Light-Gradient-Induced Spiral Wave Drifts in a Belousov-Zhabotinsky Reaction

The dynamic behaviour of spiral tip in the light-sensitive Belousov-Zhabotinsky reaction under the influence of an externally applied light gradient was experimentally studied. The gradient causes different drifts for different spiral patterns. The centre of the spiral wave moved toward the region of lower light intensity. The direction of an additional perpendicular drift depended on the chirality of the spiral wave. The dependences of the drifting angle and the drifting velocity on light gradient have been measured.     

Pseudo-Spin-Valve Trilayer Using Amorphous CoNbZr Layer： Giant Magnetoresistance, Domain Structures and Potentials for Spin-Electronic Devices

We propose a pseudo-spin-valve (PSV) trilayer using amorphous CoNbZr Mloy for soft magnetic layers. The giant magnetoresistance (GMR), domain structures and their variation upon thermal annealing are investigated. The GMR effect is not only stable up to 300℃ but also enhanced due to the improvement of the interfaces between Cu and magnetic layers. With high annealing temperature, the magnetoresistance (MR) ratio decreases rapidly as a result of serious layer interdiffusion. Dense stripe domains, which disappear after annealing at 300℃ for 1h, are observed in the sandwiched films. It is found that after patterning to elliptic stripe with aspect ratio of 6:1, the trilayers have a single domain and their MR ratio increases. The dynamic MR behaviour under an ac magnetic field indicates that the patterned stripes have good linear MR responses. Therefore, it is believed that the CoNbZr/Cu/Co PSV trilayers have strong potentials for spin-electronic devices including magnetic random access memory.     

基于小波分解系数的贝叶斯人脸识别方法

本文给出了贝叶斯人脸识别方法中匹配准则的多个近似表达式及一种实用的快速计算方法.在此基础上,利用反对称双正交小波变换的微分算子功能,提出了一种利用两幅人脸图象的小波变换系数差作为模式矢量的贝叶斯人脸识别方法,并利用AR人脸图象库进行了实验.实验结果表明本文方法与基于图象灰度的类似方法相比,识别率提高8%左右.此外本文方法也提供了一条在图象压缩数据域中实现人脸识别的可能途径.     

Plakinidines生物碱的研究进展

Plakinidines是从海洋生物中分离得到的一种活性物质,也是人们首次发现具有吡咯[2,3,4-kl]吖啶骨架结构的天然产物,相应的生物活性探讨与合成工作也相继地展开.在本文中,结合本课题组的合成工作报道plakinidines的发现、生物活性以及相关的合成进展.     

基于改进区域生长法的电力设备红外图像分割

为实现电力设备红外图像中目标设备图像的分割,对传统区域生长法需要人工选择初始种子点,以及易产生过分割与欠分割的不足提出了改进,将红外图像中邻域均值最大的像素点作为种子点,实现种子点的自动选取。提出了使用Sobel算子计算梯度幅值作为附加限定条件的生长准则。改进的区域生长法的分割效果比传统的区域生长法效果更好。     

电力设备红外图像的小波阈值去噪方法研究

对于电力设备的红外图像自动检测系统,图像去噪是非常关键的。针对传统的小波硬、软阈值函数在去噪时存在的不足,在传统小波硬、软阈值函数的基础上对其进行了改进。改进的阈值函数克服了硬阈值函数不连续的缺陷,改善了软阈值函数具有恒定偏差的不足,并引入了两个变量,具有一定的灵活性。同时还使用了一种新的分层阈值选择函数代替统一阈值方法,以改善实际应用的效果。实验结果表明:改进的小波阈值去噪方法在视觉效果、峰值信噪比和均方误差方面都优于传统的硬、软阈值去噪方法;改进的小波阈值去噪方法可以运用到红外图像自动检测系统中,使系统具有更好的去噪效果。     

Room-Temperature Ferromagnetism of Co-Doped CeO2 Thin Films on Si（111） substrates

Using Co2O3 as the Co source, doped cerium oxide thin films with the composition of Ce0.97C00.03O2-δ （CCO） are deposited on Si（111） and glass substrates by pulse laser deposition technique. X-ray diffraction reveals that CCO films with （111） preferential orientation are grown on Si, while the fihn on glass is polycrystalline with nanocrystal. X-ray photoelectron spectroscopy shows that the （Jo displaces the （;e atom and exists in high spin state rather than low spin state, which contributes to the room-temperature ferromagnetism confirmed by vibration sample magnetometer. I~ilms on Si and glass are different in ferromagnetism, which is believed to be induced by different film microstructures. Based on these results, the possible ferromagnetism in this insulating film is discussed. Anyway, successful fabrication of CCO films with room-temperature ferromagnetism on Si substrates is of great importance in both technological and theoretical aspects.     

基于小波分解系数的贝叶斯人脸识别方法

本文给出了贝叶斯人脸识别方法中匹配准则的多个近似表达式及一种实用的快速计算方法,在此基础上,利用反对称双正交小波变换的微分算子功能,提出了一种利用两幅人脸图像的小波变换系数差作为模式矢量的贝叶斯人脸识别方法,并利用AR人脸图象库进行了实验,实验结果表明本文方法与基于图像灰度的类似方法相比,识别率提高8％左右,此外本文方法也提供了一条在图像压缩数据域中实现人脸识别的可能途径。     

多级聚焦-偏转复合系统的相对论象差理论

本文在文献[1]的基础上,导出了聚焦-偏转复合系统的相对论一级色差及另一形式的相对论三级几何象差公式,得出了各种象差系数的明显公式,应用上述理论,本文讨论了多级电-磁的偏转复合系统中象差的叠加问题。 关键词：     

扭摆法测转动惯量实验装置的研究

传统的扭摆法测转动惯量多使用单线摆、三线摆等,针对传统的扭摆法测转动惯量装置的一些缺陷,比如由于产生摆动、计时方法不科学使计时结果不准确、装置不能保持在水平面上转动等造成的测量误差较大的问题,研究制造了一种新的实验装置。这套装置用涡卷弹簧提供扭摆的动力,用光电对管配合单片机进行精确计时,并且采用了变面接触为线接触等多种减小摩擦的设计来提高测量精度,使误差大大减小了。整套装置具有测量结果精确、操作简单、体积小、能测量不规则的及难以直立的物体的转动惯量、能很好地验证平行轴定理等优点。