Mathematical modeling of synchronous electric drive of reversible rolling stand

Данная статья посвящена разработке математической модели синхронного электропривода реверсивной прокатной клети применительно к одноклетьевым толстолистовым станам горячей прокатки. Представлена математическая модель электромеханической системы главного электропривода прокатной клети. Достоверное математическое описание главного электропривода позволяет анализировать ударные приложения нагрузки на электромеханическую систему клети при прокатке слябов из труднодеформируемых марок стали. Модель рекомендуется для анализа динамических режимов электроприводов реверсивных прокатных клетей при отработке управляющих и возмущающих воздействий.This article addresses the development of a mathematical model of a synchronous electric drive of a reversible rolling stand. There is the mathematical model of the electromechanical system of main electric drive of rolling mill in the article. The mathematical model allows one to analyze a shock loading on the mec hanical system of rolling stand. The mathematical model is recommended to research shock and control dynamic conditions of synchronous electric drives

Self-diffusion in fluids in porous glass: Confinement by pores and liquid adsorption layers

Diffusion coefficients of 10 different polar and nonpolar liquids filled in porous glasses with mean pore diameters of 4 or 30 nm were determined with the aid of the NMR field-gradient technique. In the time scale of these experiments (0.3 to 500 ms) diffusion coefficients were found to be time independent. Within the experimental error, no influence of the polarity of the adsorbate can be stated. The diffusion coefficients of all investigated fluids in glass with 4 and 30 nm pores were reduced by factors of 0.17 and 0.63, respectively, relative to the bulk values. This relatively weak reduction can be explained by considering the known porosities of the adsorbents. The second objective of this study was to examine the diffusion behaviour below the melting point of adsorbates in porous glass. Fluids confined in pores do not freeze at the bulk freezing temperatures. In this respect, two phases must be distinguished. A maximal two monolayer thick film adsorbed on the inner surfaces does not crystallize at all, whereas the 'free' fraction of the fluid in the pores freezes at reduced temperatures according to the Gibbs-Thompson relation. The nonfrozen surface layers form a network in which self-diffusion can be investigated. Experiments have been carried out with cyclohexane. A reduction factor of 0.06 was found relative to the extrapolated values of the entirely unfrozen fluid in porous glass with a mean pore diameter of 30 nm. It is, thus, demonstrated that molecules in adsorption layers virtually retain their translational degrees of freedom along the surfaces. The lowering of the diffusivity is mainly due to the geometric restriction rather than to the interaction with the surface

Proton and deuteron field-cycling NMR relaxometry of liquids confined in porous glasses

Polar and non-polar liquids in porous glasses have been studied by proton and deuteron field-cycling NMR relaxometry. The mean pore diameters were 4 nm, 30 nm and 208 nm. The frequency dependence of the spin-lattice relaxation time T1 is strongly influenced by the polarity of the adsorbate. Non-polar liquids show a flat T1 dispersion compared with polar species. We designate the two cases as 'weak' and 'strong' adsorption respectively. Molecules of liquids at surfaces are known to adopt a preferential orientation, whereas they retain a high diffusivity. Therefore, reorientations mediated by translational displacements (RMTD) must contribute to the correlation function which decays on a timescale of up to eight orders of magnitude greater than in the bulk. The high diffusivity at the surface is made plausible by a mechanism called bulk-mediated surface diffusion recently proposed by Bychuk and O'Shaughnessy [O.V. Bychuk and B. O'Shaughnessy, J. Chem. Phys., 101 (1994) 772]. These authors found that the displacements effective on the surface can be described as the result of Levy walks. They therefore obey a Cauchy distribution. This work employs the Cauchy distribution for a numerical derivation of a surface correlation function, g(r/c), which correctly reproduces the typical correlation lengths of the substrate and thus renders the notion of the liquid molecules performing Levy walks reasonable. The difference in T1 dispersion behaviours of polar and non-polar adsorbates disappears when the free liquid is frozen while the approximately two monolayers thick surface film remains liquid. The T1 dispersions are then equally steep irrespective of the polarity. This indicates that a non-polar liquid confined to a thin, topologically two-dimensional layer on a polar surface undergoes the same relaxation mechanism as a strongly adsorbed polar liquid which is dominated by RMTD processes. | Polar and non-polar liquids in porous glasses have been studied by proton and deuteron field-cycling NMR relaxometry. The frequency dependence of the spin-lattice relaxation time T1 is strongly influenced by the polarity of the adsorbate. Non-polar liquids show a flat T1 dispersion compared with polar species. The difference in T1 dispersion behaviors of polar and non-polar adsorbates disappears when the free liquid is frozen while the approximately two monolayers thick surface film remains liquid. The T1 dispersions are then equally steep irrespective of the polarity. This indicates that a non-polar confined to a thin, topologically two-dimensional layer on a polar undergoes the same relaxation mechanism as a strongly adsorbed polar liquid dominated by RMTD processes

ЭФФЕКТ ВЛИЯНИЯ ОРИЕНТАЦИИ И НАПРЯЖЕННОСТИ ВНЕШНЕГО МАГНИТНОГО ПОЛЯ НА ПРОЦЕСС КОРРОЗИИ ФЕРРОМАГНИТНЫХ ТОНКИХ ПЛЕНОК ЖЕЛЕЗА

The results of a study on the rate of galvanic corrosion of thin ferromagnetic iron films in an external uniform magnetic field are presented. It is shown that the direction of the external magnetic field has different influence on the corrosion rate in the presence of a magnetic field. The shape of the micro-relief surface iron film subjected to a short-term treatment with a solution of acetic acid was studied. The relief is formed on the surface due to the heterogeneity of the corrosion rate on the surface of the film. Areas of high corrosion rates correspond to areas of the domain boundaries of the ferromagnetic film. When the orientation of the external magnetic field is changed, the domain structure changes, which is reflected in the change of the average rate of corrosion.Представлены результаты исследования скорости электрохимической коррозии тонких ферромагнитных пленок железа в присутствии внешнего однородного магнитного поля. Показано, что направление внешнего магнитного поля по-разному влияет на характер зависимости скорости коррозии от напряженности магнитного поля

Semantic segmentation of microbial alterations based on SegFormer

IntroductionPrecise semantic segmentation of microbial alterations is paramount for their evaluation and treatment. This study focuses on harnessing the SegFormer segmentation model for precise semantic segmentation of strawberry diseases, aiming to improve disease detection accuracy under natural acquisition conditions.MethodsThree distinct Mix Transformer encoders - MiT-B0, MiT-B3, and MiT-B5 - were thoroughly analyzed to enhance disease detection, targeting diseases such as Angular leaf spot, Anthracnose rot, Blossom blight, Gray mold, Leaf spot, Powdery mildew on fruit, and Powdery mildew on leaves. The dataset consisted of 2,450 raw images, expanded to 4,574 augmented images. The Segment Anything Model integrated into the Roboflow annotation tool facilitated efficient annotation and dataset preparation.ResultsThe results reveal that MiT-B0 demonstrates balanced but slightly overfitting behavior, MiT-B3 adapts rapidly with consistent training and validation performance, and MiT-B5 offers efficient learning with occasional fluctuations, providing robust performance. MiT-B3 and MiT-B5 consistently outperformed MiT-B0 across disease types, with MiT-B5 achieving the most precise segmentation in general.DiscussionThe findings provide key insights for researchers to select the most suitable encoder for disease detection applications, propelling the field forward for further investigation. The success in strawberry disease analysis suggests potential for extending this approach to other crops and diseases, paving the way for future research and interdisciplinary collaboration

Parental breeding age effects on descendants' longevity interact over 2 generations in matrilines and patrilines

Individuals within populations vary enormously in mortality risk and longevity, but the causes of this variation remain poorly understood. A potentially important and phylogenetically widespread source of such variation is maternal age at breeding, which typically has negative effects on offspring longevity. Here, we show that paternal age can affect offspring longevity as strongly as maternal age does and that breeding age effects can interact over 2 generations in both matrilines and patrilines. We manipulated maternal and paternal ages at breeding over 2 generations in the neriid fly Telostylinus angusticollis. To determine whether breeding age effects can be modulated by the environment, we also manipulated larval diet and male competitive environment in the first generation. We found separate and interactive effects of parental and grand-parental ages at breeding on descendants' mortality rate and life span in both matrilines and patrilines. These breeding age effects were not modulated by grand-parental larval diet quality or competitive environment. Our findings suggest that variation in maternal and paternal ages at breeding could contribute substantially to intrapopulation variation in mortality and longevity

Female responses to experimental removal of sexual selection components in Drosophila melanogaster

Despite the common assumption that multiple mating should in general be favored in males, but not in females, to date there is no consensus on the general impact of multiple mating on female fitness. Notably, very little is known about the genetic and physiological features underlying the female response to sexual selection pressures. By combining an experimental evolution approach with genomic techniques, we investigated the effects of single and multiple matings on female fecundity and gene expression. We experimentally manipulated the opportunity for mating in replicate populations of Drosophila melanogaster by removing components of sexual selection, with the aim of testing differences in short term post-mating effects of females evolved under different mating strategies