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Influence of the finish rolling temperatures on the microstructure and texture evolution in the ferritic stainless steels

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Acta Metallurgica Sinica(English Letters) 2011年第5期24卷 343-350页

作者： fei gao Zhenyu LIU Haitao LIU Guodong WANG The State Key Laboratory of Rolling and Automation Northeastern University Shenyang 110819 China

The influence of the finish rolling temperature on the microstructure and texture evolution of Nb and B micro-alloyed ultra purified Cr17 ferritic stainless steels was investigated. The hot rolled bands were produced by conventional rolling process and the finish rolling at relatively low temperatures or ＂warm rolling＂. The microstructure was observed by optical microscopy, scanning electron microscopy and transmission electron microscopy, and X-ray diffraction was used to characterize the texture evolution processes. The results showed that as compared to conventional hot rolling process, the warm rolling has led to the refined and homogeneous microstructure and uniform recrystallization texture along γ-fiber in final sheets, indicating that the finish rolling at relatively low temperatures can be the effective way to improve significantly the formability of final sheets.

关键词： Ultra purified Cr17 ferritic stainless steel Finish rolling temperature Microstructure Texture

Object detection based on combination of local and spatial information

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Journal of Systems Engineering and Electronics 2011年第4期22卷 715-720页

作者： Qinkun Xiao Nan Zhang fei Li Yue gao School of Electronics and Information Engineering Xi'an Technological University Xi'an 710032 E R. China Fujitsu Research & Development Center Co. LTD. Beijing 100025 E R. China Department of Automation Tsinghua University Beijing 100084 P. R. China

A method of object detection based on combination of local and spatial information is proposed. Firstly, the categorygiven representative images are chosen through clustering to be templates, and the local and spatial information of template are ex- tracted and generalized as the template feature. At the same time, the codebook dictionary of local contour is also built up. Secondly, based on the codebook dictionary, sliding-window mechanism and the vote algorithm are used to select initial candidate object win- dows. Lastly, the final object windows are got from initial candidate windows based on local and spatial structure feature matching. Experimental results demonstrate that the proposed approach is able to consistently identify and accurately detect the objects with better performance than the existing methods.

关键词： object detection codebook dictionary spatial matching local contour matching.

Effect of Na^+ on xonotlite crystals in hydrothermal synthesis

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International Journal of Minerals,Metallurgy and Materials 2013年第1期20卷 88-93页

作者： fei Liu Xiao-dan Wang jian-xin Cao School of Chemistry and Chemical Engineering Guizhou University

The effect of Na＋ ion concentration on the crystalline phase composition and morphology of xonotlite crystals pre- pared in a CaO-SiO2-H20 system via hydrothermal synthesis was analyzed. X-ray diffraction （XRD） and scanning electron mi- croscopy （SEM） results indicate that Na＋ ion concentration has a significant impact on the composition and morphology of crystalline phases in the products under the initial conditions of a molar ratio of CaO/SiO2 of 1.0 and a reactant concentration of 0.05 mol.L-1 at 225℃ for 15 h. The main crystalline phase in the products has a phase transition from xonotlite to pectolite, and the morphology changes from fibrous to broomlike shape with the Na＋ ion concentration increasing. Therefore, the content of Na^O in the raw material should be less than 5wt% for preparing pure xonotlite crystals via hydrothermal synthesis in a CaO-SiO2-H20 system.

关键词： crystals xonotlite pectolite hydrothermal synthesis morphology

QKD-based quantum private query without a failure probability

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Science China(Physics,Mechanics & Astronomy) 2015年第10期58卷 12-17页

作者： LIU Bin gao fei HUANG Wei WEN QiaoYan State Key Laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications College of Computer Science Chongqing University

In this paper, we present a quantum-key-distribution(QKD)-based quantum private query(QPQ) protocol utilizing single-photon signal of multiple optical pulses. It maintains the advantages of the QKD-based QPQ, i.e., easy to implement and loss tolerant. In addition, different from the situations in the previous QKD-based QPQ protocols, in our protocol, the number of the items an honest user will obtain is always one and the failure probability is always zero. This characteristic not only improves the stability(in the sense that, ignoring the noise and the attack, the protocol would always succeed), but also benefits the privacy of the database(since the database will no more reveal additional secrets to the honest users). Furthermore, for the user's privacy, the proposed protocol is cheat sensitive, and for security of the database, we obtain an upper bound for the leaked information of the database in theory.

关键词： quantum private query quantum key distribution single-photon signal

Primary and secondary control in DC microgrids: a review

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Journal of Modern Power Systems and Clean Energy 2019年第2期7卷 227-242页

作者： fei gao Ren KANG Jun CAO Tao YANG Department of Engineering Science University of OxfordOxfordUK Mixergy OxfordUK School of Geography Geology and the EnvironmentKeele UniversityKeeleUK Department of Electric and Electronic Engineering The University of NottinghamNottinghamUK

With the rapid development of power electronics technology, microgrid(MG) concept has been widely accepted in the field of electrical engineering. Due to the advantages of direct current(DC)distribution systems such as reduced losses and easy integration with energy storage resources, DC MGs have drawn increasing attentions nowadays. With the increase of distributed generation, a DC MG consisting of multiple sources is a hot research topic. The challenge in such a multi-source DC MG is to provide voltage support and good power sharing performance. As the control strategy plays an important role in ensuring MG’s power quality and efficiency, a comprehensive review of the state-of-art control approaches in DC MGs is necessary. This paper provides an overview of the primary and secondary control methods under the hierarchical control architecture for DC MGs. Specifically,inner loop and droop control approaches in primary control are reviewed. Centralized, distributed and decentralized approach based secondary control is discussed in *** findings and future trends are also presented at last.

关键词： Primary control Secondary control DC microgrids Droop control Power sharing

Quantum private query: A new kind of practical quantum cryptographic protocol

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Science China(Physics,Mechanics & Astronomy) 2019年第7期62卷 10-21页

作者： fei gao SuJuan Qin Wei Huang QiaoYan Wen State Key Laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications Science and Technology on Communication Security Laboratory Institute of Southwestern Communication State Key Laboratory of Cryptology

This research aims to review the developments in the field of quantum private query(QPQ), a type of practical quantum cryptographic protocol. The primary protocol, as proposed by Jacobi et al., and the improvements in the protocol are ***, the advancements made in sability, theoretical security, and practical security are summarized. Additionally, we describe two new results concerning QPQ security. We emphasize that a procedure to detect outside adversaries is necessary for QPQ, as well as for other quantum secure computation protocols, and then briefly propose such a strategy. Furthermore, we show that the shift-and-addition or low-shift-and-addition technique can be used to obtain a secure real-world implementation of QPQ, where a weak coherent source is used instead of an ideal single-photon source.

关键词： quantum cryptography quantum private query quantum secure multiparty computation quantum oblivious key transfer quantum key distribution

Springback Prediction and Optimization of Variable Stretch Force Trajectory in Three-dimensional Stretch Bending Process

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Chinese Journal of Mechanical Engineering 2015年第6期28卷 1132-1140页

作者： TENG fei ZHANG Wanxi LIANG Jicai gao Song State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology School of Automotive Engineering Dalian University of Technology

Most of the existing studies use constant force to reduce springback while researching stretch force. However, variable stretch force can reduce springback more efficiently. The current research on springback prediction in stretch bending forming mainly focuses on artificial neural networks combined with the finite element simulation. There is a lack of springback prediction by support vector regression（SVR）. In this paper, SVR is applied to predict springback in the three-dimensional stretch bending forming process, and variable stretch force trajectory is optimized. Six parameters of variable stretch force trajectory are chosen as the input parameters of the SVR model. Sixty experiments generated by design of experiments（DOE） are carried out to train and test the SVR model. The experimental results confirm that the accuracy of the SVR model is higher than that of artificial neural networks. Based on this model, an optimization algorithm of variable stretch force trajectory using particle swarm optimization（PSO） is proposed. The springback amount is used as the objective function. Changes of local thickness are applied as the criterion of forming constraints. The objection and constraints are formulated by response surface models. The precision of response surface models is examined. Six different stretch force trajectories are employed to certify springback reduction in the optimum stretch force trajectory, which can efficiently reduce springback. This research proposes a new method of springback prediction using SVR and optimizes variable stretch force trajectory to reduce springback.

关键词： springback prediction support vector regression(SVR) response surface particle swarm optimization(PSO)

Effect of Sn on Corrosion Behavior of Ultra-pure 17 mass% Cr Ferritic Stainless Steels in Sulphuric Acid

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Journal of Iron and Steel Research International 2016年第10期23卷 1044-1053页

作者： Xiang-jun ZHANG fei gao Zhen-yu LIU State Key Laboratory of Rolling and Automation Northeastern University School of Material and Metallurgy Northeastern University

The effect of Sn on corrosion behavior of ferritic stainless steels in 20mass% H2SO4 was investigated by alternating current and direct current electrochemical methods and gravimetric tests at 25 ℃.The results show that Sn can effectively improve general corrosion resistance of ferritic stainless steels in H2SO4,mainly due to highly raised hydrogen evolution overpotential which is in favour of strong suppression of hydrogen evolution reaction,and inhibitive effect of dissolved Sn^2＋ on elementary anodic *** increasing Sn content,the better corrosion resistance can be *** Electrochemical Impedance Spectroscopy（EIS）includes four time constants and can be perfectly fitted by equivalent circuit：Rs（CdlRct）（QadsRads（RL1（L1（RL2L2））））.

关键词： stainless steel tin sulphuric acid general corrosion hydrogen overpotential

New progress in understanding the origins of modern humans in China

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Science China Earth Sciences 2017年第12期60卷 2160-2170页

作者： gao Xing PENG fei FU QiaoMei LI Feng Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences Institute of Vertebrate Paleontology and PaleoanthropologyChinese Academy of SciencesBeijing 100044 University of the Chinese Academy of Sciences Beijing 100049China Department of Early Prehistory and Quaternary Ecology University of TubingenTubingen 72070Germany

Hypotheses concerning the origins of modern humans have been intensively debated, and two competing models, the recent "Out-of-Africa" and "Multiregional Evolution" paradigms, have dominated research and discussions for decades. Evidence from China has played a fundamental role in this debate: regional continuity and replacement by populations in-migrated from Africa have both been suggested and supported mainly by paleoanthropologists and geneticists, respectively. As more evidence has accumulated, new results obtained, and more scholars from various disciplines become involved, supporters of the recent "Out-of-Africa" model agree more or less with the "Multiregional Evolution" model regarding the complex history of modern humans and their interbreeding with other archaic populations(e.g., Neandertals). Recent discoveries of new human fossils, Paleolithic archaeological materials, and ancient DNA evidence in China have yielded a large body of information regarding the formation and development of modern humans in this region. However, controversies continue, including that most molecular biologists insist on the replacement of archaic populations by modern humans dispersed from Africa, while most paleoanthropologists and archaeologists propose an enhanced "Continuity with Hybridization" model. In this paper, we compile new results and progress in China and present the current debates and issues on the origins of modern humans. Finally, we offer several suggestions for future studies.

关键词： China Origins of modern humans Modern behavior Recent out-of-Africa Continuity with hybridization Interdisciplinary research