Персона: Рябов, Павел Николаевич
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Институт лазерных и плазменных технологий
Стратегическая цель Института ЛаПлаз – стать ведущей научной школой и ядром развития инноваций по лазерным, плазменным, радиационным и ускорительным технологиям, с уникальными образовательными программами, востребованными на российском и мировом рынке образовательных услуг.
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Рябов
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Павел Николаевич
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- ПубликацияОткрытый доступStatistical features of plastic flow localization in materials(2019) Kudryashov, N. A.; Muratov, R. V.; Ryabov, P. N.; Кудряшов, Николай Алексеевич; Муратов, Родион Владимирович; Рябов, Павел Николаевич© 2019 Published under licence by IOP Publishing Ltd.We consider the processes of plastic flow localization in dipolar materials undergoing high speed shear deformations. The mathematical model of the processes of plastic flow localization is formulated taking into account dipolar effect. We introduce the numerical algorithm which is based on adaptive mesh refinement technique. We show that this algorithm allows to increase performance of computations. We also studied the statistical properties of shear bands formation. We show that dipolar effect changes average characteristics of the processes considered such as average temperature, stress and etc. Moreover this effect leads to increase in initiation time, changes the widths of localization zones and distances between them.
- ПубликацияОткрытый доступA Python software to evaluate geometric discrepancies between stereotactic CT and MR images in radiosurgery(2021) Bannikova, I. I.; Kostjuchenko, V. V.; Zavolovich, B. D.; Dalechina, A. V.; Ryabov, P. N.; Заволович, Богдан Дмитриевич; Далечина, Александра Владимировна; Рябов, Павел Николаевич© 2020 Elsevier B.V.. All rights reserved.Due to its excellent soft tissue contrast, magnetic resonance imaging (MRI) is widely used for target delineation in stereotactic radiosurgery. However, because of a number of factors (inhomogeneity of the constant magnetic field, nonlinearity of the gradient fields, etc.), MR images are more susceptible to spatial distortion as opposed to Computed tomography (CT) images, which could be considered as the reference studies in terms of the accuracy of target localization. It is crucial to assess the geometric errors in MR images as the accuracy of dose delivery strongly depends on MRI quality. One of the ways of MRI distortion evaluation is to scan a phantom with multiple marker points on both CT and MRI scanner and compare coordinates of the points defined on CT and MR images, respectively. Performing this test as a routine part of MRI quality assurance (QA) program for stereotactic radiosurgery is complicated by lack of a software for the automatic calculations of the discrepancies. The aim of our work was to develop a software to calculate discrepancies between stereotactic coordinates of the phantom's plastic rods defined on the MR and CT images of the Elekta MR phantom. A special Python software was developed and the spatial accuracy of the stereotactic MR images was assessed. The calculated total differences between the coordinates of the CT and T1 weighted MR images, CT and T2 weighted MR images exceeded 1 mm in 3,5%, 0.1% of the points, respectively. Using the software in clinic routines could both speed up the time needed for the test performance and eliminate subjective visual assessment of the discrepancies.
- ПубликацияОткрытый доступNumerical simulation of adiabatic shear bands formation processes on two-dimensional eulerian meshes(2020) Muratov, R. V.; Kudryashov, N. A.; Ryabov, P. N.; Муратов, Родион Владимирович; Кудряшов, Николай Алексеевич; Рябов, Павел Николаевич© Published under licence by IOP Publishing Ltd.In this work we suggest a mathematical model of motion of the elasto-plastic materials with nonlinear plasticity constitutive law; we also propose an effective numerical method for numerical simulations of such tasks on two-dimensional eulerian meshes. Based on the method, we research formation of multiple adiabatic shear bands (ASB) at high-speed shear deformations. We test our approach on two-dimensional problem where the initial heterogeneity of temperature leads to formation of adiabatic shear band.