Hub location problems: A review of models,classification, solution techniques,and applications

Hub location problem (HLP) is a relatively new extension of classical facility location problems. Hubs are facilities that work as consolidation, connecting, and switching points for flows between stipulated origins and destinations. While there are few review papers on hub location problems, the most recent one (Alumur and Kara, 2008. Network hub location problems: The state of the art. European Journal of Operational Research, 190, 1–21) considers solely studies on network-type hub location models prior to early 2007. Therefore, this paper focuses on reviewing the most recent advances in HLP from 2007 up to now. In this paper, a review of all variants of HLPs (i.e., network, continuous, and discrete HLPs) is provided. In particular, mathematical models, solution methods, main specifications, and applications of HLPs are discussed. Furthermore, some case studies illustrating real-world applications of HLPs are briefly introduced. At the end, future research directions and trends will be presented.     

浅析WSN的网络安全管理机制

多数WSN的应用都是以节点位置信息为基础,其所监测的事件与节点的物理位置信息存在着密切的联系,若无位置信息,监测数据也就无意义,而节点的位置信息又与网络安全息息相关,因此,WSN的网络安全管理至关重要。本文简单阐述了WSN的特征与应用,分析了WSN的网络安全特征与需求,并探讨了WSN的密钥管理与安全定位两种网络安全管理机制。     

基于行为的访问控制应用于多级安全信息系统

网络位置探测是基于行为的访问控制模型应用的关键问题之一.给出了ABAC的多级安全信息系统访问控制机制,提出了网络位置探测器架构,描述了网络逻辑位置探测原理以及网络物理位置探测原理,给出了依赖DHCP获取网络逻辑位置的方法与基于SNMP、MIB提取网络物理地址的方法.在此基础上,设计并实现了应用于多级安全信息系统的网络位置探测器,并给出了应用示例.     

基于位置信息的流式移动应用推送系统的研究

目前与位置相关的移动应用越来越多,传统应用分发模式中,用户需要手动对应用进行搜索、下载、安装以及卸载,不利于提升用户使用应用服务的体验。设计并实现了基于位置信息的流式移动应用推送系统,该系统中服务器利用移动终端位置信息将相关应用解析、安装,并推送到移动终端显示,移动终端根据用户的选择从服务器流式加载应用。该系统使得用户在切换位置时,不用下载、安装即可使用和当前位置相关的应用服务。实验表明,和传统应用分发模式相比,在3G网络环境下可以减少64.37%的应用获取时延,在4G网络环境下可以减少74.49%的应用获取时延。     

Context-aware,self-scaling Fuzzy ArtMap for received signal strength based location systems

Location awareness is the key capability of mobile computing applications. Despite high demand, indoor location technologies have not become truly ubiquitous mainly due to their requirements of costly infrastructure and dedicated hardware components. Received signal strength (RSS) based location systems are poised to realize economical ubiquity as well as sufficient accuracy for variety of applications. Nevertheless high resolution RSS based location awareness requires tedious sensor data collection and training of classifier which lengthens location system development life cycle. We present a rapid development approach based on online and incremental learning method which significantly reduces development time while providing competitive accuracy in comparison with other methods. ConSelFAM (Context-aware, Self-scaling Fuzzy ArtMap) extends the Fuzzy ArtMap neural network system. It enables on the fly expansion and reconstruction of location systems which is not possible in previous systems.     

Mobile guides: Taxonomy of architectures,context awareness,technologies and applications

Portable devices are increasingly employed in a wide range of mobile guidance applications. Typical examples are guides in urban areas, museum guides, and exhibition space aids. The demand is for the delivery of context-specific services, wherein the context is typically identified by a combination of data related to location, time, user profile, device profile, network conditions and usage scenario. A context-aware mobile guide is intended to provide guidance services adjusted to the context of the received request. The adjustment may refer to tailoring the user interface to the perceived context, as well as delivering the right type of information to the right person at the right time and the right location. It may also refer to intermediary adaptation, as in the case of mobile multimedia transmission. This paper offers a taxonomy of mobile guides considering multiple criteria. The taxonomy considers several aspects of the mobile applications space, including context awareness, client architectures, mobile user interfaces, as well as offered functionalities, highlighting functional, architectural, technological, and implementation issues. Existing implementations are classified accordingly and a discussion of research issues and emerging trends is offered.     

基于移动锚节点无线传感器网络定位的算法

无线传感器网络应用在很多场合中,监测目标进行定位和跟踪是最基本的应用。在无线传感器网络中基于移动锚节点的定位算法进行设计仿真,网络部署成本显著减少。节点能耗减少,运行时间延长,而且在网络边缘上的节点100％都能获得节点位置．该设计算法能得到完整的网络信息,即使在网络节点出现故障后,通过移动锚节点来重新确认所有无故障节点的位置,进行重新定位。     

局域网典型故障解决方法探索

局域网在实际应用中会出现网络连接异常的各类故障,可根据网络故障现象先分析故障产生原因,借助网络调试指令来确定故障位置和范围,通过修复软件和网络配置、更换网络硬件等方法有效解决故障问题。     

无线传感器网络LQI测距定位算法及其误差研究

无线传感器定位算法对无线传感器的工程应用具有重要的意义.针对基于LQ I测距的无线传感器网络,研究了测距模型的建立并对比分析了最小二乘定位算法和质心定位算法,相关仿真研究结果表明:该两种定位算法的精度与测距误差的性质具有鲜明的规律性,当测距误差正向分布时,最小二乘定位比质心算法精度高;当测距误差正负双向分布时,质心算法比最小二乘定位精度高.最后,文中通过搭建的Z igBee硬件平台实验验证了仿真的结果.本文从测距误差模型入手对无线传感器定位算法进行研究,仿真结果与实验验证相一致,有利于W SN的推广应用.     

Network measurement based modeling and optimization for IP geolocation

IP geolocation plays a critical role in location-aware network services and network security applications. Commercially deployed IP geolocation databases may provide outdated or incorrect location of Internet hosts due to slow record updates and dynamic IP address assignment by the ISPs. Measurement-based IP geolocation is used to provide real time location estimation of Internet hosts based on network delays. This paper proposes a measurement-based IP geolocation framework that provides location estimation of an Internet host in real time. The proposed frame work models the relationship between measured network delays and geographic distances using segmented polynomial regression model and semidefinite programming for optimization. Weighted and non-weighted schemes are evaluated for location estimation. The proposed framework shows close to 17 and 26 miles median estimation error for nodes in North America and Europe, respectively. The proposed schemes achieve 70-80% improvement in median estimation error comparing to the first order regression approach for experimental data collected from Planet-Lab.     

基于改进遗传算法的开放式鲁棒融合定位方法

针对现有蜂窝网定位技术在实际应用中没有完整的定位测量参数就无法完成定位的缺点,提出了一种开放式的鲁棒融合定位新方法。该方法以信息融合技术为理论基础,融合异质异构的定位信息进行定位,在保证定位精度的前提下提高了定位算法的鲁棒性。仿真结果验证了该方法的有效性、开放性和鲁棒性。     

Services Discovery for Distributed Network Measurement

More and more distributed applications are deployed around interconnected network, which makes it necessary for network measurement services to address the scalability and robustness requirements. This paper discusses a service discovery for integrated network measurement architecture (INMA), including finding the location of measurement agent, the path of the measurement and the network attributes of the end-to-end path or host. It also describes the functions of the major building blocks used to construct the measurement architecture.     

Efficient solution techniques for the integrated coverage, sink location and routing problem in wireless sensor networks

Sensors are tiny electronic devices having limited battery energy and capability for sensing, data processing and communicating. They can collectively behave to provide an effective wireless network that monitors a region and transmits the collected information to gateway nodes called sinks. Most of the applications require the operation of the network for long periods of times, which makes the efficient management of the available energy resources an important concern. There are three major issues in the design of sensor networks: sensor deployment or the coverage of the sensing area, sink location, and data routing. In this work, we consider these three design problems within a unified framework and develop two mixed-integer linear programming formulations. They are difficult to solve exactly. However, it is possible to compute good feasible solutions of the sink location and routing problems easily, when the sensors are deployed and their locations in the sensor field become known. Therefore, we propose a tabu search heuristic that tries to identify the best sensor locations satisfying the coverage requirements. The objective value corresponding to each set of sensor locations is calculated by solving the sink location and routing problem. Computational tests carried out on randomly generated test instances indicate that the proposed hybrid approach is both accurate and efficient.     

Energy efficient indoor tracking on smartphones

Continuously identifying a user’s location context provides new opportunities to understand daily life and human behavior. Indoor location systems have been mainly based on WiFi infrastructures which consume a great deal of energy mostly due to keeping the user’s WiFi device connected to the infrastructure and network communication, limiting the overall time when a user can be tracked. Particularly such tracking systems on battery-limited mobile devices must be energy-efficient to limit the impact on the experience of using a phone. Recently, there have been a lot of studies of energy-efficient positioning systems, but these have focused on outdoor positioning technologies. In this paper, we propose a novel indoor tracking framework that intelligently determines the location sampling rate and the frequency of network communication, to optimize the accuracy of the location data while being energy-efficient at the same time. This framework leverages an accelerometer, widely available on everyday smartphones, to reduce the duty cycle and the network communication frequency when a tracked user is moving slowly or not at all. Our framework can work for 14 h without charging, supporting applications that require this location information without affecting user experience.     

Generation of an adaptive simulation driven by product trajectories

The tracking of products trajectories involves major challenges in simulation generation and adaptation. Positioning techniques and technologies have become available and affordable to incorporate more deeply into workshop operations. We present our 2-year effort into developing a general framework in location and manufacturing applications. We demonstrate the features of the proposed applications using a case study, a synthetic flexible manufacturing environment, with product-driven policy, which enables the generation of a location data stream of product trajectories over the whole plant. These location data are mined and processed to reproduce the manufacturing system dynamics in an adaptive simulation scheme. This article proposes an original method for the generation of simulation models in discrete event systems. This method uses the product location data in the running system. The data stream of points (product ID, location, and time) is the starting point for the algorithm to generate a queuing network simulation model.     

基于差分隐私的社交网络位置近邻查询方法

针对社交网络中近邻位置查询时个人位置隐私泄漏的问题,采用地理不可区分性机制对位置数据添加随机噪声,提出了一种隐私预算分配方法。首先,对空间区域进行网格化分割,根据用户在不同区域的位置访问量来个性化分配隐私预算;然后,为了解决在扰动位置数据集中近邻查询命中率偏低的问题,提出了一种组合增量近邻查询（CINQ）算法,以扩大需求空间的检索范围,并利用组合查询过滤冗余数据。在仿真实验中,与SpaceTwist算法相比,CINQ算法的查询命中率提高了13.7个百分点。实验结果表明,CINQ算法有效解决了因为查询目标的位置扰动所带来的查询命中率偏低问题,适用于社交网络应用中扰动位置的近邻查询。     

基于RSSI的无线传感器网络定位技术的研究

节点定位技术是无线传感器网络(WSN)的支撑技术之一,给无线传感器网络的各种应用提供节点的位置信息,具有重要的作用。本文分析了无线传感器网络的节点定位算法的原理和分类,并着重分析了基于信号强度测距法(RSSI)的无线定位技术,提出了将信号强度理论值与经验值相融合的定位方法。     

Mitigating Denial-of-Service Attacks on the Chord Overlay Network: A Location Hiding Approach

Serverless distributed computing has received significant attention from both the industry and the research community. Among the most popular applications are the wide area network file systems, exemplified by CFS, Farsite and OceanStore. These file systems store files on a large collection of untrusted nodes that form an overlay network. They use cryptographic techniques to maintain file confidentiality and integrity from malicious nodes. Unfortunately, cryptographic techniques cannot protect a file holder from a Denial-of-Service (DoS) or a host compromise attack. Hence, most of these distributed file systems are vulnerable to targeted file attacks, wherein an adversary attempts to attack a small (chosen) set of files by attacking the nodes that host them. This paper presents LocationGuard - a location hiding technique for securing overlay file storage systems from targeted file attacks. LocationGuard has three essential components: (i) location key, (ii) routing guard, a secure algorithm that protects accesses to a file in the overlay network given its location key, and (iii) a set of location inference guards. Our experimental results quantify the overhead of employing LocationGuard and demonstrate its effectiveness against DoS attacks, host compromise attacks and various location inference attacks.     

基于三角划分的复杂3D山体表面定位算法

在复杂环境下, 网络呈现出三维分布、链路非确定、应用场景异构、部署区域非结构化等新特点, 传统的定位技术已无法适用。不规则的网络形状很可能导致不准确的传感器节点定位结果, 从而导致定位误差较大。提出一种基于三角划分和MDS的3D节点定位算法。首先, 基于三角划分的方法将不规则的3D网络模型分解为若干个较规则的三角区域; 其次, 在每一个三角区域上采用改进的MDS算法对节点进行定位, 从而建立起局部相对位置地图; 最后, 合并三角子区域, 建立起整个网络全局的位置地图。实验结果表明, 该算法有效地提高了定位精度, 具有一定的实用意义。     

多信息融合的轨迹追踪系统设计与实现

轨迹可以看做是对象随着时间变化在空间中留下的印迹.近年来,随着移动终端使用的普及以及生活的信息化,大量的轨迹数据在日常生活中日益积累并为不同的应用所服务.针对用户在移动社交网络以及校园信息化统一管理平台留下的位置痕迹信息,研究和开发了多信息融合的轨迹追踪系统Argo.Argo系统分析了微博、邮件、BBS、一卡通等应用层留下的位置痕迹信息,并结合覆盖校园的无线接入点,采用无线接入点被动定位获取用户位置,实现了多信息融合下的用户轨迹追踪.实验结果表明,该系统能够有效地实现轨迹追踪,并依此提供更好的服务.