一个基于本体的觉察上下文计算模型

觉察上下文计算（Context-Awareness Computing）中必然涉及到知识的共享，引入了本体融合（Ontology Fusion）概念，构建了一个基于本体的觉察上下文计算模型，讨论了该模型的基本框架，分析了上下文信息的获得，设计了上下文信息与本体库的映射过程，研究了本体融合、本体信息存储以及本体库与行为的映射中的相关问题。结合普适计算场景，用实例演示了该模型的运行过程。     

Multi-layer faults in the architectures of mobile, context-aware adaptive applications

Modern hand-held devices are equipped with multiple context sensors exploited by increasingly sophisticated software applications, called Context-Aware Adaptive Applications (CAAAs), that adapt automatically to changes in the surrounding environment, such as by responding to the location and speed of the user. The architecture of CAAAs is typically layered and incorporates a context-awareness component to support processing of context values and triggering of adaptive changes. While this layered architecture is very natural for the design and implementation of CAAAs, it exhibits new kinds of failures that arise as a result of faults that are specific to the choice of technology for specific layers. In this paper we investigate the occurrence of such faults and failures that manifest across architectural layers, and we describe samples of such failures in four CAAAs.     

移动中间件中上下文相关的对象模型

在对上下文、上下文相关和反射机制的概念进行分析研究的基础上,提出了一种基于上下文视图的上下文相关对象模型,并且定义了描述和操作上下文信息的操作元语.最后介绍了这种模型在MACAM移动中间件中的实现.     

普适计算环境下基于构件化中间件的上下文管理技术研究

上下文相关技术已经成为普适计算环境中用于应用服务的不可或缺的核心技术之一。对于基于构件的中间件来说,对高性能的上下文管理的需求更是必不可少,因为它构成了普适计算环境中构件适配和部署的重要基础。因此,在已有构件中间件的基础上,我们针对普适计算环境的特点提出了一种整体的上下文管理方法,将上下文管理集成在已有的构件化中间件中。应用表明,该方法能够更好地支持普适计算环境下上下文相关的构件化应用开发。     

Look, Ma, My homepage is Mobile!

Much of the ongoing research in ubiquitous computing has concentrated on providing context information, e.g. location information, to the level of services and applications. Typically, mobile clients obtain location information from their environment which is used to provide “locally optimal” services. In contrast, it may be of interest to obtain information about the current context a mobile user or device is in, from a client somewhere on the Web, i.e. to use the mobile device as an information provider for Internet clients. As an instance of such services we propose the metaphor of a “location-aware” Web homepage of mobile users providing information about, e.g. the current location a mobile user is at. Requesting this homepage can be as easy as typing a URL containing the mobile user's phone number such ashttp://mhp.net/+49123456789 in an off-the-shelf browser. The homepage is dynamically constructed as Web users access it and it can be configured in various ways that are controlled by the mobile user. We present the architecture and implementation and discuss issues around this example of “inverse” ubiquitous computing.     

传感器网络中基于移动代理的数据融合方法研究

在传感器网络中采用移动代理来进行数据融合是一个新颖的思路,它与传统的数据融合方法相比拥有诸多优势,有必要为数据融合设计一种基于移动代理的计算模型,使得移动代理在传感节点间迁移的同时能够进行有效的数据融合.我们对基于移动代理的数据融合方法进行了深入的探索,设计了基于移动代理的数据融合框架,提出了一种与移动代理路由紧密结合的按分辨率并行量化交叠的数据融合算法--PQOR,并将其成功地运用到目标分类识别的应用场景中.仿真结果表明:与传统的数据融合算法相比,PQOR能够以较小的代价达到应用的要求,其优势随着网络节点规模的增长更为明显.     

上下文感知在Smart Home系统中的应用

针对Smart Home环境的复杂性问题,提出了利用上下文技术来提高其智能化的方法.阐述了在普适环境下的上下文在智能家居环境中的重要性,介绍了上下文和上下文感知计算的定义,采用了基元组的形式定义了不同的上下文信息;提出了基于上下文感知的Smart Home系统模型,并对其功能进行了详细的描述;在Smart Home系统中,应用该模型对具体的上下文实例进行了描述和推理.     

Functionality-power-packaging considerations in context aware wearable systems

Wearable computing places tighter constraints on architecture design than traditional mobile computing. The architecture is described in terms of miniaturization, power-awareness, global low-power design and suitability for an application. In this article we present a new methodology based on three different system properties. Functionality, power and electronic Packaging metrics are proposed and evaluated to study different trade offs. We analyze the trade offs in different context recognition scenarios. The proof of concept case study is analyzed by studying (a) interaction with household appliances by a wrist worn device (acceleration, light sensors) (b) studying walking behavior with acceleration sensors, (c) computational task and (d) gesture recognition in a wood-workshop using the combination of accelerometer and microphone sensors. After analyzing the case study, we highlight the size aspect by electronic packaging for a given functionality and present the miniaturization trends for ‘autonomous sensor button’.     

Refining visualization reference model for context information

Context-awareness can be used to decrease the need for interaction with a mobile device. This is increasingly important since the functionality of mobile devices and personal digital assistants gets more and more complex while the input and output capabilities remain restricted. An important aspect of context-awareness is to present the current context to the user. We propose a model for visualizing contextual information on the mobile terminal screen. The model is a refinement of a well-known visualization reference model; it takes into account the specific characteristics of mobile use and context information. We present the design of the model in detail, and discuss its applicability for a variety of contexts and tasks by providing a full-fledged use case.     

A ferry-assisted solution for forwarding function in Wireless Sensor Networks

For sure, Wireless Sensor Networks (WSNs) are becoming an ultimate part of next generation mobile networks. They are a master piece for Ubiquitous computing. Indeed, they sustain development of numerous paradigms/ technologies such as distributed ambient intelligence, context-awareness and future mobile networking (e.g., B4G and 5G). Battery life remains one of the crucial problems to handle. In this article we propose an infrastructure-based topology using mobile ferries (mobile micro-base stations). In real life, a ferry could be robot, bus, tram, train or any other engine scrutinizing periodically a given area. Yet, message ferries are moving along concentric annulus and may collect data generated by the static sensors (could be classic sensors, smart meters, wearable devices, etc.) randomly distributed on given area. Next, transmissions are performed in a ferry-to-ferry forwarding scheme till arriving at the sink. Considered ferries could sense themselves data and therefore behave as mobile sensors allowing better awareness on the area state [1], [2], [3]. Our scheme could also assist Machine-to-Machine communications to increase the network lifetime, with potentially some cognitive-radio capabilities and opportunistic detection and access. Our proposal can easily be integrated in a smart-city for better interaction and green communications. Next, we present a queueing model (queues with finite capacity) to handle the generated traffic and to analyze the behavior of mobile ferries. We provided a close-form expression for both end-to-end throughput and end-to-end delay. The main objective of this work is to improve the energy efficiency of the cognitive sensors by asking cognitive sensors to not care about forwarding data of each other except for urgent data, this latter point is out of the scope of the paper. These static sensors will only care about data sensing, which will reduce their individual energy consumption.     

Implementing adaptive mobile GI services based on ontologies: Examples from pedestrian navigation support

As we are facing the dawn of ubiquitous computing (UbiComp) by emerging mobile devices and distributed applications, personalization is leaving the desktop domain, because adaptation and context-awareness play a major role in UbiComp in order to realize the user friendliness postulated for UbiComp applications. Adaptation is a relatively new concept for GI services. Therefore we introduce the related research areas. The two most important factors for adaptation are (a) context as the representation of the current situation and (b) the user itself. In particular how to dynamically derive information on the users’ properties is a research area applying learning strategies introduced shortly. We see these two concepts not isolated but propose an integrated situation model including several types of context as well as user parameters. After this introduction we present several approaches to realizing adaptive mobile GI services in the domain of pedestrian navigation and tourist information – representing first steps towards UbiGIS (www.ubigis.org). These include context and user-aware proactive tips, personalized tour planning and adaptive maps. Implementations and new concepts for extensions of these are presented. The paper closes by an outlook on open research issues related to adaptive GI services.     

Consistent Modelling of Users, Devices and Sensors in a Ubiquitous Computing Environment

This paper describes the use of an accretion-resolution user modelling representation to model people, places and objects. We explain the motivation for the key properties of the representation, especially those of particular importance for ubiquitous computing: firstly, for flexibility in interpreting the typically noisy and potentially conflicting evidence about users’ locations; secondly, to support users in scrutinising their user model, the processes that determine its contents and the way that it is used in the ubiquitous computing environment. A novel and important aspect of this work is our extension of the representation beyond modelling just users, using it also to represent the other elements such as devices, sensors, rooms and buildings. We illustrate our approach in terms of models we have been building for a system which enables users to gain personalised information about the sensors and services in a ubiquitous computing environment. We report experiments on the scalability and the management of inconsistency in modelling of location, based on accretion-resolution     

Mobile edge-enabled trust evaluation for the Internet of Things

The Internet of Things (IoT), including wireless sensors, is one of the highly anticipated contributors to big data; therefore, avoiding misleading or forged data gathering in cases of sensitive and critical data through secure communication is vital. However, due to the relatively long distance between remote cloud and end nodes, cloud computing cannot provide effective and direct management for end nodes, which leads to security vulnerabilities. In this paper, we propose a novel trust evaluation model based on the trust transitivity on a chain assisted by mobile edge nodes, which is used to ensure the reliability of nodes in the Internet of Things and prevent malicious attacks. The mobile edge nodes offer a new solution to solve the above problems with relatively strong computing and storage abilities. Firstly, we design calculation approaches to different trust chains to measure their trust degrees. Secondly, we propose an improved Dijkstra’s algorithm for collecting trust information of sensor nodes by mobile edge nodes. Finally, the experimental results show that our trust model based on mobile edge nodes can evaluate sensor nodes more precisely and enhance the security on the Internet of Things.     

A hybrid positioning system for technology‐independent location‐aware computing

Location‐aware computing is a form of context‐aware mobile computing that refers to the ability of providing users with services that depend on their position. Locating the user terminal, often called positioning, is essential in this form of computing. Towards this aim, several technologies exist, ranging from personal area networking, to indoor, outdoor, and up to geographic area systems. Developers of location‐aware software applications have to face with a number of design choices, that typically depend on the chosen technology. This work addresses the problem of easing the development of pull location‐aware applications, by allowing uniform access to multiple heterogeneous positioning systems. Towards this aim, the paper proposes an approach to structure location‐aware mobile computing systems in a way independent of positioning technologies. The approach consists in structuring the system into a layered architecture, that provides application developers with a standard Java Application Programming Interface (JSR‐179 API), and encapsulates location data management and technology‐specific positioning subsystems into lower layers with clear interfaces. In order to demonstrate the proposed approach we present the development of HyLocSys. It is an open hybrid software architecture designed to support indoor/outdoor applications, which allows the uniform (combined or separate) use of several positioning technologies. HyLocSys uses a hybrid data model, which allows the integration of different location information representations (using symbolic and geometric coordinates). Moreover, it allows support to handset‐ and infrastructure‐based positioning approaches while respecting the privacy of the user. The paper presents a prototypal implementation of HyLocSys for heterogeneous scenarios. It has been implemented and tested on several platforms and mobile devices. Copyright © 2009 John Wiley & Sons, Ltd.     

普适计算中基于移动代理的应用follow me迁移技术*

为了更好地利用普适计算环境中的计算资源、减少人为干预、提高工作效率,提出了应用的follow-me迁移需求,即计算可以随着用户的移动在异构设备和计算环境中移动,让移动中的用户能够体验到不间断的计算。提出了基于移动代理的普适计算中间件FollowMeAgent。结合情境感知技术,利用软件代理所具备的移动性实现应用的自主迁移,并根据应用特点对迁移策略进行了细分。在此平台上开发了若干应用,通过性能测试证明其可行性和有效性。     

Location awareness through trajectory prediction

Location-aware computing is a type of ubiquitous computing that uses user’s location information as an essential parameter for providing services and application-related optimization. Location management plays an important role in location-aware computing because the provision of services requires convenient access to dynamic location and location-dependent information. Many existing location management strategies are passive since they rely on system capability to periodically record current location information. In contrast, active strategies predict user movement through trajectories and locations. Trajectory prediction provides richer location and context information and facilitates the means for adapting to future locations. In this paper, we present two models for trajectory prediction, namely probability-based model and learning-based model. We analyze these two models and conduct experiments to test their performances in location-aware systems.     

一种智能手机上下文信息获取的代价模型及其应用

随着信息技术的发展和应用需求的增长,智能手机中嵌入了各种传感器和网络接口,它们是获取上下文信息,进而构建智能型移动应用的关键。尽管在智能手机中获取上下文信息的代价很大,但是这种代价却通常被移动应用开发者所忽视。提出了一个上下文信息获取的代价模型,它能对上下文信息获取的代价进行度量。设计并实现了一个上下文信息获取代价模型的测量工具CRCTest,并对Android智能手机的代价模型进行了测量。基于测量得到的Android平台上下文信息获取的代价模型实现了一个应用实例,通过对比两种位置上下文信息生成方式的代价,说明了基于代价模型优化设计上下文获取的可行性。     

Context-awareness in wearable and ubiquitous computing

A common focus shared by researchers in mobile, ubiquitous and wearable computing is the attempt to break away from the traditional desktop computing paradigm. Computational services need to become as mobile as their users. Whether that service mobility is achieved by equipping the user with computational power or by instrumenting the environment, all services need to be extended to take advantage of the constantly changing context in which they are accessed. This paper will report on work carried out by the Future Computing Environments Group at Georgia Tech to provide infrastructure for context-aware computing. We will describe some of the fundamental issues involved in contextaware computing, solutions we have generated to provide a flexible infrastructure and several applications that take advantage of context awareness to allow freedom from traditional desktop computing.     

A System Architecture for Context-Aware Service Discovery

Recent technological advances have enabled both the consumption and provision of mobile services (m-services) by small, portable, handheld devices. However, mobile devices still have restricted capabilities with respect to processing, storage space, energy consumption, stable connectivity, bandwidth availability. In order to address these shortcomings, a potential solution is context-awareness (by context we refer to the implicit information related both to the requesting user and service provider that can affect the usefulness of the returned results). Context plays the role of a filtering mechanism, allowing only transmission of relevant data and services back to the device, thus saving bandwidth and reducing processing costs. In this paper, we present an architecture for context-aware service discovery. We describe in detail the system implementation and we present the system evaluation as a tradeoff between a) the increase of the quality of service discovery when context-awareness is taken into account and b) the extra cost/burden imposed by context management.