数控机床回参考点及其故障诊断

根据数控系统的设计原理,数控机床每次开机后都必须先回参考点,才能进行相应的操作。通过介绍西门子802S数控机床回参考点的作用及其工作原理,举例说明数控机床在回参考点的过程中出现的故障报警,提出了排除故障的步骤和措施。     

IEEE1588协议在NT6000分散控制系统中的应用

分析目前时间同步技术现状,阐述IEEE1588时间同步原理,为了满足分散控制系统对时钟高精度的要求,给出IEEE1588在分散控制系统中的应用方案,详细介绍系统中对时的具体实施方法。实践证明,该对时方案精度高、成本低。     

无线局域网和蓝牙在ISM频段共存性研究

在短距离的无线数据传输中，IEEE802.11b和蓝牙技术是两种最受关注的无线应用技术、由于两者工作于同一频段，必然会产生相互干扰．本文依据以下参数：802.11b的数据传输速率和数据包长、蓝牙微微网数目、蓝牙微微网利用率、蓝牙802．11b设备间的距离，给出了存在蓝牙及高斯白噪声干扰情况下，802．11b的吞吐量．并阐述了两者共存性的解决途径。     

On service differentiation in mobile Ad Hoc networks

A network model is proposed to support service differentiation for mobile Ad Hoc networks by combining a fully distributed admission control approach and the DIFS based differentiation mechanism of IEEE802.11. It can provide different kinds of QoS (Quality of Service) for various applications. Admission controllers determine a committed bandwidth based on the reserved bandwidth of flows and the source utilization of networks. Packets are marked when entering into networks by markers according to the committed rate. By the mark in the packet header, intermediate nodes handle the Received packets in different manners to provide applications with the QoS corresponding to the pre-negotiated profile.Extensive simulation experiments showed that the proposed mechanism can provide QoS guarantee to assured service traffic and increase the channel utilization of networks.     

宽带综合业务智能小区

随着办公自动化的深入,进行微机互联的单位越来越多,家庭上网为在家办公、休闲、娱乐创造更好的条件。如何组建一个经济、实用的智能小区局域网成为一热门话题。本文为你提供一种较为经济、实用、易于维护的组网方式。     

SUI无线信道仿真

本文在深入了解IEEE802.16协议中规定SC-FDE技术使用的主要信道(2-11GHz频段固定无线信道)及其数学模型的基础上,根据课题研究的需要,选择SUI信道模型进行了仿真。仿真结果表明仿真方法及流程是正确的。     

A wireless solution for greenhouse monitoring and control system based on ZigBee technology

With the rapid development of wireless technologies, it is possible for Chinese greenhouses to be equipped with wireless sensor networks due to their low-cost, simplicity and mobility. In the current study, we compared the advantages of ZigBee with other two similar wireless networking protocols, Wi-Fi and Bluetooth, and proposed a wireless solution for green- house monitoring and control system based on ZigBee technology. As an explorative application of ZigBee technology in Chinese greenhouse, it may promote Chinese protected agriculture.     

Performance analysis of IEEE 802.11 DCF networks

This paper presents an analytical saturation throughput model of IEEE 802.11DCF （distributed coordination function） with basic access in ad hoc mode. The model takes into account freezing of the backofftimer when a station senses busy channel. It is shown that taking into account this feature of DCF is important in modeling saturation throughput by yielding more accurate and realistic results than models known from literature. The proposed analytical model also takes into account the effect of transmission errors. All essential features of the proposed analytical approach are illustrated with numerical results. The presen- tation of the model is proceeded by an overview of approaches to IEEE 802.11 network performance evaluation presented in the literature.     

基于TMI1451.2-SC平台网络化智能传感器的应用研究

介绍最新的总线标准IEEE1451,该标准定义了网络适配处理器(NCAP)和智能传感器接口模型(STIM),为研究解决通用智能传感器的设计开发问题提供了一个可以共同遵循的基础,使得智能传感器的即插即用成为可能;文中根据IEEE1451.2模块TMI1451.2-SC平台,结合实际监控领域的要求,设计和配置了网络化智能传感器的电子数据表单(TEDS)。     

E-learning标准面面观

对当今主流的e—learning规范与标准进行较全面地介绍,并对其中最具有影响力的几种进行详实的论述与深入的分析。