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基于分子束外延技术可控制备Ga原子团簇的研究

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原子与分子物理学报 2025年第3期42卷 77-84页

本研究基于分子束外延(Molecular Beam Epitaxy,MBE)技术在Si(100)衬底表面成功制备金属Ga原子团簇.通过控制变量法,研究其尺寸形貌与工艺参数之间的关系.第一组对照实验分别在940℃、970℃、1000℃的Ga源温度下制备Ga原子团簇.实验结... 详细信息

本研究基于分子束外延(Molecular Beam Epitaxy,MBE)技术在Si(100)衬底表面成功制备金属Ga原子团簇.通过控制变量法,研究其尺寸形貌与工艺参数之间的关系.第一组对照实验分别在940℃、970℃、1000℃的Ga源温度下制备Ga原子团簇.实验结果表明,Ga源温度的升高导致Ga的蒸发量增加,进而沉积在Si衬底表面的Ga原子增多,Ga原子自组装成团簇,最终表现为Ga原子团簇的高度升高.第二组对照实验分别在3 s、6 s、10 s、40 s、50 s、60 s的沉积时长下制备Ga原子团簇.实验结果表明,沉积时长增加导致团簇的高度逐渐增加,主要由新吸附原子和竞争效应驱动.第三组对照实验分别在0 s、60 s、300 s的退火时长下制备Ga原子团簇.实验结果表明,退火时长的增加导致团簇的高度下降和团簇内的原子重新排列和分布有关.第四组对照实验分别在420℃、500℃的退火温度下制备Ga原子团簇.实验结果表明,升温至500℃退火会促进Ga原子团簇呈现有序排列,是表面原子的热运动和Ga原子团簇与Si(100)的晶格匹配度的共同作用的结果.

关键词： MBE Ga原子团簇 Ga源温度沉积时长退火时长

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Acta Mathematica Sinica,English Series 2019年第11期35卷 1827-1840页

作者： Xun xiang guo Department of Mathematics Southwestern University of Finance and Economics

In this paper, we give an operator parameterization for the set of dilations of a given pair of dual g-frames and the set of dilations of pairs of dual g-frames of a given g-frame. In particular,for the dilations of a given pair of dual g-frames, we introduce the concept of joint complementary g-frames and prove that the joint complementary g-frames of a pair of dual g-frames are unique in the sense of joint similarity, which then helps to obtain a sufficient condition such that the complementary g-frames of a g-frame are unique in the sense of similarity and show that the set of dilations of a given dual g-frame pair are parameterized by a set of invertible diagonal operators. For the dilations of pairs of dual g-frames, we prove that the set of dilations of pairs of dual g-frames are parameterized by a set of invertible upper triangular operators.

关键词： g-frame dual g-frame pair dilation g-Riesz basis joint similarity

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Acta Mathematica Sinica,English Series 2017年第12期33卷 1671-1683页

作者： Xun xiang guo Department of Mathematics Southwestern University of Finance and Economics Chengdu 611130 P. R. China

In this paper, firstly, in order to establish our main techniques we give a direct proof for the existence of the dilations for pairs of dual group frames. Then we focus on proving the uniqueness of such dilations in certain sense of similarity and giving an operator parameterization of the dilations of all pairs of dual group frames for a given group frame. We show that the operators which transform different dilations are of special structured lower triangular.

关键词： Group frame group Riesz basis dilation dual group frame

Non-probabilistic reliability method and reliability-based optimal LQR design for vibration control of structures with uncertain-but-bounded parameters

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Acta Mechanica Sinica 2013年第6期29卷 864-874页

作者： Shu-xiang guo Ying Li Faculty of Mechanics College of ScienceAir Force Engineering University

Uncertainty is inherent and unavoidable in almost all engineering systems. It is of essential significance to deal with uncertainties by means of reliability approach and to achieve a reasonable balance between reliability against uncertainties and system performance in the control design of uncertain systems. Nevertheless, reliability methods which can be used directly for analysis and synthesis of active control of structures in the presence of uncertainties remain to be developed, especially in non-probabilistic uncertainty situations. In the present paper, the issue of vibration con- trol of uncertain structures using linear quadratic regulator （LQR） approach is studied from the viewpoint of reliabil- ity. An efficient non-probabilistic robust reliability method for LQR-based static output feedback robust control of un- certain structures is presented by treating bounded uncertain parameters as interval variables. The optimal vibration con- troller design for uncertain structures is carried out by solv- ing a robust reliability-based optimization problem with the objective to minimize the quadratic performance index. The controller obtained may possess optimum performance un- der the condition that the controlled structure is robustly re- liable with respect to admissible uncertainties. The proposed method provides an essential basis for achieving a balance between robustness and performance in controller design ot uncertain structures. The presented formulations are in the framework of linear matrix inequality and can be carried out conveniently. Two numerical examples are provided to illustrate the effectiveness and feasibility of the present method.

关键词： Structural control Vibration control Robust control Linear quadratic regulator (LQR) Robust reliabil- ity Structural reliability

Modeling static friction behavior of elastic–plastic spherical adhesive microcontact in full-stick condition

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Friction 2024年第11期12卷 2594-2610页

作者： guo xiang Roman GOLTSBERG Izhak ETSION Department of Mechanical Engineering TechnionHaifa 32000Israel

The static friction behavior of an elastic–plastic spherical adhesive microcontact between a rigid flat and a deformable sphere under combined normal and tangential loading is studied by the finite element method(FEM).The contact between the sphere and the rigid flat is assumed to be full-stick,and the sliding inception is related to a loss of tangential *** intermolecular force between the rigid flat and the sphere is assessed by the Lennard–Jones(LJ)potential,which is applied to the sphere and the rigid flat by a user *** evolution of the adhesive force with tangential displacement in the full-stick condition is *** results indicate that the increasing effect of adhesive energy on the static friction coefficient gradually diminishes with an increase in the adhesive energy and the external normal ***,based on an extensive parametric study,an empirical dimensionless expression is obtained to predict the static friction coefficient of the spherical adhesive microcontact considering the intermolecular force.

关键词： adhesive spherical microcontact Lennard–Jones(LJ)potential elastic–plastic static friction

Korteweg-de Vries Description of Dark Solitons in Bose-Einstein Condensates

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Chinese Physics Letters 2001年第5期18卷 628-630页

作者： HUANG guo-xiang Key Laboratory for Optical and Magnetic Resonance Spectroscopy and Department of Physics East China Normal UniversityShanghai 200062

We investigate the dynamics of pulses in a cigar-shaped Bose-Einstein condensate with repulsive atom-atom interactions without using Thomas-Fermi *** the linear level our results give the Bogoliubov excitation spectrum for sound propagation with speed c=c0/√2,where c_(0) is the speed for the case without *** develop a Korteweg-de Vries(KdV)description for dark soliton propagation in the system and show that it is the quantum pressure that contributes the dispersion necessary for the formation of the dark solitons.

关键词： Einstein soliton propagation

Efficient Processing of Distributed Twig Queries Based on Node Distribution

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Journal of Computer Science & Technology 2017年第1期32卷 78-92页

作者： Xin Bi xiang-guo Zhao guo-Ren Wang College of Computer Science and Engineering Northeastern University Shenyang 110815 China

Massive XML data are increasingly generated for the representation, storage and exchange of web information. Twig query processing over massive XML data has become a research focus. However, most traditional algorithms cannot be directly implemented in a distributed manner. Some of the existing distributed algorithms generate a lot of useless intermediate results and execute many join operations of partial results in most cases; others require the priori knowledge of query pattern before XML partition, storage and query processing, which is impractical in the cases of large-scale data or frequent incoming new queries. To improve efficiency and scalability, in this paper, we propose a 3-phase distributed algorithm DisT3 based on node distribution mechanism to avoid unnecessary intermediate results. Furthermore, we propose a lightweight local index ReP with an enhanced XML partitioning approach using arbitrary partitioning strategy, and based on ReP we propose an improved 2-phase distributed algorithm DisT2ReP to further reduce the communication cost. After the performance guarantees are analyzed, extensive experiments are conducted to verify the efficiency and scalability of our proposed algorithms in distributed twig query applications.

关键词： XML twig query distributed computing node distribution

Type Ⅰ interferon receptor knockout mice as models for infection of highly pathogenic viruses with outbreak potential

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Zoological Research 2018年第1期39卷 3-14页

作者： Gary Wong xiang-guo Qiu Shenzhen Key Laboratory of Pathogen and Immunity State Key Discipline of Infectious DiseaseShenzhen Third People's HospitalShenzhen Guangzhou 518020China Key Laboratory of Pathogenic Microbiology and Immunology Institute of MicrobiologyChinese Academy of SciencesBeijing 100101China Special Pathogens Program National Microbiology LaboratoryPublic Health Agency of CanadaWinnipegManitoba R3E 3R2Canada Department of Medical Microbiology and Infectious Diseases University of ManitobaWinnipegManitoba R3E 0J9Canada

Due to their inability to generate a complete immune response, mice knockout for type I interferon （IFN） receptors （Ifnar-/-） are more susceptible to viral infections, and are thus commonly used for pathogenesis studies. This mouse model has been used to study many diseases caused by highly pathogenic viruses from many families, including the Flaviviridae, Filoviridae, Arenaviridae, Bunyaviridae, Henipaviridae, and Togaviridae. In this review, we summarize the findings from these animal studies, and discuss the pros and cons of using this model versus other known methods for studying pathogenesis in animals.

关键词： Ifnar Mice Animal model Flavivirus Filovirus Arenavirus Bunyavirus Henipavirus Togavirus

High-Dimensional Nonlinear Envelope Equations and Nonlinear Localized Excitations in Photonic Crystals

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Communications in Theoretical Physics 2006年第1X期46卷 149-154页

作者： HANG Chao HUANG guo-xiang Department of Physics East China Normal University Shanghai 200062 China

We investigate the nonlinear localized structures of optical pulses propagating in a one-dimensional photonic crystal with a quadratic nonlinearity. Using a method of multiple scales we show that the nonlinear evolution of a wave packet, formed by the superposition of short-wavelength excitations, and long-wavelength mean fields, generated by the self-interaction of the wave packet, are governed by a set of coupled high-dimenslonal nonlinear envelope equations, which can be reduced to Davey-Stewartson equations and thus support dromionlike high-dimensional nonlinear excitations in the system.

关键词： photonic crystal dromion