Configuring Traffic Grooming VPλNs

A VPN is an optical virtual private network (oVPN) built of wavelength paths within a multihop wavelength routing (WR) dense wavelength division multiplexing (DWDM) network. An efficient and general graph-theoretic model (the wavelength-graph (WG)) has been proposed along with an integer linear programming (ILP) formulation of setting up VPNs with given traffic requirements over a given WR-DWDM network with two protection scenarios. Here, we have exploited the advantages of traffic grooming, i.e., numerous traffic streams of a VPN can share a wavelength path. We have also generalized the model for setting up VPNs over a WR-DWDM system where multiple VPNs can share a single wavelength path. The objective of the optimization is in all cases to reduce resource usage at upper (electrical) layers (i.e., to reduce the load of the virtual routers), subject to constrained amount of capacity of each wavelength channel and limited number of wavelengths. Here, we propose and compare three basic methods for configuring oVPNs and investigate various parameter settings.     

A nature-inspired firefly algorithm based approach for nanoscale leakage optimal RTL structure

Optimization of leakage power is essential for nanoscale CMOS (nano-CMOS) technology based integrated circuits for numerous reasons, including improving battery life of the system in which they are used as well as enhancing reliability. Leakage optimization at an early stage of the design cycle such as the register-transfer level (RTL) or architectural level provides more degrees of freedom to design engineers and ensures that the design is optimized at higher levels before proceeding to the next and more detailed phases of the design cycle. In this paper, an RTL optimization approach is presented that targets leakage-power optimization while performing simultaneous scheduling, allocation and binding. The optimization approach uses a nature-inspired firefly algorithm so that large digital integrated circuits can be effectively handled without convergence issues. The firefly algorithm optimizes the cost of leakage delay product (LDP) under various resource constraints. As a specific example, gate-oxide leakage is optimized using a 45 nm CMOS dual-oxide based pre-characterized datapath library. Experimental results over various architectural level benchmark integrated circuits show that average leakage optimization of 90% can be obtained. For a comparative perspective, an integer linear programming (ILP) based algorithm is also presented and it is observed that the firefly algorithm is as accurate as ILP while converging much faster. To the best of the authors׳ knowledge, this is the first ever paper that applies firefly based algorithms for RTL optimization.     

基于改进粒子群优化算法的电力系统无功电压综合控制

在基本粒子群优化算法的基础上,提出了一种改进的粒子群优化算法用于电力系统无功电压综合控制。该算法改进了随机初始化种群的方法,采用均匀初始化,引进了粒子的自身探索机制,用多个位于可行域中的粒子个体引导粒子的更新,以保证全局搜索的有效性,同时采用混沌变异算子对陷入局部最优的粒子进行变异,提高了算法的寻优性能。通过对IEEE-30节点标准系统模型的无功电压综合控制计算和分析,证明了此改进的粒子群优化算法具有更高的全局寻优效率。     

基于半导体光放大器中交叉偏振调制效应的波长转换器

了改善基于半导体光放大器(SOA)中交叉偏振调制效应(CPM)的波长转换器的转换信号码型效应，对交叉偏振调制一半导体光放大器波长转换器的工作原理进行了分析；通过讨论交叉偏振调制一半导体光放大器波长转换脉冲的上升沿和下降沿的频率啁啾，结合滤波器的透过谱特性，提出了一种利用滤波器的波长正斜率边和波长负斜率边分别对正相转换信号和反相转换信号进行码型优化的方案，并进行了实验验证。在信号码率为10Gb／s的交叉偏振调制一半导体光放大器波长转换实验中，采用光带宽为0．3nm的JDS滤波器优化转换信号的波形，基本消除了转换信号中长“1”码和长“0”码的码型效应，并将正相转换信号和反相转换信号的功率代价分别改善了3dB以上。     

Optimization and experimentation of nanoimprint lithography based on FIB fabricated stamp

The maskless and resistless focused ion beam (FIB) fabrication approach to make imprint stamp is straightforward and rapid compared to the traditional electron beam method. FIB etched stamp consisting of grooves was employed to nanoimprint polymer mr-I 9020. Taguchi orthogonal experiment with four parameter elements, one at three levels was used to optimize the experiment parameters by the analysis of means and variances. The most significant factor influencing the height of replicated lines is imprint temperature and the optimal combination of the process parameters are the imprint temperature at 160 °C, imprint force at 1200 N, loading force velocity at 0.2 mm/min, and imprint time at 300 s.     

基于改进粒子群算法的后向泵浦RFA设计北大核心CSCD

为了满足第六代移动通信(6G)系统对光通信网络的高速率及大容量的要求,进一步提高光传输网络中光纤放大器的带宽、响应速率及放大倍数等成为目前的研究重点。在使用碲酸盐光纤作为光纤增益介质的同时,提出一种改进粒子群优化算法,通过在迭代过程中动态的调整速度、位置及惯性权重值,获得更高收敛速度,增强全局搜索的能力。应用该算法对拉曼光纤放大器的各个泵浦光参数配置进行优化、分析及仿真验证,最终设计出平均开关增益为23.738 8 dB,增益平坦度为0.209 8 dB的后向泵浦拉曼光纤放大器。结果表明,改进的粒子群优化算法对拉曼放大器泵浦光的参数配置有很强的适应性,能够获得较低的增益平坦度,对未来拉曼光纤放大器的设计具有一定的参考意义。     

基于遗传算法的TSP问题求解与仿真

TSP问题常用的自然编码方式在进行遗传操作时,会产生不合法路径.设计了一种新的编码方式,能有效避免这一问题,遗传操作简单易行,无需对不合理的基因片段进行合法化修正.在求解过程中,为了解决遗传算法的收敛速度和全局收敛性之间的矛盾、避免早熟,运用了Doping策略和参数切换方法.最后进行了仿真测试.结果表明,该算法能迅速淘汰劣解,具有较快的收敛速度;能有效遏制早熟,对不同规模的TSP问题能有效求得最优解.     

Mesh-Tree两级层次结构P/G网布线优化方法

本文采用Mesh-Tree两级层次结构作为P／G网布线拓扑结构，并提出了一个对于该结构的线宽优化方法，使超大型P／G网的布线优化速度大大提高。