检索结果-南通市图书馆

A novel 2.2.wavelength selective cross-connect based on Mach-Zehnder interferometer

在线全文

学校读者我要写书评

暂无评论

Optoelectronics Letters 2008年第1期4卷 15-18页

作者： FENG Yong-hua,LUO Feng-guang, and YUAN Jing School of Optoelectronic science and technology, {2. university of science and technology, wuhan, 430074, china School of Optoelectronic science and technology Huazhong University of Science and Technology Wuhan China

A novel 2.2.wavelength selective cross-connect (WSXC) module, which is composed of a Bragg-grating-based Mach- Zehnder interferometer (MZI), a pair of optical waveguides, a pair of 1×2.optical switches (OSWs) and a pair of Y-model combiners is proposed. The mathematical description of the proposed 2.2.WSXC module is given and explained. Multi- channel multi-wavelength selective cross-connect can be fabricated with the proposed 2.2.WSXC module, together with multistage interconnection networks (MINs). A four-wavelength 4×4 WSXC is demonstrated by simulation to validate the flexibility of the proposed WSXC.

关键词：波长选择正交连接 Mach-Zehnder干涉计布拉格光栅光学转换

INTERACTION BETWEEN V_4C_3 PARTICLES AND DEFORMATION TWINS

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 1991年第3期4卷 214-217页

作者： XIE Changsheng huazhong university of {2. and technology,wuhan,china

By using Moire′ pattern formed by the double diffraction of precipitated V_4C_3 and matrix of γ-phase,the nature of the structure of the interface between precipitated V_4C_3 and matrix as well as the retarding effect of V4C3 particles on the development of deformation twins have been *** is shown that partially coherent interfaces exist between V_4C_3 and ma- *** dislocations may transform into interfacial dislocations under external stress, and may move continuously through bypassing or cross-sliping.

关键词： V_4C_3 deformation twin Moire' pattern

Nano-flower spherical SnS2.combined with a special lithium storage mechanism as a multifunctional separator for lithium-sulfur batteries contributes to ultra-high initial discharge specific capacity

在线全文

学校读者我要写书评

暂无评论

science china(Technological sciences) 2024年第2期67卷 509-519页

作者： LIU huazhong XIONG YaPing HUANG MouZhi CHEN ZongMin YANG Xiao ZHANG Ze YANG ZhenYu CAI JianXin School of Chemistry&Chemical Engineering Nanchang UniversityNanchang 330031China

The critical factors that limit the electrochemical performance of lithium-sulfur(Li-S)batteries are mainly the“shuttle effect”of polysulfides and the slow redox reaction between lithium polysulfides(LiPSs).Herein,a nano-sphere-type material selfassembled from tin disulfide nanosheets is designed and applied to the Li-S cell separator in this *** SnS_(2.@PP modified separator not only acts as a dual restriction for LiPSs by chemisorption and physical *** the same time,it improves the catalytic activity of the redox reaction between *** SnS_(2.has extremely high electrochemical ***,a portion of the lithium ions can be inserted into SnS_(2.to form Li_(x)SnS_(2.and contribute to the capacity during the first discharge of the *** addition,Li_(x)SnS_(2.possesses a high degree of stability,and it does not undergo further de-alloying reactions even at the high potential of the Li-S *** benefit is that the steady-state Li_(x)SnS_(2.acts as a lithium-containing *** can form special Li^(+)channels on the surface of the separator,thus greatly improving the efficiency of Li+*** results showed that the SnS_(2.@PP-based cell exhibited extremely high initial discharge specific capacity(1477 m Ah g^(-1)at 0.1 C)and excellent rate performance(631 m Ah g^(-1)at 5 C).Even after 1000 cycles at 2.C,the cell exhibited a low decay rate of 0.06%per cycle on *** addition,the superior electrochemical performance was obtained even with a high sulfur loading of 5.1 mg cm^(-2.and low electrolyte of E/S=8μL mg^(-1).

关键词： Li-S batteries modified separators polysulfides catalytic conversion high electrochemical activity

Minimal systems of generators for central division algebra and semi-simple algebra

在线全文

学校读者我要写书评

暂无评论

Chinese science Bulletin 1998年第21期43卷 1777-1780页

作者： QIU Qizhang 1 and SUN Ling 2.1. Department of Mathematics, wuhan university, wuhan 430072. china 2. Department of Information science, wuhan university, wuhan 430072. china. Department of Mathematics Wuhan University Wuhan China Department of Information science Wuhan University Wuhan China

Suppose that F is a field of characteristic zero and (ⅰ) D is a finite-dimensional central division algabra over F; (ⅱ) A is a finite-dimensional semi-simple algabra over F. It is proved that as F-algebras, D and A ... 详细信息

关键词： central division algebra semi-simple algebra generator minimal system of generators.

Surface Nanocrystallization of Magnesium Alloy AZ91D by High-Energy Shot Peening

在线全文

学校读者我要写书评

暂无评论

Journal of wuhan university of {2.(Materials science) 2009年第4期24卷 515-519页

作者：张津 School of Materials science & Engineering University of Science and Technology Beijing College of Materials science & Engineering Chongqing University of Technology

High-energy shot peening （HESP）, a method to produce severe plastic deformation by high velocity flying balls, was applied on die cast magnesium alloy AZ91D. Effects of surface nanocrystallization by HESP and heat treatment at different temperatures were investigated. The mi- crostructure evolution was conducted using X-ray diffraction （XRD） and field emission scanning electronic microscopy （FESEM）. The hardness was measured by microhardness tester. The experimental results show that surface nanocrystrallization of AZ91D obtained by HESP would lead to the increase of microhardness. Low temperature heated at 100℃ for 1 h do not change the property obviously. However, both the microstructure and microhardness vary greatly after heat treatment at 400℃ for 1 h.

关键词： AZ91 D surface nanocrystallization HESP microhardnss corrosion resistance

Global optimization of tool path for five-axis flank milling with a cylindrical cutter

在线全文

学校读者我要写书评

暂无评论

science china(Technological sciences) 2009年第8期52卷 2449-2459页

作者： DING Han1 & ZHU LiMin2.1 State Key Laboratory of Digital Manufacturing Equipment and technology, huazhong {2. of science and technology, wuhan 430074, china 2.School of Mechanical Engineering, Shanghai Jiao Tong {2., Shanghai 2.02.0, china State Key Laboratory of Digital Manufacturing Equipment and technology Huazhong University of Science and Technology School of Mechanical Engineering Shanghai Jiao Tong University

In this paper, optimum positioning of cylindrical cutter for five-axis flank milling of non-developable ruled surface is addressed from the perspective of surface approximation. Based on the developed interchangeability principle, global optimization of the five-axis tool path is modeled as approximation of the tool envelope surface to the data points on the design surface following the minimum zone criterion recommended by ANSI and ISO standards for tolerance evaluation. By using the signed point-to-surface distance function, tool path plannings for semi-finish and finish millings are formulated as two constrained optimization problems in a unified framework. Based on the second order Taylor approximation of the distance function, a sequential approximation algorithm along with a hierarchical algorithmic structure is developed for the optimization. Numerical examples are presented to confirm the validity of the proposed approach.

关键词： five-axis flank milling tool path optimization tool axis trajectory surface surface approximation distance function minimax optimization

Determination of the Thermal Expansion Coefficient of Concrete at Early Ages by Using Temperature-stress Testing Machine

在线全文

学校读者我要写书评

暂无评论

Journal of wuhan university of {2.(Materials science) 2006年第4期21卷 146-149页

作者：霍凯成 Hubei Key Laboratory of Roadway Bridge & Structure Engineering Wuhan University of TechnologyWuhan 430070China

By using the uptodate temperatuer-stress testing machine, the thermal expansion coefficient of concrete at early ages was studied and indicative conclusions were achieved ： temperature rising due to hydration heat is not directly correlated with cracking, but the temperature and stress evolation process should be taken into consideration in the same time. Proper chemical admixtures and mineral cornpasitions can improve the mechanical properties of concrete such as thermal expansion coefficient, which is very indicative in practice.

关键词： concrete coefficient of thermal expansion temperature-stress test

Cu+Al_2._3 composite coating on AISI 1045 steel surface by laser cladding

在线全文

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 1999年第3期9卷 462-467页

作者： Wang Maoqiu(王毛球), Xie Changsheng(谢长生), Zeng Dawen(曾大文) School of Materials science and Engineering, huazhong {2. of science and technology, wuhan 430074, P. R. china huazhong Univ of science and Technology Wuhan China

Perfect composite coatings have been successfully produced with preplaced mixture of Cu+Al 2. 3(2.～2.%) on AISI 1045 steel substrate by using a 2.kW CO 2.laser. A suitable amount of Al 2. 3 in Cu as additive can improve the processing conditions of laser cladding. Fe rich particles were observed in the clad layer during microstructural observation with SEM and chemical composition analysis by EDAX. The experimental results showed that microhardnesses of the coatings were over 150HV 0.05 and the electric resistivities were about 4.0×10 -8 ～4.5×10 -8 Ω·m. Perfect composite coatings have been successfully produced with preplaced mixture of Cu+Al 2. 3(2.～2.%) on AISI 1045 steel substrate by using a 2.kW CO 2.laser. A suitable amount of Al 2. 3 in Cu as additive can improve the processing conditions of laser cladding. Fe rich particles were observed in the clad layer during microstructural observation with SEM and chemical composition analysis by EDAX. The experimental results showed that microhardnesses of the coatings were over 150HV 0.05 and the electric resistivities were about 4.0×10 -8 ～4.5×10 -8 Ω·m.

关键词： laser cladding conductive coating microhardness tests resistance

The Role of Calcium in Microstructural Refinement of AZ91 Magnesium Alloy

在线全文

学校读者我要写书评

暂无评论

Journal of wuhan university of {2.(Materials science) 2006年第4期21卷 45-47页

作者：刘生发 School of Materials science and Engineering Wuhan University of Technology Wuhan 430070China

The effect of calcium addition on the microstructures of AZ91 magnesium alloy was investigated. It was found that a small amount of calcium in AZ91 allay produced a large decrease in the α- Mg grain size and the dispersed fine β-Mgt7 Alt2.phases. In addition, some Al4Ca particles were found to exist in the AZ91 alloy containing 0.5wt% Ca. EDS analysis and water-quenched technique revealed that the grain-refining mechanism of calcium for the AZ91 alloys was mainly attributed to the role of restricting growth of calcium in the primary α-Mg crystals.

关键词： AZ91 magnesium alloy calcium microstructural refinement