近等温变形量对TC4-DT钛合金组织参数和拉伸性能的影响

利用光学显微镜、扫描电镜、电子探针、金相图像分析软件等研究近等温变形量对TC4-DT钛合金显微组织和拉伸性能的影响规律。研究发现:随热变形程度的增大,晶界α相逐渐被破碎,晶内粗大的片状α相宽度逐渐增大,但是细片状的α相宽度变化不大。粗片状α相是由元素扩散引起的成分偏析形成,60%的变形程度下元素扩散充分,不同形态α相之间合金元素成分差别降低,使得最终组织较为均匀。晶内粗片状α相含量和位向随变形程度升高而变化,低变形程度下(20%)α/β相界不会成为位错滑移的障碍,位错主要集聚于晶界导致沿晶断裂。高变形程度(60%)使原来的两相位向关系被打破,相界成为位错滑移的障碍,强度和塑性都得到提高,室温拉伸断口呈现穿晶断裂。实验结果表明在本实验条件下60%的变形量可以获得较好的强度和塑性匹配。     

导弹鲁棒高阶滑模制导控制一体化研究

针对传统制导与控制系统分开设计在拦截高速机动目标时的缺陷,提出一种高阶滑模制导控制一体化方法.综合考虑弹目拦截几何与导弹动态,根据零化视线(LOS)角速率的准则,将导弹制导控制问题转化为一个三阶积分链系统的镇定问题.基于几何齐次理论设计了标称系统的全局有限时间镇定控制律,同时针对目标机动和导弹气动参数摄动等带来的不确定性,利用超扭曲算法(STA)设计了补偿控制律.仿真结果表明,与传统制导与控制系统分开设计相比,本文所提出的鲁棒高阶滑模制导控制一体化方法具有更小的脱靶量,且导弹姿态和控制舵偏角的变化更加平缓.     

基于灰色局势决策的航空弹药库选址问题研究

以弹药库选址问题为事件,以备选库址作为对策构成局势,采用局势决策建立数学模型,以寻找最优库址为目标,对不同量纲的目标量值以效果测度统一计量,并通过最优效果测度确定最优局势,对四个备选方案的综合优劣状况进行排序,最后得到最优的选址方案,所得结论具有很强的客观性和实用性。     

一种新型电涡流位置传感器

分析了现有位置传感器存在的问题,简要介绍了电涡流位置传感器的测量原理、性能优势和推广应用.     

铣床夹具的对刀装置

本文介绍铣削工艺中铣床夹具的对刀装置设计以及有关的计算。     

流媒体技术及其应用

本文主要研究了流媒体的相关原理和技术支持，包括流媒体技术基础、流媒体播放方式、媒体服务器平台等主要内容，并简要介绍了视频直播解决方案、校园网视频解决方案和网上流式视音频解决方案等流媒体技术应用方案。     

关于高职高专数控专业实训与实训基地建设探讨

数控专业人才是国家级紧缺人才，为了能更好、更快地培养满足社会需求的有用人才，必须重视和加强实训建设，本文就实训环节的安排、实训基地的建设及师资队伍的建设等问题进行了探讨。     

雅思考试对大学英语教学改革的启示

论文对雅思考试的特点及其对大学英语考试的影响进行分析,并阐述了雅思考试对大学英语教学改革的启示。     

Modeling of Heat Conduction in Thermoplastic Honeycomb Core/Face Sheet Fusion Bonding

Honeycomb sandwich materials have been widely used in aerospace industry as secondary structural materials or interior panels. Recently the research of full thermoplastic honeycomb sandwich materials has been of interest due to their recyclability. In their production, they usually demand an adhesive-free process, namely fusion bonding, to connect thermoplastic honeycomb core and face sheets. It is a heat induced process where a parameter of temperature should be well controlled to guarantee the product quality. This article presents a mathematical model of heat conduction to analyze the transient temperature distribution from heating tools towards inner part of the core under fusion bonding conditions. In order to simplify the complexity of 3D honeycomb geometry, a homogenization method is used to obtain average thermal properties of the honeycomb along the major heat flux direction. The model is validated by comparing with the results of in-situ temperature measurement during fusion bonding. The presented model can also be applied to analyzing general out-of-plane heat conduction through honeycomb sandwich structures made from other materials.     

A micro-gravity simulation of the Marangoni convection

An experimental verification of Marangoni convection in the liquid inter-space between two-coaxial discs is carried out at reduced gravity effect using small Bond's number obtained by choice of small characteristical diameter. Silicon oil is used as working fluid. The upper or lower disc can be heated electrically. The flow is visualized by illuminating fine powder of Titandioxide in the fluid with a vertical “light cut” of about 0.1 mm thickness, which is produced by a laser with a cylindrical glass rod and a microscope objective. Photographs and moving pictures are taken from a TV monitor. From these the vortex configuration and the velocity distribution can be determined, which would be expected for the Marangoni convection in the zero-g condition, for example in the spacelab.