基于二值离散运算的自适应数字图像水印算法

论文提出了一种在小波变换域内基于二值离散运算的自适应数字图像水印算法.算法利用人眼视觉掩盖特性,根据要嵌入的伪随机数水印长度自适应地选择原始图像小波逼近子图中纹理信息丰富的图像子块,通过对这些图像子块系数的二值离散修改实现水印的嵌入,水印检测无需原始图像.由于水印的嵌入与检测是基于二值离散运算,所嵌入的水印具有很理想的鲁棒性,能免疫于常规图像处理方法的有限攻击.同时,嵌入的水印具有理想的隐蔽效果,完全满足水印不可觉察性要求.     

羟基对掺铒铋酸盐玻璃1.53 μm波段荧光及信号放大特性的影响

用高温熔融法制备了组分为Bi2O3-B2O3-SiO3铋酸盐掺铒玻璃,研究了羟基含量对玻璃中Er3+的1.53 μm波段荧光和对光纤中信号放大特性的影响.研究表明:通过氧气鼓泡除水处理.能有效地去除玻璃中羟基,从而显著提高1.53μm波段荧光强度.同时,对铋酸盐掺铒玻璃光纤中Er3+离子数速率方程和光功率传输方程的理论模拟表明:减少纤芯玻璃中羟基含量可以使1 520～1 620mm范围内信号增益得到不同程度的提高.因此,除水处理对于铋酸盐掺铒玻璃应用于1.53μm波段宽带光纤放大器是非常必要的.     

基于有限状态机的类人足球机器人决策系统设计

RoboCup类人组(Humanoid League)机器人的决策系统是基于单目视觉自主决策的核心子系统,是决定比赛胜败的关键因素之一。本文以高效性为原则,设计了基于有限状态机的新决策系统,将复杂的机器人决策行为控制层划分为可以独立调试和优化的4个状态机模块,使机器人各状态之间的转换更加灵活,决策效率极大提高,决策算法更加易于继承和开发。将该决策系统应用于类人足球机器人平台,通过试验及比赛证明了其有效性和高效性。     

980 nm 和1480 nm 抽运下铋基EDFA放大特性的比较研究

The population rate and power propagation equations are presented and solved to compare the amplification performances of bismuth-based Er3+-doped fiber amplifier (EDFA) pumped by 980-and 1480-nm lasers,respectively.In both single signal and coarse wavelength-division-multiplexing(CWDM)signals inputs,the 1480-nm pumped bismuth-based EDFA provides a larger signal gain than the 980-nm pumped one does,whereas the latter provides a relatively lower noise figure (NF).Comparative results indicate that the 1480-nm pumping scheme is more advantageous for bismuth-based EDFA regarding the band width and gain property.     

掺铒铋酸盐玻璃和掺铒碲酸盐玻璃的荧光俘获和浓度猝灭效应

用高温熔融法制备了系列掺铒铋酸盐和碲酸盐玻璃,用分光光度计测试吸收光谱,并用荧光光谱仪测试了不同铒离子掺杂浓度时玻璃样品的荧光光谱和荧光寿命.结果显示:掺铒后,铋酸盐玻璃和碲酸盐玻璃中存在着强烈的荧光俘获和浓度猝灭效应.随着玻璃中铒离子掺杂浓度的增加,1.53 μm波段荧光谱展宽,1 560 m波长处荧光次峰增强,但相对于铋酸盐玻璃,碲酸盐玻璃具有更为强烈的荧光俘获效应.同时,随着铒离子掺杂浓度的增加,4I13/2能级荧光寿命和1.53 μm波段荧光强度呈先增加后减小趋势.根据Dexter能量转移理论,计算并分析比较了这2种宽带玻璃系统中铒离子发生浓度猝火的临界距离R0及相互作用参数Cer-Er.     

Tm^3＋-doped tellurite glass with Yb^3＋ energy sensitized for broadband amplifier at 1400-1700 nm bands

A kind of novel experiment was disclosed as it possessed two bands of fluorescence emission at 1.4 and 1.6 μm, which were perfectly complimentary to the current C band of optic communication. The fluorescence was based on energy transfer and up-conversion processes between Tm^3＋ and Yb^3＋ under direct pumping of 975 nm LD. The spectra and lifetimes of Tm^3＋ fluorescence in the tellurite glass were described. The corresponding fluorescence characteristics and energy migration process were analyzed by the method of lifetime and intensity comparison. The mechanism of the up-conversion based IR fluorescence was presented upon analyzing the multi-photon pumping process. The potential advantages of Tm^3＋/Yb^3＋ co-doped tellurite glass as amplifier material were concluded.     

掺铒铋基玻璃的荧光俘获和浓度猝灭效应研究

用高温熔融法制备了系列掺铒铋硼锗酸盐玻璃,测试分析了不同铒离子掺杂浓度下玻璃样品的吸收光谱和荧光光谱.结果显示,掺铒铋硼锗酸盐玻璃中存在着强烈的荧光俘获和浓度猝灭效应.随着铒离子掺杂浓度的增加,1.53 μm波段荧光谱展宽,1 560 nm波长处荧光次峰相对增强.对此用一个等效的四能级模型予以了定性分析.同时,随着铒离子掺杂浓度的增加,4I13/2能级荧光寿命和1.53 μm波段荧光强度呈现出先增加后减小趋势.依据Dexter能量转移理论,计算了该玻璃系统中铒离子发生浓度猝灭的临界距离R0及相互作用参数CEr-Er,并与其它玻璃基质进行了比较.