一种基于无线电环境地图的路由优化机制

设计认知无线网络路由算法时，需要兼顾主用户保护与路由性能两个方面。为了提高认知无线网络中次用户之间路由的端到端性能，提出了基于无线电环境地图的路由优化机制，该机制中无线电环境地图能够为次用户提供主用户保护有关的无线电环境数据。首先，无线电环境地图根据次用户的数据请求将各授权频段的可用概率与功率控制相关信息反馈到该次用户；其次，次用户可以计算出与上一跳次用户之间的链路稳定性以及传输时延；最后，目的次用户通过计算每条路由的端到端吞吐量的期望值，然后选取期望值最大的一条路由。仿真结果表明，该路由机制在平均分组投递率、平均端到端吞吐量、平均端到端时延方面均优于对比路由算法。     

Heritage tours and trails on foot in Hong Kong: towards a typology that crosses the tourist-local divide

Hong Kong's retrocession to Chinese sovereignty in 1997 initiated intense interest in cultural heritage on the part of divergently positioned actors, including activists, the state, and entrepreneurs. Heritage walking tours have proliferated, providing a wide range of examples suitable for comparison. This article develops a typology of heritage trails and tours in order to consider how they are situated in relation to the tourist economy and local context. Theoretically it builds on insights in new walking studies and debates in tourism and heritage studies on the ‘tourist-local divide.’ The article relies on qualitative research conducted in Hong Kong, including participant observation and interviews, and a review of various secondary sources. The typology distinguishes between government-generated, market-oriented, and community-based heritage walks. Three key issues are discussed: the ways that tours and trails develop, how they engage with official and unofficial heritage places, and how they reference urban issues including state-led urban renewal and redevelopment. The article argues that, while walking in general is a format that is suited to both tourist and local visitor engagement, some trails and tours reinforce dominant narratives of heritage and urban space, while others challenge them.     

Demystifying residents' walking behaviors: Active transport in South East Queensland,Australia

This study investigates the correlates of a resident's walking behaviors and aims to shed light on mechanisms through which walking may be encouraged. The results of this investigation paint a complex and nuanced picture of the residents’ walking behaviors in South East Queensland, Australia. The results suggest that sociodemographic characteristics separately may contribute greatly to whether or not one engages in walking behaviors. Further, cumulatively these differences might be greater for some groups of residents compared to others. One of the most prominent findings of the study is that the purpose, the characteristics of the origin, and the characteristics of the destination of a trip tended to be similar in the heterogeneity they exhibit over the distribution of time spent walking. For example, pick something up, undertake work, or engage in personal business, move to or from a workplace, shop, or social place are activities that tend to be associated with walking as a main mode of transport and a higher number of walking episodes. However, these trips tended to be short.     

Cost savings from trajectory deviations in the European air space

Air transport deregulation has lead to an increase of air traffic, together with a reduction of air fares. Air fare reduction has narrowed operational margins of airlines, bringing financial and employment instability. This has brought airlines to pay increasing attention to flying costs reduction. Two important components of flying costs airlines can try to cut modifying the planned flight are en route charges and operational costs. We rely on Demand Data Repository (DDR2) data to calculate deviations from planned flight trajectories to analyse the extent to what airlines try to cut operational costs making shorter flights than planned if possible, and cut en route charges providing a planned flight with lower en route charges than the planned flight. Our findings show that there is no generalised strategy among airlines to reduce en-route charges asking for deviations of the planned route. On the other hand, airlines are achieving savings of operational costs regularly. Higher savings per nautical mile are obtained in night flights, with longer planned distance and operated by low cost carriers.     

基于两阶段法的多车型卷烟配送路径优化研究

在烟草商业企业中,物流是其重要的环节,是连接客户与烟草企业间的纽带,其卷烟配送线路设计的合理与否直接影响到卷烟的配送效率和配送成本,就如何合理的规划线路成为卷烟配送的关键问题。文章以Q烟草公司为例,运用先分组后路线的两阶段法对问题进行求解,先利用K-means聚类算法对区域进行划分,再考虑工作量均衡的条件下引入遗传算法对区域进一步调整,最后利用混合遗传算法对各配送区域进行线路优化,通过实例从线路数、车辆数、空载率、配送里程及总成本等指标上可以看出两阶段法的配送效果更优。     

提升我国服务业发展水平的跨位思考

提升我国服务业发展水平,分析我国服务业的发展现状。服务业的产值与吸收就业能力呈现明显增长趋势,但同国际发达国家服务业的发展情况相比,差距明显。研究表明,我国服务业具有向资本密集型、知识密集型现代服务业发展的趋势,并逐渐在经济活动中取得主导地位。     

论"旅游目的地"与"旅游过境地"

旅游地的空间竞争与合作是当前学术界颇为关注的一个热点问题.处在同一旅游线路①上的不同旅游地之间产业和产品的空间竞争与合作是区域旅游竞争与合作的典型代表,较少有学者进行研究.本文在回顾以往研究成果的基础上,分析了旅游目的地与旅游过境地在竞争与合作中旅游产业定位和空间布局等重大问题对两地在旅游开发、投资等方面的影响.     

中国企业对外直接投资的区位选择和路径安排

随着中国综合国力增强和国内企业参与国际经济分工的深化,目前中国企业具有对外直接投资的基本条件和现实需要,近年来关于中国企业如何实施“走出去”战略已成为学术界和企业界共同关注的热点问题之一。文章综合发达国家和发展中国家的对外直接投资理论,结合我国企业的具体实际,对我国企业在实施“走出去”战略过程中的东道国区位选择和路径安排进行研究。     

纳米氧化锌制备技术与工业生产

介绍了国内外纳米氧化锌制备技术的研究进展.通过对国内外制备技术和生产现状的比较,提出以尿素为沉淀剂,以硝酸锌为含锌原料,采用均匀沉淀法制备纳米ZnO的工艺路线,研究了相关的工艺过程及反应条件、反应产物的过滤洗涤和纳米ZnO的煅烧,对存在的问题和今后的研究方向进行了讨论.     

论内审价值实现途径

服务的内向性是内部审计的基本特点,建立新型审计管理体制,加强法制建设,提高法治水平及更新内部审计思维观念,处理好内审与外审的关系,监督与服务的关系,不断提高审计人员素质是实现内审价值的有效途径。