一种P波段数字阵列模块的设计

收发全数字阵列雷达体制,其核心内涵是接收和发射波束均以数字方式来实现,实现其功能的硬件基础是高度集成化的数字阵列模块(Digital Array Module,以下简称DAM)。本文介绍了一种P波段数字阵列模块的设计,该模块包含独立可控的多个通道,易于实现收发数字波束形成。     

TD-SCDMA系统智能天线波束形成算法的研究

TD-SCDMA系统基站端的智能天线通过波束形成能够显著减小多址干扰,改善通信质量.提出了一种加入扩频序列的协方差矩阵求逆最小二乘恒模(SMI-LSCMA)波束形成算法,该算法在SMI-LSCMA基础上利用特定用户信号的扩频序列信息来锁定该用户接收信号,这样可以使权值向量更新算法更快收敛.经过仿真验证,该算法具有较好的...     

全金属定向宽波束L波段干扰机天线阵列设计

为了提升干扰机天线的功率容量、工作带宽和方位辐射覆盖角度，分析归纳了地面设备对空中目标的卫星导航干扰天线设计需求，提出采用顶端加载折叠、加载金属背板的单极子天线作为阵元，设计了1×4线形排列的天线阵列。采用HFSS有限元仿真分析该天线阵列的性能指标，通过观察S参数中S₁₁随天线各调谐参数的变化，进行优化设计分析。结果表明：天线的输入参数对于结构参数变化均会产生一定的影响，但大多数参数的变化对整个带宽的影响并不是很大，而天线距离底板较近则会产生新的频点；提出的天线阵列经过优化后，方位角宽度为158°,俯仰角宽度为26°,最大增益达到9.4 dB,能够实现宽频段、宽角度的定向集中辐射。所设计的全金属宽波束L波段干扰机天线阵列具备结构简单、小型化的特点，十分适合地面卫星导航干扰机天线应用，可为低慢小无人机的一体化干扰天线设计提供借鉴。     

多波束成像技术在ROV上的应用

水下能见度低下为海洋工程项目中常见的水文状况,ROV无法通过其摄像头直接对水下结构物进行清晰的观察监控,导致其无法高效、安全的开展水下作业。在此时,多波束成像技术的应用则成为ROV顺利完成水下工程作业的一把利器。文章主要介绍了多波束成像技术在ROV上的应用。     

水陆一体化地形测量技术的集成与应用

智慧化水利系统的应用和研发已经进入到高速、高质量发展的时期，为实现智慧水利平台感知方面的需求，文章基于机载激光雷达和无人船多波束测深系统集成应用技术，总结并实践了1种生产水陆一体化三维地形数据的解决方法。结果表明该技术可行并具备较高精度，对智慧水利工程平台的搭建具有积极意义。     

网络基础设施建设对城市绿色创新的影响研究——基于“宽带中国”战略试点的准自然实验

绿色创新是推动我国经济高质量发展的必然选择，本文基于2010～2020年中国283个城市面板数据，视“宽带中国”战略试点为一项准自然实验，运用渐进双重差分模型实证分析网络基础设施建设对城市绿色创新的影响及作用机制。研究发现：(1)“宽带中国”战略试点能促进城市绿色创新“增量提质”,经过多种稳健性检验后，这一结论依旧成立；(2)“宽带中国”战略试点通过强化政府科教投入、提升人才集聚水平和推动数字金融发展三条路径有效提升城市绿色创新的“量”与“质”;(3)“宽带中国”战略试点对城市绿色创新的提升作用存在大中小规模城市异质性。本文研究结论为加强“宽带中国”战略推动经济绿色发展提供了经验启示。     

近场声全息技术在电机轴肋板故障检测中的应用

机械设备的安装环境随需求的变化而变化。为了实现电机轴肋板在各种工况下的故障检测,通过采集电机工作时肋板的振动信息,采用图像处理的方法,将故障下的特征向量与标准正常状态下的特征向量对比后进行分类,从而辨识出故障的类别。通过模拟仿真和实验两种方式对声成像方法进行验证,证明了其正确性和普遍适应性。声成像检测方法,不仅解决了检测机械设备的传感器在某些工作环境中安装不便的问题,而且进一步提高了故障检测的准确性。     

数字奥运耀北京--2004年中国国际广播电视信息网络展览会(CCBN)亮点展示

由国家广播电影电视总局主办的2004年中国国际广播电视信息网络展览会(CCBN)于2004年3月23-25日在北京中国国际展览中心举行。 2004年的CCBN不仅是全球排名首位的宽带网络与数字电视展览会,而且是亚太地区规模最大的IT类展会。“数字奥运展区”是本届CCBN的一大亮点。该展区是与第29届奥林匹克运动会科技委员会联合主办的。虽然离奥运会还有4年时间,但有关数字奥运的各项创新工程都正在有序地进行着。此     

正交多极子阵列声波测井资料在ZH油田的应用

ZH油田沙三段深层砂砾岩储层以岩性复杂、低孔低渗为主要特点,在开发过程中需要进行压裂施工,本文利用正交多极子阵列声波测井（X M AC-Ⅱ）资料分析得到了地层的横波各向异性及方位,反映地层最大主应力方向的横波各向异性方位为井网的部署提供了依据;通过压裂前后的各向异性对比分析对压裂高度进行了检测。     

人民币升值对个人和家庭影响几何

7月21日，中国人民银行宣布，新的人民币汇率形成机制启动，人民币汇率不再盯住单一美元，而是按照我国对外经济发展的实际情况，选择若干种主要货币，赋予相应的权重，组成一个货币篮子。同时，根据国内外经济金融形势，以市场供求为基础，参考一篮子货币计算人民币多边汇率指数的变化，对人民币汇率进行管理和调节，维护人民币汇率在合理均衡水平上的基本稳定。参考一篮子的做法表明，外币之间的汇率变化会影响人民币汇率，但参考一篮子不等于盯住一篮子货币，它还需要将市场供求关系作为另一重要依据，据此形成有管理的浮动汇率。     

基于数字签名和数字水印技术的电子签章算法研究

将数字签名技术、数字水印技术和时间戳技术相结合提出了一种电子签章的实现算法。该算法在数字签名中添加时间戳信息,进一步提高了签章的安全性和抗攻击性。在签章算法中设计了一个基于小波分解信号的局部极大值的数字水印嵌入算法,可以将签名信息作为水印嵌入到签章图片中,增强了签章信息的隐蔽性。经过仿真实验,该方案能够较好地完成电子商务交易中的合同签章应用,实现身份认证和保证合同文本的完整性和不可篡改性。     

Implementing policy on next-generation broadband networks and implications for equity of access to high speed broadband: A case study of Australia's NBN

Next generation telecommunications infrastructure is expanding and supporting rapid growth of broadband technologies and a digital economy. In this context, digital information and communications technologies (ICTs) are of increasing importance as a means for people to gain access to health or social services, employment opportunities, information and social networks. In this article we draw on our recent case study research to examine the policy (and politics) shaping implementation of Australia's National Broadband Network (NBN) and its likely effects on equity of access to high speed broadband (HSB) services. We monitored NBN policy and implementation from 2015 to 2018 through policy documents, reports, and media. To assess likely effects of NBN policy on implementation and subsequently on equity of access to HSB we: a) applied a framework defining four elements of equity of access; and b) analysed stakeholder views drawn from media articles and 22 interviews with experts on NBN policy including politicians, government staff, and industry representatives. We found that equity considerations competed with political and commercial imperatives during the rollout of the NBN. This resulted in positive and negative consequences for equity of access to HSB, with a change in policy and implementation in 2013 bringing greater risks to equity of access. The case study provides a framework for considering equity in the implementation of next generation telecommunications infrastructure and highlights the importance of considering equity in the evaluation of telecommunications infrastructure.     

Private participation in government-led backbone network projects: Lessons from three Latin American experiments

This study presents an ex post comparative assessment of the relative performance of three Latin American broadband network emblematic projects implemented through public-private projects (PPP). Results show that the relative performance of these projects is extremely sensitive to differences in contractual design and regulatory approaches applied in each case. The detailed examination and comparative analysis of these experiences allowed us to extract important lessons in terms of design and implementation of PPP in telecommunications sector. In particular, our analysis finds that imperfect financing and demand risk allocations in projects can jeopardize their operational and financial sustainability. As well, the examination of these experiences allows us to conclude that in markets characterized by continuous economic and technological transformations, vertical separation restrictions imposed for reducing the risk of increasing market power and concentration may not be justified. As well, analysis shows that in such evolving contexts, a more flexible and adaptable regulatory approach is recommendable. Finally, our analysis reveals the role of complementary policies in the context of the implementation of countries’ digital strategies, as a means that contribute to ensure the accomplishment of broadband accessibility national targets.     

基于定向天线无线自组网的快速随机邻居发现算法

为了减少无线自组网的组网所需时间,提升随机发现算法邻居发现的概率,提出了一种基于定向天线的随机邻居发现算法.根据相控阵天线能够自由切换宽波束和窄波束的特点,发挥宽波束搜索能力强、窄波束传输能力强的优势,使用宽波束和窄波束来进行邻居发现,并结合碰撞重传机制和邻居节点辅助发现机制,对碰撞重传的最优竞争窗口值进行了计算.仿真...     

Spatial data constraints: Implications for measuring broadband

The accurate determination of where broadband telecommunication services are available in the United States continues to be a significant challenge. Existing data regarding broadband provision, such as that provided by the Federal Communication Commission (FCC) simply designate ZIP codes with at least one high-speed Internet subscriber. As ZIP code areas vary greatly in size and shape, the lack of geographic specificity as to exactly where broadband is available, particularly within ZIP code areas, confounds communications policymaking. Further, there are a number of additional geographic nuances concerning broadband availability that also inhibit empirical examination and policy generation, including the spatial limitations of digital subscriber line services. The purpose of this paper is to briefly review the issues concerning broadband measurement in the United States and provide an empirical analysis of several spatial data constraints that must be accounted for when interpreting and constructing public telecommunications policy.     

Demand-side broadband policy in the context of digital transformation: An examination of SME digital advisory policies in Wales

Increasing attention has been paid to the potential for demand-side policies to stimulate use of broadband networks. Such policies form part of the increasing digitalisation of the economy and wider society. This is an area where governments are also facing challenges in their efforts to maximise the efficiency and effectiveness of their policies. The paper sheds light on the impact that the transition towards digital has had on demand-side policies supporting the adoption of broadband and digital technologies by SMEs, and draws out the implications for policy, using a case study of Wales in the UK over a ten-year period. It shows that digitalisation has seen policy mechanisms and messages evolving as policy makers have created a more integrated and multi-channel approach to the delivery of advisory support to SMEs, but that the emergence of multiple types of actors (large digital platform businesses) and ongoing digitalisation are adding complexity to policies and their interaction with other forms of public and private business support.     

基于决策融合的多卫星通信系统态势分析技术

为了解决高轨宽带、高轨移动、低轨星座卫星通信系统融合使用时，运行态势不全面、不精确等问题，设计了基于决策融合的多卫星通信系统态势分析技术。首先，借鉴数字孪生理论，建立板卡级、设备级、节点级、网络级、应用级5个层级体系化数字空间模型。其次，提取数据特征，得到高质量数据样本。最后，通过决策融合分析方法，对数据样本运用多种算法进行初步分析，再将不同算法的分析结果进行融合得出最终结果。结果表明，基于决策融合分析，能够对真实多卫星通信系统的不同指标主题得出较好的分析结果。因此，决策融合得到的分析结果可以帮助卫星通信系统运维人员更好地优化多卫星通信系统的运行状态。     

Emerging issues in white space regulation

The secondary use of vacant television channels (TV white spaces) and the reallocation of the digital dividend to provide wireless broadband services are in the final stages of implementation in some countries. Originally seen as a once in a generation opportunity to better allocate UHF spectrum, further digital dividends are now underway as regulators and industry strive to meet exponential increases in demand for mobile data services. Concurrent developments suggest that TV white spaces may be rapidly exploited by global networks with billions of supported devices. The potential for sub-optimal outcomes is identified if the prospect of further digital dividends is not taken into account as technical and regulatory arrangements are put in place to allow productive use of TV white spaces. The importance of considering the potential interaction between further digital dividends and the use of TV white spaces is discussed and technical and regulatory approaches to support optimal outcomes are identified.     

An econometric approach for evaluating the linkages between broadband and knowledge intensive firms

In addition to highlighting improvements in the availability and speed of broadband as a national priority, the National Broadband Plan also includes several recommendations for improving access and use of broadband by small businesses. The plan also recommends economic development officials include broadband in their local development strategies. While these are certainly import goals, more research is needed to evaluate how broadband impacts the regional business environment, and regional capacity to retain and attract businesses in particular industries. In order to further our understanding about the linkages between broadband and businesses, and the ability of places to retain and attract businesses in particular industries, this study will develop and estimate econometric models to better understand the linkages between broadband and firms in the knowledge intensive sector. Specifically, 54 metropolitan area specific models will be developed to examine regional variations in the linkages between broadband and firms in the knowledge intensive sector in 2004. Model results highlight the importance of broadband to knowledge firms in all but five metropolitan areas across the U.S. They also reveal variations in the impact of broadband on knowledge firm presence related to metropolitan area size and industrial legacy.     

Unbundling and infrastructure competition for broadband adoption: Implications for NGA regulation

The common idea of open access policy is that it refers to the sharing of particular elements, such as wholesale access networks, backhaul, under-sea cable and internet exchange points in fixed and mobile networks. In broadband networks, the use of open access policy usually refers to the infrastructure parts, which are considered a bottleneck. Many regulators have generally focused open access policy on fixed broadband networks, especially digital subscriber line (DSL) technology, in the last decade. Local loop unbundling (LLU) regulation is one of the main strategies for the regulator to open access to an incumbent’s bottleneck network in order to soften its monopoly power and encourage competition in the DSL broadband market. The OECD countries have different strategies regarding unbundling local loop and infrastructure competition, as the characteristics and infrastructure networks of countries vary. There are currently more choices of next generation network (NGN) technologies to develop. While local loop unbundling may not be applied fully to NGN development (the cost is not sunk, more technologies are available to implement, incentive of investment by operator), it can indicate benefits and drawbacks of open access policy in the past decade that can be adapted to NGN.The empirical results of this study show that during 2002–2008, LLU regulation was one of the strategies used to increase broadband adoption in countries that had difficulty encouraging infrastructure competition. Unbundling regulation can therefore be implemented carefully and differently in each country that has inefficiency that is harmful to consumers in its market from a monopoly incumbent. Infrastructure competition, on the other hand, is introduced as another strategy to increase broadband adoption. The empirical results of this study indicate that infrastructure competition can be used as a strategy when there are already enough infrastructures in the area or country. These results support the idea of using open access and infrastructure competition policy depending on the existing competition of broadband infrastructure in each country.