视频图像压缩处理的研究与应用

介绍了MPEG-4压缩标准,阐述了其编码结构和语法.在此基础上设计了一个以MAP-CA DSP芯片为核心的视频压缩系统.系统可同时完成两路MPEG-4视频压缩,支持视频图像实时预览,视频由它直接传送到显存,压缩的码流也由它直接传送到内存,无需主机CPU介入作任何操作,并通过PCI接口传送到内存中,不占用CPU资源.     

以低纯度钆研究Gd5Si2Ge2的磁热效应及制备工艺

以99%级的低纯度金属Gd为原料, 采用真空感应炉制备工艺, 辅以1470 K热处理工艺, 获得了与99.99%级高纯度Gd为原料制备的Gd5Si2Ge2合金相近的磁热效应, 5 T外场下最大磁熵变达17.5 J·kg^-1·K^-1, 对比电弧熔炼与感应熔炼两种制备方法, 感应熔炼条件下C, N, O杂质含量明显降低, 发现了Gd5Si2Ge2合金巨磁熵变与相结构的本质联系.     

稀土熔盐电解用干式防渗料的研究

将铝电解干式防渗料用于稀土熔盐电解试验,该干式防渗料能阻止电解质中LiF的渗透但不能阻挡LaF3的渗透。以铝电解用干式防渗料为基体,通过添加CaO、MgO、La2O3、Fe2O3和SiC等成分进行改性,研究改性后的防渗料的防渗效果。结果表明,添加CaO、La2O3或MgO,会加快稀土熔盐对防渗料的腐蚀破坏,但添加Fe2O3或SiC的防渗料有较好的防渗性能,而同时添加Fe2O3和SiC的干式防渗料效果最好。     

油气管道环焊缝搅拌摩擦焊机的研制

为了保障油气管道对接环焊缝的焊接质量,提高焊接效率,开发设计了专门用于油气管道对接环焊缝的搅拌摩擦焊机。介绍了搅拌摩擦焊接（friction stir welding,FSW）的焊接机理以及油气管道对接环焊缝搅拌摩擦焊机的主要构成及其工作参数。该焊机的机械系统主要由支撑系统、夹持系统、环形运动驱动系统、搅拌头系统与退出孔消除系统等组成,焊机最大扭矩达186 N·m,可以在较宽的焊接参数范围内完成多种材质、不同直径管道的搅拌摩擦焊接。     

熔盐电解精炼金属镧的研究

研究了LiF-LaF3体系下,以La-Ni合金和La金属作可溶性阳极,以Ta为阴极,熔盐电解精炼镧过程中不同工艺条件对槽电压、沉积物形貌、产物杂质含量的影响。采用扫描电镜(SEM)对电解精炼所得La沉积物形貌进行观察,采用电感耦合等离子体质谱法(ICP-MS),辉光放电质谱法(GD-MS),高频燃烧-红外法与惰气脉冲-红外热导法进行最终产品金属La的成分分析。结果表明:槽压与电流之间的线性关系受到接触压降、熔盐性质等因素的影响,控制较高电解温度、使用La-Ni合金代替金属La作阳极时槽压较低;沉积物均为枝晶形貌,电流密度增大导致沉积物的形貌由三维多面体转变为二维片状,电解温度升高导致颗粒几何规则性减弱,低电流密度下沉积物生长机制应为阶梯状生长;金属杂质中W,Ta可由50~100μg·g-1降至2~3μg·g-1,使用La阳极的实验所得精炼产物金属镧纯度为99.867%(分析77个杂质元素)。     

数据加密标准算法的DSP实现

DES(Data encryption standard)是ISO颁布的数据加密标准,通过对DES算法的分析,提出了用DSP实现数据加密标准算法,通过循环或迭代,将简单的基本运算(如左移、右移、模2加法等)和变换(选择函数、置换函数)构造成数据流的非线性变换(加密变换或解密变换),从而实现对计算机数据进行密码保护.DSP快速运算有利于数据加密、解密和数据的传输.     

静叶片钢冷轧变形的研究

本文对１Ｃｒ１１ＭｏＶ静叶片钢进行了冷轧变形的研究。确定了宽展面积与压缩面积的关系，各道次的宽展面积与压缩面积比值，宽展与压下量的关系，以及压下量沿轧件宽向的分布。为选择坯料外形和尺寸，孔型设计以及制定压下制度提供依据。     

Fabrication of PDMS microfluidic chips used in rapid diagnosis by micro jetting

Multimedia Tools and Applications - In this paper, a simple method was demonstrated to fabricate polydimethylsiloxane (PDMS) microfluidic chips used in rapid diagnosis based on printing the liquid...     

Effects of Tool Rotation Rates on Superplastic Deformation Behavior of Friction Stir Processed Mg-Zn-Y-Zr AlloyEI北大核心CSCD

Compared to conventional Mg-Al and Mg-Zn system magnesium alloys, the Mg-Zn-Y-Zr heat-resistant alloy exhibits high thermal stability due to the addition of Y earth element, which is an ideal candidate for producing high strain rate superplasticity (HSRS, strain rate >= 1 x 10(-2) s(-1)). Recently, the HSRS of Mg-Zn-Y-Zr alloy was achieved by friction stir processing (FSP), because the FSP resulted in the generation of fine and equiaxed recrystallized grains and fine and homogeneous second phase particles. However, the study on superplastic deformation mechanism of FSP Mg-Zn-Y-Zr alloy at various parameters is limited relatively. Therefore, at the present work, six millimeters thick as-extruded Mg-Zn-Y-Zr plates were subjected to FSP at relatively wide heat input range of rotation rates of 800 r/min to 1600 r/min with a constant traverse speed of 100 mm/min, obtaining FSP samples consisting of homogeneous, fine and equiaxed dynamically recrystallized grains and fine and uniform Mg-Zn-Y ternary phase (W-phase) particles. With increasing rotation rate, within the FSP samples the W-phase particles were broken up and dispersed significantly and the recrystallized grains were refined slightly, while the fraction ratio of the high angle grain boundaries (grain boundaries misorientation angle >= 15 degrees) was increased obviously. Increasing rotation rate resulted in an increase in both optimum strain rate and superplastic elongation. For the FSP sample obtained at 1600 r/min, a maximum elongation of 1200% was achieved at a high-strain rate of 1x10(-2) s(-1) and 450 degrees C. Grain boundary sliding was identified to be the primary deformation mechanism in the FSP samples at various rotation rates by superplastic data analyses and surfacial morphology observations. Furthermore, the increase in rotation rate accelerated superplastic deformation kinetics remarkably. For the FSP sample at 1600 r/min, superplastic deformation kinetics is in good agreement with the prediction by the superplastic constitutive equation for fine-grained magnesium alloys governed by grain boundary sliding mechanism.