宽带印刷天线与双极化微带及波导缝隙天线阵(英文)

In order to meet the urgent needs in wireless com-munications , microwave i mage synthetic aperture ra-dars (SAR) ,and electronic warfare systems ,this dis-sertation studies several types of broadband dual-polar-ized planar antenna elements and arrays ,and proposesa few of novel designs with experi mental verification.The main accomplishments reported in the dissertationare as follows . First ,the phenomena of symmetryin electromagne-tism, both in theory and in applications , are sum-marized.…     

GII发展态势及其对计算机和通讯技术的影响

GII是信息技术发展中一个重要概念 ,文章对GII的由来和含义做出明确的解释 ,并对其发展态势———三网融合进行定性描述 ,最后阐明GII对计算机和通讯的影响以及计算机和通讯技术在GII中作用     

宽带啁啾脉冲放大理论研究

从麦克斯韦方程组出发,推导了宽带啁啾脉冲放大的理论模型方程.该方程和非线性Schr dinger方程有相同的形式,可用分步傅里叶算法对其在数值上求解.     

宽带接入以太网交换机的软件系统

以太网接入是实现宽带接入的主要方法之一.一个完整的宽带接人交换机软件系统应该包括交换机驱动程序、配置界面、应用程序和网络管理等部分.在接入交换设备中采用VLAN技术能够有效的利用带宽和增加数据的安全性.首先说明了接人交换机的体系结构,然后给出了交换机软件系统的整体框架,并着重讨论了宽带交换机软件系统各主要功能模块的设计与实现.     

宽带接入以太网交换机的软件系统(英)

以太网接入是实现宽带接入的主要方法之一。一个完整的宽带接入交换机软件系统应该包括交换机驱动程序、配置界面、应用程序和网络管理等部分。在接入交换设备中采用VLAN技术能够有效的利用带宽和增加数据的安全性。首先说明了接入交换机的体系结构,然后给出了交换机软件系统的整体框架,并着重讨论了宽带交换机软件系统各主要功能模块的设计与实现。     

基于DMT和DWMT宽带接入的理论与实践

论述了目前宽带接入网中的两种调制解调新技术———离散多音频调制(DMT)技术和离散小波多音频调制(DWMT)技术,对二者的原理和关键技术进行了分析,并对其性能、优缺点和使用范围作了比较。同时介绍了宽带接入中调制技术的发展动向。     

Rob Kling Remembered: The Early Beginnings of Social Analysis of Computing in the URBIS Project 1

This article challenges conventional policy development and evaluation approaches that emphasize the instrumental side of technology. There is a growing gap between conventional planning and evaluation approaches for rural broadband ICTs that seek to demonstrate a direct link between investments and results on the one hand, and on the other, with evidence that the contribution of ICTs to rural economic, social and cultural wellbeing is increasingly difficult to demonstrate beyond short-term measurable indicators. The article proposes an alternative paradigm based on sociotechnical systems, stakeholder engagement, an acknowledgment of the multiple dimensions at play, and the growing evidence of unpredictability of ICTs. The article emphasizes a perspective based on “contribution,” not attribution; policymaking that is both adaptive and inclusive of multiple perspectives; methodological testing of emerging evaluation methodologies; and projects as learning experiments. This alternative theoretical and policymaking paradigm is encapsulated in a metaphor based on the management of natural resources where stakeholders track their own indicators of impact by reading how the system responds to a project intervention.     

凸透镜对宽带激光束变换特性的数值研究

基于惠更斯-菲涅耳衍射积分和透镜的相位变换性质,得到了宽带激光束通过凸透镜的传播算法,并用数值方法研究了它的变换特性。     

移动宽带网条件下的若干移动教育研究课题

通过实例,探讨了我国移动宽带网的发展趋势,提出要重视移动宽带网下的教育应用与研究。提出了远程手把手教学、移动情景教学、远程协作学习、新型家教支持平台等四种移动宽带网条件下的应用情景。建议从移动教育需求识别、具体的移动教育应用开发、移动教育评价方法以及移动教育应用生成工具等方面开展移动教育研究。