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Large scale hybrid Monte Carlo simulations for structure and property prediction

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npj Computational Materials 2018年第1期4卷 1-7页

作者： sergei Prokhorenko Kruz Kalke Yousra Nahas Laurent Bellaiche Physics Department and Institute for Nanoscience and Engineering University of ArkansasFayettevilleAR 72701USA

The Monte Carlo method is one of the first and most widely used algorithms in modern computational *** condensed matter physics,the particularly popular flavor of this technique is the Metropolis Monte Carlo *** being incredibly robust and easy to implement,the Metropolis sampling is not well-suited for situations where energy and force evaluations are computationally *** search for a more efficient technique,we here explore the performance of Hybrid Monte Carlo sampling,an algorithm widely used in quantum electrodynamics,as a structure prediction scheme for systems with long-range *** results show that the Hybrid Monte Carlo algorithm stands out as an excellent computational scheme that can not only significantly outperform the Metropolis sampling but also complement molecular dynamics in materials science applications,while allowing ultra-large-scale simulations of systems containing millions of particles.

关键词： prediction property scheme

Learning surface molecular structures via machine vision

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npj Computational Materials 2017年第1期3卷 194-202页

作者： Maxim Ziatdinov Artem Maksov sergei V.Kalinin Institute for Functional Imaging of Materials Oak Ridge National LaboratoryOak RidgeTN 37831USA Center for Nanophase Materials sciences Oak Ridge National LaboratoryOak RidgeTN 37831USA Bredesen Center for Interdisciplinary Research University of TennesseeKnoxvilleTN 37996USA

Recent advances in high resolution scanning transmission electron and scanning probe microscopies have allowed researchers to perform measurements of materials structural parameters and functional properties in real space with a picometre *** many technologically relevant atomic and/or molecular systems,however,the information of interest is distributed spatially in a non-uniform manner and may have a complex multi-dimensional *** of the critical issues,therefore,lies in being able to accurately identify(‘read out’)all the individual building blocks in different atomic/molecular architectures,as well as more complex patterns that these blocks may form,on a scale of hundreds and thousands of individual atomic/molecular *** we employ machine vision to read and recognize complex molecular assemblies on ***,we combine Markov random field model and convolutional neural networks to classify structural and rotational states of all individual building blocks in molecular assembly on the metallic surface visualized in high-resolution scanning tunneling microscopy *** show how the obtained full decoding of the system allows us to directly construct a pair density function—a centerpiece in analysis of disorderproperty relationship paradigm—as well as to analyze spatial correlations between multiple order parameters at the nanoscale,and elucidate reaction pathway involving molecular conformation *** method represents a significant shift in our way of analyzing atomic and/or molecular resolved microscopic images and can be applied to variety of other microscopic measurements of structural,electronic,and magnetic orders in different condensed matter systems.

关键词： allowed classify spatially

Distribution and changes of active layer thickness(ALT) and soil temperature(TTOP) in the source area of the Yellow River using the GIPL model

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science China Earth sciences 2014年第8期57卷 1834-1845页

作者： LUO DongLiang JIN HuiJun sergei MARCHENKO Vladimir ROMANOVsKY state Key Laboratory of Frozen soils Engineering Cold and Arid Regions Environmental and Engineering Research InstituteChinese Academy of Sciences Geophysical Institute University of Alaska FairbanksFairbanks Alaska 99775 USA

Active layer thickness（ALT） is critical to the understanding of the surface energy balance, hydrological cycles, plant growth, and cold region engineering projects in permafrost regions. The temperature at the bottom of the active layer, a boundary layer between the equilibrium thermal state（in permafrost below） and transient thermal state（in the atmosphere and surface canopies above）, is an important parameter to reflect the existence and thermal stability of permafrost. In this study, the Geophysical Institute Permafrost Model（GIPL） was used to model the spatial distribution of and changes in ALT and soil temperature in the source Area of the Yellow River（sAYR）, where continuous, discontinuous, and sporadic permafrost coexists with seasonally frozen ground. Monthly air temperatures downscaled from the CRU Ts3.0 datasets, monthly snow depth derived from the passive microwave remote-sensing data sMMR and ssM/I, and vegetation patterns and soil properties at scale of 1：1000000 were used as input data after modified with GIs techniques. The model validation was carried out carefully with in-situ ALT in the sAYR interpolated from the field-measured soil temperature data. The results of the model indicate that the average ALT in the sAYR has significantly increased from 1.8 m in 1980 to 2.4 m in 2006 at an average rate of 2.2 cm yr–1. The mean annual temperature at the bottom of the active layer, or temperature at the top of permafrost（TTOP） rose substantially from –1.1°C in 1980 to –0.6°C in 2006 at an average rate of 0.018°C yr–1. The increasing rate of the ALT and TTOP has accelerated since 2000. Regional warming and degradation of permafrost has also occurred, and the changes in the areal extent of regions with a sub-zero TTOP shrank from 2.4×104 to 2.2×104 km2 at an average rate of 74 km2 yr–1. Changes of ALT and temperature have adversely affected the environmental stability in the sAYR.

关键词： GIPL model active layer thickness TTOP degradation of permafrost

On the liquid-phase technology of carbon fiber/aluminum matrix composites

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International Journal of Minerals,Metallurgy and Materials 2019年第12期26卷 1578-1584页

作者： sergei Galyshev Andrew Gomzin Rida Gallyamova Igor Khodos Fanil Musin Institute of solid state Physics of Russian Academy of sciences Chernogolovka 142432Russia Ufa state Aviation Technical University Ufa 450000Russia Ufa Chemistry Institute of Russian Academy of sciences Ufa 450000Russia Institute of Microelectronics Technology and High Purity Materials Russian Academy of sciences Chernogolovka 142432Russia

The main problems with the liquid-phase technology of carbon fiber/aluminum matrix composites include poor wetting of the fiber with liquid aluminum and formation of aluminum carbide on the fibers’*** paper aims to solve these *** theoretical and experimental dependence of porosity on the applied pressure were *** possibility of obtaining a carbon fiber/aluminum matrix composite wire with a strength value of about 1500 MPa was *** correlation among the strength of the carbon fiber reinforced aluminum matrix composite,the fracture surface,and the degradation of the carbon fiber surface was discussed.

关键词： carbon fiber/aluminum matrix composite liquid-phase fabrication infiltration pressure composite porosity composite wire ultrasonic

Applications of physical methods in estimation of soil biota and soil organic matter

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soil Ecology Letters 2020年第3期2卷 165-175页

作者： Chagovetc sergei shenglei Fu Key Laboratory of Geospatial Technology for the Middle and Lower Yellow River Regions Ministry of EducationCollege of Environment and PlanningHenan UniversityKaifeng 475004China Henan Key Laboratory of Integrated Air Pollution Control and Ecological security Henan UniversityKaifeng 475004China

soil biota is the living component of soil organic matter(sOM),and plays a key role in the decomposition of *** soil biota and sOM are indicators of soil fertility and soil ***,they both are sensitive to soil *** researchers developed various technologies to detect soil biota and sOM,they are mostly destructive and cause disturbance to soil,which may not reflect the actual situation of soil biota and ***,here we mostly focused on the non-destructive physical methods for estimating soil biota and sOM and discussed their advantages and *** methods include but not limited to acoustic detection,radio frequency identification,radioactive tagging,hyperspectral sensing and electron energy loss *** addition,we pointed out the current research problems and the potential research directions for applications of physical methods in estimation of soil biota and sOM.

关键词： soil organic matter soil biota Advanced method Acoustic method spectroscopy Tagging

Acoustic emission characterization of sliding wear under condition of direct and inverse transformations in lowtemperature degradation aged Y-TZP and Y-TZP-Al_2O_3

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Friction 2018年第3期6卷 323-340页

作者： Nikolai L sAVCHENKO Andrey V FILIPPOV sergei Yu TARAsOV Andrey I DMITRIEV Evgeny V sHILKO Aleksandr s GRIGORIEV Institute of strength Physics and Materials science sB RAs National Research Tomsk Polytechnic University National Research Tomsk state University

In this research, results of the investigation of the sliding friction and wear of yttria-stabilized tetragonal zirconia polycrystalline(Y-TZP) and Y-TZP-Al_2O_3 samples preliminarily subjected to low-temperature degradation are reported. The investigation was carried out using a pin-on-disk tribometer with simultaneous recording of acoustic emission(AE) and vibration acceleration. The sliding wear process was found to be determined by dynamic direct and inverse Y-TZP transformations detected by monoclinic and tetragonal X-ray diffraction peak ratios. The AE signals generated under direct and inverse transformations can be used to characterize wear and friction mechanisms as well as direct and inversed sliding-induced phase transformations. The AE signal energy grows with the friction coefficient and the inverse transformation degree. Reduction of the AE signal energy indicates establishing the mild wear stage caused by effective stress-induced direct martensitic transformation. The AE signal median frequency increases in the case of lower friction. Numerical studies of wear subsurface fracture under conditions of stress-induced martensitic transformation were used to elucidate the role played by the phase transformation in Y-TZP and Y-TZP-Al_2O_3. Martensitic transformation in Y-TZP was described with use of the non-associated dilatant plasticity model. simulation results particularly show that increase in the value of dilatancy coefficient from 0 to 0.2 is accompanied by 25%-30% reduce in characteristic length and penetration depth of sliding-induced subsurface cracks. As shown the AE may be an effective tool for in-situ monitoring the subsurface wear of materials experiencing both direct and inverse transformations.

关键词： zirconia transformation toughening low-temperature degradation friction acoustic emission numerical modeling movable cellular automata method

Deep neural networks for understanding noisy data applied to physical property extraction in scanning probe microscopy

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npj Computational Materials 2019年第1期5卷 932-939页

作者： Nikolay Borodinov sabine Neumayer sergei V.Kalinin Olga s.Ovchinnikova Rama K.Vasudevan stephen Jesse Center for Nanophase Materials science Oak Ridge National LaboratoryOak RidgeTN 37831USA

The rapid development of spectral-imaging methods in scanning probe,electron,and optical microscopy in the last decade have given rise for large multidimensional *** many cases,the reduction of hyperspectral data to the lower-dimension materialsspecific parameters is based on functional fitting,where an approximate form of the fitting function is known,but the parameters of the function need to be ***,functional fits of noisy data realized via iterative methods,such as least-square gradient descent,often yield spurious results and are very sensitive to initial ***,we demonstrate an approach for the reduction of the hyperspectral data using a deep neural network approach.A combined deep neural network/least-square approach is shown to improve the effective signal-to-noise ratio of band-excitation piezoresponse force microscopy by more than an order of magnitude,allowing characterization when very small driving signals are used or when a material’s response is weak.

关键词： neural networks property

structural Changes and Electrodynamic Effects in Polymers under Fast Uniaxial Compression

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Chinese Journal of Polymer science 2021年第5期39卷 601-609,I0007页

作者： Aleksey.I.Aleksandrov Ivan A.Aleksandrov Vitaliy G.shevchenko Aleksandr N.Ozerin N.s.Enikolopov Institute of synthetic Polymeric Materials RAs 117393 Moscow Profsoyuznaya70 Russian Federation

Rheological explosion in polymers under uniaxial compression in an open volume occurs at the end of continuous rapid plastic deformation after several stages of *** types of polymers were chosen for this study:brittle glassy amorphous polystyrene and thermoplastic semi-crystalline *** pulses were detected during explosion,and their spectra were analyzed with two models.X-ray diffraction methods were used to investigate changes in the structure and morphology of polymers during deformation and rheological *** pores appear in polymer in this process,and their shape and size distribution were derived from X-ray *** main reason for the formation of pores in polymer samples in rheological explosion experiments is the intense microshifts in the polymer volume under the action of high applied pressure.

关键词： Polystyrene Polypropylene X-ray Mechanical properties Compression

The Training of Future Teachers in Ukraine and China

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Frontiers of Education in China 2018年第2期13卷 288-314页

作者： Liubov HUNKO Nataliia PAZIURA Katerina shevchenko Institute of Education studies and Adult Education National Academy of Pedagogical Sciences of UkraineKyiv 02000Ukraine Department of Aviation English National Aviation University03058 KyivUkraine

This paper explores distinctive features of Bachelor of Education(***.)training at several well known Ukrainian and Chinese *** analysis was performed taking into consideration important criteria in the educational process of the degree programs(legislative,social,organizational,technological).The Chinese experience is of particular interest to Ukrainian educators because of China’s ancient history and educational *** changes took place in the education systems of both countries in the period of transition to a market-based economy in the 1990s and to knowledge-based *** contribution of the educational system to fast economic development of China has brought the county to second place among the largest economies in the *** authors found similarities in the documentation on the organization of educational processes at the universities,the shared purpose of the training,the use of traditional forms of education,and the emphasis on the practical part of the *** the same time,different features were found in the content of theoretical training,the organization of practical training,the approaches to innovation,the social benefits provided to teachers,the prestige of the teaching profession,principles of moral education,as well as financial and technical *** authors considered a number of progressive ideas in China’s ***,the implementation of which,at national and institutional levels in Ukraine,might contribute considerably to the modernization of pedagogical education.

关键词： Bachelor of Education(B.Ed.) university teacher pedagogical education comparative analysis