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The Continuity of Barrier Function with Respect to the Parameter

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Chinese Annals of Mathematics,Series B 2009年第2期30卷 145-152页

作者： Xinxiang li jun yan School of Mathematical Sciences Fudan University Shanghai 200433 China

The authors study the continuity of barrier function Be（x） with respect to the parameter. A sufficient condition which makes Be（x） be continuous with respect to c is obtained, and an example of discontinuity when ... 详细信息

关键词： Lagrangian systera Average action Barrier function Minimal measure Uniquely ergodic

Microstructure and Martensitic Transformation Behaviors of Explosively Welded NiTi/NiTi Laminates

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Chinese Journal of Aeronautics 2007年第2期20卷 168-171页

作者： yan Zhu CUI li-shan ZHENG yan-jun Department of Materials Science and Engineering China University of Petroleum Beijing 102249 China

The study is a first attempt to prepare bulk NiTi/NiTi shape memory alloy （SMA） laminates with a macroscopic heterogeneous composition by explosive welding and investigate their microstructures and martensitic transformation behaviors. After explosive weld- ing, a perfect interfacial bonding between the two components and a reversible martensitic transformation are realized in the tandem. Results show achievement of a fine granular structure and the maximum value of microhardness near the welding interface because of the excessive cold plastic deformation and the high impact velocity during the explosive welding. Meanwhile, the effects of aging on the transformation of the welded tandem are investigated by differential scanning calorimeter （DSC） and subject to discussion. The trans- formation temperatures of NiTi/NiTi SMAs increase with the rise of the aging temperature. The experimental results indicate the shape memory properties of NiTi/NiTi SMA fabricated by explosive welding can be improved by optimizing the aging technology.

关键词： NiTi shape memory alloy explosive welding martensitic transformation

Calibration of line structured light vision system based on camera’s projective center

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光学精密工程 2005年第5期13卷 584-591页

作者： ZHU Ji-gui li yan-jun YE Sheng-hua State Key Laboratory of Precision Measuring Technology and Instrument Tianjin Universality Tianjin 300072China

Based on the characteristics of line structured light sensor, a speedy method for the calibration was established. With the coplanar reference target, the spacial pose between camera and optical plane can be calibrated by using of the camera’s projective center and the light’s information in the camera’s image surface. Without striction to the movement of the coplanar reference target and assistant adjustment equipment, this calibration method can be implemented. This method has been used and decreased the cost of calibration equipment, simplified the calibration procedure, improved calibration efficiency. Using experiment, the sensor can attain relative accuracy about 0.5%, which indicates the rationality and effectivity of this method.

关键词：投影中心线性结构光传感器标度可视性系统

Radar target recognition based on micro-Doppler effect

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Optoelectronics Letters 2008年第6期4卷 456-459页

作者： DONG Wei-guang li yan-jun College of Astronautics Northwestern Polytechnical University Xi ＇an 710072 China

Mechanical vibration of target structures will modulate the phase function of radar backscattering,and will induce the frequency modulation of returned signals from the target. It generates a side bands of the target body Doppler frequency shift,which is helpful for target recognition. Based on this,a micro-Doppler atomic storehouse is built for the target recognition,and four kinds of common classifiers are used separately to perform the classified recognition. The simulation experimental results show that this method has high recognition rate above 90%.

关键词：雷达目标显微多普勒效应信息处理后向散射

Cloning, expression and chitin-binding activity of two peritrophin-like protein genes in the common cutworm, Spodoptera fitura

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Insect Science 2014年第4期21卷 449-458页

作者： Wei-jun Chen li-Xia Huang Dan Hu li-yan liu jun Gu li-Hua Huang Qi-li Feng Guangdong Provincial Key Laboratory of Biotechnology for Plant Development School of Life Sciences South China Normal UniversityGuangzhou China

Insect midgut secretes a semi-permeable peritrophic membrane （PM）, which plays important roles in protecting the midgut and helping with food digestion. The lep- idopteran larvae produce type 1 PM, which is degraded when insects develop into the metamorphic stages. However, the underlying mechanism is unclear. In the present study, two peritrophin-like proteins （peritrophin-57 and 37） were identified from the midgut expression sequence tag library and transcriptome of the common cutworm, Spodoptera litura. The temporal and spatial expression patterns and responses to the induction of 20- hydroxyecdysone （20E） and starvation were examined by real-time quantitative polymerase chain reaction according to their common sequence region. The chitin-binding activity was also studied using a competitor, calcofluor. The open reading frames are 1 554 and 1 020 bp, respectively. They shared four highly conserved peritrophin-A domains and were ex- pressed only in the midgut rather than in the other tissues, including fat body, epidermis, Malpighian tube and hemolymph. Their transcriptional expression could only be detected at the larval stages rather than in eggs, prepupae, pupae and adults. The purified protein of peritrophin-37 bound to chitin in a dose-dependent manner. These results indicate that the two proteins are peritrophins, the structural components of PM. In addition, the messenger RNA levels of the two peritrophins were significantly down-regulated by 20E injection, whereas feeding/starvation had no effect on the expression. These findings suggest that the increase of20E titer may be an important factor which controls the degradation of PM during metamorphosis.

关键词： metamorphosis peritrophic membrane peritrophin starvation 20-hydroxyecdysone

Novel chiral thioureas for highly enantioselective Michael reactions of malonates to nitroalkenes

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Chinese Chemical Letters 2009年第3期20卷 310-313页

作者： li jun yan Quan Zhong liu Xue lian Wang Laboratory of Applied Chemistry and Pollution Control Technology College of Chemistry and Chemical Engineering China West Normal University Nanchong 637002 China

Highly efficient Michael addition reactions of malonates to nitroalkenes catalyzed by novel chiral thioureas derived from optically pure BINOL and amino acids are reported. Various trans-nitroalkenes reacted with malo... 详细信息

关键词： Michael addition Thiourea Enantioselectivities Nitroalkene and malonate

Synthesis of TiNi/Ti_2Ni Composite Particles in Molten Salts

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Chinese Journal of Aeronautics 2006年第B12期19卷 139-141页

作者： yanG Rui-song CUI li-shan ZHENG yan-jun Department of Materials Science and Engineering China University of Petroleum Beijing 102249 China

A new process of synthesizing TiNi/Ti2Ni composite particles, high temperature molten salts method, is introduced. This method uses molten salts as a reaction medium that does not take part in the chemical reaction and can be easily dissolved in rinsing water. According this method, the composite particles were prepared in molten salts at 700 ℃-900 ℃. By means of differential scanning calorimetry （DSC）, the reversible martensific transformation of TiNi particles in these composite particles was contemned.

关键词： TiNi oarticles martensitic transformation molten salts

The optimal time-frequency atom search based on a modified ant colony algorithm

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Optoelectronics Letters 2008年第3期4卷 227-230页

作者： GUO jun-feng li yan-jun YU Rui-xing ZHANG Ke College of Astronautics Northwestern Polytechnical University Xi＇ an 710072China

this paper, a new optimal time-frequency atom search method based on a modified ant colony algorithm is proposed to improve the precision of the traditional methods. First, the discretization formula of finite length time-frequency atom is inferred at length. Second; a modified ant colony algorithm in continuous space is proposed. Finally, the optimal time- frequency atom search algorithm based on the modified ant colony algorithm is described in detail and the simulation experiment is carried on. The result indicates that the developed algorithm is valid and stable, and the precision of the method is higher than that of the traditional method.

关键词：最优化频率原子计算方法

The Two-step Reverse Martensitic Transformations of TiNi Shape Memory Alloy Based on Solution-treatment and Aging

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Chinese Journal of Aeronautics 2006年第B12期19卷 198-201页

作者： JIANG Da-qiang CUI li-shan ZHENG yan-jun JIANG Xiao-hua Department of Materials Science and Engineering China University of Petroleum Beijing 102249 China

A TiNi-alloy is solution-treated in a vacuum furnace of 6.7×10^-3 Pa at 1 223 K for 3.6 ks, and then aged at 773 K for 1.8 ks. The differential scanning calorimetry （DSC） measurements show that after the heat-treatment, takes place a two-step reverse Martensitic transformation, from which results the two-stage recovery strain in a prestrained Martensitic TiNi-alloy wire during heating. The Vickers microhardness indentation test in cross-sectional areas of the TiNi-alloy wire indicates the compositional heterogeneity between its surface layers and its inside. The fact that the sizes of the indentation in surface layers smaller than those in the inside bears witness to the existence of slightly harder surface layers. It is believed that these phenomena are related to the compositional fluctuation caused by the evaporation and oxidization of Ti-element during the solution-treatment and heterogeneity formed during the subsequent aging treatment.

关键词： shape memory alloy (SMA) TiNi solution-treatment heterogeneity