FY-2多通道扫描辐射计的可见光外场定标

可见光定标是FY-2气象卫星多通道扫描辐射计研制的关键技术之一,发射前的精确定标是气象资料定量化和数字化应用的主要依据.基于Beer定理,详细说明定标的原理,摸索出一套适合于FY-2扫多通道描辐射计的可见光外场定标方法,建立起定标的规范程序,并对误差来源进行了分类和分析.通过在昆明的多次外场试验,获取了良好的定标结果,验证了这一方法的正确可行.     

基于颜色的运动目标快速识别与跟踪

在自主式移动机器人对运动目标进行跟踪时,视觉系统主要完成目标的识别与跟踪,提高目标识别与跟踪的实时性和准确性是保证机器人跟踪顺利进行的关键。针对此提出了一种基于颜色色度Hs的向量判定算法,并运用这种算法结合动态窗口和螺旋扫描等技术,有效地提高了目标识别与跟踪的实时性和准确性。     

Selective laser sintering/melting (SLS/SLM) of pure Al,Al–Mg,and Al–Si powders: Effect of processing conditions and powder properties

Selective laser sintering/melting (SLS/SLM) processing difficulties of aluminium powders had been attributed to issues associated with laser–materials interaction only while neglecting the role of powder properties. This study provides a wholistic understanding of factors that influence the development of SLS/SLM processing window, densification, and microstructure of pure Al, Al–Mg, and Al–Si powders, fabricated in single and multiple layer parts by exploring the roles of processing and material parameters. It was demonstrated that similarities existing in the SLS/SLM processing maps of the powders could be attributed to similarities in their packing densities with the alloying addition of magnesium and silicon having no predominant effect on their processing maps’ boundaries. Rather, alloying addition has significant effect on the nature of the evolved surface morphology of SLS/SLM processed aluminium powders in their processing windows. In addition, the flow and solidification behaviour of the melt pool of the powders during single layer scan was strongly influenced by the particle morphology and oxygen content of the powders as well as applied energy density. The energy density in the range of 12–16 J/mm² was found to be the threshold below which SLS was predominant and above which SLM occurred for the investigated powders. Moreover, successful oxide disruption phenomena which is necessary for inter-particulate coalescence in multi-layered SLS/SLM processed aluminium powders are found to be mainly controlled by the amount of oxide in the as-received powder, the degree of the uniformity of the distribution of the surface oxide film covering the aluminium particles, the nature of thermal mismatch existing between the oxide film and the parent aluminium particle which was dependent on the phase present in the oxide film. Al–12 wt% Si powder is hereby affirmed as a suitable candidate material for SLS/SLM process due to its low thermal expansion and uniform distribution of its surface oxide films as well as the mullite phase in its oxide film.     

数模混合边界扫描技术的研究现状与进展

数模混合电路的集成度和复杂度不断提高,电路测试的难度越来越大,混合信号边界扫描技术的推出为数模混合电路的测试提供了一种有效解决方案;文章以近年来国内外有关的文献报道为依据,对目前混合信号边界扫描技术的测试规范及测试方法进行系统的归纳,重点对该技术的新应用、新进展和发展动态进行详细介绍;针对混合信号边界扫描技术应用过程中遇到的实际问题提出了急需研究解决的主要关键技术,最后总结了该技术的发展方向和应用前景。     

Zn添加对挤压态Mg-Zn-Ce-Zr合金微观组织及力学性能的影响

通过光学显微镜(OM)、扫描电镜(SEM)、背散射电子衍射(EBSD)和力学性能检测,研究不同Zn含量(0.5%、1.5%和2.0%(质量分数))的Mg-Zn-Ce-Zr合金在温度为350℃,挤压比为9,挤压速率为10 mm/s条件下挤压后的微观组织和力学性能。结果表明:随着Zn含量的增加,铸态下晶间析出相明显增多;挤压后,Zn含量对合金晶粒度的影响不大,但棒材的丝织构随Zn含量增加而增强。由于第二相粒子的强化作用,随Zn含量增加,合金的拉伸屈服强度从158 MPa增加到192 MPa,而抗拉强度从219 MPa提高到246 MPa。由于丝织构强度增加,合金塑性随Zn含量增加从33%降低至18%,添加0.5%Zn合金的伸长率和拉压对称性最好。     

光谱仪器测试参数对测试结果的影响

光谱仪器测试参数，如狭窄宽度，扫描速率和响应时间等对光谱测试精度例如测光精度（透过率或反射率）、波长精度和光谱分辨率等有很大的影响，本文利用Ｌａｍｂｄａ９高精度分光光度计和窄带滤光片进行了多种仪器测试参数条件下的测试实验研究，给出了测试参数对测量结果影响的规律、如何选择最佳测试参数实现准确测量及如何弥补修正的方法。     

视频数据的基于多趟跳跃扫描的离散打包方法

打包技术是一种有效的、重要的抗误码技术。针对离散片打包方法的局限性,本文在研究传统的光栅扫描打包方法和新近的离散片方法的基础上,将两者的优点相结合,提出了一种新颖的基于多趟跳跃扫描的离散打包方法。由于该打包方法对离散后的宏块按照一定的规律进行了多次扫描,从而突破了离散片算法基于固定宏块数目的局限性,实现了优化的、离散的基于比特数的打包。     

分组轮回扫描法的摩托车电喇叭耐久检测

为了实现大批量摩托车电喇叭耐久性检测，根据摩托车电喇叭耐久检测的国家标准及用户要求，提出了分组轮回扫描检测电喇叭耐久性的方法，用单驱动电源依次轮回驱动，采用二个电源分组实现一批次8只电喇叭的耐久性检测，研制出了适用于两种标称电压、不同规格尺寸的摩托车电喇叭的耐久性试验台，阐述了系统的工作原理和故障判别模式．所设计试验台减少了驱动电源数目，简化了控制系统，降低了系统成本。     

激光二极管端面抽运Nd:YAG的端面形变

研究了端面抽运Nd：YAG晶体的抽运面形变场分布，采用一种新的测量端面形变场分布的实验方法——光束扫描法。让参考光沿晶体的端面小步距扫描，比较有无抽运光时各扫描点在探测面上光点位置的移动情况，通过几何分析与数值计算，可逐段得到端面的形变场分布。通过与理论上在理想模型下所求解的结果比较，发现实验值与理论值基本一致，晶体的端面形变场最大峰值处的抽运光在端面的聚焦位置处。另外发现端面的形变场分布的对称性受抽运光对称性影响，且曲线不光滑。该方法解决了端面抽运Nd：YAG晶体的抽运面形变场分布难以测量的问题，旦易于实现和操作。