检索结果-南通市图书馆

Ni60-SiC Coating Prepared by Plasma Spraying, Plasma Re-melting and Plasma Spray Welding on Surface of Hot Forging Die

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan university of Technology(materials {2.) 2011年第4期26卷 715-718页

作者：王洪福 school of Mechanical engineering and Automation North University of China

In order to produce the hear-resistant inner layer of hot-forging die, plasma spraying and plasma re-melting and plasma spray welding were adopted. Substrate material was W6Mo5Cr4V2. including 10%, 2.%, 30% SiC ceramic powder used as coating material to obtain different Ni-based SiC alloys coating. Micro-structure and micro-hardness analysis of the coating layer were followed, as well as thermophysical properties for the coating layer were measured. The experimental results show that the coating prepared with 70% Ni60, 30% SiC powder has best properties with plasma spray welding, in which the micro-hardness can achieve 1100 HV, meanwhile can improve the thermal property of hot-forging die dramatically.

关键词： hot forging die plasma spraying plasma re-melting plasma spray welding thermo- physical properties

The Antifreeze Critical Strength of Low-temperature Concrete Effected by Index

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan university of Technology(materials {2.) 2011年第2期26卷 355-360页

作者：刘军 school of Material science and {2. Shenyang Jianzhu University

The antifreeze critical strength and the pre-curing time of low-temperature concrete were studied by means of guaranteed rate of compressive strength and antifreeze performance for the structural safety requirement of concrete engineering,suffering once freeze damage under air *** is shown that the antifreeze critical strength is 3.7-4.4MPa,pre-curing time is 18-32.h by guaranteed rate of compressive strength,and the antifreeze critical strength is 3.7-4.4MPa,pre-curing time is 18-32.h by guaranteed rate of antifreeze *** can be found that the method of guaranteed rate of compressive strength is sensitive to the defect which generated by freeze damage in the concrete *** method is fit to evaluate the antifreeze critical strength of low-temperature concrete.

关键词： guaranteed rate of compressive strength guaranteed rate of antifreeze performance antifreeze critical strength once freeze under air environment

Comparison of Structure and Properties among Various PAN Fibers for Carbon Fibers

在线全文

学校读者我要写书评

暂无评论

Journal of materials science & Technology 2005年第3期21卷 376-380页

作者： Dongxin HE, Chengguo WANG, Yujun BAI and Bo ZHU College of materials science and {2., shandong university, Jinan 2.0061, china College of materials science and {2. Shandong University Jinan 250061 China

To find out the high-quality polyacrylonitrile (PAN) fibers, some differences are sought by comparing domestic PAN fibers with the foreign ones. X-ray diffractometer (XRD), transmission electron microscope (TEM), Fourier transform infrared (FT-IR) spectrometer, elemental analyzer, tensile-testing machine and high-temperature differential scanning calorimeter (DSC) are used to characterize the individual microstructure, chemical structure, elemental content, mechanical properties and thermal properties. It is found that high-quality PAN fibers have high density, lower titre, higher or adequate tensile strength, and they also have better conglomeration structure, smaller crystal dimension with dispersive distribution, less microvoids and flaws.

关键词： Polyacrylonitrile (PAN) fiber Carbon fiber Structure Properties

A new approach to adaptive control design without overparametrization for a class of uncertain nonlinear systems

在线全文

学校读者我要写书评

暂无评论

science china(Information sciences) 2011年第7期54卷 1419-1429页

作者： ZHANG Jian & LIU YunGang school of Control science and {2.,shandong university,Jinan 2.0061,china 1. school of Control science and {2. Shandong University Jinan 250061 China

This paper considers the globally stabilizing adaptive controller design for a class of more general uncertain high-order nonlinear systems with unknown control *** the existing literature has solved the problem,for n-dimensional systems,the existing methods need at least n + 1 dynamic updating laws for the unknown parameters to construct the stabilizing adaptive controller;that is,the dimension of the dynamic compensator is not less than n + 1,and therefore,there exists serious *** this paper,by defining some new unknown parameters which need dynamic updating,also by using adding a power integrator and related adaptive technique,the overparametrization is successfully solved and a new approach is given to design stabilizing adaptive controller based on only one parameter updating law.A simulation example is finally provided to demonstrate the validness of the proposed approach.

关键词： high-order nonlinear systems unknown control coefficients overparametrization stabilizing con- trol design adding a power integrator adaptive technique

Adaptive bidirectional diffusion for image restoration

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

science china(Information sciences) 2010年第12期53卷 2452-2460页

作者： FU ShuJun 1,2.& ZHANG CaiMing 1 1 school of Computer science and Technology, {2. university, Jinan 2.0101, china 2.school of Mathematics, {2. university, Jinan 2.0100, china 1. school of Computer science and Technology Shandong University Jinan 250101 China2. School of Mathematics Shandong University Jinan 250100 China

A large number of applications in image processing and computer vision depend on image quality. In this paper, combining the forward diffusion with the backward diffusion by different weights, we present an adaptive bidirectional diffusion method for image denoising and deblurring simultaneously. Further, we introduce a gradient factor into the data fidelity term, which forms a spatially varying constraint and allows a better restoration of image edges and fine details. In order to obtain a stable solution, we develop a numerically stable scheme and give its theoretical analysis. Finally, we show advantages of this method in deblurring edges, denoising and restoring fine details of image compared with other related methods in experiments.

关键词： image restoration bidirectional diffusion inverse diffusion anisotropic diffusion stabilizing scheme spatially varying constraint

Synthesis and magnetic properties of CdS/α-Fe_2._3 hierarchical nanostructures

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

science china(Physics,Mechanics & Astronomy) 2009年第7期52卷 997-1002页

作者： CHEN YuJin1,2.3, SHI XiaoLing1, CAO MaoSheng1 & ZHU ChunLing4 1 school of materials {2. and engineering, Beijing Institute of Technology, Beijing 100081, china 2.Micro-Nano Technologies Research Center, Hunan university, Changsha 410082. china 3 College of {2., Harbin engineering university, Harbin 150001, china 4 College of Material {2. and Chemical engineering, Harbin engineering university, Harbin 150001, china 1. school of materials {2. and engineering Beijing Institute of Technology Beijing 100081 China 2. Micro-Nano Technologies Research Center Hunan University Changsha 410082 China 3. College of science Harbin Engineering University Harbin 150001 China 4. College of Material science and Chemical engineering Harbin Engineering University Harbin 150001 China

CdS/α-Fe2.3 hierarchical nanostructures, where the CdS nanorods grow irregularly on the side surface of α-Fe2.3 nanorods, were synthesized via a three-step process. The diameters and lengths of CdS nanorods can be tuned by changing the ethylenediamine (EDA) and Cd ion concentrations. The magnetic investigations by superconducting quantum interference device indicate that the hierarchical nanostructures have an Morin transition at lower temperature (2.0 K) than that of the single bulk α-Fe2.3 materials (2.3 K). Importantly, the hierarchical nanostructures exhibit weakly ferromagnetic characteristics at 300 K. A sharp peak assigned to the surface trap induced emission are observed in room temperature PL spectra. Combining with the optoelectronic properties of CdS, the CdS/ α-Fe2.3 hierarchical nanostructures may be used as multi-functional materials for optoelectronic and magnetic devices.

关键词： α-Fe2.3 CdS hierarchical nanostructures magnetic properties

Oxidation-induced strengthening behavior of reaction formed Al_4SiC_4 ceramics

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2007年第S1期26卷 94-98页

作者： HUANG Xiaoxiao1,2.,WEN Guangwu1,3),LIU Ruitang2.,and ZHENG Xin1)1) school of materials {2. and Technology,Harbin Institute of Technology,Harbin 150001,china 2. school of Material {2. and Chemical engineering,Harbin engineering university,Harbin 150001,china 3) school of materials {2. and Technology,Harbin Institute of Technology at Weihai,Weihai 2.42.9,china Harbin Inst Technol Sch Mat Sci & Technol Harbin 150001 Peoples R China Harbin Inst Technol Sch Mat Sci & Chem Engn Harbin 150001 Peoples R China Harbin Inst Technol Sch Mat Sci & Technol Weihai 264209 Peoples R China

The bending strengths of Al4SiC4 ceramics were investigated from room temperature to 1300 ℃ in air and in vacuum,*** is a novel property that the bending strength increases with increasing test temperatures up to 1300 ℃ in *** strength value of Al4SiC4 ceramics is 449.7 MPa at 1300 ℃ in air,which is about 1.5 times of that at room temperature(300 MPa).The self-healing behavior of the flaws on the specimen surface due to the oxidation of the surface layer of the Al4SiC4 ceramics is considered as the main enhancement mechanism at high temperatures.

关键词： calcination and hot pressing surface strength Al_4SiC_4

Global practical tracking by output-feedback for nonlinear systems with unknown growth rate

在线全文

学校读者我要写书评

暂无评论

science china(Information sciences) 2011年第10期54卷 2079-2090页

作者： YAN XueHua & LIU YunGang school of Control science and {2.,shandong university,Jinan 2.0061,china 1. school of Control science and {2. Shandong University Jinan 250061 China

This paper is devoted to the global practical tracking by output-feedback for a class of uncertain nonlinear systems with only the tracking error *** from the closely related works,the systems have unmeasured states dependent growth with unknown constant rate,and the reference signal,as well as its first order derivative,has unknown *** because of these,the tracking problem can hardly be solved by straightforwardly extending the existing *** the paper,motivated by the related stabilization results,and flexibly using the ideas of universal control and dead zone,an adaptive output-feedback controller is designed to make the tracking error prescribed arbitrarily small after a finite time while keeping all the states of the closed-loop system bounded.A numerical example demonstrates the effectiveness of the theoretical results.

关键词： uncertain nonlinear systems global practical tracking adaptive control output-feedback dynamic high-gain

Microstructure evolution in the high temperature compression of Ti-5.6Al-4.8Sn-2.0Zr alloy

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2010年第5期29卷 533-537页

作者： LI Miaoquan,LUO Jiao,and PAN Hongsi school of materials {2. and engineering,Northwestern Polytechnical university,Xi’an 710072.china school of materials {2. and engineering Northwestern Polytechnical University Xi’an China

Isothermal compression of a Ti-5.6Al-4.8Sn-2.0Zr alloy was conducted on a Thermecmaster-Z simulator at the deformation temperatures ranging from 960 to 1060℃, the strain rates ranging from 0.001 to 10.0 s^-1, and the maximum height reduction of 70.0%. In the two-phase region of the Ti-5.6Al-4.8Sn-2.0Zr alloy, the volume fraction of α phase decreases with an increase in deformation temperature, but the grain size has a slight variation with deformation temperature. The strain rate affects both morphologies and grain size of the α phase in the isothermal compression of the Ti-5.6Al-4.8Sn-2.0Zr alloy. The optimal height reduction also contributes to the small and well-distributed α phase in the isothermal compression of Ti-5.6Al-4.8Sn-2.0Zr alloy.

关键词： titanium alloys isothermal compression microstructure mechanism