Effects of non-resonant interaction in ensembles of phase oscillators

We consider general properties of groups of interacting oscillators, for which the natural frequencies are not in resonance. Such groups interact via non-oscillating collective variables like the amplitudes of the order parameters defined for each group. We treat the phase dynamics of the groups using the Ott-Antonsen ansatz and reduce it to a system of coupled equations for the order parameters. We describe different regimes of co-synchrony in the groups. For a large number of groups, heteroclinic cycles, corresponding to a sequental synchronous activity of groups, and chaotic states, where the order parameters oscillate irregularly, are possible.Comment: 21 pages, 7 fig

Identification of corner separation modelling in axial compressor stage

The paper presents a study of corner separations in hub to blade region at various operation conditions towards compressor stall. It is known that for compressor flows with low or none separations computation fluid dynamics with RANS methods work quite well, however, for highly separated flows they are no longer entirely valid. Therefore, several criteria were applied for prediction and quantification of possible corner separation, and the main interest of this work is in predicting the separation just before it will actually happen by certain flow metrics, so these metrics can be further used as a 'pre-stall' criteria whilst the RANS CFD operating point still behave within its appropriate limits. Also the effect of shear lean is discussed in the presented context. © The Authors, published by EDP Sciences, 2020

Redesign of an axial compressor with mass flow reduction of 30%

In this paper redesign process of an axial compressor of a Gas Turbine for mechanical drive is discussed together with computational results and experimental data. The goal of the project was to reduce compressor mass flow by 30% and at the same time to increase compressor specific work by about 10%. This could not be achieved by conventional methods such as re-staggering of Inlet Guide Vanes. Throughflow and CFD calculations were performed for redesigned versions. As a result an updated compressor was produced for the real engine and achieved design objectives. This paper shows how the swept area distribution along the compressor affects stage loading distribution and surge limits. © 2019 WIT Press

Target mass number dependence of subthreshold antiproton production in proton-, deuteron- and alpha-particle-induced reactions

Data from KEK on subthreshold \bar{\mrm{p}} as well as on $\pi^\pm$ and \mrm{K}^\pm production in proton-, deuteron- and $\alpha$-induced reactions at energies between 2.0 and 12.0 A GeV for C, Cu and Pb targets are described within a unified approach. We use a model which considers a nuclear reaction as an incoherent sum over collisions of varying numbers of projectile and target nucleons. It samples complete events and thus allows for the simultaneous consideration of all final particles including the decay products of the nuclear residues. The enormous enhancement of the \bar{\mrm{p}} cross section, as well as the moderate increase of meson production in deuteron and $\alpha$ induced compared to proton-induced reactions, is well reproduced for all target nuclei. In our approach, the observed enhancement near the production threshold is mainly due to the contributions from the interactions of few-nucleon clusters by simultaneously considering fragmentation processes of the nuclear residues. The ability of the model to reproduce the target mass dependence may be considered as a further proof of the validity of the cluster concept.Comment: 9 pages, 4 figure

The Ethnic 'Other' in Ukrainian History Textbooks: The Case of Russia and the Russians

This paper examines portrayals of Russia and the Russians in two generations of Ukrainian history textbooks. It observes that the textbooks are highly condemning of Ukraine's main ethnic other in the guise of foreign ruler: the tsarist authorities and the Soviet regime are always attributed dubious and malicious intentions even if there is appreciation for some of their policies. By contrast, the books, certainly those of the second generation, refrain from presenting highly biased accounts of the ethnic other as a national group (i.e. Russians). Instances where negative judgements do fall onto Russians are counterbalanced by excerpts criticizing ethnic Ukrainians or highlighting conflicting interests within the Ukrainian ethnic group. The negative appraisal of the ethnic other as foreign ruler is clearly instrumental for the nation-building project as it sustains a discourse legitimating the existence of Ukraine as independent state. However, recent trends in history education, the paper concludes, suggest that the importance of nurturing patriotism as a national policy objective is diminishing

Investigation of the Influence of Ambient Conditions on the Thermodynamic Characteristics of Air as a Working Fluid for Gas Turbines

The study focuses on estimating thermodynamic characteristics at constant pressure for ambient air as a working fluid for gas turbines. The objective of this paper is to carry out a thermodynamic analysis of the properties of air as a working gas for a power plant. Various values of relative humidity, as well as temperatures, were examined in this study. Code was written using EES (Engineering Equations Solver) to conduct the simulation. This code contains the necessary equation to compute the thermodynamic characteristics of the working fluid. According to the results, both temperature and relative humidity remarkably influence the specific heat capacity (C_p), isentropic exponent (γ_h) as well as the gas constant of air (R_h). According to the results, when the ambient air temperature is increased from 0 to 45 ℃ with constant relative humidity values of either 10% or 90%, the specific heat capacity increases by 5.01% and 17.6%, respectively. Furthermore, the isentropic exponent decreases by 1.07% and 4.5%, respectively. The results show that the gas constant of air increases with ambient air temperature and relative humidity. One can conclude that the ambient conditions have considerable influence on the thermodynamic characteristics of a gas turbine working fluid. © 2023, Semarak Ilmu Publishing. All rights reserved.This research was not funded by any grant

Structure changes in InP and GaAs crystals double irradiated with electrons and swift heavy ions

We have studied InP and GaAs crystal structure changes under the influence of swift Kr and Bi ions irradiation by means of scanning electron microscopy, atomic force microscopy and selective chemical etching. The previous disordering of samples by electron irradiation is shown to be leading to macrodefect formation in the form of cracks and breaks at the depths near the ion end-of-range and on the crystal surface. A possible explanation of the observed effects is proposed.Вивчено вплив змін структури ІnP і GaAs при опроміненні іонами Kr і Bі й електронами при вивченні методом електронної мікроскопії, атомної силової мікроскопії й сективного хімічного травлення. Основними ефектами при цьому впливі були утворення тріщин і руйнувань структури поверхні, які найбільше значно проявлялися наприкінці пробігу іонів і поблизу поверхні. Можливе пояснення виявлених ефектів представлено.Изучено влияние изменений структуры InP- и GaAs- при облучении ионами Kr и Bi и электронами при изучении методом электронной микроскопии, атомной силовой микроскопии и сективного химического травления. Основными эффектами при этом воздействии являлись образование трещин и разрушений структуры поверхности, которые наиболее значительно проявлялись в конце пробега ионов и вблизи поверхности. Возможное объяснение обнаруженных эффектов представлено

Influence of Surrounding Air Temperature and Humidity upon the Performance of a Gas Turbine Power Plant

Nowadays, energy demand continuously rises while energy stocks are dwindling. Using current resources more effectively is crucial for the world. A wide method to effectively utilize energy is to generate electricity using thermal gas turbines (GT). One of the most important problems that gas turbines suffer from is high ambient air temperature especially in summer. The current paper details the effects of ambient conditions on the performance of a gas turbine through energy audits taking into account the influence of ambient conditions on the specific heat capacity (Cp), isentropic exponent (γh) as well as the gas constant of air (Rh). A computer program was developed to examine the operation of a power plant at various ambient temperatures and relative humidities. The ambient temperatures ranged from 0 to 45 ºC, with relative humidities from 10 to 90%. The obtained results show that a GT operated at increased inlet air temperatures is characterized by lower net power and thermal efficiency. At higher inlet air temperatures, increased relative humidity has a slight positive impact on the GT cycle net power and its thermal efficiency. Net output power of the GT decreased from 93.3 MW at 15 °C to 70 MW at 45 °C. Its efficiency decreased from 32.32% at 5 °C to 28.3% at 30 °C. Although fuel consumption is reduced, the heat rate as well and the specific fuel consumption (SFC) are enhanced. SFC increased by 5.36% with a 10 °C temperature rise in temperature at a constant relative humidity. Therefore, use of a gas turbine with inlet air cooling and humidification is appropriate for improved GT efficiency. © 2023, Semarak Ilmu Publishing. All rights reserved.This research was not funded by any grant

Near-threshold production of omega mesons in the pn -> d omega reaction

The first measurement of the p n -> d omega total cross section has been achieved at mean excess energies of Q = 28 and 57 MeV by using a deuterium cluster-jet target. The momentum of the fast deuteron was measured in the ANKE spectrometer at COSY-Juelich and that of the slow "spectator" proton p(sp) from the p d -> p(sp) d omega reaction in a silicon telescope placed close to the target. The cross sections lie above those measured for p p -> p p omega but seem to be below theoretical predictions.Comment: 7 pages, 8 figures; second approach to describe the background has been added; results changed insignificantly, EPJ in pres