N掺杂的ZnO薄膜发光性质研究

以醋酸锌为前驱体、醋酸铵为掺杂源,采用溶胶—凝胶法制备出N掺杂的ZnO薄膜,研究了其表面形貌、晶体结构和变温下的光致发光光谱,探讨了N作为受主掺杂的热力学性质。结果表明,掺杂后的薄膜是六角纤锌矿结构,光谱中表现出和N相关的受主束缚激子、自由激子—受主和施主—受主对发光现象。通过理论计算得到,N作为受主的电离能大小为0.255~0.310 eV,表明N是一种有效的浅受主,其能级上的电子在较小的能量下就能够电离。     

稀土元素对精密铸钢裂纹形成的影响

设计了精密铸件裂纹敏感试样,通过在铸件成分中添加不同比例的稀土元素,探讨稀土元素对铸件产生裂纹倾向的影响.试验结果表明:合适的稀土添加量的增加,铸件裂纹率显著降低:金相组织分析表明,稀土元素添加能较好地细化晶粒,并有效改善夹杂物的数量、尺寸和分布,从而降低了铸钢的裂纹倾向.     

基于FLUENT的硅油减振器热片散热性能分析

散热片的散热性能好坏严重影响硅油减振器的使用寿命.利用计算流体力学软件FLUENT,建立了硅油减振器散热片的三维模型,模型中将热场与流场进行了耦合;通过对散热片表面的温度分布特性、空气流动特性和散热率进行数值模拟,研究分析了散热片不同结构型式对其散热性能的影响.本文的分析方法可用于指导硅油减振器散热片的设计和选型.     

齿轮副接触分析软件的开发

利用VB软件和有限元软件ANSYS的命令流及其APDL参数化设计语言,开发出齿轮副接触应力分析软件,实现了软件自动完成模型的创建、分析计算的功能,提高了分析问题的效率.并对软件仿真值与齿轮接触赫兹应力公式进行对比,结果表明,理论计算值和仿真值吻合的较好.     

Human and bicycle detection system using range sensor

This paper presents a full-scale solution to the detection of the traffic data using laser device. Range images, gathered by a particular laser camera, are used in the multi-threshold segmentation. The multi-threshold segmentation is based on the height of the moving objects. In order to get the precise height of the moving objects, mapping of the original terrain is performed on the first step. On each layer, the clustering algorithm called iteration-self organizing data analysis techniques algorithm (ISODATA) is conducted afterwards. Kalman filtering technique is applied to recognize and track the moving objects. Extensive experiments show that these algorithms are effective in object recognition and tracking, as well as robust in the applications.     

Fusion of remote sensing images based on nonsubsampled contourlet transform and region segmentation

The purpose of remote sensing images fusion is to produce a fused image that contains more clear, accurate and comprehensive information than any single image. A novel fusion method is proposed in this paper based on nonsubsampled contourlet transform (NSCT) and region segmentation. Firstly, the multispectral image is transformed to intensity-hue-saturation (IHS) system. Secondly, the panchromatic image and the component intensity of the multispectral image are decomposed by NSCT. Then the NSCT coefficients of high and low frequency subbands are fused by different rules, respectively. For the high frequency subbands, the fusion rules are also unalike in the smooth and edge regions. The two regions are segregated in the panchromatic image, and the segmentation is based on particle swarm optimization. Finally, the fusion image can be obtained by performing inverse NSCT and inverse IHS transform. The experimental results are evaluated by both subjective and objective criteria. It is shown that the proposed method can obtain superior results to others.     

参数和结构对超晶格成像特性的调制

利用传输矩阵方法研究了不同结构和不同参数调制下的成像特征.结果表明:在近似相同总层数和相同的参数下,不同结构对成像有一定影响:周期结构完美成像的波矢范围最大,thue-mose模型次之,fibonacci模型最小;进一步研究当负折射率介质的介电常数或磁导率偏离1时的成像特点,发现除了可以通过调节负折射率介质的介电常数或...     

容错控制在电力系统中的应用研究

在介绍容错控制基本思想的基础上,从容错控制的角度对提高电力系统可靠性的措施进行了分析,总结了电力系统中已有的用以提高可靠性的方法与客错控制之间的关系,综述了电力系统中容错控制方法的应用,分析了其面临的问题和将来的发展趋势,对容错控制在电力系统中的应用进行了展望.     

随机利率下的外汇欧式期权定价

在随机利率情况下,利用鞅方法研究了外汇欧式期权的定价问题,得到了欧式期权(看涨和看跌)价格的解析表达式,及其评价关系.文中考虑了期权的对冲问题及本国和外国利率波动的非零相关性,本国和外国利率波动对汇率波动的影响.     

夹层板在舰艇冲击防护中的研究进展

为了提高舰艇抗冲击能力,已发展了各种舰艇冲击防护方法。传统的冲击防护手段会使舰艇的重量大幅增加,影响舰艇总体性能。夹层板的出现给舰艇冲击防护提供了另外一条途径,成为近期国内外相关研究的热点。文中以舰艇冲击防护为背景,从夹层板的冲击变形模式、微惯量效应、应变率效应、几何非线性效应、流固耦合效应、以及均匀化和模拟试验方法等方面,回顾了近期国内外相关研究进展。