінчастого валу, тягового генератора постійного струму незалежного збудження та тягового електричного приводу. Проведене тестування роботи імітаційної моделі на профілі ділянки шляху Харків - Мерефа, при цьому основними обмеженнями є час руху, який для даного перегону не повинен перевищувати 45 хв., а також максимальна допустима швидкість, яка для вантажних потягів складає 80км/год. Отримана тривимірна поверхня, що показує залежність витрат палива локомотива від режиму ведення потяга машиністом при виконанні однакової роботи, тобто однакового часу руху по перегону

Analyzing X-Ray Pulsar Profiles: Geometry and Beam Pattern of Her X-1

We report on our analysis of a large sample of energy dependent pulse profiles of the X-ray binary pulsar Hercules X-1. We find that all data are compatible with the assumption of a slightly distorted magnetic dipole field as sole cause of the asymmetry of the observed pulse profiles. Further the analysis provides evidence that the emission from both poles is equal. We determine an angle of 20 deg between the rotation axis and the local magnetic axis. One pole has an offset of 5 deg from the antipodal position of the other pole. The beam pattern shows structures that can be interpreted as pencil- and fan-beam configurations. Since no assumptions on the polar emission are made, the results can be compared with various emission models. A comparison of results obtained from pulse profiles of different phases of the 35-day cycle indicates different attenuation of the radiation from the poles being responsible for the change of the pulse shape during the main-on state. These results also suggest the resolution of an ambiguity within a previous analysis of pulse profiles of Cen X-3, leading to a unique result for the beam pattern of this pulsar as well. The analysis of pulse profiles of the short-on state indicates that a large fraction of the radiation cannot be attributed to the direct emission from the poles. We give a consistent explanation of both the evolution of the pulse profile and the spectral changes with the 35-day cycle in terms of a warped precessing accretion disk.Comment: 24 pages, 12 figures. To appear in ApJ 529 #2, 1 Feb 200