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Feng X.,Sichuan University | Feng X.,CSR Zhuzhou Electrical Co. | Huang W.,Sichuan University | Shi Q.,Sichuan University | And 3 more authors.
Qiangjiguang Yu Lizishu/High Power Laser and Particle Beams | Year: 2013

Antimony doped tin oxide (ATO) powder was prepared by liquid phase chemical coprecipitation method with the SnCl4·5H2O and SbCl3 used as raw materials. The effects of the doping concentration of Sb on the energy gap, and the transmission characteristics in 0.2-1.6 THz were investigated. In particular, the THz time-domain and frequency-domain spectra, the absorption and shielding effect of the ATO were measured. The results indicate that, the energy gap of the ATO decreases first but then increases with the increase of the Sb doping amount. The same tendency emerges in the change of the THz absorption and shielding effect. In the 1.24-1.60 THz range, the ATO with a Sb doping amount of 9% exhibits the highest shielding efficiency of about 45 dB. Source

Nie G.,Jiangsu University | Nie G.,CSR Zhuzhou Electrical Co. | Feng A.,Jiangsu University | Feng A.,Wenzhou University | And 4 more authors.
Qiangjiguang Yu Lizishu/High Power Laser and Particle Beams | Year: 2013

2024 aluminum alloy samples were treated by multiple laser shock processing (LSP). Residual stresses of impact zone were analyzed by XRD. The distribution of residual stress state by multiple LSP was studied. The quality of laser shock processing was evaluated by the distribution of residual stress state. Experimental results show that plastic deformation and plastic strain gradient decreased with the increasing shock times, and the measured points were in two-direction compressive stress state. Plastic strain gradient was increased by 4 LSP impacts. The point center was in one-direction compressive stress state and the others were in two-direction compressive stress state. The quality of LSP was optimum by the laser power density of 2.8 GW/cm2 and 3 LSP impacts, with measured points in two-direction compressive stress state. In this condition, the mean values of maximum principal residual stresses and stress intensity were maximum, the variances of them were minimum, the distribution of them was uniform, and the plastic strain gradient was minimum. Source

Liu X.,Southwest Jiaotong University | Zhang K.-L.,Southwest Jiaotong University | Yao Y.,Southwest Jiaotong University | Zhang J.,CSR Zhuzhou Electrical Co.
Tiedao Xuebao/Journal of the China Railway Society | Year: 2015

In order to study the local mechanical properties of welded joints, the elastic notch stress method is used to analyze the fatigue strength of a complex welded structure. The paper assesses the micro-structural notch support effect with the Neuber's stress averaging approach, and discusses the modeling theory and parameter selection of the fictitious notch rounding. The paper presents that, in the analysis of notch stress with FEM, when it comes to controlling the boundary conditions of the local model, the use of the nodal force can better avoid stress concentration and uneven stress distribution than the displacement method. Fatigue analysis by notch stress method is performed on the locomotive welded frame in the design stage. Notch stress and cumulative damage for welding joints are calculated through the establishment of the 3D overall model and sub-model. This paper provides a new method for the fatigue assessment of key welded structures of locomotives. ©, 2014, Science Press. All right reserved. Source

Wei C.,National University of Defense Technology | Wu T.,National University of Defense Technology | Fu H.,National University of Defense Technology | Shang S.,CSR Zhuzhou Electrical Co.
Communications in Computer and Information Science | Year: 2014

Scan registration has a critical role in mapping and localization for Autonomous Ground Vehicle (AGV). This paper addresses the problem of alignment with only exploiting the common static objects instead of the whole point clouds or entire patches on campus environments. Particularly, we wish to use instances of classes including trees, street lamps and poles amongst the whole scene. The distinct advantage lies in it can cut the number of pairwise points down to a quite low level. A binary trained Support Vector Machine (SVM) is used to classify the segmented patches as foreground or background according to the extracted features at object level. The Iterative Closest Point (ICP) approach is adopted only in the foreground objects given an initial guesses with GPS. Experiments show our method is real-time and robust even when the the signal of GPS suddenly shifts or invalid in the sheltered environment. © Springer-Verlag Berlin Heidelberg 2014. Source

Li T.,Hunan City University | Hu J.,Hunan Institute of Science and Technology | Zhang C.,Hunan City University | Liu G.,CSR Zhuzhou Electrical Co.
Advances in Information Sciences and Service Sciences | Year: 2012

This paper presents a novel image encryption scheme based on Arnold mapping and Logistic mapping.It is a digital image encryption algorithm,dual scrambling that based on chaos of pixel position and pixel value. First we separated the three channels of a RGB mode image, then transformed them into 3 two dimensional grey images. respectively scramblinged these gray images of the three colour channels or changed their gray value by different methods,finally combined the three ciphertext into a RGB mode image.The results of experiment simulation show that the key space is large enough to resist the brute-force attack,the ciphertext varies sensitively with any minimal changes of the initial secret key and the plaintext. The algorithm improves the traditional image encryption algorithm of image scrambling based on chaos, and it is valid and has good performance. Source

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