泛在知识环境下图书馆多元化信息服务模式

文章首先介绍泛在知识环境、泛在图书馆的内涵，接着简要论述了泛在图书馆特点，最后详细探讨了泛在知识环境下图书馆多元化的信息服务模式。     

CDMA20001x EVDO网络MM4+协议监测的实现

首先对CDMA2000 1x EVDO网络中的增值业务进行了介绍,然后针对增值业务中不同网络间的多媒体消息互通问题,对关键接口MM4接口中的MM4+协议进行了介绍与监测.最后,借助哈希索引算法提出了一种新的CDR存储方案,并通过现网数据测试,验证了相关方法的可行性.     

对消防部队在地铁环境下应急通信保障的探讨

随着我国城市现代化的进展加快,地铁交通已经存在于各大城市当中,对消防部队而言在抢险救灾中现代化的通信技术必不可少,综合通信保障技术能为消防部队赢得时间、及时发现险情并及时联络各相关应急部门,有效提高工作效益。本文笔者就消防部队在地铁环境下,常规使用的无线通信信号受到太大衰减后,抢险救灾中如何进行综合通信保障,并重点就同轴电缆通信进行了一些有益肤浅的探讨,和同仁共商榷。     

具有剩余寿命且排队空间有限的M/G/1排队模型非负解的存在唯一性

研究了以剩余寿命作为增补变量,排队空间有限的M/G/1排队模型,利用泛函分析中线性算子半群的积分半群理论讨论了该模型的瞬态解的存在唯一性问题。     

Deterministic Time-Varying Packet Fair Queueing for Integrated Services Networks

In integrated services networks, the provision of Quality of Service (QoS) guarantees depends critically upon the scheduling algorithm employed at the network layer. In this work we review fundamental results on scheduling, and we focus on Packet Fair Queueing (PFQ) algorithms, which have been proposed for QoS wireline-wireless networking. The basic notion in PFQ is that the bandwidth allocated to a session is proportional to a positive weight _i . Because of the fixed weight assignment, the inherent in PFQ delay-bandwidth coupling imposes limitations on the range of QoS that can be supported. We develop PFQ with deterministic time-varying weight assignments, and we propose a low-overhead algorithm capable of supporting arbitrary piecewise linear service curves which achieve delay-bandwidth decoupling. Unlike existing service-curve based algorithms, our time-varying PFQ scheme does not exhibit the punishment phenomenon, and allows sessions to exploit the extra bandwidth in under-loaded networks.     

A Communication Multiplexer Problem: Two Alternating Queues with Dependent Randomly-Timed Gated Regime

Two random traffic streams are competing for the service time of a single server (multiplexer). The streams form two queues, primary (queue 1) and secondary (queue 0). The primary queue is served exhaustively, after which the server switches over to queue 0. The duration of time the server resides in the secondary queue is determined by the dynamic evolution in queue 1. If there is an arrival to queue 1 while the server is still working in queue 0, the latter is immediately gated, and the server completes service there only to the gated jobs, upon which it switches back to the primary queue. We formulate this system as a two-queue polling model with a single alternating server and with randomly-timed gated (RTG) service discipline in queue 0, where the timer there depends on the arrival stream to the primary queue. We derive Laplace–Stieltjes transforms and generating functions for various key variables and calculate numerous performance measures such as mean queue sizes at polling instants and at an arbitrary moment, mean busy period duration and mean cycle time length, expected number of messages transmitted during a busy period and mean waiting times. Finally, we present graphs of numerical results comparing the mean waiting times in the two queues as functions of the relative loads, showing the effect of the RTG regime.     

A Polynomial Time Approximation Scheme for the Grade of Service Steiner Minimum Tree Problem

In this paper, we present the design of a Polynomial Time Approximation Scheme (PTAS) for the Grade of Service Steiner Minimum Tree (GOSST) problem, which is known to be NP-Complete. Previous research has focused on geometric analyses and different approximation algorithms have been designed. We propose a PTAS that provides a polynomial time, near-optimal solution with performance ratio 1+. The GOSST problem has some important applications. In network design, a fundamental issue for the physical construction of a network structure is the interconnection of many communication sites with the best choice of the connecting lines and the best allocation of the transmission capacities over these lines. Good solutions should provide paths with enough communication capacities between any two sites, with the least network construction costs. Also, the GOSST problem has applications in transportation, for road constructions and some potential uses in CAD in terms of interconnecting the elements on a plane to provide enough flux between any two elements.     

Efficient medium arbitration of FSAN‐compliant GPONs

The steadily rising demand for multimedia and data services, the falling cost and omnipresence of Ethernet and the maturity of passive optical networks (PON) technology, promise to radically change the landscape in the local loop. The heart of a gigabit PON system (recently standardized by FSAN/ITU) is the medium access controller (MAC), which arbitrates access to the upstream link among users with fluctuating traffic demands and effects the multiplexing and concentration policy. At the same time, it has to safeguard the service quality and enforce the parameters agreed in the service level agreements (SLAs) between the users and the service provider. In this paper, a MAC protocol designed to serve any mix of services according to their quality of service (QoS) needs, employing four priority levels along with a high number of logically separate data queues is presented. The architecture and implementation in hardware of a MAC algorithm capable of allocating bandwidth down to a resolution of a byte with QoS differentiation is the focus of this paper. It employs the bandwidth arbitration tools of the FSAN/ITU G.984.3 standard and maps SLA parameters to GPON service parameters to create an efficient, fair and flexible residential access system. Copyright © 2005 John Wiley & Sons, Ltd.     

优化数据库的设计方法

随着软件系统应用复杂度的增加，数据库性能的优化日益显现出了它的重要性。本文结合实际案例，从数据库设计的角度出发，通过提出影响数据库性能的SQL，分析它们的成因，指出应用系统数据库设计改进方法，以提高应用系统的性能，同时也便于数据库及应用设计人员合理进行设计，提高数据库系统性能。     

Research on the measurement of the price change of telecom services in China

1 Introduction The telecom service price (TSP) is the focus of benefit of distribution between telecom enterprises and customers. With the opening of the telecom service market and the increasing competition, the changes in the TSP became more frequent, e…