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高电压技术 2014年第6期40卷 1683-1687页

作者： YANG Jie ZHANG xijun DONG Kangning ResearchInstituteofElectrostaticandElectromagneticProtection MechanicalEngineeringCollegeShijiazhuang050003China

Adding transient voltage suppressor (TVS) transistors to an electric circuit is an important method to protect it from the fast-risetime electromagnetic pulse (FREMP) damage. The package form of the TVS transistors influences the volume, response time, and power consumption of the circuit. However, the influence of the package form on the clamp voltage of TVS transistors affected by FREMP is not considered yet. In this article, the results of the experiment comparing the influence of package form are described, where the rectangular pulses with rise time shorter than 1 ns are used to test protection performance of three different TVS transistors, which have the same framework but different breakdown voltages. The influence of the different package forms on the clamp voltage is analyzed by using the fitting model. It is found that the package form of TVS transistors has less influence on the current characteristics of their protection performance, but more on the voltage characteristics. It is concluded that the diameter or width of the TVS transistors is the main factor determining the clamp voltage. Thus, the diameter or width of the TVS transistors should be big enough to ensure the stabilization of clamp voltage, but, at the same time, fit the allowing volume.

关键词：瞬态电压抑制器晶体管防护性能包装形式瞬变电压抑制器上升时间保护性能封装形式

IMPROVED SINGULAR VALUE DECOMPOSITION TECHNIQUE FOR DETECTING AND EXTRACTING PERIODIC IMPULSE COMPONENT IN A VIBRATION SIGNAL

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Chinese Journal of Mechanical Engineering 2004年第3期17卷 340-345页

作者： LiuHongxing LiJian ZhaoYing QuLiangsheng DepartmentofElectronicScienceandEngineering NanjingUniversityNanjing210093China mechanicalengineeringcollege Xi＇anJiaotongUniversityXi＇an710049China

Vibration acceleration signals are often measured from case surface of arunning machine to monitor its condition. If the measured vibration signals display to have periodicimpulse components with a certain frequency, there may exist a corresponding local fault in themachine, and if further extracting the periodic impulse components from the vibration signals, theseverity of the local fault can be estimated and tracked. However, the signal-to-noise ratios (SNRs)of the vibration acceleration signals are often so small that the periodic impulse components aresubmersed in much background noises and other components, and it is difficult or inconvenient for usto detect and extract the periodic impulse components with the current common analyzing methods forvibration signals. Therefore, another technique, called singular value decomposition (SVD), istried to be introduced to solve the problem. First, the principle of detecting and extracting thesignal periodic components using singular value decomposition is summarized and discussed. Second,the infeasibility of the direct use of the existing SVD based detecting and extracting approach ispointed out. Third, the approach to construct the matrix for SVD from the signal series is improvedlargely, which is the key program to improve the SVD technique; Other associated improvement is alsoproposed. Finally, a simulating application example and a real-life application example ondetecting and extracting the periodic impulse components are given, which showed that the introducedand improved SVD technique is feasible.

关键词： Fault diagnosis Vibration Signal processing Singular value decomposition

SHS Flame Spraying TiC-TiB_(2) Multiphase Coatings

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材料热处理学报 2004年第5B期25卷 981-983页

作者： WANGJian-jiang DUXin-kang LUDa-qin YEMing-hui ZHANGLong AdvancedMaterialInstitute MechanicalEngineeringCollegeShijiazhuangChina MaterialsScienceandEngineeringCollege Xi＇anJiaotongUniversityXi＇anChina／／ AdvancedMaterialInstituteMechanicalEngineeringCollegeShijiazhuangChina AdvancedMaterialInstitute MechanicalEngineeringCollegeShijiazhuangChina／／CenterofPhysicsandChemistryBeihangUniversityBeijingChina

Utilizing SHS Reactive Flame Spraying (RFS) technology, TiC-TiB2-Al2O3 multiphase ceramics coatings were produced on steel substrate. Phase constituents and microstructure of the ceramic coatings were analyzed. The procedure of chemical combustion and structure transformation, reactive mechanism, and solidifying behavior during spaying were emphasized. Reactants which influenced on SHS spraying was discussed. SHS reactive spraying processes were studied. Mechanical properties of the coatings were tested.

关键词： SHS 火焰喷镀 TiC-TiB2 多相涂层

Practical Calculation of Thermal Deformation and Manufacture Error in Surface Grinding

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Journal of Shanghai University(English Edition) 2002年第2期6卷 163-166页

作者：周里群李玉平 mechanicalengineeringcollege XiangtanUniversityXiangtan411105China；InstituteofFundamentalMechanicsandMaterialsEngineeringXiangtanUnuiversityXiangtan411105China MechanicalEngineer

The paper submits a method to calculate thermal deformation and manufacture error in surface grinding. The author established a simplified temperature field model, and derived the thermal deformation of the ground workpiece. It is found that there exists not only a upwarp thermal deformation, but also a parallel expansion thermal deformation. A upwarp thermal deformation causes a concave shape error on the profile of the workpiece, and a parallel expansion thermal deformation causes a dimension error in height. The calculations of examples are given and compared with presented experiment data.

关键词： surface grinding thermal deformation manufacture error.

Attractivity in a Delayed Three-species Ratio-dependent Predator-prey System without Dominating Instantaneous Negative Feedback

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Acta Mathematicae Applicatae Sinica 2003年第2期19卷 317-332页

作者： RuiXu Lan-sunChen M.A.J.Chaplain DepartmentofMathematics MechanicalEngineeringCollegeShijiazhuang050003China InstituteofMathematics AcademyofMathematicsandSystemSciencesChineseAcademyofSciencesBeijing100080China DepartmentofMathematics UniversityofDundeeDundeeDD14HNUK

Abstract A delayed three-species ratio-dependent predator-prey food-chain model without dominating instantaneous negative feedback is investigated. It is shown that the system is permanent under some appropriate condi... 详细信息

关键词： Keywords Time delay uniform persistence global attractivity