光突发交换的交换控制策略和光缓存配置

光突发交换是面向下一代互联网的光交换模式.讨论了异步光突发交换系统的交换控制策略以及相应光缓存的优化配置策略.除了传统预约模式的交换策略,还研究了非预约和改进型预约模式,它们的性能评估由计算机仿真给出.结果表明:在条件相当情况下,改进型预约模式具有最低的丢包率.同时光缓存的配置对上述几类交换控制策略的性能都有很大影响,仿真结果指出:光缓存的粒度对系统性能具有重要影响,所讨论的几类交换模式都存在最佳时延粒度,研究结果对光交换矩阵的设计有指导意义.     

Dynamic Survivability in WDM Mesh Networks Under Dynamic Traffic

Network survivability is a crucial requirement in WDM mesh networks. In this paper, we systematically consider the problem of dynamic survivability with dynamic single link failure in WDM networks under dynamic traffic demands. Specifically, we investigate various protection schemes, such as dedicated path protection (DPP), shared path protection (SPP), dedicated link protection (DLP), shared link protection (SLP), and two restoration schemes, path restoration (PR) and link restoration (LR). Moreover, two new shared protection methods are proposed, i.e., SRLG-based shared link protection (SRLG-SLP) and SRLG-based shared path protection (SRLG-SPP). The SRLG (shared risk link group) constraint defines the availability of protection resources to a working path, which requires that any two working paths sharing the same risk of failure (or in the same SRLG) cannot share the same protection resources. Furthermore, in our study, we consider a more practical dynamic single-link failure model, in which the link-failure-interarrival time and link-failure-holding time are considered as two independent parameters. Based on this link-failure model, extensive simulations are done to analyze and compare the dynamic survivable performance of various protection and restoration schemes. Resource utilization, protection efficiency, restoration efficiency, and service disruption ratio are employed as survivable performance metrics versus traffic load, link-failure frequency, and link-failure reparation time to evaluate the survivable performance. Many meaningful results are given. In addition, we show that the developed SRLG-SLP and SRLG-SPP protection schemes perform very well in terms of protection efficiency and service disruption ratio, while sacrificing some performance in terms of resource utilization.     

利用红外转换屏研制短波红外探测器

采用重力沉积技术制备了CaS:Eu2+,Sm3+红外上转换荧光屏,确定了最佳制屏工艺参数,研究了红外转换荧光屏的性能。设计和制作了耦合短波红外CCD 相机,对相机的成像性能进行了试验,结果表明研制的短波红外CCD 相机能够实现对1 064 nm、1 550 nm 等短波红外激光的探测和成像。采用红外转换荧光屏制作红外CCD 相机为短波红外探测器的研制提供了简便、有效的途径。     

用传统光学薄膜技术改进菲涅耳波带板

利用二元光学理论改进菲涅耳波带板, 能大幅度提高衍射效率.本文介绍利用传统的照相复制和真空镀膜技术制作位相型菲涅耳波带板的方法, 指出了膜料选择和膜厚控制的依据, 实测了位相台阶数为2时的衍射效率, 为通常菲涅耳波带板的近4 倍.     

The complexity of problems in wireless communication

Ad hoc networks become increasingly important in our life, for their advantages without relying on existing infrastructures and for their ability to be fast implemented, especially in the aspects of rescue after disasters and military. However, since every node in an ad hoc network can move freely, we are confronted with many new problems when compared with cellular networks and WiFi, such as the change of connectivity between nodes and signal interference and blockage by obstacles. Thus, it is important to understand solutions and complexities of various programming problems in ad hoc networks. In this paper, based on an existing mobility model for ad hoc networks, we study solutions and complexities of a series of problems proposed by Greenlaw, Kantabutra, and Longani, including the multiusers simultaneous communication problem (MUSCP), the longer communication problem (LCP), the obstacle removal problem (ORP) and the user communication, limited number of sources problem (UCLNSP). For MUSCP and LCP, we provide efficient algorithms to solve them and prove that they are P problems. On the other hand, for ORP and UCLNSP, by applying reduction from the set covering decision problem, we prove that they are NP-complete, and thus, they are intractable, unless \(P=NP.\)     

改善大功率CO_2激光模式的位相统一输出镜

介绍用高斯芯腔改善大功率CO2激光模式，以GaAs基片为例阐明位相统一输出镜的膜系设计方法和制作技巧.应用该镜获得了准基模700W输出;并有进一步提高功率和效率的潜力.     

面向城域网的多业务提供平台技术

多业务传输平台技术是为了兼容目前城域网大量应用的TDM业务,同时满足日益增长的数据业务的要求而提出的,这种传输平台能更好地承载基于分组交换的数据业务,同时保证语音业务的高质量和可靠性。文中简要概括了多业务传输平台技术的基本特点、种类及其若干关键技术。     

MBE生长InSb外延层特性及红外探测器研究

本文报道了采用含有ＩｎＳｂ非晶过渡层的两步ＭＢＥ生长技术，在ＧａＡｓ（１００）衬底上异质外延生长的ＩｎＳｂ外延层材料特性及初步的器件性能。５μｍ厚的ｎ型本征ＩｎＳｂ外延层７７Ｋ时的电子浓度和迁移率分别为：ｎ～２．４×１０￣（１５）ｃｍ￣（－３），μ～５．１２×１０￣４ｃｍ￣２Ｖ￣９－１）ｓ￣（－１），高质量ＩｎＳｂ外延层的Ｘ射线双晶衍射半峰宽（ＦＷＨＭ）＜１５０″。ＩｎＳｂ表面的相衬显微形貌，ＩｎＳｂ／ＧａＡｓ界面的ＴＥＭ形貌相和ＩｎＳｂ外延层的红外透射谱等测试结果都肯定了ＭＢＥＩｎＳｂ外延层的质量。研究结果已基本达到目前国外同类研究水平。用ＭＢＥ生长的ｎ型ＩｎＳｂ外延层薄膜首次制作了中波（３～５μｍ）多元光导线列器件，终测表明，器件的光导响应率较高Ｒ（Ｖ）～７８００Ｖ／Ｗ，均匀性很好ΔＲ（Ｖ）／Ｒ（Ｖ）＜７％，ＭＢＥＩｎＳｂ外延薄膜展示了良好的红外探测器应用前景。     

Network traffic prediction model based on improved VMD and PSO-ELM

The rapid update of computing power leads to exponential data traffic growth, and the incidence of network attacks is also increasing. It is significantly important to analyze and predict network traffic accurately in the early stage and take corresponding preventive measures. The existing network flow integrated forecasting models still have some bottlenecks that are difficult to solve, for example, the slow optimization speed of modal decomposition parameters, easy falling into local optimal solutions, the slow convergence speed of the training process, and poor generalization capability. In this paper, particle swarm optimization (PSO) is utilized to improve the parameters selection process of the variational mode decomposition (VMD) algorithm and the extreme learning machine (ELM) algorithm. First, the PSO-VMD combined with multi-scale permutation entropy (MPE) is utilized to decompose the original network flow, and multiple eigenmode components are obtained. Second, the PSO-ELM is utilized to train the network traffic prediction model, and the PSO parameters in PSO-ELM are updated through adaptive weight adjustment and synchronous learning factors to increase the training and prediction speed, and the component prediction results are reconstructed to get a high-precision network flow forecasting result. Finally, through the prediction and verification of the public network flow data of the WIDE backbone, the result of this experiment indicates that the VMD-PSO-ELM can break through the bottlenecks of slow optimization speed of VMD decomposition parameters, reduce the computational complexity of ELM, accelerate the convergence speed, and increase the forecasting accuracy.     

基于微分法的新傅里叶测量轮廓术

在傅里叶测量轮廓术中,为了得到真实相位值,必须进行相位解包裹处理的繁锁过程,为此提出一种可以直接获得真实相位值的新算法.这种算法的原理是空域中的微分(一阶)等效于频域中乘以一个线性因子,由此得到相位微分与光强的关系,求出相位的微分值后将其积分就获得相位的真实值.计算机仿真显示该方法确实有效可行.