Mitigation of polarization-mode dispersion in multichannel lightwave transmission systems

We propose a novel polarization-mode dispersion (PMD) compensation scheme for wavelength-division-multiplexing (WDM) systems, in which many WDM channels share one or a few PMD compensators at receiver site. It is shown, both analytically and numerically, that this scheme can achieve virtually the same performance as that using per-channel-based PMD compensation.     

一个基于优化的有限元模型修正方法

本文提供了一个基于一阶搜索优化的有限元模型修正方法。它只需利用结构模态试验的部分固有频率，就能获得较精确的有限元模型。文中附有某无人机上垂尾有限元模型修正的实例。根据上垂尾前二阶试验的固有频率，采用本文方法，对有限元模型进行了修正。修正后有限元模型的前二阶固有频率与试验值的相对误差在2．35％以内，而第三阶固有频率与试验值的相对误差仅为5．81％。它不仅大大地缩小了用修正前有限元模型算得的固有频率与试验值的相对误差，而且还能较精确地预测无试验结果的高阶固有频率值。     

IEEE802.11g研究综述

全面介绍了IEEE802.11g标准的WLAN，详细讲述了IEEE802.11g草案标准的概念、特点、构件及体系结构、发展前景等，并探讨了实现IEEE802.11g WLAN所需的几项关键技术，同时分析了IEEE802.11g标准的网络性能。其关键技术包括直序列扩频调制技术及补码键控技术，包二进制卷积，正交频分复用技术等。有关IEEE802.11g的兼容性，同频共存性，自身的OFDM问题分析将成为研究的热点。     

东营凹陷南斜坡储集层成岩作用及对储集性能的影响

东营凹陷南斜坡孔店组岩石类型以岩屑长石砂岩为主 ,长石砂岩和岩屑砂岩次之 ,其中岩屑长石砂岩含量超过 90 %。砂岩成岩作用包括压实作用、胶结作用、溶蚀作用、交代作用等 ,其中胶结作用使储层原生孔隙迅速变差 ,而溶蚀作用是次生空隙发育的主要因素。孔店组砂岩成岩作用进入晚成岩A期 ,期间经历了早成岩A期、B期。影响成岩作用的主要因素为构造演化背景、岩石成分、沉积环境、孔隙流体性质等。     

黄河天桥水电站工程建设及泥沙处理主要经验

天桥水电站是黄河中游北干上的第一座高泥沙、低水头、大流量的径流式试验电站。它成功的施工与运营经验不仅对在黄河中游北干上开发梯级水电站，而且对中小型径流式水电站的施工都具有重要的借鉴作用。这篇文章总结了两期截流工程、基坑排水、固结灌浆、帷幕灌浆方面的施工经验。在诸如厂房位置的选择以及它的布置，泥沙、冰凌、洪水以及拦污方面的工程设计与运营的宝贵经验，使得水库长期保持高的有效库容和良好的运营状态。特剐是防止进水口淤积和水轮机的磨蚀方面的七条措施是非常有价值的。     

Novel algorithms for shared segment protection

The major challenges in designing survivable schemes are how to allocate a minimal amount of spare resources (e.g., bandwidth) using fast (e.g., polynomial-time) algorithms, and, in case a failure occurs, to be able to recover quickly from it. All existing approaches invariably make tradeoffs. We propose novel shared segment protection algorithms which make little or no compromise . We develop an elegant integer linear programming (ILP) model to determine an optimal set of segments to protect a given active path. Although the ILP approach is useful for a medium-size network, it is too time consuming for large networks. Accordingly, we also design a fast heuristic algorithm based on dynamic programming to obtain a near-optimal set of segments. Although the heuristic algorithm has a polynomial time complexity, it can achieve a bandwidth efficiency as high as some best-performing shared path protection schemes and, at the same time, much faster recovery than these shared path protection schemes. The proposed scheme is also applicable to a wide range of networking technologies, including Internet Protocol and wavelength-division multiplexing networks under the generalized multiprotocol label switched framework.     

Measurement of gain spectrum for Fabry-Perot semiconductor lasers by the Fourier transform method with a deconvolution process

To improve the accuracy of measured gain spectra, which is usually limited by the resolution of the optical spectrum analyzer (OSA), a deconvolution process based on the measured spectrum of a narrow linewidth semiconductor laser is applied in the Fourier transform method. The numerical simulation shows that practical gain spectra can be resumed by the Fourier transform method with the deconvolution process. Taking the OSA resolution to be 0.06, 0.1, and 0.2 nm, the gain-reflectivity product spectra with the difference of about 2% are obtained for a 1550-nm semiconductor laser with the cavity length of 720 /spl mu/m. The spectra obtained by the Fourier transform method without the deconvolution process and the Hakki-Paoli method are presented and compared. The simulation also shows that the Fourier transform method has less sensitivity to noise than the Hakki-Paoli method.     

基于质粒的DNA计算模型研究

论文给出了一种基于环状质粒DNA计算的新方法,这种计算质粒包含一个特殊的插入DNA序列片断,每个片断定位在匹配的限制性内切位点,通过剪切和粘贴实现计算过程。论文同时给出了生物计算模型和相关的数学描述,这种模式的计算有待进一步研究。     

Courtesy piggybacking: supporting differentiated services in multihop mobile ad hoc networks

Due to the salient characteristics such as the time-varying and error-prone wireless links, the dynamic and limited bandwidth, the time-varying traffic pattern and user locations, and the energy constraints, it is a challenging task to efficiently support heterogeneous traffic with different quality of service (CoS) requirements in multihop mobile ad hoc networks. In the last few years, many channel-dependent mechanisms are proposed to address this issue based on the cross-layer design philosophy. However, a lot of problems remain before more efficient solutions are found. One of the problems is how to alleviate the conflict between throughput and fairness for different prioritized traffic, especially how to avoid the bandwidth starvation problem for low-priority traffic when the high-priority traffic load is very high. In this paper, we propose a novel scheme named Courtesy Piggybacking to address this problem. With the recognition of interlayer coupling, our Courtesy Piggybacking scheme exploits the channel dynamics and stochastic traffic features to alleviate the conflict. The basic idea is to let the high-priority traffic help the low-priority traffic by sharing unused residual bandwidth with courtesy. Another noteworthy feature of the proposed scheme is its implementation simplicity: The scheme is easy to implement and is applicable in networks using either reservation-based or contention-based MAC protocols.