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Effect of Microgravity on Interface Structural Features in Space Crystal Growth

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Chinese Physics Letters 1998年第8期15卷 613-614页

作者： chen wan-chun MAI Zhen-hong K.Kato Institute of Physics Chinese Academy of SciencesBeijing 100080 National Microgravity Laboratory Chinese Academy of SciencesBeijing 100080 Institute for Hydrospheric and Atmospheric Science Nagoya UniversityChikusa-ku461-01Japan

The distribution of Ca^(2+)at boundary layer ofα-LiIO3 crystal grown both in space and on earth was studied by the synchrotron x-ray fluorescence *** was found that:(1)the Ca^(2+)concentration in the space-crystal is higher than that in the earth-crystal,(2)a sharp discontinuity of Ca^(2+)concentration is found at boundary layers of space-crystals *** finding provides an evidence of microgravity effect on interface structural features in space crystal growth.

关键词： LiIO3 crystal earth

Dielectric Characteristics and Layer Periodic Effects of Ferroelectric Superlattice BaTiO_(3)/SrTiO_(3)

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Chinese Physics Letters 2001年第9期18卷 1271-1274页

作者： ZHANG Jiang YIN Zhen ZHANG Ming-Sheng chen wan-chun National Laboratory of Solid State Microstructures and Center for Materials Analysis Nanjing UniversityNanjing 210093 Institute of Physics Chinese Academy of SciencesBeijing 100080

A pseudospin-phonon coupled model in double-time Green's function theory has been developed to investi- gate the dielectric susceptibility of the ferroelectric-dielectric superlattice BaTiO_(3)/SrTiO_(3) (BTO/STO). As the pseudospin-pseudospin and pseudospin-phonon interactions increase, the dielectric susceptibility changes from a narrow shape into the strong and broad shape with the peak shifting to a higher temperature region. With increasing pseudospin-phonon interaction in the BTO layer and at smallpseudospin-pseudospin interaction in BTO layer, the dielectric susceptibility was sensitively adjusted around the transition temperature of strontium titanate, and at large pseudospin-pseudospin interaction in the BTO layer, the dielectric susceptibility was increased in the high-temperature region covering the tetragonal-cubic transition temperature of barium titanate. A critical period of 10/I0 in the BTO/STO superlattice has been obtained, which is in good agreement with the experimental data of 40A, for ten unit cells.

关键词： dielectric susceptibility interaction

Computational Analysis of the Vertical Bridgman Growth of Te Doped GaSb Under Microgravity

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Chinese Physics Letters 2000年第10期17卷 775-777页

作者： LIU Yong-Cai chen wan-chun GE Pei-Wen HUO Chong-Ru Institute of Physics Chinese Academy of SciencesBeijing 100080 School of Chemical Engineering Tianjin UniversityTianjin 300072 National Microgravity Laboratory Chinese Academy of SciencesBeijing 100080

A transient analysis of Te doped GaSb melt growth process is performed using finite element *** solute concentration at the growth interface increases with time because of k<*** growth interface shape becomes a little flat at the beginning of the growth compared with the initial *** segregation occurs even under theμg *** segregation increases with the increase of gravity when gravity is small,and reaches a maximum at g=10^(-3)for our system.

关键词： interface shape Bridgman

Role of Ba^(2+) Ion in the Crystal Growth of Sr(NO_(3))_(2)

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Chinese Physics Letters 2000年第2期17卷 139-141页

作者： WU Li-Jun LI Chao-Rong chen wan-chun LIANG Jing-Kui Institute of Physics Chinese Acadermy of SciencesBeijing 100080 National Microgravity Laboratory Chinese Acadermy of SciencesBeijing 100080 International Center for Materials Physics Chinese Academy of SciencesShenyang 110015

A series of crystals of Ba_(x)Sr_(1-x)(NO_(3))_(2) (x=0-0.98) were grown from aqueous solutions by the evaporation method and characterized by x-ray powder diffraction and high resolution x-ray diffraction. All diffraction data are well indexed according to simple cubic structure. The variation of lattice constants with the concentrations of Ba^(2+) in the crystals accorded quite well to the Vegard's Law. The results of high-resolution x-ray diffraction show that the crystalline quality of Ba_(x)Sr_(1-x)(NO_(3))_(2) decreases with x increasing. The distribution of Ba^(2+) between the solution and solid phase indicated that Ba^(2+) is enriched in the solid phase. It could be attributed to the solubility of Ba(NO3)2 in water being less than that of Sr(NO_(3))_(2).

关键词： diffraction structure solubility

SPACE MATERIALS SCIENCE

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空间科学学报 1998年第S1期18卷 104-111页

作者： chen wan-chun Wei B.(Institute of Physics, The Chinese Academy of Sciences, Beijing 100080)(Department of Applied Physics in Northwestern Polytechnical Univerity)

The main studying activities and results on space materials science during 1996-1997 in China were summarized. The typical research subjects are crystal growth from melt, crystal growth from solution, nucleation, undercooling,solidification of alloys and space experimental hardware. They are carried out by the ground-based studies, the short duration microgravity missions and orbital experiments.

关键词： Space materials science Crystal growth Solidification Microgravity

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一种带导引头视角和落角约束的导引方法

宇航学报 2013年第6期34卷 782-787页

作者：顾家立陈万春北京航空航天大学宇航学院北京100191

针对导弹大落角需求下引起的目标超出导引头视场造成锁定失败的情况,提出了一种采用开关逻辑的导引律。该方法在落角控制导引律的基础上引入了一个开关项,当导引头视角超出设定阈值时开启开关项,通过反向原指令加速度来抑制视角的增大,... 详细信息

针对导弹大落角需求下引起的目标超出导引头视场造成锁定失败的情况,提出了一种采用开关逻辑的导引律。该方法在落角控制导引律的基础上引入了一个开关项,当导引头视角超出设定阈值时开启开关项,通过反向原指令加速度来抑制视角的增大,使目标始终处在导引头视场之内,当导引头视角小于设定阈值时关闭开关项以发挥原导引律的优势。新导引律能有效攻击固定与运动目标,且无需弹目相对距离信息。仿真表明,该导引律既有效地限制了导引头视角,又保留了原导引律高落角精度和指令加速度在末段收敛到零的特性。

关键词：导引头视场视角限制大落角约束开关制导律

Kill probability modeling of multi-purpose guided missile against gunship and its application

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Journal of Measurement Science and Instrumentation 2014年第2期5卷 9-18页

作者： DU Zheng chen wan-chun School of Astronautics Beijing University of Aeronautics and Astronautics Beijing 100191 China

Aimed at current deficiencies of multi-purpose guided missile kill probability model against gunship, the concept of the important coefficient of vulnerability blade unit is proposed in this paper. Laser fuze actuation model and warhead condition kill probability model of rotor blades are established by Monte Carlo method and kinetics theory with new ideas. Based on limited data, armor thickness of gunship is estimated, and a complete multi-purpose guided missile kill probability mathematical model is established, which provides necessary mathematical tool for the accurate and objective analysis of multi-purpose guided missile kill probability against gunship. Based on the establishment of the model, sensitivity analysis and optimal design of the main factors of multi-purpose guided missile kill probability are conducted, and the results show that the single multi-purpose guided missile lethality performance can be improved significantly by sensitivity analysis and optimization.

关键词： multi-purpose guided missile gunship rotor blade the important coefficient of vulnerability blade unit armorthickness kill probability

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具有脉冲姿控发动机的导弹控制策略设计

系统工程与电子技术 2008年第9期30卷 1724-1729页

作者：王进陈万春殷兴良北京航空航天大学宇航学院北京100191 中国航天科工集团公司北京100830

在导弹动力学模型中使用4个因子描述喷流干扰效应。在俯仰平面内设计了导弹的控制策略,设计思路强调导弹对指令的快速响应要求。姿控发动机的点火指令按等周期计算,通过分析导弹在一个点火周期内的动力学,用李雅普诺夫函数设计指令趋近... 详细信息

在导弹动力学模型中使用4个因子描述喷流干扰效应。在俯仰平面内设计了导弹的控制策略,设计思路强调导弹对指令的快速响应要求。姿控发动机的点火指令按等周期计算,通过分析导弹在一个点火周期内的动力学,用李雅普诺夫函数设计指令趋近律,最后得到了离散化的舵指令和脉冲姿控发动机点火指令。仿真结果表明,脉冲姿控发动机参与控制产生的脱靶量远远小于气动舵单独控制时产生的脱靶量,显示了控制策略的有效性及使用侧向推力装置的优势。

关键词：导弹控制自动驾驶仪脉冲姿控发动机喷流干扰效应拦截

LOCALIZED MOLECULAR ORBITAL STUDY ON ELECTRONIC STRUCTURES OF BOWL-SHAPED AROMATIC HYDROCARBONS

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Chinese Chemical Letters 1993年第11期4卷 963-964页

作者： Zhi Da chen chun wan LIU Jia Xi LU Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences State Key Laboratory of Structural Chemistry, Fuzhou, Fujian 350002

The localized molecular orbitals for typical bowl-shaped circulenes are obtained by the use of INDO-LMO method. It is found that these bowl-shaped circulenes with strained π-electron systems are still aromatic and th... 详细信息

关键词： In LOCALIZED MOLECULAR ORBITAL STUDY ON ELECTRONIC STRUCTURES OF BOWL-SHAPED AROMATIC HYDROCARBONS 工工