Fundamental aspects of access control for geospatial data

Abstract

In recent years, geographical information systems have been employed in a wide variety of application domains, and as a result many research efforts are being devoted to those upcoming problems. Geospatial data security, especially access control, has attracted increased research interests within the academic community. The tendency towards sharing and interoperability of geospatial data and applications makes it common to acquire and integrate geospatial data from multiple organisations to accomplish a complex task. Meanwhile, many organisations have the requirement for securing access to possessed sensitive or proprietary geospatial data. In this heterogeneous and distributed environment, consistent access control functionality is crucial to promote controlled accessibility. As an extension of general access control mechanisms in the IT domain, the mechanism for geospatial data access control has its own requirements and characteristics of granularity and geospatial logic. In this paper, we address several fundamental aspects concerning the design and implementation of an access control system for geospatial data, including the classification, requirements, authorisation models, storage structures and management approaches for authorisation rules, matching and decision-making algorithms between authorisation rules and access requests, and its policy enforcement mechanisms. This paper also presents a system framework for realising access control functionality for geospatial data, and explain access control procedures in detail.     

空间数据访问集成与分布式空间数据源对象查询

目前,针对空间数据库的访问与处理方法,无法满足分布式环境下异构数据源的服务化存取和面向空间数据源的对象查询处理需求。本文给出了数据网格环境下的分布式空间数据访问与查询的方法和实现,并在服务化查询处理过程中,嵌入符合SQL/MM查询规范的空间拓展函数,实现分布式空间数据对象查询和嵌入查询过程中的空间数据分析处理。在此基础上,给出空间数据对象查询树的构造过程,以及分布式空间查询工作流的执行流程。数据访问与集成策略在空间数据处理上的应用,对异构空间数据源协同处理等,涉及大规模空间数据存取访问的应用需求,有很好的理论和实际应用价值。     

Managing sino-ghanaian fishery relations: A political ecology approach

A global recurring challenge for marine managers and policy makers is the effective management of fisheries conflicts. This study demonstrates the usefulness of a political ecology approach in understanding the complexity of conflict in increasingly internationalized national fisheries. By doing so it aims to provide an alternative approach to the environmental security perspectives, predicated on scarcity narratives, that often underpin policy on fishery conflicts. Using a localised example of industrial Chinese and local artisanal fishermen conflict in Ghana, this paper reveals a complex account of contesting ‘access’ to resources, in material and nonmaterial terms, that moves beyond an ‘absolute scarcity’ driven narrative. The conflict is shown to be one, in part, focussed around spatially fixed areas as well as moral claims of correct ways of fishing that reflect social tensions within the local fishing community. Both aspects show long term motivations to keep resource access, rather than being concerned with in the moment struggles over scarce resources. This work also highlights the existence of cooperation between groups of artisanal fishermen involved in transhipment with Chinese fishermen, revealing the complex nexus of winners and losers produced by environmental, social and political factors. In sum, policy must acknowledge that conflict is rarely produced purely by scarcity, and that broader social and political factors often combine in a variety of forms to produce localised conflict. If these complexities are ignored, fisheries policy runs the risk of unintentionally exacerbating conflicts and disadvantaging those who it aims to help.     

基于DMVPN接入地震行业网络设计

介绍山东省地震行业网络建设中县级地震台网使用的动态多点VPN接入方式,对中心站点和分支站点的配置进行说明,分析DMVPN相较于其他VPN的优势。作为一种经济有效的地震行业网络接入方式,DMVPN具有较强的推广、应用价值。     

Access在基层土地登记管理中的应用

针对基层土地登记管理信息化现状,利用Access数据库管理软件,开发了“土地登记管理系统”,实现了土地登记发证、档案管理、宗地图管理自动化,信息检索自动化,提高了工作效率和工作质量。     

Access,Equity, and Urban Greenways: An Exploratory Investigation

Recurring issues in the social sciences concern the distribution of public facilities such as parks and equity of access to them. Geographers have observed that access has perceptual as well as physical dimensions and that perceptions of difference can affect use of public space. This study explores the nature of greenways as public space and a set of issues related to equity of access to greenway trails in Indianapolis, Indiana. The study uses proximity as a measure of access and simple GIS analyses of census and other data to assess equality of access. Evidence is provided that suggests that minorities and the poor have disproportionate access to trails. It is also shown that populations adjacent to the trails differ and that the populations along particular trails are segregated. Spatial differences in trail populations are associated with historic land use patterns and population movements within the city. The implications of the findings of difference for use of the greenways system are explored. Implications for management of the greenways system—including achievement of the goal of linking neighborhoods—are also discussed.     

新疆矿产开发与产业发展战略构想

新疆矿产的特点是总量丰富，勘查程度低：矿种齐全，丰度不一；分布广泛；地域不均；超大型矿床少，中小型多；共伴生矿多，单矿种少。新疆矿业发展具有资金和市场两头在外的特点。新疆矿业开发与发展应实施“以市场为导向的黑（石油、天然气、煤、铁、蛭石）黄（铜、镍、金）白（盐类、水泥灰岩、膨润土、石棉）优势矿产为重点”的综合开发战略，加强地质矿产勘查基础地位、加快矿业体制改革、加大矿业投入、实施矿业一体化、加大矿业结构调整、实现知识创新和技术跨越、充分利用两种资源和两个市场、加强矿业管理和建立矿业经济特区等。     

Modelling Access with GIS in Urban Systems (MAGUS): capturing the experiences of wheelchair users

Access and mobility are important dimensions of quality of life. For wheelchair users, everyday trips are often fraught with problems, with many barriers imperceptible to the able-bodied, hindering or totally restricting movement. This paper describes a project undertaken with wheelchair users, which has developed, tested and applied a Geographic Information System model. This model acts both as a navigational device for wheelchairs users – enabling them to make informed route choices through urban places – and as a decision support and planning tool for urban planners – making visible the ways in which built environments are often distorted and hostile spaces for wheelchair users.     

省级外网气象大数据服务平台研究与实现

随着社会经济发展，气象大数据已成为国家大数据基础性战略资源的重要组成部分。然而各省市集约化气象大数据环境均建设于气象业务内网，面向社会的气象数据服务则存在集约化程度低、时效性差、数据量少、安全隐患多等问题，因此，建立外网环境的统一、高效、安全的气象大数据中心是气象业务社会化服务发展的迫切需求。本文建立了外网气象大数据服务平台,采用GoldenGate和sersync+rsync技术实现内网与DMZ区(Demilitarized Zone,两个防火墙之间区域)实时稳定的触发式秒级数据同步；跨平台、多语言开发，标准化调用的统一访问接口设计，可实现高并发、稳定的数据响应请求；分时分类的用户数据访问控制，可实现数据权限的安全控制。该平台通过防火墙双网段控制，向互联网环境用户提供高效、安全、权威的气象大数据服务。     

Accessibility tradeoffs in public transit planning

 Spatial accessibility is a critical consideration in the provision of services, both public and private. In public transit planning, accessibility is comprised of access and geographic coverage. Interestingly, these two considerations are somewhat at odds with each other. Access is important because it is the process associated with getting to and departing from the service. Such access is typically perceived of in spatial terms as the physical proximity to transit stops or stations. Additional stops along a route usually mean greater access, because a stop is more likely to be within an acceptable walking/driving standard for a larger number of people. On the other hand, more stops and greater access slow transit travel speeds, thereby decreasing the area of service reachable given a travel time budget. More stops along a route translate to greater service interruption and longer travel times. The faster the travel time, the more desirable the service. Further, if travel times become excessive, then user demand for service will decrease. All of this means that stop spacing along a route is central to accessibility, as it is a tradeoff of access (more stops) and geographic coverage (service efficiency through less stops). This paper details modeling approaches for addressing accessibility concerns in an integrated fashion. Bus-based transit service in Columbus, Ohio will be utilized to illustrate the usefulness of these approaches in transit planning. Received: September 2002 / Accepted: January 2003 This research was supported in part by an Ohio State University seed grant.