一种在PPT中嵌入视频文件的方法

文中详细分析了PowerPoint演示文稿中实现视频引入的三种传统方法,指出了它们的缺点和不足,提出了ShockwaveFlash Object控件实现视频嵌入的方法.阐述了Shockwave Flash Object控件的使用方法和技巧.通过该技术的应用,实现了演示文稿中视频文件的嵌入,解决了课件中视频文件不能正常播放或丢失的问题.     

3-PRS serial-parallel machine tool error calibration and parameter identification

3-PRS serial-parallel machine tool consists of a 3-degree-of-freedom (DOF) implementation platform and a 2-DOF X-Y platform. The error modeling and parameter identification methods were deduced based on 3-PRS serial-parallel machine tool. 3-PRS serial-parallel machine tool was researched, and the mechanism of error analysis, modeling, identification of error parameters and measurement equipment for the use of agency error of measurement were conducted. In order to achieve the geometric parameters calibration and error compensation of the serial-parallel machine tool, the nominal structural parameters of the controller was adjusted by identifying the structure of the machine tool. With the establishment of a vector space size chain, we can do the error analysis, error modeling, error measurement and error compensation can be done.     

CAI要件在高校食品生物化学教学中的应用

以食品生物化学中的一些实验为例,论述了CAI课件与实验相结合的重要性及教学效果,对CAI系统中所采用的主要技术作简单的介绍,并对CAI的未来发展方向作了简单概括。     

随钻双感应测井仪器刻度响应研究

介绍一种随钻双感应测井仪器,利用三维有限元方法模拟实际仪器结构对仪器响应的影响,针对该仪器设计刻度环和刻度水箱,并探讨最优刻度环参数和水箱刻度校正系数。结果表明:钻铤和反射层是导致仪器响应非线性变化的主要因素,磁环主要导致仪器响应幅值增大。通过刻度环或水箱刻度,仪器响应和真实地层电导率具有较宽的线性响应范围。模拟结果可为随钻双感应测井仪器设计和刻度提供理论参考。     

鞋楦高速数控加工的列表曲线B样条刀具半径偏置方法

针对鞋楦高速加工要求,提出了采用B样条曲线对离散数据进行刀具半径偏置的方法．通过矢量分析判别,实现了测头半径偏置曲线的光顺,并直接进行加工刀具半径二次偏置,获得精确的刀具中心轨迹。针对二阶连续曲线拐点的偏置计算误差,对偏置曲线自相交现象进行了判断和处理,解决了样条曲线高速加工存在的过切和少切问题．     

切削运动——刀具切削刃毛刺分类新体系及其应用

本文对金属切削毛刺分类体系的现状进行了系统的概述和分析,指出其存在的主要问题。提出并建立了切削运动——刀具切削刃毛刺分类新体系,将金属切削毛刺分为两侧、进给和切削方向毛刺三大类,清晰地找出了影响毛刺生成及变化的主要因素。在刨削和钻削加工中应用该毛刺分类体系,表明:切削运动——刀具切削刃毛刺分类体系术语明确、系统完整、简便易行。     

Experimental and numerical study on plasma nitriding of AISI P20 mold steel

In this study, plasma nitriding was used to fabricate a hard protective layer on AISI P20 steel, at three process temperatures (450°C, 500°C, and 550°C) and over a range of time periods (2.5, 5, 7.5, and 10 h), and at a fixed gas N₂:H₂ ratio of 75vol%:25vol%. The morphology of samples was studied using optical microscopy and scanning electron microscopy, and the formed phase of each sample was determined by X-ray diffraction. The elemental depth profile was measured by energy dispersive X-ray spectroscopy, wavelength dispersive spectroscopy, and glow dispersive spectroscopy. The hardness profile of the samples was identified, and the microhardness profile from the surface to the sample center was recorded. The results show that ε-nitride is the dominant species after carrying out plasma nitriding in all strategies and that the plasma nitriding process improves the hardness up to more than three times. It is found that as the time and temperature of the process increase, the hardness and hardness depth of the diffusion zone considerably increase. Furthermore, artificial neural networks were used to predict the effects of operational parameters on the mechanical properties of plastic mold steel. The plasma temperature, running time of imposition, and target distance to the sample surface were all used as network inputs; Vickers hardness measurements were given as the output of the model. The model accurately reproduced the experimental outcomes under different operational conditions; therefore, it can be used in the effective simulation of the plasma nitriding process in AISI P20 steel.     

机床颤振的一种新的控制方法

首先评述了目前对机床颤振的各种控制方法,然后提出在线变刀具前、后角抑制颤振的方法,并讨论了这种新方法的抑振原理。试验表明,该方法效果明显。所研制的控制装置结构简单,不需对机床作任何改装,故有可能成为普通车床及数控车床上具有抑制颤振能力的一个功能部件。     

BKX-Ⅰ型变轴数控机床的建模与控制

针对所研制的基于Stewart机构的变轴数控机床原型样机BKX-Ⅰ,对其数学建模过程及插补控制过程进行了详细分析.提出由轨迹规划中刀具位姿表示动平台位姿的有效方法,并结合变轴数控机床的结构特点,提出粗、精插补相结合的插补策略与离、在线控制相结合的控制策略,最后通过试验对上述方法进行了验证.     

自抗扰精密跟踪运动控制器的设计

为了提高非圆车削中快速伺服刀架的跟踪精度和抗干扰性,研制了一种自抗扰控制器。通过对执行机构建模分析,将模型中的非线性部分归结为系统的内扰,将加工过程中切削力干扰归结为系统外扰,设计出相应的扩张状态观测器,对系统内、外扰的总和做出实时估计和补偿。仿真实验表明,自抗扰控制性能优于传统的PID控制。通过DSP(digital signal processor)编程,将自抗扰控制器应用于非圆车削。切削加工试验结果表明,自抗扰控制具有良好的控制品质,快速伺服刀架跟踪精度控制在±5μm以内。