Rationing and vibration monitoring of knife refiners

The subject of the research is rationing and monitoring of the vibration of knife refiners. GOST 26493-85, specifying the permissible values of the vibration amplitude of the mills, is outdated. This standard does not take into account new designs of knife refiners and the requirements of national and international standards. It is proposed to establish two criteria for assessing the vibration state of the refiners. The first criterion normalizes the amplitude of vibration in octave strips of frequencies, while the second criterion specifies the vibration trend on the general level. It is proposed to use the vibration velocity as the measured parameter. The necessity of separating the refiners into two groups was revealed: with a disc or cone diameter up to 1000 mm and with a diameter over 1000 mm. The boundaries of zones and vibration trends are determined: good; satisfactorily; need improvement and unacceptable. After that, a decision is made to limit the functioning of these machines (prevention and stop). The introduction of standards and vibration monitoring will accelerate the transition to repairs of machines on the technical condition. Methods of rationing and monitoring can be used in other industries, for example, in the mining and metallurgical industries. © Published under licence by IOP Publishing Ltd

Flexural fluctuations of the rotors of knife refiners

The subject of the study is the flexural fluctuations of the rotors of knife refiners. The dynamic and mathematical models of rotors of disk mills are developed. As a result of research, a method for vibration calculation of rotors is proposed and tested. Research was also conducted using the Ansys software package. The error in determining the lower frequencies of free fluctuations of the mill rotors does not exceed 9%. Failure to take into account the elastic compliance of the rotor bearings leads to an error in determining the frequencies of free flexural fluctuations by no more than 15%, and the gyroscopic moment increases the above frequencies by no more than 25%. The cantilever arrangement of the disk reduces the frequencies of free fluctuations of the mill rotor by 1.1 - 1.4 times in comparison with the inter-support arrangement. The developed calculation procedure can be used in other industries, for example, mining and metallurgy. © Published under licence by IOP Publishing Ltd

Collective modes in uniaxial incommensurate-commensurate systems with the real order parameter

The basic Landau model for uniaxial systems of the II class is nonintegrable, and allows for various stable and metastable periodic configurations, beside that representing the uniform (or dimerized) ordering. In the present paper we complete the analysis of this model by performing the second order variational procedure, and formulating the combined Floquet-Bloch approach to the ensuing nonstandard linear eigenvalue problem. This approach enables an analytic derivation of some general conclusions on the stability of particular states, and on the nature of accompanied collective excitations. Furthermore, we calculate numerically the spectra of collective modes for all states participating in the phase diagram, and analyze critical properties of Goldstone modes at all second order and first order transitions between disordered, uniform and periodic states. In particular it is shown that the Goldstone mode softens as the underlying soliton lattice becomes more and more dilute.Comment: 19 pages, 16 figures, REVTeX, to be published in Journal of Physics A: Mathematical and Genera

Landau Model for Commensurate-Commensurate Phase Transitions in Uniaxial Improper Ferroelectric Crystals

We propose the Landau model for lock-in phase transitions in uniaxially modulated improper ferroelectric incommensurate-commensurate systems of class I. It includes Umklapp terms of third and fourth order and secondary order parameter representing the local polarization. The corresponding phase diagram has the structure of harmless staircase, with the allowed wave numbers obeying the Farey tree algorithm. Among the stable commensurate phases only those with periods equal to odd number of lattice constants have finite macroscopic polarizations. These results are in excellent agreement with experimental findings in some A2BX4 compounds.Comment: 9 pages, 5 figures, revtex, to be published in Journal of Physics: Cond. Matter as a Letter to the Edito

Поліморфізм і диференціація популяцій Pinus syilvestris в Українських Карпатах

The analysis and synthesis of the data on allozyme structure, polymorphism and degree of genogeographic differentiation of mountain populations of Scots pine isolated in the Ukrainian Carpathians showed considerable genetic variability of foothill and mountain populations of Pinus sylvestris L., as well as the average genetic distance between these groups of populations. The differentiation between these groups of populations isolated by the ridges corresponds to the rank of geographic groups of populations. On the basis of our results there are sufficient grounds to separate the Carpathian mountain geographical race of Pinus sylvestris L. – var. carpatica Klika. Проанализированы и обобщены основные результаты исследований аллозимной структуры, полиморфизма и степени геногеографической дифференциации системы разновысотных горных популяций-изолятов сосны обыкновенной в Украинских Карпатах. Выявлена значительная генетическая вариабельность предгорных и горных популяций Pinus sylvestris L., а также cредняя генетическая дистанция между группами этих популяций. Дифференциация между группами популяций, изолированных отрогами хребтов, соответствует рангу географических групп популяций. На основаниии полученных результатов имеются достаточные аргументы для выделения карпатской горной географической расы Pinus sylvestris L. – var. carpatica Klika. Проаналізовано та узагальнено основні результати досліджень алозимної структури, поліморфізму та ступеня геногеографічної диференціації системи різновисотних гірських популяцій-ізолятів сосни звичайної в Українських Карпатах. Виявлено значну генетичну варіабельність передгірських і гірських популяцій Pinus sylvestris L., а також cередню генетичну дистанцію між групами цих популяцій. Диференціація між групами популяцій, ізольованих відрогами хребтів, відповідає рангу географічних груп популяцій. На основі отриманих результатів є достатні підстави для виділення карпатської гірської географічної раси Pinus sylvestris L. – var. carpatica Klika.

Landau model for uniaxial systems with complex order parameter

We study the Landau model for uniaxial incommensurate-commensurate systems of the I class by keeping Umklapp terms of third and fourth order in the expansion of the free energy. It applies to systems in which the soft mode minimum lies between the corresponding commensurate wave numbers. The minimization of the Landau functional leads to the sine-Gordon equation with two nonlinear terms, equivalent to the equation of motion for the well-known classical mechanical problem of two mixing resonances. We calculate the average free energies for periodic, quasiperiodic and chaotic solutions of this equation, and show that in the regime of finite strengths of Umklapp terms only periodic solutions are absolute minima of the free energy, so that the phase diagram contains only commensurate configurations. The phase transitions between neighboring configurations are of the first order, and the wave number of ordering goes through harmless staircase with a finite number of steps. These results are the basis for the interpretation of phase diagrams for some materials from the I class of incommensurate-commensurate systems, in particular of those for A$_2$BX$_4$ and BCCD compounds. Also, we argue that chaotic barriers which separate metastable periodic solutions represent an intrinsic mechanism for observed memory effects and thermal hystereses.Comment: 12 pages, 14 figures, LaTeX, to be published in Phys. Rev.

Review of Epidemiological Situation on Rickettsioses in the Russian Federation in 2022 as Compared with 2013–2021, Forecast for 2023

The aim of the review was to characterize the epidemiological situation on tick-borne rickettsioses (TR) in the Russian Federation in 2022 in comparison with the pandemic years of 2020–2021 and the pre-pandemic period of 2013–2019, to give the forecast for 2023. During 2013–2022, a pattern was observed in the incidence of rickettsiosis of the tick-borne spotted fever group (with the exception of Astrakhan spotted fever – ASF), that is also characteristic of most other natural focal infections (NFIs): a sharp decrease in registered incidence rates in 2020–2021 with the subsequent increase in 2022 almost up to pre-pandemic levels or even exceedance in some regions. The absence of a defining influence of the frequency of contacts of the population with vectors on the decrease in the incidence in the period of 2020–2021 and the rise in the value in 2022 confirms the registration-related nature of the changes. Given due attention to the problem of effective detection and reporting of NFIs, we expect the incidence of tick-borne rickettsioses to remain within the confidence intervals of long-term average values in most endemic regions in 2023. Relaxed vigilance to the problem of NFIs may lead to a decline in the reported incidence of Siberian tick-borne typhus in the Krasnoyarsk and Zabaikalsky Territories, Republics of Tuva and Khakassia, Novosibirsk and Amur Regions; reduction in the incidence of ASF in Astrakhan Region. The main issue in detecting and registration of the tick-borne rickettsiosis incidence, objective assessment and forecasting of the epidemic situation as regards this group of infections is conditioned by the lack of domestic certified diagnostic test kits for laboratory verification of rickettsioses. Close cooperation between epidemiologists and clinicians is required to establish and register cases of TR based on clinical and epidemiological data

Diversity-Oriented Synthesis of Novel Trihalomethyl-Containing Spirochromeno[3,4- a ](thia)pyrrolizidines and Spirochromeno-[3,4- a ]indolizidines by One-Pot, Three-Component [3+2]-Cyclo addition Reaction

Regio- and stereoselective methods for the synthesis of 6′-trifluoro(trichloro)methyl substituted spiro[acenaphthylene-1,11′-chromeno[3,4- a ](thia)pyrrolizidin]-2-ones and spiro[acenaphthylene-1,12′-chromeno[3,4- a ]indolizidin]-2-ones have been developed based on the three-component reaction of 3-nitro-2-trifluoro(trichloro)methyl-2 H -chromenes with azomethine ylides generated in situ from acenaphthenequinone and cyclic α-amino acids. The cycloaddition proceeds under mild conditions in ethanol or DMSO, and only endo -isomers of the products with cis -arrangement of nitro and trifluoromethyl groups are formed. The relative configuration of cycloadducts is reliably confirmed by X-ray diffraction analysis and by 2D NOESY spectroscopy. © 2021 Georg Thieme Verlag. All rights reserved.The work was financially supported by the Russian Foundation for Basic Research (grant 20-03-00716) and by the Ministry of Science and Higher Education of the Russian Federation (project FEUZ-2020-0052)