Transaction links through cities: ‘decision cities’ and ‘service cities’ in outsourcing by leading Brazilian firms

Most world city studies focus on where the provision of advanced producer services takes place, but in this study the location of the service clients are also taken into account. Production-service transactions are identified as links between ‘service city’ and ‘decision city’ (client HQ) and classified as intra-city (where a firms uses local (same city) services) and inter-city which may be domestic or foreign depending on whether the client uses services in or out of the country. Sampling the leading firms in Brazil, 218 transaction links are described and analysed in terms of cities, firm sectors, ownership and market. The analyses are used to inform a rereading of gateway city functions that takes into account the concentration/dispersal nexus in economic globalization. Thus, whereas the dominance of Sao Paulo in the Brazilian economy is confirmed, this is not interpreted as a simple gateway function with this one city ‘articulating’ the national economy into the world economy. A much more complex situation is revealed with by-passing of the gateway also much in evidence. The conclusion is that this shows concentration and dispersion of economic activity happening simultaneously in Brazil.     

Revisiting gateway cities: connecting hubs in global networks to their hinterlands

Gateway cities have received much attention from urban geographers. In spite of outstanding contributions being made, we think that the concept needs to be revisited with regard to regional development implications. Bringing together research on global production networks (GPNs) and world cities, this article shows that gateway cities are critical for development in networks, generating impulses for peripheral locations by engaging them in processes of “strategic coupling.” Yet, gateway cities also concentrate segments of GPNs to the detriment of their hinterlands. We conceptualize gateway cities with the aid of five features: logistics and transport, industrial processing, corporate control, service provision and knowledge generation. Our concept allows for an understanding of cities in global and regional economic processes beyond corporate headquarters, corporate services and governance – that is, beyond the boundaries of existing research. It unsettles traditional understandings of strategic coupling and world cities, filling a lacuna on city–hinterland connections.     

大倾角煤层回采巷道矿压显现规律研究

大倾角煤层回采巷道因处于显著的各向异性环境中而难以维护。本文用离散元法分析了回采巷道的变形破坏机理和形式, 结合现场巷道的围岩松动范围实测, 证实巷道的上帮普遍破坏严重, 是整个巷道破坏的突破点, 应重点防范并采用综合支护进行治理。     

MED路由策略研究

边界网关协议是目前用于广域网中最主要的域间分布式动态路由协议,具有丰富的路由控制机制。MED属性的使用不当通常会引起热土豆路由和MED振荡。介绍热土豆路由和MED振荡,总结分析了避免热土豆路由和MED振荡的方法,并针对广域网和专网分别提出了整体的MED路由策略,最后利用仿真软件加以验证。     

虚拟天文台教育门户建设构想

本文从天文教育的重要性及现状出发，探讨了基于虚拟天文台建设天文教育门户的必要性和可行性；初步设想了结合元数据描述方法，利用虚拟天文台的资源注册和发现机制、元数据记录自动生成机制、元数据集管理机制以及对元数据所标记的资源的查询机制来建设天文教育门户；提供了对我们有借鉴意义的美国教育资源门户网站的运行管理机制；最后对基于虚拟天文台的科学教育的发展前景作了展望。     

气象元数据标准与信息发布技术研究

元数据在数据交换、网络信息资源发现和共享系统建设中具有很重要的作用。文章简论了元数据和元数据标准的最新研究和应用概况, 并重点介绍了WMO核心元数据标准, 以及我国气象数据集元数据格式标准制定的原则、依据和内容。还论述了元数据系统的构建和发布流程; 最后结合气象科学数据共享项目建设规划和分布式共享平台的建设实践, 详细阐述了中国气象科学数据共享服务网元数据发布系统的设计方案和实现方式。     

12322地震速报短信服务平台优化设计与应用

针对震后(特别是大震后)地震行业短信突发应用场景,在12322地震速报短信服务平台的基础上提出了复合优先级策略和多线程处理模式,以解决震后速报业务人员及其他特定人员的优先服务问题和网关速率弹性扩充问题,并设计自助式交换服务框架,方便平台的运行服务工作。最后对平台服务局限性和实际应用中出现的问题进行讨论,总结了平台近年来的运行和服务情况。     

远程服务终端设计

远程服务终端是气象服务的现代化手段,盘锦市气象局立足本地服务,设计了ＷｉｎｄｏｗｓＮＴ网络,与Ｎｏｖｅｌｌ网互联,用户远程终端可访问市局网络,并且设计了Ｗｉｎｄｏｗｓ９５操作系统下的终端软件,提供了卫星云图,天气预报,雨情,水情等防汛抗旱服务的气象,水文信息,软件设计合理,操作简单,功能完备,界面友好。     

波浪涌动机®通讯中继在海上应急协同组网监测中的应用

如何突破海气界面的通讯壁垒,将地球上层大气的卫星遥感观测/光电通讯与地球底层水体中的海底节点观测/水声通讯连接起来,成为在垂向上认识海洋,实现海洋数据观测和实时传输的关键。而波浪涌动机~?由于机动灵活、能够长时间进行海上无人值守,即可作为海洋观测的通信中继,又可作为海上无人移动监测平台进行多台组网协同作业,特别是在构建小卫星应急组网监测的空天一体化建设中,为我国领海内的权益岛礁和海上溢油预警监测提供了一种全新的监测手段。本文将对基于北斗数据链的波浪涌动机~?在我国未来海上应急组网观测建设中的优势特点和应用场景进行详细阐述,供相关学者参考。     

大倾角煤层回采巷道的锚固分析

结合理论分析及工程实践、提出回采巷道支护的四个基本原则。用离散元法对大倾角煤层回采巷道锚杆的作用原理进行分析，说明综合支护的必要性，建立大倾角煤层回采巷道锚杆支护的倾斜组合梁模型，并进行解算，给出锚杆支护的参数的表达式。