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铸态Mg-8Y-6Gd-1Nd-0.17Zn稀土镁合金高温压缩本构行为及加工图

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稀有金属材料与工程 2020年第8期49卷 2591-2598页

作者：刘崇亮权高峰周明扬郭阳阳范玲玲西南交通大学材料先进技术教育部重点实验室四川成都610031 中国核动力研究设计院核反应堆系统设计技术重点实验室四川成都610213

研究了铸态Mg-8Y-6Gd-1Nd-0.17Zn镁合金在应变量为50%、温度350~450℃、应变速率0.0001~0.1 s^-1条件下热压缩过程中的本构行为、组织演变和热加工性能。选用双曲正弦本构方程描述合金的流变行为以及变形参数间的关系。结果表明,温度和... 详细信息

研究了铸态Mg-8Y-6Gd-1Nd-0.17Zn镁合金在应变量为50%、温度350~450℃、应变速率0.0001~0.1 s^-1条件下热压缩过程中的本构行为、组织演变和热加工性能。选用双曲正弦本构方程描述合金的流变行为以及变形参数间的关系。结果表明,温度和应变速率对Mg-8Y-6Gd-1Nd-0.17Zn镁合金的流变应力行为有重要影响,其流变应力随温度的降低和应变速率的增加而增大,并且在温度高于400℃压缩时,合金的真应力应变曲线具有典型的动态再结晶特性。在本实验条件下,该合金变形期间的活化能(Q)和应力指数(n)分别为359.258 k J/mol和5.24,实验值与计算值之间的平均误差(ARE)为3.37%。最后基于动态材料模型加工理论,结合热加工图和压缩过程中的组织演变,确定了该合金的最佳热加工参数为:加热温度400~450℃,应变速率为0.0001~0.001 s^-1。

关键词： Mg-Gd-Y-Nd-Zn镁合金热压缩微观结构演变本构方程热加工图

Secure and Efficient Pseudorandom Bit Generator for Chaotic Stream Ciphers

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Chinese Physics Letters 2007年第5期24卷 1166-1169页

作者：王小敏张家树 Key Lab of Signal and Information Processing Southwest 3iaotong University Chengdu 610031

Based on the entropy criterion and n-dimensional uniform distribution of nonlinear digital filter （NDF）, we present an efficient NDF-based pseudorandom bit generator （NDF-PRBG） for chaotic stream ciphers. The cryptographic properties of the proposed NDF-PRBG are analysed, and some experiments are made. The results show that it has desirable cryptographic properties, and can be used to construct secure stream ciphers with high speed.

关键词： NONLINEAR AUTOREGRESSIVE FILTER SEQUENCES

Multi-objective optimization design method of the high-speed train head

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Journal of Zhejiang university-Science A(Applied Physics & Engineering) 2013年第9期14卷 631-641页

作者： Meng-ge YU Ji-ye ZHANG Wei-hua ZHANG State Key Laboratory of Traction Power Southwest Jiaotong University

With the continuous improvement of the train speed, the dynamic environment of trains turns out to be aerodynamic domination. Solving the aerodynamic problems has become one of the key factors of the high-speed train head design. Given that the aerodynamic drag is a significant factor that restrains train speed and energy conservation, reducing the aerodynamic drag is thus an important consideration of the high-speed train head design. However, the reduction of the aerodynamic drag may increase other aerodynamic forces (moments), possibly deteriorating the operational safety of the train. The multi-objective optimization design method of the high-speed train head was proposed in this paper, and the aerodynamic drag and load reduction factor were set to be optimization objectives. The automatic multi-objective optimization design of the high-speed train head can be achieved by integrating a series of procedures into the multi-objective optimization algorithm, such as the establishment of 3D parametric model, the aerodynamic mesh generation, the calculation of the flow field around the train, and the vehicle system dynamics. The correlation between the optimization objectives and optimization variables was analyzed to obtain the most important optimization variables, and a further analysis of the nonlinear relationship between the key optimization variables and the optimization objectives was obtained. After optimization, the aerodynamic drag of optimized train was reduced by up to 4.15%, and the load reduction factor was reduced by up to 1.72%.

关键词： High-speed train Multi-objective optimization Parametric model Aerodynamic drag Load reduction factor

Damming of Large River by Debris Flow: Dynamic Process and Particle Composition

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Journal of Mountain Science 2014年第3期11卷 634-643页

作者： DU Cui YAO Ling-kan SHAKYA Subhashsagar LI Lun-gui SUN Xiao-dan School of Civil Engineering Southwest Jiaotong University MOE Key Laboratory of High-speed Railway Engineering Southwest Jiaotong University Road and Railway Engineering Research Institute Sichuan Key Laboratory of Aseismic Engineering and Technology

The frequency and extent of debris flows have increased tremendously due to the extreme weather and the Wenchuan earthquake on May 12, 2008. Previous studies focused on the debris flow from gullies damming the mountain streams. In this paper, an equation for the run-out distance of debris flow in the main river is proposed based on the dynamic equation of debris flow at different slopes given by Takahashi. By undertaking field investigations and flume experiments, a new calculation method of the volume of debris flow damming large river is obtained. Using the percolation theory and the renormalization group theory it was deduced that the large particles should comprise more than 50% for forming a stable debris flow dam. Hence, the criteria of damming large river by debris flow is presented in terms of run-out distance and grain composition which was then validated through the event of damming river by debris flow at Gaojia gully, the upper reaches of the Minjiang River, Sichuan, China, on July 3, 2011.

关键词： Debris flow Damming.large river Criteria Run-out distance Grain composition

Time-Delay Signature of Chaotic Vertical-Cavity Surface-Emitting Lasers with Polarization-Rotated Optical Feedback

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Chinese Physics Letters 2011年第1期28卷 98-101页

作者： XIANG Shui-Ying PAN Wei YAN Lian-Shan LUO Bin ZOU Xi-Hua JIANG Ning WEN Kun-Hua Center for Information Photonics and Communications Southwest Jiaotong University Chengdu 610031

To quantitatively evaluate the time-delay （TD） signatures of chaotic signals generated by vertical-cavity surface- emitting lasers （VCSELs） with polarization-rotated optical feedback （PROF）, we propose four cases of resolution coefficients R based on correlation functions. The resolution coefficient characteristics for the x-polarization （XP） mode, g-polarization （YP） mode and the total output are considered. The dependences of R on the feedback strength and feedback delay are discussed and compared carefully. The two-dimensional maps of R show that the TD signatures for the single polarization mode （i.e., XP or YP mode） are much more difficult to retrieve than those for the total output in the entire parameter space. Thus, by using single polarization mode as a chaotic carrier, the TD signatures are extremely difficult to be identified, which contributes a lot in the security-enhanced VCSELs-based chaotic optical communication systems.

关键词： Optics quantum optics and lasers

From high-yield Ti3AlCN ceramics to high-quality Ti3CNTx MXenes through eliminating Al segregation

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Chinese Chemical Letters 2020年第4期31卷 1044-1048页

作者： Ningjun Chen Haichao Huang Zhong Xu Yanting Xie Da Xiong Xiang Chu Bingni Gu Bo Zheng Weili Deng Haitao Zhang Weiqing Yang Key Laboratory of Advanced Technologies of Materials Ministry of EducationSchool of Materials Science and EngineeringSouthwest Jiaotong UniversityChengdu 610031China State Key Laboratory of Traction Power Southwest Jiaotong UniversityChengdu 610031China

Ti3CNTx MXenes with unique electrical conductivity can be widely applied for supercapacitors and electromagnetic ***,its relatively low-yield quaternary nitrogen-containing Ti3AlCN ce ramics precursor(less than 50%),due to the inevitable Al segregation during the synthesizing process,significantly hindered its widely commercial ***,we employed the controllable AlNoversaturation precursor strategy to precisely tune the phase transition point of quaternary Ti3AlCN ceramics to obtain high-yield Ti3 AlCN precursor for the purpose of high conductivity Ti3 CNTx *** energy dispersive X-ray spectrometer(XRD)with X-ray photoelectron spectroscopy(XPS)characterizations,the yield of the quaternary nitrogen-containing Ti3 AlCN ceramics was evidently proved to be up to 70%,which is 1.4 times than that of previously reported *** relatively highyield quaternary Ti3AlCN is mainly ascribed to the elimination of Al *** on it,we further developed accordion-like two-dimensional(2D)MXene via hydrofluoric acid etch and vacuum *** novel accordion-like 2D Ti3CNTx MXene possesses high electrochemical capacitive properties(209 F/g).Therefore,this controllable AlN-oversaturation precursor strategy will pave a way to exploit costly high-yield MAX ceramics precursor for high conductivity MXenes and also play a powerful role in promoting their practical applications including electrical and magnetic engineering fields.

关键词： Al segregation High-yield Ti3AlCN MAX phase Ti3CNTx MXenes Supercapacitors

Monitoring subsidence rates along road network by persistent scatterer SAR interferometry with high-resolution TerraSAR-X imagery

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Journal of Modern Transportation 2013年第4期21卷 236-246页

作者： Bing Yu Guoxiang Liu Rui Zhang Hongguo Jia Tao Li Xiaowen Wang Keren Dai Deying Ma Department of Remote Sensing and Geospatial Information Engineering Southwest Jiaotong University

Ground subsidence is one of the key factors damaging transportation facilities, e.g., road networks consisting of highways and railways. In this paper, we propose to apply the persistent scatterer synthetic aperture radar interferometry （PS-InSAR） approach that uses high- resolution TerraSAR-X （TSX） imagery to extract the regional scale subsidence rates （i.e., average annual sub- sidence in mm/year） along road networks. The primary procedures involve interferometric pair selection, interfer- ogram generation, persistent scatterer （PS） detection, PS networking, phase parameterization, and subsidence rate estimation. The Xiqing District in southwest Tianjin （China） is selected as the study area. This district contains one railway line and several highway lines. A total of 15 TSX images covering this area between April 2009 and June 2010 are utilized to obtain the subsidence rates by using the PS-InSAR （PSI） approach. The subsidence rates derived from PSI range from -68.7 to -1.3 mm/year. These findings show a significantly uneven subsidence pattern along the road network. Comparison between the PSI-derived subsidence rates and the leveling data obtained along the highways shows that the mean and standard deviation （SD） of the discrepancies between the two types of subsidence rates are 0.1 and 4-3.2 mm/year, respectively. The results indicate that the high-resolution TSX PSI is capable of providing comprehensive and detailed subsidence information regarding road networks with millimeter-level accuracy. Further inspections under geo- logical conditions and land-use categories in the study area indicate that the observed subsidence is highly related to aquifer compression due to groundwater pumping. Therefore, measures should be taken to mitigate groundwater extraction for the study area.

关键词： Subsidence Road network - Persistent scatterer interferometry TerraSAR-X Highway Railway

Identification and Expression of a b-actin Gene from Liposcelis bostrychophila Badonnel(Psocoptera:Liposcelididae)

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Agricultural Sciences in China 2011年第9期10卷 1391-1401页

作者： JIANG Hong-bo SHEN Guang-mao DOU Wei TANG Pei-an LIU Yong-hua ZHOU An-wei WANG Jin-jun Key Laboratory of Entomology and Pest Control Engineering College of Plant Protection Southwest University Chongqing 400716 P. R. China College of Food Science and Engineering Nanjing University of Finance and Economics Nanjing 210003 P.R. China

A β-actin gene, Libβ-actinl, from the psocid, Liposcelis bostrychophila, was isolated, sequenced, and expressed in Escherichia coll. The cDNA sequence was 1 281 bp in length and contained an open reading frame of 1 131 bp encoding 376 amino acids with a predicted molecular weight of 41.82 kDa. According to a B lastN search, the coding region shared the highest identity （97%） with Pediculus hurnanus actin 5C, while the deduced amino acid sequence was completely identical to a mutant of Drosophila melanogaster actin 5C. Comparison of the nucleotide and deduced amino acid sequences confirmed the high similarity between Libβ-actinl and homologs in other insect species. The 3＇ untranslated region （3＇ UTR） of the Libβ-actinl mRNA had a high A＋U content （approximately 75%） and contained three repeats of the AUUUUUA and AUUUA motifs, which may play a role in regulating mRNA decay. The expression of Libβ-actinl was further analyzed in insecticide induced and control psocids. The results indicated that there was no significant difference in expression of Libβ-actinl between the induced and control groups, suggesting that Libβ-actinl may be an appropriate internal control for the gene expression profiling in this insect. Furthermore, Libβ-actinl was also heterologously expressed in Escherichia coli, which provided a basis to investigate the physiological functions of actin genes in the psocid.

关键词： actin sequence analysis expression real-time PCR

Safety threshold of high-speed railway pier settlement based on train-track-bridge dynamic interaction

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Science China(Technological Sciences) 2015年第2期58卷 202-210页

作者： CHEN Zhao Wei ZHAI Wan Ming CAI Cheng Biao SUN Yu State Key Laboratory of Traction Power Southwest Jiaotong University

This paper presents a method to determine the safety threshold of bridge pier settlement in high-speed *** analytical expression of the mapping relationship between the pier settlement and the rail deformation is derived theoretically for the double block ballastless track-bridge *** adopting the superposition of the track random irregularity and the rail deformation caused by the pier settlement as the excitation inputs,the variations of vehicle dynamics indices with pier settlement are comparatively ***,the safety threshold of the bridge pier settlement is obtained according to the limit of vehicle running safety and ride comfort indices of the high-speed *** show that the dynamics indices of different trains have different sensitivities to the pier settlement,and the train CRH2C is the most sensitive one among all the types of Chinese high-speed *** passing through the bridges in common span with pier settlement at the speed of 250–350 km/h,the trains suffer the low-frequency excitations,and the vertical acceleration of car body is most sensitive to the pier settlement of all the dynamics *** the car body vertical acceleration just exceeds the allowable limit,the critical settlement value is 23.4 mm,which is much bigger than the pier differential settlement limit in the current code for Chinese high-speed railways.

关键词： high-speed railway pier settlement safety threshold dynamic characteristics train-track-bridge dynamic interaction