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Model of fractured medium and nondestructive control of composite materials

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Chinese Journal of Aeronautics 2024年第2期37卷 93-99页

作者： Vasily GOLUBEV Ilia nikitin Katerina BEKLEMYSHEVA Department of Computers Science and Numerical Mathematics Moscow Institute of Physics and TechnologyDolgoprudny 141700Russia Mathematical Modeling and Management Department of InformatizationInstitute of Computer Aided Design RASMoscow 123056Russia

Non-destructive testing of composites is an important issue in the modern aircraft *** are susceptible to the barely visible impact damage which can affect the residual strength of the material and occurs both during production and *** continuum model for describing the damaged zone is *** slip theory relations used for a continuous distribution of slip planes are *** the initial stage,the isotropic background model is *** model allows the material slippage along the fractures based on the Coulomb friction law with the small viscous *** this regime,the govern system of equations becomes *** overcome this difficulty,the explicit-implicit grid-characteristic scheme is *** standard ultrasound diagnostic procedure of damaged composite materials is successfully *** with the trivial free-surface fracture model,different reactions on the compression and stretch waves are *** approach provided an effective way for the simulation of complex dynamic behavior of damage zones.

关键词： Non-destructive testing Composite materials Numerical modeling Continuum model Grid-characteristic method

Inhibition of CXCR4/CXCL12 signaling:a translational perspective for Alzheimer’s disease treatment

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Neural Regeneration Research 2022年第1期17卷 108-109页

作者： Yuval Gavriel Inna Rabinovich-nikitin Beka Solomon The Shmunis School of Biomedicine and Cancer Research George S.Wise Faculty of Life SciencesTel Aviv UniversityTel AvivIsrael

The mechanism of AD remains uncovered:The current mainstream doctrine in Alzheimer’s disease(AD)is the amyloid cascade *** to this hypothesis,amyloid-β(Aβ)deposition is the main reason for neurofibrillary tangles f... 详细信息

关键词： Alzheimer amyloid Aβ

Hereditary effect of Al-based modifiers and grain refiners on structure and properties of A356.2 alloys

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中国有色金属学会会刊：英文版 2002年第2期12卷 233-237页

作者：李培杰张燕飞 V.I.nikitin E.G.Kandalova K.V.nikitin Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China Physical and Technological Department Samara State Technical UniversitySamara 443010Russia

The hereditary effect of Al Ti, Al Ti B, Al Sr master alloys on the structure and properties of A356.2 alloys was investigated, and comparison analysis between the master alloys used in the foundry industry and the fine crystalline grain refiners produced by technologies of Samara State Technical University was conducted. The results show that less than 0.5% additions of FCR master alloys can promote 8%～20% in the elongation of as cast A356.2 alloys. FCR additives are more efficient in comparison with conventional grain refiners and modifiers. Their effectiveness depends on their genetic effect of their finer structures.

关键词：中间合金遗传效应晶粒细化 A356.2合金铝合金

A NUMERICAL METHOD FOR THE SIMULATION OF FREE SURFACE FLOWS OF VISCOPLASTIC FLUID IN 3D

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Journal of Computational Mathematics 2011年第6期29卷 605-622页

作者： Kirill D. nikitin Maxim A. Olshanskii Kirill M. Terekhov Yuri V. Vassilevski Institute of Numerical Mathematics Russian Academy of Sciences Moscow Russia Department of Mechanics and Mathematics Moscow State University Moscow Russia

In this paper we study a numerical method for the simulation of free surface flows of viscoplastic （Herschel-Bulkley） fluids. The approach is based on the level set method for capturing the free surface evolution and on locally refined and dynamically adapted octree cartesian staggered grids for the discretization of fluid and level set equations. A regu- larized model is applied to handle the non-differentiability of the constitutive relations. We consider an extension of the stable approximation of the Newtonian flow equations on staggered grid to approximate the viscoplastic model and level-set equations if the free boundary evolves and the mesh is dynamically refined or coarsened. The numerical method is first validated for a Newtonian case. In this case, the convergence of numerical solutions is observed towards experimental data when the mesh is refined. Further we compute several 3D viscoplastic Herschel-Bulkley fluid flows over incline planes for the dam-break problem. The qualitative comparison of numerical solutions is done versus experimental investigations. Another numerical example is given by computing the freely oscillating viscoplastic droplet, where the motion of fluid is driven by the surface tension forces. Altogether the considered techniques and algorithms （the level-set method, compact discretizations on dynamically adapted octree cartesian grids, regularization, and the surface tension forces approximation） result in efficient approach to modeling viscoplastic free-surface flows in possibly complex 3D geometries.

关键词： Free surface flows Viscoplastic fluid Adaptive mesh refinement Oetree meshes.

Magnetic properties, magnetoresistivity and magnetocaloric effect in Gd_xLa_(1-x)-MnSi alloys

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Journal of Rare Earths 2009年第4期27卷 684-687页

作者： T.I.Ivanova S.A.nikitin W.Suski G.A.Tskhadadze I.A.Ovtchenkova D.Badurski Physics Department Moscow State University 119992 Moscow Russia International Laboratory of High Magnetic Fields and Low Temperatures Wroclaw Poland Polish Academy of Sciences Trzebiatowski Institute of Low Temperatures and Structure Research P.O.Box 1410 50-950 Wroclaw 2 Poland

The results of magnetization, magnetoresistivity and magnetocalofic effect （MCE） studies performed on polycrystalline samples of the GdxLa1-xMnSi （x=0.5, 0.6, 0.7, 0.8, 0.9, 1.0） compounds were presented. Complex measurements were carried out on the GdxLa1-xMnSi compounds to determine the influence of substitution in the rare earth （R） sublattice on the magnetic and related properties of these compounds. The compounds with x≤0.6 demonstrated two magnetic phase transitions （ferromagnetic to paramagnetic and antiferro- magnetic to ferromagnetic） both of which were first order. Anomalies in the magnetocaloric effect, electroresistivity and magnetoresistivity were observed in the temperature ranges of the magnetic phase transitions. The temperature dependences of MCE and magnetoresistivity for these compounds correlated with the temperature dependence of magnetization.

关键词： magnetocaloric effect magnetoresistivity magnetic phase Iransition itinerant magnetism rare earths

Study of laser beam scattering by inhomogeneous ensemble of red blood cells in a shear flow

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Journal of Innovative Optical Health Sciences 2015年第4期8卷 85-96页

作者： S.Yu nikitin A.E.Lugovtsov V.D.Ustinov M.D.Lin A.V.Priezzhev Physics Faculty Lomonosov Moscow State University Moscow Russia International Laser Center Lomonosov Moscow State University MoscowRussia Faculty of Computational Mathematics and Cybernetics Lomonosov Moscow State University Moscow Russia Faculty of Fundamental Medicine Lomonosov Moscow State University Moscow Russia

Laser elktacytometry is a technique widely used for measuring the deformability of red blood cells(erythrocytes)in blood samples in *** ektacytometer,a flow of highly diluted suspension of erythrocytes in variable shear stress conditions is iluninated with a laser beam to obtain a diffraction *** diffraction pattern provides information about the shapes(shear induced elongations)of the cells under *** paper is dedicated to developing the technique of laser ektacytometry s0 that it would enable one to measure the distrilbution of the erythrocytes in *** discuss the problem of calibration of laser elktacytometer and test a novel data processing algorithm allowing to determine the parameters of the distribution of ery-throcytes ***,we examined 12 specimens of blood of rats under the action of 4 shear *** of the data shows that in conditions of a limited range of digitizing the diffraction patterns,the measurement errors for the mean deformability,deform-ability scatter and the skewness of erythrocytes distribution in deformability by our method are respectively 15%,20%and 20%.

关键词： Laser ifractometry ektacytometry shear flow difraction pattern deformability of erythrocytes erythrocytes variance in shapes image analysis

SHS法制备Al_3Ti/Al复合材料的研究

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稀有金属材料与工程 2000年第3期29卷 145-148页

作者：介万奇 E.G.Kandalova 张瑞杰 V.I.nikitin 西北工业大学西安710072 萨马拉国立工业大学

介绍了高熔点化合物颗粒增强的铝基复合材料的一种先进制备方法 ,即自蔓延高温合成法 (SHS法 ) ,并以Al3Ti/ Al为例进行了实验研究。结果表明 ,将 Ti粉与 Al粉混合 ,在铝合金液中进行自蔓延高温合成 ,可有效地控制 Al3Ti的形态。其中 Al... 详细信息

介绍了高熔点化合物颗粒增强的铝基复合材料的一种先进制备方法 ,即自蔓延高温合成法 (SHS法 ) ,并以Al3Ti/ Al为例进行了实验研究。结果表明 ,将 Ti粉与 Al粉混合 ,在铝合金液中进行自蔓延高温合成 ,可有效地控制 Al3Ti的形态。其中 Al∶Ti比是控制 Al3Ti形态的关键参数。当 Al∶Ti比远小于理论化学计量比 3∶ 1时 ,获得针状 Al3Ti组织。而当该比值等于或大于 3∶ 1时则获得块状 Al3Ti组织 ,其分布也更均匀。但该比值太大 (大于约3.75∶ 1)时 ,则因 Al粉升温和熔化吸热 ,将使得自蔓延合成反应终止。

关键词： SHS法复合材料 A13Ti/Al 制备

Boceprevir plus peginterferon/ribavirin for treatment ofchronic hepatitis C in Russia

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World Journal of Hepatology 2016年第6期8卷 331-339页

作者： Vasily Isakov Igor nikitin Vladimir Chulanov Pavel Ogurtsov Ekaterina Lukyanova Jianmin Long JaniceWahl Frans A Helmond the P08160 Trial Investigators Department of Gastroenterology and Hepatology Institute of NutritionMoscow 115446Russia Department of Gastroenterology and Hematology Russian Academy of SciencesMoscow 117593Russia Clinical Diagnostics and Research Center Central Research Institute of EpidemiologyMoscow 111123Russia Hospital Medicine Peoples’Friendship University of RussiaMoscow 117198Russia Medical Affairs MSD Pharmaceuticals LLCMoscow 115093Russia Clinical Research Merck&Co.Inc.KenilworthNJ 07033United States 不详

AIM: to evaluate addition of boceprevir to peginterferon/ribavirin(PR) in Russian patients with chronic hepatitis C virus(HCV).METHODS: treatment-naive(t N) and treatmentexperienced(t E) patients(who had failed prior treatment with PR for ≥ 12 wk) with chronic HCV genotype 1 infection were enrolled in this placebocontrolled, double-blind study. All patients initially received PR for 4 wk. Patients randomized to control treatment then received PR for an additional 44 wk. t N patients randomized to triple therapy received boceprevir(800 mg three times daily) plus PR for 24 wk and then further therapy according to treatment week 8(t W8) HCV RNA levels. t E patients received boceprevir plus PR for 32 wk and then further therapy according to t W8 HCV RNA levels. treatment was discontinued for t N patients with detectable HCV RNA at t W24 and t E patients with detectable HCV RNA at t W12 because of futility. the primary efficacy end point was sustained virologic response(SVR) defined as undetectable HCV RNA 24 wk after completing all study ***: SVR was 74.8% in the boceprevir plus PR arm compared with 46.2% in the control arm, with a stratification-adjusted treatment difference of 29.2%(95%CI: 16.4-41.5; P < 0.0001). Rates of SVR were higher in the boceprevir arm in both t N and t E patient groups(t N 78.4% vs 56.3%; t E 69.4% vs 30.0%). Within t E patients, the rates of SVR were higher with boceprevir plus PR compared with PR, regardless of treatment failure type(null responder, partial responder, and relapser). Most patients receiving boceprevir plus PR in both t N(86%) and t E(71%) populations were eligible for reduced treatment duration. Anemia was increased in patients receiving boceprevir plus PR vs PR alone(47.2% vs 24.4%); there was a corresponding increase in ribavirin dose reduction and erythropoietin use. Among patients receiving boceprevir plus PR, SVR rates were similar in patients with anemia(< 10 g/d L) and those without anemia(71.2% vs 77.4%).C

关键词： hepatitis C virus boceprevir peginterferon ribavirin randomized clinical trial sustained virologicresponse

A Multi-layer Charging of Blast Furnaces with the Help of the Rotary Distributor of Burden

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A Multi-layer Charging of Blast Furnaces with the Help of th...