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The Main Results and the Perspectives in the Researches at SSRT

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空间科学学报 2005年第5期25卷 351-355页

作者： g.Y.Smolkov S.V.Lesovoy V.g.Zandanov A.T.Altyntsev A.V.gubin Radioastrophysical observatory Institute of Solar-Terrestrial PhysicsSiberian BranchRussian Academy of SciencesIrkutsk 664033Russia

In this report briefly presented the contemporary state of the experimental base of Radio Astrophysical Observatory(RAO)of the Institute of Solar-Terrestrial Physics(ISTP),the methodology of radioheliographic monitoring of the solar corona,the SSRT database,the RAO Web-pages,factors limiting the effective use of *** are formulated the original results of the basic directions of the solar activity researches and the problems solutions on SSRT:(1)active regions at various development stages,morphology,modeling,signs of energy accumulation and flares buildup,forecast of powerful flares;(2)scenario,topology and the fine temporal picture of flares development,signs of primary energy release,radio emission mechanisms,scatter effects of radio emission in turbulent corona,energetic particles fluxes;(3)filaments;(4)CME with the localization of their initiation at the solar disk background,development scenario of filament activation+CME+flare;(5)coronal holes,and(6)bright coronal points.

关键词： Monitoring Diagnostic Space weather Solar factors Microwave emission

Microstructure and pitting corrosion of shielded metal arc welded high nitrogen stainless steel

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Defence Technology（防务技术） 2015年第3期11卷 237-243页

作者： RAFFI MOHAMMED g.MADHUSUDHAN REDDY K.SRINIVASA RAO Department of Metallurgical Engineering Andhra University Defence Metallurgical Research Laboratory

The present work is aimed at studying the microstructure and pitting corrosion behaviour of shielded metal arc welded high nitrogen steel made of Cromang-N electrode. Basis for selecting this electrode is to increase the solubility of nitrogen in weld metal due to high chromium and manganese content. Microscopic studies were carried out using optical microscopy(OM) and field emission scanning electron microscopy(FESEM). Energy back scattered diffraction(EBSD) method was used to determine the phase analysis, grain size and orientation image mapping. Potentio-dynamic polarization testing was carried out to study the pitting corrosion resistance in aerated 3.5% NaCl environment using a gillAC electrochemical system. The investigation results showed that the selected Cr-Mn-N type electrode resulted in a maximum reduction in delta-ferrite and improvement in pitting corrosion resistance of the weld zone was attributed to the coarse austenite grains owing to the reduction in active sites of the austenite/delta ferrite interface and the decrease in galvanic interaction between austenite and delta-ferrite.

关键词：耐点蚀性能高氮不锈钢焊缝金属电弧焊接研究组织屏蔽场发射扫描电子显微镜奥氏体晶粒

An Electron Microscopy Study of Vein-like grain Boundary Microstructure in Nitrocarburized Low Carbon Steels

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Journal of Materials Science & Technology 2013年第7期29卷 669-672页

作者： Wanglin chen Cuilan Wu Jianghua chen Aigui He Center of High Resolution Electron Microscopy College of Materials Science and EngineeringHunan University

The coarsened grain boundaries （gBs） with vein-like morphology frequently appear in the nitrogen diffusion layer of nitrocarburized carbon steels. The electron probe X-ray microanalysis shows that such vein-like gBs are rich in nitrogen and carbon atoms. Transmission electron microscopy and scanning electron microscopy further reveal that the coarsened gBs consist of γ＇-nitrocarbide （Fe4（C,N）） and ε-nitrocarbide lamellas that are formed during nitrocarburizing due to high nitrogen concentration at gBs. It is shown that many of {111}〈112〉 micro twins exist in the γ＇-phase lamellas and thin ε-phase slices prefer to nucleate at their twin boundaries with the orientation relationship of {0001}ε//{111}γ＇. Upon growing large γ＇-Iamellas may become faceted and thin ε-Iamellas may grow thicker and become the main portions in the vein-like gBs. The microstructure evolution occurring in the vein-like gBs can be depicted as： α ＋ [N]/[C] → ＋ [C,N] →ε-nitrocarbides.

关键词： Nitrocarburizing grain boundary γ'-Fe4(C,N) e-Nitrocarbide

半边旗中二萜类化合物5F葡糖糖苷的分离鉴定及其抗肿瘤作用

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中成药 2010年第2期32卷 257-260页

作者：龚先玲陈志红梁念慈邓亦峰 george g.chen 广东医学院天然药物研究与开发重点实验室广东湛江524023 广东医学院分析中心广东湛江524023 香港中文大学外科系

目的:进一步研究半边旗的抗肿瘤活性成分。方法:运用反复硅胶柱层析的方法对半边旗中的化学成分进行分离纯化,以LC-MS及各种有机波谱法鉴定化学单体结构;并通过MTT法对分离鉴定的单体化合物及其苷元进行抗肿瘤活性研究。结果:从中分离鉴... 详细信息

目的:进一步研究半边旗的抗肿瘤活性成分。方法:运用反复硅胶柱层析的方法对半边旗中的化学成分进行分离纯化,以LC-MS及各种有机波谱法鉴定化学单体结构;并通过MTT法对分离鉴定的单体化合物及其苷元进行抗肿瘤活性研究。结果:从中分离鉴定1个二萜苷类化合物,为11β-hydroxy-15-oxo-ent-kaur-16-en-19-oic acid 19-β-D-glucoside(Ⅰ);化合物Ⅰ及其苷元5F均可抑制两种肿瘤细胞A549和CNE-2Z的生长,且它们对两种肿瘤细胞的抑制作用呈一定剂量依赖关系和时间依赖关系,化合物5F的活性强于化合物Ⅰ。结论:α,β不饱和环戊酮结构是其活性部位,5F中19位碳上的羧基与糖连接形成酯苷,成为化合物Ⅰ后,其抗肿瘤活性大大降低。

关键词：半边旗抗肿瘤成分二帖化合物成分分析

A theoretical model of semi-elliptic surface crack growth

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Chinese Journal of Aeronautics 2014年第3期27卷 730-734页

作者： Shi Kaikai Cai Lixun chen Long Bao chen School of Mechanics and Engineering Southwest Jiaotong University

A theoretical model of semi-elliptic surface crack growth based on the low cycle strain damage accumulation near the crack tip along the cracking direction and the Newman-Raju formula is developed. The crack is regarded as a sharp notch with a small curvature radius and the process zone is assumed to be the size of cyclic plastic zone. The modified Hutchinson, Rice and Rosengren （HRR） formulations are used in the presented study. Assuming that the shape of surface crack front is controlled by two critical points： the deepest point and the surface point. The theoretical model is applied to semi-elliptic surface cracked A1 7075-T6 alloy plate under cyclic loading, and five different initial crack shapes are discussed in present study. good agreement between experimental and theoretical results is obtained.

关键词： Fatigue crack propagation Linear damage accumulation Low cycle fatigue Newman-Raju formula Semi-elliptic surface crack

A Pseudopotential Lattice Boltzmann Analysis for Multicomponent Flow

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Communications in Computational Physics 2022年第9期32卷 1156-1178页

作者： Yong Zhao gerald g.Pereira Shibo Kuang Zhenhua Chai Baochang Shi School of Mathematics and Statistics Changsha University of Science and TechnologyChangsha 410114HunanChina CSIRO Data61 Private Bag 10Clayton South 3168Australia ARC Research Hub for Computational Particle Technology Department of Chemical EngineeringMonash UniversityVictoria 3800Australia School of Mathematics and Statistics Huazhong University of Science and TechnologyWuhan 430074China

This paper presents a pseudopotential lattice Boltzmann analysis to show the deficiency of previous pseudopotential models,i.e.,inconsistency between equilibrium velocity and mixture *** rectify this problem,there are two strategies:decoupling relaxation time and kinematic viscosity or introducing a system mixture relaxation ***,we constructed two modified models:a two-relaxationtime(TRT)scheme and a triple-relaxation-time(TriRT)scheme to decouple the relaxation time and kinematic ***,inspired by the idea of a system mixture relaxation time,we developed three mixture models under different collision schemes,***-SRT,mix-TRT,and mix-TriRT ***,we derived the advection-diffusion equation for the multicomponent system and derived the mutual diffusivity in a ***,we conducted several numerical simulations to validate the analysis on these *** numerical results show that these models can obtain smaller spurious currents than previous models and have a wider range for the accessible viscosity ratio with fourth-order *** to previous models,presentmodels avoid complex matrix operations and only fourth-order isotropy is *** increased simplicity and higher computational efficiency of these models make them easy to apply to engineering and industrial applications.

关键词： Lattice Boltzmann method multicomponent flows Chapman-Enskog analysis

Hot deformation behavior and dynamic recrystallization kinetics of AZ61 and AZ61+Sr magnesium alloys

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Journal of Magnesium and Alloys 2016年第2期4卷 104-114页

作者： S.Aliakbari Sani g.R.Ebrahimi A.R.Kiani Rashid school of metallurgy and materials engineering iranian university of science and technologytehraniran materials and polymers engineering department faculty of engineeringhakim sabzevari universitysabzevariran department of metallurgical and materials engineering faculty of engineeringferdowsi university of mashhadmashhadiran

In this study,the effect of strontium addition on hot deformation of AZ61 alloy was investigated by hot compression tests.A reference alloy(AZ61)and an Sr-containing alloy(AZ61+Sr)was cast while their average initial grain size were supposed to be about 140 and 40μm,*** AZ61+Sr alloy,the Sr-containing precipitations were stable at homogenization *** the hot compression curves,it was revealed that dynamic recrystallization phenomenon had occurred and controlled the thermomechanical behaviour of the *** derived constitutive equations showed that the hot deformation parameters(n and Q)in AZ61+Sr alloy is smaller than those of AZ61 alloy;this can be related to the small initial grain size and the lower amounts of solute aluminium *** analysis of DRX kinetics along with the micrographs of the deformed microstructures showed that at the same condition the development of DRXed microstructure in AZ61+Sr alloy was faster than AZ61 *** increased recrystallized microstructure was interpretated to be attributed to(1)the more grain boundaries present and(2)the existance of the Al-Mg-Sr precipitations assisted the PSN ***,the attenuated intensity of the basal texture of AZ61+Sr was related to the DRX fraction of microstructure.

关键词： AZ61 alloy Strontium DRX grain size PSN Dynamic recrystallization kinetics

Fractional-order generalized Principle of Self-support (FOgPSS) in Control System Design

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IEEE/CAA Journal of Automatica Sinica 2016年第4期3卷 430-441页

作者： Hua chen YangQuan chen Mathematics and Physics Department Hohai University MESA Laboratory University of California

This paper reviews research that studies the principle of self-support U+0028 PSS U+0029 in some control systems and proposes a fractional-order generalized PSS framework for the first time. The existing PSS approach focuses on practical tracking problem of integer-order systems including robotic dynamics, high precision linear motor system, multi-axis high precision positioning system with unmeasurable variables, imprecise sensor information, uncertain parameters and external disturbances. More generally, by formulating the fractional PSS concept as a new generalized framework, we will focus on the possible fields of the fractional-order control problems such as practical tracking, U+03BB-tracking, etc. of robot systems, multiple mobile agents, discrete dynamical systems, time delay systems and other uncertain nonlinear systems. Finally, the practical tracking of a first-order uncertain model of automobile is considered as a simple example to demonstrate the efficiency of the fractional-order generalized principle of self-support U+0028 FOgPSS U+0029 control strategy. © 2014 Chinese Association of Automation.

关键词： Control systems Delay control systems Dynamical systems Linear motors Mobile agents Robotics Time delay Uncertainty analysis

Effective Doping of Rare-earth Ions in Silica gel:A Novel Approach to Design Active Electronic Devices

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Nano-Micro Letters 2011年第3期3卷 141-145页

作者： D.Haranath Savvi Mishra Amish g.Joshi Sonal Sahai Virendra Shanker National Physical Laboratory Council of Scientific and Industrial Research

Eu^(3+)luminescence spectroscopy has been used to investigate the effective doping of alkoxide-based silica(SiO_2) gels using a novel pressure-assisted sol-gel method. Our results pertaining to intense photoluminescence(PL) from gel nanospheres can be directly attributed to the high specific surface area and remarkable decrease in unsaturated dangling bonds of the gel nanospheres under pressure. An increased dehydroxylation in an autoclave resulted in enhanced red(~611 nm) PL emission from europium and is almost ten times brighter than the SiO_2 gel made at atmospheric pressure and^50 using conventional St¨ober-Fink-Bohn process. The presented results are entirely different from those reported earlier for SiO_2:Eu3+gel nanospheres and the origin of the enhanced PL have been discussed thoroughly.

关键词： Luminescence Nanophosphor Short-range order Electron microscopy