非晶硅太阳能电池的新进展

对非晶硅材料的物理性能及工艺优势进行了阐述，其中介绍了一种新型的刻划成图工艺，即等离子CVM，简单回顾了非晶硅太阳池的历史发展，分析了非晶硅太阳电池当前所存在的问题，提出了其发展的方向，其中，主要论述了叠层非晶硅太阳电池，并介绍了几种新型的非晶硅电池，最后，概括了非晶硅太阳电池的应用现状及前景。     

高压变频器在转炉除尘风机系统改造中的应用

本文简单介绍了转炉除尘风机系统的工艺状况，经过分析，确定了利用高压变频器对转炉除尘系统进行项目改造的方案，系统改造以后有效节约了能源，产生了良好的经济效益，此外，该系统还提高了生产效率，降低了系统维护的工作强度。     

“掘金”网络优化市场——移动通信网络优化服务特点及其发展策略

移动通信网络优化服务由于借助了设备厂商和专业第三方优化服务公司的技术优势，很好地提升了现有网络运行的质量，弥补了网络运营商技术人员的缺口，培养了运行维护人员的专业技能，积极发挥了现有网络资源的利用率，有效地降低了网络的维护成本，提高了客户的满意度和运营效益，     

频道多了，节目也要跟上

频道多了，节目也要跟上吴为忠文年岁渐长，早已过了不惑之年，到了这样的年龄，晚上如果没有公务缠身就懒得外出，看电视似乎成了我业余生活的一个主要内容。但是，电视看得多了，总忍不住要说三道四，这也许是一种职业病。我的住处已经装上了闭路电视，又与有线电视台联...     

价格决定一切——Konica Minolta Dynax5D/α-5 DIGITAL

现在数码单反相机的价格已经越来越低了，甚至还出现了5000元左右的产品。当然，相机有了，除了镜头之外，剩下的最重要的东西就是存储卡了，对于那些喜欢疯狂拍片的摄友来讲，这款4GB的高速CF卡成了他们的最佳选择，有了它，你再也不用担心使用数码伴侣会意外丢失数据了。而且从何种上来讲，也会方便100倍！     

两会报道与现场直播技术实施

2008年的两会是党的十七大后召开的重要会议，是我国人民政治生活中的大事，媒体高中央级广播媒体，中央人民广播电台作了周密部署，精心策划，充分发挥了自身优势和特点，内容上突出了两会主题，正面引导热点，形式上大胆创新，与时俱进，体现时代性，确保了两会的报道和安全播出。     

马

马，本来自由自在的在山间撒野，渴了喝点山泉，累了就睡在地上晒太阳，无忧无虑。可是自从有了伯乐，马的命运就改变了，给它的头戴上笼辔，在它的背上置放鞍具，栓着它，马的死亡率已经是十之二三了，然后再逼着它运输东西，强迫它日行千里，在它的脚上钉上铁掌，马的死亡率就过半了。     

发射站固定的双站合成孔径声纳成像研究

本文建立了发射站固定的双站合成孔径声纳模型，在分析了“停-走-停”假设引起相位误差的基础上，提出了对误差补偿的方法，研究了双站SAR距离-多普勒算法，并提出了基于该算法的双站SAR成像方案，最后给出了有关计算机仿真结果，实现了双站SAR对点目标的成像，     

用于成像引信图像识别的局部特性提取技术

根据成像引信的扫描成像机理，在详细分析了引信目标图像特性的基础上，论述了四种适用于引信目标图像的局部特征：角点，轮廓曲线段形状特征，线矩和弯曲能量，并提出了一种子块特征的提取算法。最后，分析了在应用局部特征进行了识别时遇到的问题并指出了解决方法，本文的研究对于其他不完整图像识别问题，如工件识别，机器人视觉，场景分析，医学图像的解释，飞行器的识别等，同样很有意义。     

Wedding……

兄弟结婚了，朋友结婚了，朋友的朋友结婚了；男的结婚了，女的结婚了，不男不女的也结婚了；有感情的结婚了，没感情的结婚了，认识不认识的结婚已经无所谓了……     

EPON 和 GPON 的 OAM 功能及其比较

着重介绍了目前被业界看好的两种无源光接入网EPON和GPON中的网络操作维护管理(OAM)的技术,包括OAM实现的功能、帧的结构及其特点.此外,还分析比较了EPON OAM和GPON OAM的异同点.     

TOPICS IN OPTICAL COMMUNICATIONS - STARGATE: The Next Evolutionary Step toward Unleashing the Potential of WDM EPONs

WDM EPONs are rapidly becoming mature. In this article we briefly review the state of the art of cost reduction, colorless ONUs, and WDM PONs. We then lift the veil of future WDM EPONs, and elaborate on evolutionary cost-effective upgrades of WDM EPONs and their all-optical WDM integration with Ethernet-based metropolitan area networks to provide transparent connections at the wavelength and sub-wavelength granularity on demand between ONUs residing in different WDM EPONs     

WDM Ethernet passive optical networks

WDM EPONs not only allow for cautious pay-as-you-grow upgrades of single-channel TDM EPONs but also avoid linearly increasing polling cycle times for an increasing number of ONUS. In this article, we first provide a comprehensive overview of the state of the art of TDM EPONs and recently reported dynamic bandwidth allocation algorithms, including decentralized scheduling schemes. After reviewing previous work on WDM EPONs, we address the requirements of WDM upgraded EPONs and make recommendations on an evolutionary WDM upgrade at the architecture, protocol, and dynamic bandwidth allocation algorithm levels, taking backward compatibility with MPCP and future-proofness against arbitrary WDM ONU structures into account. We describe and compare online and offline scheduling paradigms for WDM EPONs. Our simulation results indicate that online scheduling can achieve lower delays, especially at high loads. We outline areas of future research on WDM EPONs.     

A midterm DBA algorithm for quality of service on aggregation layer EPON networks

This work presents a new approach on dynamic bandwidth allocation (DBA) for Ethernet Passive Optical Networks (EPONs). A brief introduction to the DBA area and major term definitions are given. The related research and standardization efforts are presented. Justification that EPONs can be used on the aggregation network is provided, based on their evolution and related research proposals. Focus is given to the Long Reach-Passive Optical Networks (LR-PONs) and their limitations which show the need for a non-polling, midterm DBA scheme for next-generation EPONs. The challenges arising, because of this new approach, are discussed along with possible solutions. Finally, this work proposes the EMDBA algorithm which is able to overcome the discussed issues. The correct operation of this algorithm is confirmed by a set of simulations using OMNet++ framework, and the outcome results show that EMDBA performance is satisfactory in terms of delay and service differentiation.     

Per-Stream QoS and Admission Control in Ethernet Passive Optical Networks (EPONs)

Ethernet passive optical networks (EPONs) are designed to deliver services for numerous applications such as voice over Internet protocol, standard and high-definition video, video conferencing (interactive video), and data traffic. Various dynamic bandwidth allocation and intra-optical network unit (ONU) scheduling algorithms have been proposed to enable EPONs to deliver differentiated services for traffic with different quality of service (QoS) requirements. However, none of these protocols and schedulers can guarantee bandwidth for each class of service nor can they protect the QoS level required by admitted real-time traffic streams. In this paper, we propose the first framework for per-stream QoS protection in EPONs using a two-stage admission control (AC) system. The first stage enables the ONU to perform flow admission locally according to the bandwidth availability, and the second stage allows for global AC at the optical line terminal. Appropriate bandwidth allocation algorithms are presented as well. An event-driven simulation model is implemented to study the effectiveness of the proposed schemes in providing and protecting QoS.     

Enhanced Dynamic Bandwidth Allocation Algorithm in Ethernet Passive Optical Networks

As broadband access is evolving from digital subscriber lines to optical access networks, Ethernet passive optical networks (EPONs) are considered a promising solution for next generation broadband access. The point‐to‐multipoint topology of EPONs requires a time‐division multiple access MAC protocol for upstream transmission. In this paper, we propose a new enhanced dynamic bandwidth allocation algorithm with fairness called EFDBA for multiple services over EPONs. The proposed algorithm is composed of a fairness counter controller and a fairness system buffer in the optical line terminal. The EFDBA algorithm with fairness can provide increased capability and efficient resource allocation in an EPON system. In the proposed EFDBA algorithm, the optical line termination allocates bandwidth to the optical network units in proportion to the fairness weighting counter number associated with their class and queue length. The proposed algorithm provides efficient resource utilization by reducing the unused remaining bandwidth made by idle state optical network units.     

Bandwidth allocation for multiservice access on EPONs

Ethernet passive optical networks are a low-cost high-speed solution to the bottleneck problem of the broadband access network. A major characteristic of EPONs is the shared upstream channel among end users, mandating efficient medium access control to facilitate statistical multiplexing and provision multiple services for different types of traffic. This article addresses and provides an overview of the upstream bandwidth allocation issue for multiservice access provisioning over EPONs, and proposes an algorithm for dynamic bandwidth allocation with service differentiation. Based on the multipoint control protocol (MPCP) and bursty traffic prediction, our algorithm enhances QoS metrics such as average frame delay, average queue length, and frame loss probability over other existing protocols     

Cyclic Polling-Based Dynamic Bandwidth Allocation for Differentiated Classes of Service in Ethernet Passive Optical Networks

Ethernet passive optical networks (EPONs) are an emerging access network technology that provides a low-cost method of deploying optical access lines between a carrier's central office and customer sites. Dynamic bandwidth allocation (DBA) provides statistical multiplexing between the optical network units for efficient upstream channel utilization. To support dynamic bandwidth distribution, a cyclic polling-based DBA algorithm for differentiated classes of service in EPONs is proposed. It is shown that an interleaved polling scheme severely decreases downstream channel capacity for user traffic when the upstream network load is low. To obtain realistic simulation results, synthetic traffic that exhibits the properties of self-similarity and long-range dependence is used. Network performance under various loads is analyzed. Specifically, frame delays for different classes of traffic are considered.     

Adaptive polling algorithm to provide subscriber and service differentiation in a Long-Reach EPON

A novel interleaved polling algorithm for Long-Reach EPONs is proposed in order to simultaneously provide subscriber and class of service differentiation. It is demonstrated that the new polling algorithm applied to a typical 100 km Long-Reach EPON performs better than centralized methods, where bandwidth prediction is needed to overcome the higher round trip time in which ONUs cannot transmit. As polling methods in Long-Reach EPONs do not require prediction, they are much simpler and show less computational complexity than centralized schemes, avoiding the inaccuracy of bandwidth prediction. Simulation results show that the new algorithm increases the achieved throughput when compared to centralized algorithms with traffic prediction, obtaining a significant reduction of both mean packet delay and packet loss ratio for the highest priority service level profiles.     

A survey of dynamic bandwidth allocation algorithms for Ethernet Passive Optical Networks

Ethernet Passive Optical Network (EPON) has been widely considered as a promising technology for implementing the FTTx solutions to the “last mile” bandwidth bottleneck problem. Bandwidth allocation is one of the critical issues in the design of EPON systems. In an EPON system, multiple optical network units (ONUs) share a common upstream channel for data transmission. To efficiently utilize the limited bandwidth of the upstream channel, an EPON system must dynamically allocate the upstream bandwidth among multiple ONUs based on the instantaneous bandwidth demands and quality of service requirements of end users. This paper introduces the fundamental concepts on EPONs, discusses the major issues related to bandwidth allocation in EPON systems, and presents a survey of the state-of-the-art dynamic bandwidth allocation (DBA) algorithms for EPONs.