OTT时代的通信网络运营商转型

近年来,得益于智能手机的迅速普及和移动互联网的火热发展,OTT业务得到飞速发展,并最终对运营商的核心业务(话音业务和短信业务)产生了严重威胁,通信网络运营商(以下简称运营商)"被管道化"的趋势越来越明显。进入OTT时代,运营商急需转型。文章从运营商面临的威胁、OTT企业与运营商的区别以及OTT时代运营商转型的方向等问题进行讨论,揭示在OTT时代,运营商转型的必要性及其深远意义。     

辽宁高法横跨双楼通讯塔整体液压提升施工技术

本文介绍了采用北京中建建筑科学技术研究院的SQD型松卡式千斤顶及配套设备和相关技术 ,在国内首次将在建的辽宁高法工程的横跨双楼通讯塔 ,于 2 0 0 0年 1 1月 1 7日平稳、安全、顺利地整体同步提升到 71 2m的高度就位。其施工安装具有高、大、精、险的特点。     

A novel approach to evaluate the equivalent dynamic stiffness of guy clusters in telecommunication masts under ground excitation

Telecommunication structures are essential components of communication and post-disaster networks and critically important facilities require reliable earthquake-resistant design procedures in seismically active regions. Calculation of the nonlinear seismic response of tall guyed masts using detailed time-step finite element methods is far more complex than linear response spectrum analysis that is routinely used in structural engineering practice. It is recognized that detailed computational procedures are not always necessary, in particular when the goal of the analysis is to provide a global earthquake-resistant design check on a regular structure with predictable response: this is when rational simplified methods are called upon to calculate the seismic demand. However, up until now, no such method exists for tall guyed masts that can account for the dynamic cable-mast interactions which dominate seismic effects in these structures. In the study reported here, the writers explore the dynamic behavior of guy cables under harmonic and seismic support ground motion through detailed computational modeling and propose a novel frequency-dependent method to evaluate the equivalent dynamic stiffness of guy clusters. This development will contribute efficiently towards a new robust rational model of general applicability for simplified seismic analysis of tall guyed telecommunication masts.Detailed numerical simulations involving 57 guy cables from eight existing towers with varying heights of 150-607 m were used in the study. A mathematical procedure was developed to replace the nonlinear time-variant cable stiffness with an equivalent linear frequency-dependent spring/mass system, based on the response spectrum of individual guy cables and the frequency content of the seismic excitation. Comparison of the main response indicators of these equivalent models and the detailed nonlinear finite element analysis results confirmed the reasonable and consistent engineering accuracy of the proposed simplified method with considerable savings in analysis effort.     

A study on cover plate design and monopole strengthening application

To ensure that the cover plate will act with the existing member as a unit for structural strengthening, mechanic bases of cover plate design that need to be understood include the relationship between the shear stress flow, which determines the intermediate connections, and the bending stress of the reinforcing plate, which controls the end connection, the tension/compression strength of cover plate, the strength adequacy of end termination, the fatigue strength of end connection, etc. However, not much analytical study on these mechanic bases of cover plate design has been seen in either text books or technical articles. Inadequate comprehension of these mechanic bases of cover plate design is causing controversial interpretation of the design code specifications during the engineering practices, and some questionable designs have been observed. In addition to in-depth discussion of miscellaneous issues of cover plate design, this work presents a study of the mechanic bases of cover plate for structural strengthening. The cover plate reinforcement design for monopole is different from those for beams and stringers due to its distinctive structural and loading properties. Telecommunication industry standard TIA-222 does not address these issues so far. This paper reviews and discusses the most critical issues of cover plate design of beams and stringers, and addresses the monopole cover plate reinforcement design in detail. Rigorous design recommendations are proposed and discussed thoroughly based on the analytical investigation.     

闲态双音频警铃信号的精确检测

介绍了一种精确检测闲态双音频警铃信号的方法，给出了具体电路和应用实例。该电路不仅检测精确，而且具有很大的灵活性，对不同标准的音频信号的检测都具有一定的参考价值。