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王卫国 《电子产品维修与制作》2009,(10):56-59
随着IT技术的不断发展,校园网络已成为了现代教育背景下学校的必要基础设施。校园网络布线系统的建设如何更好地进行统筹考虑?如何有计划、有步骤、分区域、分阶段地进行合理规划?如何最大可能地避免那种短期的、重复的低水平网络建设?如何从布线的角度协调局域网络飞速发展和实际应用需求之间的矛盾?这些问题都是我们值得认真探讨的问题。笔者长期从事局域网络布线工作,现就以下几个热点问题,谈谈自己的看法。 相似文献
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本文简要描述了用于网格的光网络总体要求,探讨了用于网格的高速大容量核心光传送网技术、波长交换技术、多层网络技术和光网络控制和管理技术的一般要求和特殊要求.最后,指出如何解决这些特殊要求将是下一代光网络研究应特别关注的问题. 相似文献
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我们讨论如何建设NGB网络时.采用“EPON+EoC”方案目前几乎已经形成共识。但是具体实现这样的方案时,这个方案具体内容与实际网络的建设环境有什么关系?网络中必须采用的设备应该具备什么功能要求才能适应业务需求?如何才能适应野外的安装条件和有利于未来的管理与维护?必须满足哪些条件才能适应业务对网络功能、传输资源的需求增长?如何才能适应技术的快速发展?这些问题是网络运营商不能回避的重要问题。 相似文献
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精彩观点:
最成功的媒体发展模式应该是将IT技术和内容制造完美地结合在一起。
未来3~5年内,内容制造商想在互联网上找到赢利模式基本不可能。
如何将非常好的文化内容跟网络和手机对接?
如果没有把你的渠道理顺,那么你的企业就会永远被市场边缘化。特别是产业链和价值链的脱节,使得渠道的作用显得更加重要。
技术、内容和渠道三者结合得越好的产业,就是越有市场价值的产业。
成功的价值链模式应该是每个环节的存在都能为其它的环节增加利润。
内容是信息网络生成和发展的基础。
产业链没有问题,是价值链存在问题。
网络音视频的发展存在政策、版权、运营模式等诸多问题。
网络传播规模不断增加,但是整个传播市场的利润在不断下降。
互联网免费的特性是不可逆转的,想在网络上找到利润。只能重新建立价值链。对传统媒体进行重新加工,然后再传输给网络用户。[编者按] 相似文献
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《电子产品维修与制作》2010,(20):17-28
随着网络的高速发展,爆炸性的数据增长使得数据管理面临着更加严峻的考验如何应对存储需求日益攀升的现状?如何将备份和归档有效地整合起来?如何有效解决文件的查重、杀重问题? 相似文献
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半速率可以有效的解决网络容量问题,但是半速率的开启将会对网络造成何种影响?半速率的开启比例建议最大到多少时不会恶化网络质量?本文针对以上问题,在分析、研究某市现网半速率开启情况的基础上,提出半速率最大开启比例的研究方法以及如何合理的应用。 相似文献
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Advance lightpath reservation is a new research topic for connecting high-speed computer servers in lambda grid applications
and for dynamic lightpath provisioning in the future optical internet. In such networks, users make call requests in advance
to reserve network resources for communications. The challenge of the problem comes from how to jointly determine call admission
control, lightpath routing, and wavelength assignment. In this paper, we propose an efficient Lagrangean relaxation (LGR)
approach to resolve advance lightpath reservation for multi-wavelength optical networks. The task is first formulated as a
combinatorial optimization problem in which the revenue from accepting call requests is to be maximized. The LGR approach
performs constraint relaxation and derives an upper-bound solution index according to a set of Lagrangean multipliers generated
through subgradient-based iterations. In parallel, using the generated Lagrangean multipliers, the LGR approach employs a
new heuristic algorithm to arrive at a near-optimal solution. By upper bounds, we assess the performance of LGR with respect
to solution accuracy. We further draw comparisons between LGR and three heuristic algorithms—Greedy, First Come First Serve,
and Deadline First, via experiments over the widely-used NSFNET network. Numerical results demonstrate that LGR outperforms
the other three heuristic approaches in gaining more revenue by receiving more call requests. 相似文献
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Shared Risk Link Group (SRLG)-Diverse Path Provisioning Under Hybrid Service Level Agreements in Wavelength-Routed Optical Mesh Networks 总被引:3,自引:0,他引:3
《Networking, IEEE/ACM Transactions on》2005,13(4):918-931
The static provisioning problem in wavelength-routed optical networks has been studied for many years. However, service providers are still facing the challenges arising from the special requirements for provisioning services at the optical layer. In this paper, we incorporate some realistic constraints into the static provisioning problem, and formulate it under different network resource availability conditions. We consider three classes of shared risk link group (SRLG)-diverse path protection schemes: dedicated, shared, and unprotected. We associate with each connection request a lightpath length constraint and a revenue value. When the network resources are not sufficient to accommodate all the connection requests, the static provisioning problem is formulated as a revenue maximization problem, whose objective is maximizing the total revenue value. When the network has sufficient resources, the problem becomes a capacity minimization problem with the objective of minimizing the number of used wavelength-links. We provide integer linear programming (ILP) formulations for these problems. Because solving these ILP problems is extremely time consuming, we propose a tabu search heuristic to solve these problems within a reasonable amount of time. We also develop a rerouting optimization heuristic, which is based on previous work. Experimental results are presented to compare the solutions obtained by the tabu search heuristic and the rerouting optimization heuristic. For both problems, the tabu search heuristic outperforms the rerouting optimization heuristic. 相似文献
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Xiujun Gong Kensuke Nakamura Hua Yu Kei Yura Nobuhiro Go 《IEEE transactions on information technology in biomedicine》2007,11(4):428-434
The emerging grid computing technologies enable bioinformatics scientists to conduct their researches in a virtual laboratory, in which they share public databases, computational tools as well as their analysis workflows. However, the development of grid applications is still a nightmare for general bioinformatics scientists, due to the lack of grid programming environments, standards and high-level services. Here, we present a system, which we named Bioinformatics: Ask Any Questions (BAAQ), to automate this development procedure as much as possible. BAAQ allows scientists to store and manage remote biological data and programs, to build analysis workflows that integrate these resources seamlessly, and to discover knowledge from available resources. This paper addresses two issues in building grid applications in bioinformatics: how to smoothly compose an analysis workflow using heterogeneous resources and how to efficiently discover and re-use available resources in the grid community. Correspondingly an intelligent grid programming environment and an active solution recommendation service are proposed. Finally, we present a case study applying BAAQ to a bioinformatics problem. 相似文献
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网格是网络发展的必然趋势,网格环境的特殊性使得网格安全成为制约网格应用的焦点。论文主要分析了网格环境下的安全问题,提出了网格的安全目标,介绍了GIG安全措施、网格信任一体化安全机制,并展望了网格安全的后续发展。 相似文献
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计算网格Portal的设计与实现 总被引:11,自引:1,他引:10
网格Portal就是网格的门户,网格Portal利用流行的Web技术提供Web界面方便用户运行网格应用程序.用户可以利用客户端浏览器通过网格Portal来方便安全透明地使用网格的各种计算资源。本文提出了计算网格Portal的设计技术和方法以及实现的功能,并分析了在设计中遇到的一些问题以及解决的办法。 相似文献
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面对高速发展的互联网应用,传统的路由与频谱分配(RSA)问题迎来新的挑战。融合降级服务(DS)技术的弹性光网络无疑为降低业务阻塞率,提高用户体验质量(QoE)提供了新方向。该文首先针对频谱资源的低效利用和DS导致的业务收益下降问题,建立以最小化频谱消耗和最小化DS等级、频次为联合优化目标的RSA问题的混合整数线性规划模型。随后,提出一种基于区分DS和自适应调制的动态RSA算法。该算法考虑业务等级的差异化,并整合自适应调制和DS技术。同时,设计区分业务等级的DS损失函数及DS窗口选择策略,为即将受阻业务分配理想的频谱位置和资源。此外,设计考虑频谱与收益均衡关系的网络收益函数,达到频谱资源高效利用,减少降级影响,提升网络收益的目的。最后,仿真验证了所提算法在业务阻塞率和网络收益等方面的优势。 相似文献
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基于混合并行遗传算法的网格资源分配策略 总被引:10,自引:2,他引:8
网格是利用互联网或专用网络将地理上广泛分布的、异构的、动态的资源互联起来实现资源高度共享与集成,为用户提供高性能的计算、管理和服务等功能的一项新技术。但如何将网格这个复杂环境中的资源有效进行管理和调度,是一个NP难问题,同时也是网格技术发展的关键。启发式算法被证明是解决这类问题的有效算法,将两个启发式算法结合起来,充分发挥各自的优势,就能有效解决网格资源分配的问题。因此,利用混合并行遗传算法来解决网格资源分配是可行的。 相似文献