中国极地考察站广域网通信建设与服务现状及展望          下载免费PDF全文

单学武江天乐  汪大立吕渊陆大海  李英旭 《极地研究》2017,29(1):142-150

通过中国极地考察"十五"能力南极两站卫星通信网络系统项目的建设,我国南极考察站的广域网通信能力和站区网络通信能力已经有了很大提高。系统阐述南极两站的广域网通信现状,内容包括南极两站卫星通信链路的建设情况、考察站计算机网络系统建设情况以及该系统所提供的服务情况,涉及卫星通信、局域网以及VOIP等技术;对未来几年极地考察通信中可能会采用的通信技术建设提出建议。  相似文献   

An artificial bee colony-based multi-objective route planning algorithm for use in pedestrian navigation at night     

Zhixiang Fang  Ling Li  Jingwei Zhu  Qingquan Li  Shengwu Xiong 《International journal of geographical information science》2017,31(10):2020-2044

Pedestrian navigation at night should differ from daytime navigation due to the psychological safety needs of pedestrians. For example, pedestrians may prefer better-illuminated walking environments, shorter travel distances, and greater numbers of pedestrian companions. Route selection at night is therefore a multi-objective optimization problem. However, multi-objective optimization problems are commonly solved by combining multiple objectives into a single weighted-sum objective function. This study extends the artificial bee colony (ABC) algorithm by modifying several strategies, including the representation of the solutions, the limited neighborhood search, and the Pareto front approximation method. The extended algorithm can be used to generate an optimal route set for pedestrians at night that considers travel distance, the illumination of the walking environment, and the number of pedestrian companions. We compare the proposed algorithm with the well-known Dijkstra shortest-path algorithm and discuss the stability, diversity, and dynamics of the generated solutions. Experiments within a study area confirm the effectiveness of the improved algorithm. This algorithm can also be applied to solving other multi-objective optimization problems.  相似文献   

Computing a hierarchy favored optimal route in a Voronoi-based road network with multiple levels of detail     

Zhenghua Hu  Guofeng Wang  Jiye Wang  Lingkui Meng 《International journal of geographical information science》2017,31(11):2216-2233

This paper introduces a robust method for computing the optimal route with hierarchy. We convert a planar road network into its Voronoi-based counterpart with multiple levels of detail (LoDs), which is subsequently assigned travel times that are estimated for different times of day using taxicab trajectory data. On the basis of this network structure, we model the path-finding process in travel, as the optimal route with hierarchy is computed in a ‘coarse-to-fine’ manner. In other words, the route is iteratively constructed from roads in a low LoD network to roads in a high LoD network. To confirm the efficiency and effectiveness of our method, comparative experiments were conducted using randomly selected pairs of origins/destinations in Wuhan, China. The results indicate that our travel lengths are on average 12% longer than those computed by the Dijkstra algorithm and 15% shorter than those computed by the hierarchical algorithm (in ArcGIS). Our travel times are on average 29% longer than those computed by the Dijkstra algorithm and 31% shorter than those computed by the hierarchical algorithm (in ArcGIS). Hence, we argue that our method is situated in terms of performance between the Dijkstra algorithm and the hierarchical algorithm (in ArcGIS). Moreover, road usage patterns confirm that our algorithm is cognitively equivalent to the hierarchical algorithm (in ArcGIS) by favoring high-class roads and outperforms the Dijkstra algorithm by avoiding choosing low-class roads. Computationally, our method outperforms the Dijkstra algorithm but is on the same level as the hierarchical algorithm (in ArcGIS) in terms of efficiency. Therefore, it has the potential to be used in real-time routing applications or services.  相似文献   

Climate visuals: A mixed methods investigation of public perceptions of climate images in three countries     

《Global Environmental Change》2016

Imagery plays a central role in climate change communication. But whereas research on the verbal communication of climate change has proliferated, far fewer studies have focused on visual communication. Correspondingly, relatively little is known about how to effectively engage the public using the visual medium. The current research is the first mixed methods, cross-national investigation of public perceptions of climate images, with a focus on photographic climate change imagery. Four structured discussion groups in the UK and Germany (N = 32) and an international survey with an embedded experiment in the UK, Germany and the US (N = 3014) were conducted to examine how different types of climate change imagery were evaluated. The qualitative research pointed to the importance of the perceived authenticity and credibility of the human subjects in climate images, as well as widespread negativity towards images depicting protests and demonstrations. Images of climate ‘solutions’ produced positive emotional responses in the survey and were less polarizing for climate change skeptics, but they were also the least motivating of action. Familiar climate images (such as a polar bear on melting ice) were easily understood in the survey (and evaluated positively as a consequence) but viewed with cynicism in discussion groups. We present a detailed discussion of these and other key findings in this paper and describe a novel application of the data through an online image library for practitioners which accompanies the research (www.climatevisuals.org).  相似文献   

中国北极航线港口界定   总被引：1，自引：0，他引：1  

李振福  曾茜  刘超 《地域研究与开发》2016,(6)

随着北冰洋夏季冰层的逐渐消融,北极航线有望全线通航。北极航线的通航将促进东亚与欧洲、北美地区的贸易往来,从而降低传统航线的地位及作用,为我国战略资源采购提供新的通道;同时也将在一定程度上改变北极航线沿线及其延长线上港口的地位及布局,但不同港口受此影响不尽相同,只有部分港口可能因为北极航线的利用实现地位提升。在假定北极航线全线开通的基础上提出北极航线港口概念,以港口所在城市的进出口贸易总额为基本界定指标,以航程缩短程度、航线密度、港口外贸箱吞吐量和港口油气吞吐能力作为竞争性界定指标进行综合评价,筛选出符合标准的中国北极航线港口,为中国利用北极航线和未来沿海港口布局提供借鉴及参考。  相似文献   

一种林业有害生物外业调查路线的规划方法     

车振磊  武红敢 《测绘科学》2016,41(11):118-123

针对青岛市利用遥感技术辅助指导枯死松木地面调查的新模式,旨在解决外业调查区划和多点路线选择问题。基于DEM数据设计和实现了复杂地形下两调查点之间互相抵达的路径成本算法,在计算中考虑了地形因素的影响。将调查区域内调查点两两之间的路径成本构造成矩阵,并采用蚁群算法求解出一条总成本较小的路径。经实验与实地验证,所提方法能够合理规划出调查线路,有效避开河流、陡坡等自然屏障,科学指导和监督地面调查工作。  相似文献   

实时威胁态势感知的室内火灾疏散路径动态优化方法     

丁雨淋  何小波  朱庆  林珲  胡明远 《测绘学报》2016,45(12):1464-1475

如何在火灾态势迅速演变的复杂室内环境下选择安全有效的疏散路线是正确引导人群疏散、减少人员伤亡的重要保障。传统静态寻径方法难以顾及火灾态势演变过程,导致疏散决策的盲目性和滞后性突出。本文提出了一种实时威胁态势感知的室内火灾疏散路径动态优化方法,充分利用实时接入的火场状态和室内建筑环境状态等火灾威胁态势场信息,动态调整和优化疏散路径。该方法建立了室内火灾实时威胁态势信息在语义空间的统一表示模型,并对多源、多尺度火灾传感器观测数据在语义空间进行统一建模,从实时接入的动态观测数据中提取室内火灾三维威胁态势信息,用于约束疏散路径的动态优化。模拟试验证明,本方法可根据火灾态势演变准确可靠地动态调整疏散路径,从而显著提高应急疏散的精准性。  相似文献   

Personalized travel route recommendation using collaborative filtering based on GPS trajectories   总被引：1，自引：0，他引：1  

Ge Cui  Jun Luo 《International Journal of Digital Earth》2018,11(3):284-307

Travelling is a critical component of daily life. With new technology, personalized travel route recommendations are possible and have become a new research area. A personalized travel route recommendation refers to plan an optimal travel route between two geographical locations, based on the road networks and users’ travel preferences. In this paper, we define users’ travel behaviours from their historical Global Positioning System (GPS) trajectories and propose two personalized travel route recommendation methods – collaborative travel route recommendation (CTRR) and an extended version of CTRR (CTRR+). Both methods consider users’ personal travel preferences based on their historical GPS trajectories. In this paper, we first estimate users’ travel behaviour frequencies by using collaborative filtering technique. A route with the maximum probability of a user’s travel behaviour is then generated based on the naïve Bayes model. The CTRR+ method improves the performances of CTRR by taking into account cold start users and integrating distance with the user travel behaviour probability. This paper also conducts some case studies based on a real GPS trajectory data set from Beijing, China. The experimental results show that the proposed CTRR and CTRR+ methods achieve better results for travel route recommendations compared with the shortest distance path method.  相似文献   

深海无缆海底基盘井口夹持系统的研制与应用          下载免费PDF全文

邓都都  阮海龙  刘广治  刘智键  蔡家品 《探矿工程》2021,48(6):68-73

在深海勘察取样作业时,由于海流作用会引起钻杆摆动或上下运动,这是导致取得样品失真的原因之一。海底基盘可在勘察作业过程中,对钻杆进行夹持稳定,以保障作业的质量,是提高勘察作业水平的核心装备之一。根据海洋石油708船的结构尺寸与勘察作业需求,研制了一套无缆海底基盘。目前该无缆基盘在我国南海及东海海域从事勘察作业服务,累计服务时间超过30个月,有力支撑了我国海洋地质调查工作。本文对该无缆基盘的工作参数及原理、水下液压系统以及通信与控制系统进行了介绍,重点对大容量深水电池的研制进行了分析。该电池能够保证无缆基盘的作业时间达到70 h,提高了勘察作业效率,可为今后相关海洋装备的研发提供基础。  相似文献   

公众为何对气候变化的科学结论信任不充分     

潘野蘅  闫隽  谢宇  贾鹤鹏 《气候变化研究进展》2022,18(1):97-109

通过系统分析世界各国气候传播领域近年来的进展,以解释为何公众对气候变化的科学结论缺乏信任这一复杂问题.文中首先概述了各国公众对气候变化的态度以及影响公众态度的社会、政治与经济因素,再分析了各国媒体对气候变化的报道及其媒体效果,并重点探究了社会心理因素如何影响人们对气候变化的认知与态度.此外国际气候传播研究对我国气候传播...  相似文献