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Symmetries and Mei Conserved Quantities for Nonholonomic Systems with Servoconstraints

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Communications in Theoretical Physics 2009年第1期51卷 1-5页

作者： XIA Li-Li WANG xian-Jun zhao xian-Lin Department of Physics Henan Institute of Education Zhengzhou 450014 China

This paper concentrates on studying the symmetries and a new type of conserved quantities called Mei conserved quantities for Nonholonomic Systems with Servoconstraints. The criterions of the Mei symmetry, the Noether symmetry, and the Lie symmetry are given. The conditions and the forms of the Mei conserved quantities deduced from these three symmetries are obtained. An example is given to illustrate the appfication of the results.

关键词： nonholonomic systems servoconstraints symmetry conserved quantity

Medical Sign Recognition of Lung Nodules Based on Image Retrieval with Semantic Features and Supervised Hashing

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Journal of Computer Science & Technology 2017年第3期32卷 457-469页

作者： Juan-Juan zhao Ling Pan Peng-Fei zhao Kiao-xian Tang College of Computer Science and Technology Taiyuan University of Technology Taiyuan 030024 China Shanxi Provincial People's Hospital Taiyuan 030012 China

Sign recognition is important for identifying benign and malignant nodules. This paper proposes a new sign recognition method based on image retrieval for lung nodules. First, we construct a deep learning framework to extract semantic features that can effectively represent sign information. Second, we translate the high-dimensional image features into compact binary codes with principal component analysis （PCA） and supervised hashing. Third, we retrieve similar lung nodule images with the presented adaptive-weighted similarity calculation method. Finally, we recognize nodule signs from the retrieval results, which can also provide decision support for diagnosis of lung lesions. The proposed method is validated on the publicly available databases： lung image database consortium and image database resource initiative （LIDC-IDRI） and lung computed tomography （CT） imaging signs （LISS）. The experimental results demonstrate our retrieval method substantially improves retrieval performance compared with those using traditional Hamming distance, and the retrieval precision can achieve 87.29%when the length of hash code is 48 bits. The entire recognition rate on the basis of the retrieval results can achieve 93.52%. Moreover, our method is also effective for real-life diagnosis data.

关键词： lung nodule medical sign recognition image retrieval supervised hashing adaptive weight

When thermoelectric materials come across with magnetism

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Rare Metals 2021年第4期40卷 752-766页

作者： Chen-Chen zhao Chong xiao Hefei National Laboratory for Physical Sciences at the Microscale University of Science and Technology of ChinaHefei 230026China Institute of Energy Hefei Comprehensive National Science CenterHefei 230031China

Nowadays,thermoelectric materials have attracted a lot of attention as they can directly convert heat into electricity and vice ***,while strenuous efforts have been made,those conventional strategies are still inevitably going to meet their performance optimization *** this reason,brand new strategies are badly needed to achieve further ***,the roles played by magnetism in recent advances of thermoelectric optimization are ***,magnetic thermoelectric materials can just be treated like other normal materials because the use of universal optimization strategies can still get good ***,it is not a situation which is all or nothing and the tactics of using magnetism for thermoelectric optimization can coexist with other ***,through magnetic doping,we can introduce and adjust magnetism in materials for further *** provides more possibilities in thermoelectric optimization as it can directly influence the spin states in ***,in the form of magnetic secondphase nanoclusters,magnetism can be introduced to thermoelectric materials to conquer the dilemma that the solid solubility of many magnetic ions in thermoelectric materials is too low to have any significant effect on thermoelectric ***,when exposed to an external magnetic field,topological materials can rely on its unique band structures to optimize.

关键词： Thermoelectricity Magnetic thermoelectric materials Magnetism Magnetic doping Magnetic second phase

Solvothermal Route to Prepare the Metastable Phase 3c-Fe_7S_8 with Hexagonal Platelet Morphology

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Chinese Chemical Letters 2003年第1期14卷 83-86页

作者： xian Yun XU xiao Guang LI DepartmentofMatcrialsScienceandEngineering.UniversityofScienceandTechnologyofChina Hefei230026 DepartmentofMatcrialsScienceandEngineering.UniversityofScienceandTechnologyofChina

The metastable phase 3c-Fe7S8 with the hexagonal platelet morphology has been prepared by using solvothermal route. The product was characterized by means of X-ray powder diffraction (XRD) and transmission electron microscopy (TEM) and X-ray photoelectron spectra (XPS). The experiment results show that the as-prepared Fe7S8 is a metastable phase with the hexagonal platelet morphology.

关键词： c-Fe_7S_8 solvothermal route hexagonal platelet.

Impacts of zinc layer and pouring method on interface performance for Al-22Si/ZL104 bi-metal

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China Foundry 2017年第1期14卷 39-45页

作者： Jun-feng zhao Fu-yang Cao Jian-fei Sun xiao-guang Yuan Hong-xian Shen Xin-yi zhao School of Materials Science and Engineering Shenyang University of TechnologyShenyang 110178China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China

Bi-metal material consisting of spray-formed Al-22Si and ZL104 is a suitable candidate for applications in internal combustion engines. This research investigated the effects of surface treatment and appropriate gating system on the microstructures and mechanical properties in evaluating the optimal strategy for producing high quality bi-metal materials. The bi-metal materials were prepared using ZL104 gravity casting by different pouring types around the spray-formed AI-22Si with varied surface treatments. The wettability between AI-22Si and ZL104 was significantly improved when Zn coating was used to remove the natural oxide layer. This research also obtained the improved interfacial microstructures and interracial bonding strength for materials when applying the appropriate pouring method. The hardness profiles of AI-22Si/ZL104 bi-metal were consistent with the observed microstructures. The average tensile strength of the bi-metal material with zinc coating is -42.3 MPa, which is much higher than that with oxide film at -10 MPa. The process presented is a promising and effective approach for developing materials in the automotive industry.

关键词： bi-metal AI alloy interface bonding zinc coating

N-Soliton Solutions of(2+1)-Dimensional Non-isospectral AKNS System

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Communications in Theoretical Physics 2008年第11期50卷 1181-1184页

作者： ZHANG xiao-xian SUN Ye-Peng Department of Mathematics Lanzhou City University Lanzhou 730070 China School of Statistics and Mathematics Shandong Economic University Jinan 250014 China

The bilinear form of the （2＋1）-dimensional non-isospectral AKNS system is derived. Its N-soliton solutions are obtained by using the Hirota method. As a reduction, a （2＋1）-dimensional non-isospectral Schrodinger... 详细信息

关键词： non-isospectral AKNS system Hirota method N-soliton solution non-isospectral Schrodinger equation

Sliding mode tracking control for miniature unmanned helicopters

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Chinese Journal of Aeronautics 2015年第1期28卷 277-284页

作者： xian Bin Guo Jianchuan Zhang Yao zhao Bo The Institute of Robotics and Autonomous System Tianjin Key Laboratory of Process Measurement and ControlSchool of Electrical Engineering and Automation Tianjin University

A sliding mode control design for a miniature unmanned helicopter is presented. The control objective is to let the helicopter track some predefined velocity and yaw trajectories. A new sliding mode control design method is developed based on a linearized dynamic model. In order to facilitate the control design, the helicopter＇s dynamic model is divided into two subsystems,such as the longitudinal-lateral and the heading-heave subsystem. The proposed controller employs sliding mode control technique to compensate for the immeasurable flapping angles＇ dynamic effects and external disturbances. The global asymptotic stability（GAS） of the closed-loop system is proved by the Lyapunov based stability analysis. Numerical simulations demonstrate that the proposed controller can achieve superior tracking performance compared with the proportionalintegral-derivative（PID） and linear-quadratic regulator（LQR） cascaded controller in the presence of wind gust disturbances.

关键词： unmanned sliding miniature compensate quadratic cascaded subsystem disturbance facilitate linearized

A Convenient Synthesis of Diacyl Selenides by Selenium Transfer Reaction of Primary Selenoamides

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Chinese Chemical Letters 2001年第10期12卷 873-874页

作者： Hua Rong zhao Xin Jian zhao xian HUANG Department of Chemistry Zhejiang UniversityHangzhou 310027 Zhejiang Institute of Calibaration and Testing for Technical Superision Hangzhou 310013

As a selenium transfer reagent, arylselenoamides react with acyl chlorides in chloroform to give diacyl selenides conveniently in good yield.

关键词： diacyl selenides selenium transfer reaction

Effect of Ti Particles on the Microstructure and Mechanical Properties of AZ91 Magnesium Matrix Composites

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Acta Metallurgica Sinica(English Letters) 2024年第3期37卷 513-524页

作者： Lu xiao Ting-Ting Liu Yue Chu Bo Song Jie zhao xian-Hua Chen Kai-Hong Zheng Fu-Sheng Pan College of Materials Science and Engineering Chongqing UniversityChongqing 400044China lntelligent Manufacturing and Automobile School Chongqing College of Electronic EngineeringChongqing 401331China School of Materials and Energy Southwest UniversityChongqing 400715China Science and Technology Research Institute of CNNC 404 Co.LTD Gansu 735100China Institute of New Materials Guangdong Academy of SciencesGuangzhou 510650China

Spherical micro-Ti particle(TiP)-reinforced AZ91 magnesium alloy composites were fabricated by semi-solid stirring assisted ultrasonic vibration,which were then subjected to hot *** microstructure results showed that the addition of Ti particles refined the grain size and decreased the texture intensity of the as-extruded AZ91 *** Al3Ti phase with a thickness of 100 nm formed at the Ti/Mg interface,which had a non-coherent relationship with the magnesium *** as-extruded 1 vol.%TiP/AZ91 composite exhibited the best comprehensive mechanical properties,with yield strength,ultimate tensile strength,and elongation at break of 366 MPa,456 MPa,and 14.6%,respectively,which were significantly higher than those of the AZ91 ***,the addition of Ti particles can improve the strength and ductility of the AZ91 alloy,demonstrating the value of magnesium matrix composites for commercial applications.

关键词： Magnesium matrix composites Ti particles Interface Mechanical properties