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2003-2020 全部
为您找到包含“performance”的内容共10972

Liqiang Zhao

IEEE 802.11 includes two medium access control (MAC) protocols, a basic distributed coordination function and an optional point coordination function (PCF). PCF is a polling-based MAC protocol able to support collision free and time bounded services. However no suitable PCF analytical model is presented now. A simple, but extremely accurate, analytical model is presented in this paper to compute the system throughout. Simulation results show that the model is valid.

2006-08-21

State Key Laboratory of Integrated Services Networks, Xidian University

#Electrics, Communication and Autocontrol Technology#

YAN Hongzhi,ZHANG Longci,LI Chao,WEN Guangxu

Based on Dowson-Higginson equation, this article obtains minimum film thickness of smooth tooth surface in meshing process. From the beginning of meshing process to its disengagement, the minimum film thickness increases gradually .its inflection point appears between the double teeth-meshing area and the single teeth-meshing area, and its maximum appears when the contact point closes the root of face gear. Using shaper to machine face gear with different module and pressure angle, it analyses backlash for the best minimum film thickness. According to the effect of grinding method to surface topography, the minimum film thickness correction factor is recommended, this paper analyzes minimum film thickness of lubrication in the tooth surfaces considering diverse rough surface. In the range of computing roughness, the minimum film thickness increases while surface roughness increases. The contact point near root in grinding wheel has maximum surface pattern parameter, and the minimum film thickness of this point has the least variation.

2014-02-24

the Ph.D. Programs Foundation of Ministry of Education of China (No. 20120162110004

State Key Laboratory of High Performance Complex Manu-factoring, Central South University, Changsha

#Mechanical Engineering#

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仇志成

2005-03-21

n Asian organization of over 5,000 staff employed a Performance Management System that was tied to

亚洲 (澳门)国际公开大学

#管理学#

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LIU Tong ,Hailong SHEN,Tongwen ZHANG,Mu ZHU

The oxide-dispersion-strengthened (ODS) ferritic alloy powders were prepared by mechanical alloying (MA) at a high rotation speed of 720 rpm for 24 h. All the elements were mixed homogenously in the powders, and Cr and Al dissolved in α-Fe after MA. The bulk samples were produced by spark plasma sintering (SPS) at 950 ℃ and 50 MPa and by hot isostatic pressing (HIP) at 1150 ℃ and 130 MPa, respectively. The sample prepared by SPS showed a tensile strength of 730 MPa and a poor ductility due to the existence of pores in microsize. The sample prepared by HIP had a high tensile strength of 980 MPa, yield strength of 710 MPa and elongation of 10.3 %. The excellent mechanical properties of ODS alloy by HIP was due to the small grain size of the matrix of about 400 nm and the fine oxide particles of 5-40 nm.

2012-08-03

the Aeronautical Science Foundation of China(No. 2011ZF51065

The authors acknowledge the support of this work by MOST of China (No. 2011AA03A408

the Fundamental Research Funds for the Central Universities (No. YWF1102212

the Specialized Research Fund for the Doctoral Program of Higher Education(No. 20091102120009

Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials

#Materials Science#

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