Helical Shell Structures of Ni-A1 Alloy Nanowires and Their Electronic Transport Properties

Six kinds of Ni-A1 alloy nanowires are optimized by means of simulated annealing. The optimized structures show that the Ni-A1 alloy nanowires are helical shell structures that are wound by three atomic strands, which is very similar to the case with pure metallic nanowires. The densities of states （DOS）, transmission function T（ E）, current-voltage （I - V） curves, and the conductance spectra of these alloy nanowires are also investigated. Our results indicate that the conductance spectra depend on the geometric structure properties and the ingredients of the alloy nanowires. We observe and study the nonlinear contribution to the I-V characteristics that are due to the quantum size effect and the impurity effect. The addition of Ni atoms decreases the conductance of the Ni-A1 alloy nanowire because the doping atom Ni change the electronic band structures and the charge density distribution. The interesting statistical results shed light on the physics of quantum transport at the nano-scale.     

一种基于DSP的星图识别技术

针对星体跟踪器星图识别算法的复杂性以及星体跟踪器对体积、功耗的要求,介绍了一种基于多边形角距匹配的星图识别算法以及该算法在以DSP为基础的硬件平台上的实现.实验结果证明,复杂的星图识别算法可以在基于DSP的嵌入式平台上实现,并能达到系统实时性的要求.     

一种混合神经网络在图像压缩中的应用

讨论了一种混合神经网络，该网络使用遗传算法与BP算法相结合的混合智能算法进行权值训练，明显地提高了神经网络的收敛速度和精度。实验证明，利用混合神经网络进行图像压缩，不仅压缩比高、信道误码率低、解码速度快，而且图像恢复质量主观效果好。     

VHF/UHF波段电波传播模型本地化研究

对VHF/UHF波段电磁波传播模型和人工神经网络算法特性进行了分析,认为可以根据大量的实测数据,利用人工神经网络算法,建立起适合于本地使用的电磁波传播模型.该算法符合现代理念的"数据驱动"思想,所建立的模型具有强非线性特点,有较好的可修正性,很好地解决了模型本地化问题.     

Electric Conductivity of Phosphorus Nanowires

We present the structures and electrical transport properties of nanowires made from different strands of phosphorus chains encapsulated in carbon nanotubes. Optimized by density function theory, our results indicate that the conductance spectra reveal an oscillation dependence on the size of wires. It can be seen from the density of states and current-voltage curves that the structure of nanowires affects their properties greatly. Among them, the DNA-like double-helical phosphorus nanowire exhibits the distinct characteristic of an approximately linear I - V relationship and has a higher conductance than others. The transport properties of phosphorus nanowires are highly correlated with their microstructures.