Модернизация тепловой системы железнодорожных станций

[For the English abstract and full text of the article please see the attached PDF-File (English version follows Russian version)].ABSTRACT The article considers the need to modernize the heat supply system of railway stations within the framework of the main guidelines of the energy strategy of the Russian Federation until 2030. The main park of boiler rooms is equipped with the aged machinery that by some features does not meet the standards of environmental friendliness, safety and efficiency. The article presents the main indicators of boiler rooms of a new type. The comparative analysis of the characteristics of the new and former boiler rooms as of an energy complex is suggested. The conformity of the proposed indicators to the guidelines of the energy strategy of the Russian Federation and subsequent innovations is determined. One of the conclusions of the authors is that in addition to replacing the equipment, it is necessary to conduct decentralization of the station’s heat supply system. Keywords: energy efficiency, operating costs, steam boilers, reserve fuel, fuel oil, diesel, block-modular boiler rooms, efficiency.Текст аннотации на англ. языке и полный текст статьи на англ. языке находится в прилагаемом файле ПДФ (англ. версия следует после русской версии).Авторами рассмотрен вопрос о необходимости модернизации системы теплоснабжения железнодорожных станций в рамках основных ориентиров энергетической стратегии Российской Федерации до 2030 года. Основной парк котельных оборудован техникой прежних лет выпуска, которая по некоторым параметрам не соответствует стандартам экологичности, безопасности и эффективности. В статье представлены основные показатели котельных нового типа. Приведен сравнительный анализ характеристик новой и прежней котельной как энергетического комплекса, определено соответствие достигаемых показателей ориентирам энергетической стратегии РФ

Fractional ac Josephson effect in unconventional superconductors

For certain orientations of Josephson junctions between two p_x-wave or two d-wave superconductors, the subgap Andreev bound states produce a 4pi-periodic relation between the Josephson current I and the phase difference phi: I ~ sin(phi/2). Consequently, the ac Josephson current has the fractional frequency eV/h, where V is the dc voltage. In the tunneling limit, the Josephson current is proportional to the first power (not square) of the electron tunneling amplitude. Thus, the Josephson current between unconventional superconductors is carried by single electrons, rather than by Cooper pairs. The fractional ac Josephson effect can be observed experimentally by measuring frequency spectrum of microwave radiation from the junction.Comment: 8 pages, 3 figures, RevTEX 4; v2. - minor typos corrected in proof

Current-voltage characteristic of narrow superconducting wires: bifurcation phenomena

The current-voltage characteristics of long and narrow superconducting channels are investigated using the time-dependent Ginzburg-Landau equations for complex order parameter. We found out that the steps in the current voltage characteristic can be associated with bifurcations of either steady or oscillatory solution. We revealed typical instabilities which induced the singularities in current-voltage characteristics, and analytically estimated period of oscillations and average voltage in the vicinity of the critical currents. Our results show that these bifurcations can substantially complicate dynamics of the order parameter and eventually lead to appearance of such phenomena as multistability and chaos. The discussed bifurcation phenomena sheds a light on some recent experimental findings

Histological classification of mesial temporal sclerosis

Mesial temporal sclerosis (MTS) is the most common histopathology occurring in patients with drug-resistant temporal lobe epilepsy. Over the past decades, there have been various attempts to classify the variants of hippocampal neuronal cell loss in relation to postoperative outcome. However, no consensus on the common international definition and classification of MTS has been reached. The article describes the modern histological classification based on a semiquantitative hippocampal cell loss model. The publications dealing with the histological classification of mesial temporal sclerosis are reviewed

Dzyaloshinskii--Moriya interaction: How to measure its sign in weak ferromagnetics?

Three experimental techniques sensitive to the sign of the Dzyaloshinskii--Moriya interaction are discussed: neutron diffraction, Moessbauer gamma-ray diffraction, and resonant x-ray scattering. Classical examples of hematite (alpha-Fe2O3) and MnCO3 crystals are considered in detailComment: 5 pages, 1 figure; to be published in JETP Letter

Dynamics of resistive state in thin superconducting channels

This article was published in the journal Physical Review B [© The American Physical Society]. It is also available at: http://dx.doi.org/10.1103/PhysRevB.87.174516We study theoretically how the dynamics of the resistive state in narrow superconducting channels shunted by an external resistor depends on channel's length L, the applied current j, and parameter u characterizing the penetration depth of the electric field in nonequilibrium superconductors. We show that changing u dramatically affects both the behavior of the current-voltage characteristics of the superconducting channels and the dynamics of their order parameter. Previously, it was demonstrated that when u is less than the critical value uc1, which does not depend on L, the phase slip centers appear simultaneously at different spots of the channel. Herewith, for u>uc1 these centers arise consecutively at the same place. In our work we demonstrate that there is another critical value for u. Actually, if u does not exceed a certain value uc2, which depends on L, the current-voltage characteristic exhibits the step-like behavior. However, for u>uc2 it becomes hysteretic. In this case, with increase of j the steady state, which corresponds to the time-independent distribution of the order parameter along the channel, losses its stability at switching current value jsw, and time-periodic oscillations of both the order parameter and electric field occur in the channel. As j sweeps down, the periodic dynamics ceases at certain retrapping current value jr<jsw. Shunting the channel by a resistor increases the value of jr, while jsw remains unchanged. Thus, for some high-enough conductivity of the shunt, jr and jsw eventually coincide, and the hysteretic loop disappears. We reveal dynamical regimes involved in the hysteresis and discuss the bifurcation transitions between them

Состав отходящих газов при каталитическом синтезе углеродных наноматериалов при пиролитическом разложении пропан-бутановой смеси

It is known that during the process of carbon nanomaterials synthesis, gaseous products and various unknown hydrocarbons are formed. Thus, the production of carbon nanomaterials could damage the environment. A detailed analysis of all gaseous products during the pyrolysis process is needed in order to clarify the nature of the formed substances and to control the technological characteristics of the catalyst. The chemical composition study of exhaust gases was made on the facility of propane-butane mixture pyrolysis for the carbon nanomaterial synthesis. The analysis of 16 polycyclic aromatic hydrocarbons (PAHs) of the extracts is made using a gas chromatography-mass spectrometry method. A quantitative analysis of gases was made by gas chromatography coupled with a heat conduction detector and a flame ionization detector. It was established that the concentrations of some PAHs exceed 14, 20, 90 and 100 times much as a maximum permissible concentration in the air. It was found that the appropriate devices of carbon nanomaterial production should be used in order to eliminate the PAHs that are formed.Анализ отходящих газов установки пиролиза легких углеводородов в процессе синтеза углеродных наноматериалов является актуальной задачей не только для оценки количества образующихся вредных веществ, но и для обеспечения наибольшей производительности реактора и максимальной степени конверсии исходного сырья. Методом газовой хроматографии проведен качественный и количественный анализ отходящих газов: неконденсируемых газообразных фракций и адсорбируемых ароматических углеводородов. В результате экспериментов было установлено, что основными компонентами отходящих газов являются водород и метан. В соответствии с утвержденной в Республике Беларусь методикой измерены значения 16 полициклических ароматических углеводородов, обнаруженных в отходящих газах. Проведено сравнение полученных значений с нормативными предельно допустимыми концентрациями канцерогенов в воздухе. Установлено, что концентрации пирена, фенантрена, аценафтилена, аценафтена превышают норму в 1,5–6 раз, а содержание таких токсикантов, как бенз(а)антрацен, антрацен, бенз(а)пирен и дибенз(а,h)антрацен значительно превышают норму. Полученная информация позволяет оценить степень опасности для экологии и возможный вклад таких установок в загрязнение окружающей среды, а также прогнозировать защитные меры по снижению вредного воздействия

Arctic Ocean fresh water changes over the past 100 years and their causes

Recent observations show dramatic changes of the Arctic atmosphere–ice–ocean system. Here the authors demonstrate, through the analysis of a vast collection of previously unsynthesized observational data, that over the twentieth century the central Arctic Ocean became increasingly saltier with a rate of freshwater loss of 239 ± 270 km3 decade−1. In contrast, long-term (1920–2003) freshwater content (FWC) trends over the Siberian shelf show a general freshening tendency with a rate of 29 ± 50 km3 decade−1. These FWC trends are modulated by strong multidecadal variability with sustained and widespread patterns. Associated with this variability, the FWC record shows two periods in the 1920s–30s and in recent decades when the central Arctic Ocean was saltier, and two periods in the earlier century and in the 1940s–70s when it was fresher. The current analysis of potential causes for the recent central Arctic Ocean salinification suggests that the FWC anomalies generated on Arctic shelves (including anomalies resulting from river discharge inputs) and those caused by net atmospheric precipitation were too small to trigger long-term FWC variations in the central Arctic Ocean; to the contrary, they tend to moderate the observed long-term central-basin FWC changes. Variability of the intermediate Atlantic Water did not have apparent impact on changes of the upper–Arctic Ocean water masses. The authors’ estimates suggest that ice production and sustained draining of freshwater from the Arctic Ocean in response to winds are the key contributors to the salinification of the upper Arctic Ocean over recent decades. Strength of the export of Arctic ice and water controls the supply of Arctic freshwater to subpolar basins while the intensity of the Arctic Ocean FWC anomalies is of less importance. Observational data demonstrate striking coherent long-term variations of the key Arctic climate parameters and strong coupling of long-term changes in the Arctic–North Atlantic climate system. Finally, since the high-latitude freshwater plays a crucial role in establishing and regulating global thermohaline circulation, the long-term variations of the freshwater content discussed here should be considered when assessing climate change and variability

Study of the characteristics of high-energy proton-induced gamma ray and neutron emission from materials that imitate surface of planets.

A proposed ISTC Project is discussed in the present paper. The proposal is aimed at experiments to determine the space-energy characteristics of the neutron and gamma ray emission fields generated by 0.2-0.8 GeV proton irradiation of thick targets composed of various elements. At present, reliable data on physical properties of secondary radiation from materials irradiated by intennediate- and high-energy protons for some fundamental and applied researches in astrophysics, space physics, atomic and nuclear physics, as well as for designing and operating the latest accelerators are lacking