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Subgrade-reinforcement techniques for the dangerously deforming sections of railway lines in the north of the Russian Far East
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作者 Alexey Piotrovich Svetlana Zhdanova 《Research in Cold and Arid Regions》 CSCD 2017年第3期197-204,共8页
This paper lists difficult railway construction conditions that are typical for the northern areas of the Russian Far East.Permafrost-bound issues of railway and highway construction and operation are described.Some o... This paper lists difficult railway construction conditions that are typical for the northern areas of the Russian Far East.Permafrost-bound issues of railway and highway construction and operation are described.Some of the authors'developments for subgrade stabilization in the foregoing conditions are given as examples. 展开更多
关键词 PERMAFROST SUBGRADE REINFORCEMENT TECHNIQUES
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Predictive modeling of the permafrost thermal regime in Russian railroad subgrade support systems 被引量:3
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作者 Sergei Kudriavtcev Tatiana Valtseva +2 位作者 Alexei Kazharskyi Elena Goncharova Iurii Berestianyi 《Research in Cold and Arid Regions》 CSCD 2013年第4期404-407,共4页
The goal of a predictive thermotechnical calculation is to model the behavior of the top permafrost boundary under current operational conditions as well as increasing average annual air temperatures that results in d... The goal of a predictive thermotechnical calculation is to model the behavior of the top permafrost boundary under current operational conditions as well as increasing average annual air temperatures that results in degradation of the permafrost layer. Numerical modeling was used to assess the efficient application of construction measures to create sustainable operation of the railroad. The numerical modeling was carried out in the programming complex FEM-models developed by geotechnical engineers of St. Petersburg, Russia under Prof. V. M. Ulitsky's guidance. The Termoground Program as a part of the FEM-models enables the research of freezing, heaving and thawing in different design solutions. Research was carried out in space resolution for a year cycle. The performed model has shown that the designing measures accepted for permafrost protection from retreat in the subrade support were generally effective. 展开更多
关键词 REINFORCEMENT modeling deformations permafrost soil EMBANKMENT
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To the issue of stabilization of permafrost soil subgrade 被引量:1
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作者 Aleksey A.Piotrovich vetlana M.Zhdanova 《Research in Cold and Arid Regions》 CSCD 2015年第4期329-334,共6页
This paper summarizes an analysis of consequences of railway subgrade construction and maintenance solutions in northern areas of the Russian Far East. An idea of the natural long-term stabilization of the subgrade-ba... This paper summarizes an analysis of consequences of railway subgrade construction and maintenance solutions in northern areas of the Russian Far East. An idea of the natural long-term stabilization of the subgrade-base geotechnical system is presented. Proposals to improve the decision-making of construction and engineering solutions are formulated. 展开更多
关键词 permafrost soil SUBGRADE STABILIZATION
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Propagation of vibrations in thawing deep seasonally frozen soils in railway subgrade 被引量:1
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作者 Gennady M.Stoyanovich Viktor V.Pupatenko 《Research in Cold and Arid Regions》 CSCD 2015年第5期534-540,共7页
In this study, in-situ testing results are given, and the analytical relationship of the vibrations' amplitudes inside an em- bankment by the thawing of the subgrade surface of seasonably deep frozen soils is provide... In this study, in-situ testing results are given, and the analytical relationship of the vibrations' amplitudes inside an em- bankment by the thawing of the subgrade surface of seasonably deep frozen soils is provided. The peculiarities of the vi- bration waves' propagation during the springtime thawing of soils compared to those during the summertime period and the correlation of the vibrations with the under-rail basement moduln~ nf ala^tieitv nro dofinod 展开更多
关键词 railroad subgrade vibrational force deep seasonable frost
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Study of moisture migration in clay soils considering rate of freezing
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作者 S.A.Kudriavtcev A.V.Kazharskii +1 位作者 E.D.Goncharova I.B.Berestianyi 《Research in Cold and Arid Regions》 CSCD 2014年第5期474-478,共5页
The paper presents some methods of numerical modeling and a study of moisture changing in frozen clay soils considering rates of freezing in the base of construction.An impact assessment of moisture changes in clay so... The paper presents some methods of numerical modeling and a study of moisture changing in frozen clay soils considering rates of freezing in the base of construction.An impact assessment of moisture changes in clay soils affecting strength characteristics during thawing was carried out in stability tests. 展开更多
关键词 numerical modeling permafrost soil FREEZING thawing
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Detection of ground ice using ground penetrating radar method
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作者 Gennady M.Stoyanovich Viktor V.Pupatenko Yury A.Sukhobok 《Research in Cold and Arid Regions》 CSCD 2015年第5期541-546,共6页
The paper presents the results of a ground penetrating radar (GPR) application for the detection of ground ice. We com- bined a reflection traveltime curves analysis with a frequency spectrogram analysis. We found s... The paper presents the results of a ground penetrating radar (GPR) application for the detection of ground ice. We com- bined a reflection traveltime curves analysis with a frequency spectrogram analysis. We found special anomalies at specific traces in the traveltime curves and ground boundaries analysis, and obtained a ground model for subsurface structure which allows the ground ice layer to be identified and delineated. 展开更多
关键词 ground penetrating radar ground ice common-offset reflection survey wide angle reflection and refractionmethod
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Selective Photorefractive Light Scattering in Rh-Doped LiNbO<sub>3</sub>Crystals
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作者 Vitaliy Maximenko Victor Krishtop 《Optics and Photonics Journal》 2013年第1期8-12,共5页
The photorefractive properties of lithium niobate crystals depend strongly on the kind of doping admixture. Study of LiNbO3 crystals with various doping admixtures using photorefractive light scattering allows insight... The photorefractive properties of lithium niobate crystals depend strongly on the kind of doping admixture. Study of LiNbO3 crystals with various doping admixtures using photorefractive light scattering allows insight into the processes taking place in the crystals. This paper presents new experimental results of non-selective and selective photorefractive light scattering investigations into rhodium-doped lithium niobate crystals and proposes a model to explain the experimental data. 展开更多
关键词 PHOTOREFRACTION Light Scattering Lithium NIOBATE Four-Wave Interaction
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Study of moisture migration in clay soils considering rate of freezing
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作者 Kudryavtsev S A Kazharskii A V +1 位作者 Goncharova E D Berestianyi I B 《Journal of Groundwater Science and Engineering》 2014年第4期35-40,共6页
The paper presents some methods of numerical modelling and a study of moisture changing in frozen clay soils considering rates of freezing in the foundation. An impact assessment of moisture changes in clay soils affe... The paper presents some methods of numerical modelling and a study of moisture changing in frozen clay soils considering rates of freezing in the foundation. An impact assessment of moisture changes in clay soils affecting strength characteristics during thawing was carried out in stability tests. 展开更多
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Elucidating elusive quaternary selenide EuCeCuSe3:Synthesis,crystal structure,properties and theoretical studies
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作者 Maxim V.Grigoriev Anna V.Ruseikina +11 位作者 Maxim S.Molokeev Vladimir A.Chernyshev Aleksandr S.Aleksandrovsky Alexander S.Krylov Svetlana N.Krylova Nikolai P.Shestakov Dmitriy A.Velikanov Alexander A.Garmonov Alexey V.Matigorov Evgeny A.Ostapchuk Thomas Schleid Damir A.Safin 《Journal of Rare Earths》 SCIE EI CAS CSCD 2024年第1期163-171,I0006,共10页
We report on the novel heterometallic quaternary selenide EuCeCuSe3,the fabrication of which has been a challenge until this work.The structure of the reported selenide was elucidated from the powder X-ray diffraction... We report on the novel heterometallic quaternary selenide EuCeCuSe3,the fabrication of which has been a challenge until this work.The structure of the reported selenide was elucidated from the powder X-ray diffraction data,which revealed the formation of EuCeCuSe3with excellent yield(96.7%)accompanied with a minor fraction of CeSe2(3.3%),and was best solved in orthorhombic space group Pnma with the BaLaCuS3structural type.Thus,the crystal structure of the title compound completes the row of the heterometallic quaternary selenides EuRECuSe3(RE=La,Pr,Nd,Sm,Eu,Gd,Tb,Dy,Ho,Er,Tm,Yb,Lu,Y),of which the cerium-based derivative exclusively belongs to the BaLaCuS3structural type.The distortion of the CuSe4polyhedron was compared for the whole series of EuRECuSe3compounds using theτ4-descriptor for four coordinated ions,which revealed the highest degree of distortion for the Ce3+-containing selenide,followed by the La3+-based derivative.Furthermore,the crystallographic and geometrical parameters of the reported selenide were discussed in comparison to the Ce3+-based sulfides SrCeCuS3and EuCeCuS3.Ab initio calculations of the crystal structure,a phonon spectrum and elastic constants for the crystal of EuCeCuSe3were also performed.The types and wavenumbers of fundame ntal modes were determined and the involvement of ions participating in the phonon modes was assessed.The experimental IR spectrum of the reported selenide was interpreted and found to be in agreement with the calculated spectrum.The experimental direct band gap of EuCeCuSe3was measured to be 1.36 eV that is consistent with the concept of its origin due to interband transitions between orbitals emerging mainly from 4f(valence band)and 5d(conduction band)levels of the Eu2+cation.The dependence of the Young’s modulus on the direction demonstrates the anisotropy of the elastic properties,while the Vickers hardness for EuCeCuSe3was calculated to be 5.2 GPa.Finally,the title compound is paramagnetic above 4 K. 展开更多
关键词 Quaternary selenide SYNTHESIS Crystal structure Ab initio calculations Magnetic measurements SPECTROSCOPY
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Emerging ultra-narrow-band cyan-emitting phosphor for white LEDs with enhanced color rendition 被引量:33
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作者 Ming Zhao Hongxu Liao +4 位作者 Maxim S.Molokeev Yayun Zhou Qinyuan Zhang Quanlin Liu Zhiguo Xia 《Light(Science & Applications)》 SCIE EI CAS CSCD 2019年第1期869-877,共9页
Phosphor-converted white LEDs rely on combining a blue-emitting InGaN chip with yellow and red-emitting luminescent materials.The discovery of cyan-emitting(470-500 nm)phosphors is a challenge to compensate for the sp... Phosphor-converted white LEDs rely on combining a blue-emitting InGaN chip with yellow and red-emitting luminescent materials.The discovery of cyan-emitting(470-500 nm)phosphors is a challenge to compensate for the spectral gap and produce full-spectrum white light.Na_(0.5)K_(0.5)Li_(3)SiO_(4):Eu^(2+)(NKLSO:Eu^(2+))phosphor was developed with impressive properties,providing cyan emission at 486 nm with a narrow full width at half maximum(FWHM)of only 20.7 nm,and good thermal stability with an integrated emission loss of only 7% at 150℃.The ultra-narrow-band cyan emission results from the high-symmetry cation sites,leading to almost ideal cubic coordination for UCr_(4)C_(4)-type compounds.NKLSO:Eu^(2+) phosphor allows the valley between the blue and yellow emission peaks in the white LED device to be filled,and the color-rendering index can be enhanced from 86 to 95.2,suggesting great applications in full-spectrum white LEDs. 展开更多
关键词 white narrow YELLOW
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Non-stoichiometry in Ca2Al2SiO7 enabling mixedvalent europium toward ratiometric temperature sensing 被引量:6
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作者 Tao Hu Yan Gao +2 位作者 Maxim Molokeev Zhiguo Xia Qinyuan Zhang 《Science China Materials》 SCIE EI CSCD 2019年第12期1807-1814,共8页
Eu^2+/Eu^3+ mixed-valence couple co-doped material holds great potential for ratiometric temperature sensing owing to its different electronic configurations and electron-lattice interaction. Here, the correlation of ... Eu^2+/Eu^3+ mixed-valence couple co-doped material holds great potential for ratiometric temperature sensing owing to its different electronic configurations and electron-lattice interaction. Here, the correlation of nonstoichiometry in chemical composition, phase structures and luminescence propertis of Ca2 Al2 Si1-xO7:Eu is discussed, and controlled Eu^2+/Eu^3+ valence and tunable emission appear with decreasing Si content. It is found that the 2 Ca^2++ Si^4+←→ Eu^2++ Eu^3++ Al^3+ cosubstitution accounts for the structural stability and charge balance mechanism. Benefiting from the diverse thermal dependent emission behaviors of Eu^2+ and Eu^3+, Ca2 Al2 Si1-xO7:Eu thermometer exhibits excellent temperature sensing performances with the maximum absolute and relative sensitivity being 0.024 K-1(at 303 K) and 2.46% K-1(at 443 K) and good signal discriminability. We propose that the emission quenching of Eu^2+ is ascribed to 5 d electrons depopulation through Eu^2+/Eu^3+ intervalence charge transfer state, while the quenching of Eu^3+ comes from multiphonon relaxation. Our work demonstrates the potential of Ca2 Al2 Si1-xO7:Eu for noncontact optical thermometry, and also highlights mixed-valence europium-containing compounds toward temperature sensing. 展开更多
关键词 temperature sensing phosphor Eu^2+/Eu^3+ intervalencecharge transfer
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Unraveling the mechanochemical synthesis and luminescence in MnⅡ-based two-dimensional hybrid perovskite(C4H9NH3)2PbCl4 被引量:5
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作者 Guojun Zhou Shaoqiang Guo +3 位作者 Jing Zhao Quanlin Liu Junying Zhang Zhiguo Xia 《Science China Materials》 SCIE EI CSCD 2019年第7期1013-1022,共10页
The mechanochemical route is a facile and fast way and has received much attention for developing versatile advanced functional materials. Herein, we reported a mechanochemical synthesis for incorporating divalent man... The mechanochemical route is a facile and fast way and has received much attention for developing versatile advanced functional materials. Herein, we reported a mechanochemical synthesis for incorporating divalent manganese ions (Mn^Ⅱ) into a two-dimensional (2D) hybrid perovskite (C4H9NH3)2PbCl4. The mild external stimuli originating from the grinding at room temperature enabled the formation of Mn^Ⅱ-doped 2D hybrid perovskites, and rapidly changed the luminescence characteristics. The photoluminescence analyses show that the violet and orange emissions are attributed to (C4H9NH3)2Pb1-xMnxCl4 band-edge emission and the T1→^6A1 transition of Mn^2+ resulting from an efficient energy transfer process, respectively. Site preference and distribution of the doped Mn^2+ cations on the locations of Pb^2+ were analyzed. The formation energy calculated by the density functional theory (DFT) indicates that the Mn^2+ ions can rapidly enter the crystal lattice due to the unique 2D crystal structure of the hybrid perovskite. Such a case of mechanochemical synthesis for the 2D hybrid perovskite motivates many novel emerging materials and the related applications. 展开更多
关键词 2D hybrid perovskite MECHANOCHEMICAL Mn-doping LUMINESCENCE PHOSPHOR
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Lattice Doping of Lanthanide Ions in Cs_(2)AgInCl_(6)Nanocrystals Enabling Tunable Photoluminescence 被引量:4
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作者 Ying Liu Maxim SMolokeev Zhiguo Xia 《Energy Material Advances》 2021年第1期209-217,共9页
Lead-free halide double perovskite Cs_(2)AgInCl_(6 )has become the research hotspot in the optoelectronic fields.It is a challenge to utilize the lattice doping by different lanthanide ions with rich and unique photol... Lead-free halide double perovskite Cs_(2)AgInCl_(6 )has become the research hotspot in the optoelectronic fields.It is a challenge to utilize the lattice doping by different lanthanide ions with rich and unique photoluminescence(PL)emissions for emerging photonic applications.Here,we successfully incorporated Dy^(3+),Sm^(3+),and Tb3+ions into Cs_(2)AgInCl_(6) nanocrystals(NCs)by the hot-injection method,bringing diverse PL emissions of yellowish,orange,and green light in Cs_(2)AgInCl_(6):Ln^(3+)(Ln^(3+)=Dy^(3+),Sm^(3+),Tb^(3+)).Moreover,benefiting from the energy transfer process,Sm^(3+)and Tb^(3+)ion-codoped Cs_(2)AgInCl_(6) NCs achieved tunable emission from green to yellow orange and a fluorescent pattern from the as-prepared NC-hexane inks by spray coating was made to show its potential application in fluorescent signs and anticounterfeiting technology.This work indicates that lanthanide ions could endow Cs_(2)AgInCl_(6) NCs the unique and tunable PL properties and stimulate the development of lead-free halide perovskite materials for new optoelectronic applications. 展开更多
关键词 LANTHANIDE ORANGE PEROVSKITE
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Negative thermal expansion in one-dimension of a new double sulfate AgHo(SO_(4))_(2)with isolated SO_4 tetrahedra
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作者 Yuriy G.Denisenko Victor V.Atuchin +10 位作者 Maxim S.Molokeev Naizheng Wang Xingxing Jiang Aleksandr S.Aleksandrovsky Alexander S.Krylov Aleksandr S.Oreshonkov Alexander E.Sedykh Svetlana S.Volkova Zheshuai Lin Oleg V.Andreev Klaus Müller-Buschbaum 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2021年第17期111-121,共11页
A double holmium-silver sulfate was obtained for the first time.The temperature intervals for the formation and stability of the compound were determined by differential scanning calorimetry.The crystal structure of A... A double holmium-silver sulfate was obtained for the first time.The temperature intervals for the formation and stability of the compound were determined by differential scanning calorimetry.The crystal structure of AgHo(SO_(4))_(2)was determined by Rietveld method.The X-ray diffraction(XRD)analysis showed that the compound crystallizes in the monoclinic syngony,space group P2_1/m,with the unit cell parameters a=4.71751(4)A,b=6.84940(6)A and c=9.89528(9)A,β=95.1466(4)·,V=318.448(5)A^(3),Z=2,R_B=1.55%,T=303 K.Two types of sulfate tetrahedra were found in the structure,which significantly affected the spectral properties in the infrared range.In the temperature range of 143-703 K,a negative thermal expansion along the b direction accompanied by a positive thermal expansion along the a and c directions was observed.It was established that negative thermal expansion is the result of the deformation of sulfate tetrahedra,which is affected by the movement of holmium and silver atoms.The excitation in the blue spectral range(457.9 nm)produces a luminescence in light blue(489 nm),green(545 nm)and red(654 nm)spectral ranges,and the latter two were of comparable intensity that is favorable for WLED sources.The observed luminescent band distribution is ascribed to the specific crystal field at Ho^(3+)ion sites rather than a variation of radiationless probability. 展开更多
关键词 SULFATE Crystal structure Thermal expansion RAMAN Photoluminescence Band structure
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