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1.
Increasing widespread use of sensor and networking technologies are yielding ubiquitous sensors and applications that pervade daily life. At the same time, context-aware pervasive computing has experienced tremendous developments in terms of context modelling and reasoning, and applications. Such developments coupled with a cloud computing model are yielding sensor-cloudlets and context-cloudlets based on sensors and applications deployed as services that can be harnessed in applications on-demand, ad-hoc and on a pay-per-use model. Sensor-cloudlets and context-cloudlets depend on and adapt to the available resources at the time, and involve context-aware systems (including sensors) that need to be dynamically composed as needed. This paper first outlines current trends and key issues and challenges in sensor-cloudlets and context-cloudlets. We then present a key contribution of this paper, which is an application of an abstract model of context-aware systems for specifying compositions of context-aware systems used in sensor-cloudlets and context-cloudlets. We show how expressions in our formalism can be embedded into a programming language (which we show via an example extending the logic programming language Prolog). We then present numerous examples illustrating applications expressed in our extended Prolog language. We also show how compositions specified in our formalism supports estimating the reliability and cost of using such compositions of resources in computations, in a well-defined semantics. Finally, we describe meta-level control operators on evaluation of queries posed to compositions of resources and specify a service-based interface on context-aware systems. We conclude with issues to be tackled in the future.  相似文献   

2.
Recent pervasive systems are designed to be context-aware so that they are able to adapt to continual changes of their environments. Rule-based adaptation, which is commonly adopted by these applications, introduces new challenges in software design and verification. Recent research results have identified some faulty or unwanted adaptations caused by factors such as asynchronous context updating, and missing or faulty context reading. In addition, adaptation rules based on simple event models and propositional logic are not expressive enough to address these factors and to satisfy users'' expectation in the design. We tackle these challenges at the design stage by introducing sequential event patterns in adaptation rules to eliminate faulty and unwanted adaptations with features provided in the event pattern query language. We illustrate our approach using the recent published examples of adaptive applications, and show that it is promising in designing more reliable context-aware adaptive applications. We also introduce adaptive rule specification patterns to guide the design of adaptation rules.  相似文献   

3.
A context-aware application in the pervasive computing environment provides intuitive user centric services using implicit context cues. Personalization and control are important issues for this class of application as they enable end-users to understand and configure the behavior of an application. However most development efforts for building context-aware applications focus on the sensor fusion and machine learning algorithms to generate and distribute context cues that drive the application with little emphasis on user-centric issues. We argue that, to elevate user experiences with context-aware applications, it is very important to address these personalization and control issues at the system interface level in parallel to context centric design. Towards this direction, we present Persona, a toolkit that provides support for extending context-aware applications with end-user personalization and control features. Specifically, Persona exposes a few application programming interfaces that abstract end-user customization and control mechanisms and enables developers to integrate these user-centric aspects with rest of the application seamlessly. There are two primary advantages of Persona. First, it can be used with various existing middlewares as a ready-to-use plug-in to build customizable and controllable context-aware applications. Second, existing context-aware applications can easily be augmented to provide end-user personalization and control support. In this paper, we discuss the design and implementation of Persona and demonstrate its usefulness through the development and augmentation of a range of common context-aware applications.  相似文献   

4.
物联网情景感知技术研究   总被引:2,自引:0,他引:2  
与互联网不同,物联网(Internet of Things, IoT)通过各类通信技术将具有标识、感知或者执行能力的物理实体互联,形成了“物物互连”的虚拟网络。随着计算机及通信技术的迅速发展,计算资源将通布人们周围的环境,情景感知技术应运而生。情景感知获得传感器采集的情景信息以后,对信息进行智能处理,自主地为用户提供服务。物联网具有海量信息的特性,传统的情景信息处理方法已不再适用。对物联网情景感知技术进行了详细的介绍,首先给出情景和情景感知的概念及其研究发展和应用。然后,结合物联网特性,以情景感知流程为主线,探讨了信息获取、建模和智能处理等内容。最后,系统结构是情景感知的关键,因此对现有的系统结构进行了分析和对比,结合物联网环境论述了当前情景感知系统的不足之处,并给出了情景感知系统的参考结构。  相似文献   

5.
The implementation of context-aware systems can be supported through the adoption of techniques at the architectural level such as middlewares or component-oriented architectures. It can also be supported by suitable constructs at the programming language level. Context-oriented programming (COP) is emerging as a novel paradigm for the implementation of this kind of software, in particular in the field of mobile and ubiquitous computing. The COP paradigm tackles the issue of developing context-aware systems at the language-level, introducing ad hoc language abstractions to manage adaptations modularization and their dynamic activation. In this paper we review the state of the art in the field of COP in the perspective of the benefits that this technique can provide to software engineers in the design and implementation of context-aware applications.  相似文献   

6.
Information in a context-aware system has diverse natures. Raw data coming from sensors are aggregated and filtered to create more abstract information, which can be processed by context-aware application components to decide what actions should be performed. This process involves several activities: finding the available sources of information and their types, gathering the data from these sources, facilitating the fusion (aggregation and interpretation) of the different pieces of data, and updating the representation of the context to be used by applications. The reverse path also appears in context-aware systems, from changes in the context representation to trigger actions in certain actuators. FAERIE (Framework for AmI: Extensible Resources for Intelligent Environments) is a framework that facilitates management and fusion of context information at different levels. It is implemented as a distributed blackboard model. Each node of the system has a private blackboard to manage pieces of information that can be accessed by observer components, either locally or remotely (from other nodes) in a transparent way. The use of the framework is illustrated with a case study of an application for guiding people to meetings in a university building.  相似文献   

7.
Modeling privacy control in context-aware systems   总被引:2,自引:0,他引:2  
Significant complexity issues challenge designers of context-aware systems with privacy control. Information spaces provide a way to organize information, resources, and services around important privacy-relevant contextual factors. In this article, we describe a theoretical model for privacy control in context-aware systems based on a core abstraction of information spaces. We have previously focused on deriving socially based privacy objectives in pervasive computing environments. Building on Ravi Sandhu's four-layer OM-AM (objectives, models, architectures, and mechanisms) idea, we aim to use information spaces to construct a model for privacy control that supports our socially based privacy objectives. We also discuss how we can introduce decentralization, a desirable property for many pervasive computing systems, into our information space model, using unified privacy tagging.  相似文献   

8.
The paper gives an overview of a recently started research project addressing the question: Can context be exploited to add value to IT-services? Beyond today's way-finding services based on GPS and maps, we believe there is a new class of context-aware pervasive services making good use of a broad range of context information (e.g. identity, time of day, temperature, history as well as relative location of friends and belongings). Last but not least we believe one can find ways of adding value to IT-services by using disembodied conversational agents based on voice, sounds and visual signals integrated into the environment, instead of being guided by explicit directions shown on a display. The project aims at giving both new fundamental insight about the theory behind IT-services, their architecture and user interfaces and at building a number of prototypes demonstrating innovative context-aware pervasive IT-services.  相似文献   

9.
Future pervasive computing applications are envisioned to adapt the applications’ behaviors by utilizing various contexts of an environment and its users. Such context information may often be ambiguous and also heterogeneous, which make the delivery of unambiguous context information to real applications extremely challenging. Thus, a significant challenge facing the development of realistic and deployable context-aware services for pervasive computing applications is the ability to deal with these ambiguous contexts. In this paper, we propose a resource optimized quality assured context mediation framework based on efficient context-aware data fusion and semantic-based context delivery. In this framework, contexts are first fused by an active fusion technique based on Dynamic Bayesian Networks and ontology, and further mediated using a composable ontological rule-based model with the involvement of users or application developers. The fused context data are then organized into an ontology-based semantic network together with the associated ontologies in order to facilitate efficient context delivery. Experimental results using SunSPOT and other sensors demonstrate the promise of this approach.  相似文献   

10.
上下文感知是普适计算的核心技术之一,而描述和理解上下文信息是上下文感知的前提。由于上下文信息种类繁多、感知方式迥异,目前开发面向特定应用的上下文感知系统缺乏统一的机制和通用的架构,增加了系统开发的成本。引入语义Web技术,利用本体对上下文信息进行建模,采用本体描述语言描述上下文模型,提供了一个公共的上下文本体以实现多个独立开发的上下文感知系统对知识的共享和推理,构建了通用的上下文感知中间件框架,从而实现对域内上下文知识的共同理解。  相似文献   

11.
In this work, we introduce a Model Driven Development method for developing context-aware pervasive systems. This method allows us to specify a context-aware pervasive system at a high level of abstraction by means of a set of models, which describes both the system functionality and the context information. From these models, an automated code generation strategy is applied. This strategy allows us to generate the system Java code that provides the system functionality and as well as an OWL specification that represents the context information and allows us to manage this information without additional burden. Furthermore, this specification is used by a reasoner at runtime to infer context knowledge that is not directly observable, and it is also used by machine learning algorithms to give support to the system adaptation according to the context information.  相似文献   

12.
Privacy-Aware Autonomous Agents for Pervasive Healthcare   总被引:1,自引:0,他引:1  
This article is part of a special issue on Intelligent Agents in Healthcare. Hospitals are natural candidates for pervasive computing technology, but they have significant privacy requirements. Autonomous agents can help developers design privacy-aware systems for pervasive healthcare environments. An extension of the SALSA agent framework incorporates customizable privacy mechanisms to adapt applications to a certain quality-of-privacy level, thereby harnessing the properties of autonomous agents. An implementation of a context-aware pervasive hospital application shows how this framework can help developers manage user privacy.  相似文献   

13.
Context-awareness enables the personalization of computer systems according to the users' needs and their particular situation at a given time. The personalization capabilities are usually implemented by programmers due to the complex processes that are involved. However, an important trend in software development is that more and more software systems are being implemented not only by programmers but also by people with expertise in other domains. Since most of the existing context-aware development toolkits are designed for programmers, non-technical users cannot develop these kinds of systems. The design of tools to create context-aware systems by users that do not have programming skills but are experts in the domain where the system is going to be deployed, will contribute to speed up the adoption of these kinds of services by the society. This paper presents a cloud-based platform to ease the development of context-aware mobile applications by people without programming skills. The platform has been designed to be used in a tourism domain. This way, tourism experts can send tourist information to mobile users according to their context data (indoor/outdoor location, language, and date and time range). An energy-efficient mobile app has been developed in order to obtain context data from the user's device and to receive personalized information in real time based on these data. The architecture and implementation details of the system are presented and the evaluation of the platform by tourism domain experts is discussed.  相似文献   

14.
Uncertainty handling is one of the most important aspects of modelling of context-aware systems. It has direct impact on the adaptability, understood as an ability of the system to adjust to changing environmental conditions or hardware configuration (missing data), changing user habits (ambiguous concepts), or imperfect information (low quality sensors). In mobile context-aware systems, data is most often acquired from device’s hardware sensors (like GPS, accelerometer), virtual sensors (like activity recognition sensor provided by the Google API) or directly from the user. Uncertainty of such data is inevitable, and therefore it is obligatory to provide mechanisms for modelling and processing it. In this paper, we propose three complementary methods for dealing with most common uncertainty types present in mobile context-aware systems. We combine modified certainty factors algebra, probabilistic interpretation of rule-based model, and time-parametrised operators into a comprehensive toolkit for modelling and building robust mobile context-aware systems. Presented approach was implemented and evaluated on the practical use-case.  相似文献   

15.
An infrastructure approach to support context-aware pervasive computing is advantageous for rapid prototyping of context-aware distributed applications and beneficial for unifying modelling of context and reasoning in uncertain conditions. This paper presents the ECORA framework for context-aware computing, which is designed with a focus on reasoning about context under uncertainty and addressing issues of heterogeneity, scalability, communication and usability. The framework follows an agent-oriented hybrid approach, combining centralized reasoning services with context-aware, reasoning capable mobile software agents. The use of a centralized reasoning engine provides powerful reasoning capabilities and deploying context-aware mobile agents enables agility and robustness of components in the pervasive system. The design and implementation of the framework at different levels, as well as three case studies, are presented.  相似文献   

16.
In open heterogeneous context-aware pervasive computing systems, suitable context models and reasoning approaches are necessary to enable collaboration and distributed reasoning among agents. This paper proposes, develops, and demonstrates the following: 1) a novel context model and reasoning approach developed with concepts from the state-space model, which describes context and situations as geometrical structures in a multidimensional space; and 2) a context algebra based on the model, which enables distributed reasoning by merging and partitioning context models that represent different perspectives of computing entities over the object of reasoning. We show how merging and reconciling different points of view over context enhances the outcomes of reasoning about the context. We develop and evaluate our proposed algebraic operators and reasoning approaches with cases using real sensors and with simulations. We embed agents and mobile agents with these modeling and reasoning capabilities, thus facilitating context-aware and adaptive mobile agents operating in open pervasive environments.  相似文献   

17.
Toward an OSGi-based infrastructure for context-aware applications   总被引:6,自引:0,他引:6  
Applications and services must adapt to changing contexts in dynamic environments. However, building context-aware applications is still complex and time-consuming due to inadequate infrastructure support. We propose a context-aware infrastructure for building and rapidly prototyping such applications in a smart-home environment. This OSGi-based infrastructure manages context-aware services reliably and securely and efficiently supports context acquisition, discovery, and reasoning. A formal, ontology-based context model enables semantic context representation, reasoning, and knowledge sharing. We propose an ontology-based context model that leverages Semantic Web technology and OWL (Web Ontology Language). OWL is an ontology markup language that enables context sharing and context reasoning. Based on our context model, we also propose a service-oriented context-aware middleware (SOCAM) architecture, including a set of independent services that perform context discovery, acquisition, and interpretation.  相似文献   

18.
Games have not received the full attention of the requirements engineering community. This scenario is becoming more critical as we move towards newer forms of games, such as pervasive games. Pervasiveness (the quality that distinguishes pervasive games from traditional digital games) holds several meanings, including being ubiquitous, permeating something, or spreading something, somewhere, in a physical space. Pervasiveness can be recognized in by the boundaries of the game expanding every time it is played, from the virtual (or fictional) world to the real world. Pervasive games are a new form of digital entertainment that has evolved in different forms, such as alternate reality games, transmedia games, and crossmedia games. Sensor technologies, networking capabilities, augmented reality systems, computer vision technology, the internet, and, especially, mobile devices have been responsible for the rapid evolution of this new form of digital product. This paper is focused on “pervasive mobile games”, which we define as context-aware games that use mobile devices. We bear in mind that mobile devices are currently the main driver for fulfilling the promises of pervasive game playing. Our investigations and experiments on this class of games led us to study the quality requirements for pervasive mobile games. Using different information sources, we gathered a set of interrelated characteristics that are crucial to the success of these games. In this paper, we begin to clarify the definition and scope of pervasive mobile games, which are controversial issues in the literature. Using these fundamentals, we propose a two-level conceptual map of non-functional requirements that helps to realize pervasiveness in pervasive mobile games. These non-functional requirements are then associated with a set of questions that help the designers in verifying tasks and operationalizing the requirements of a game. We also propose a dependence matrix for pervasive game qualities that enhances the insight into pervasiveness and reveals important guidelines for the game designers.  相似文献   

19.
Ambient Assisted Living (AAL) systems must provide adapted services easily accessible by a wide variety of users. This can only be possible if the communication between the user and the system is carried out through an interface that is simple, rapid, effective, and robust. Natural language interfaces such as dialog systems fulfill these requisites, as they are based on a spoken conversation that resembles human communication. In this paper, we enhance systems interacting in AAL domains by means of incorporating context-aware conversational agents that consider the external context of the interaction and predict the user’s state. The user’s state is built on the basis of their emotional state and intention, and it is recognized by means of a module conceived as an intermediate phase between natural language understanding and dialog management in the architecture of the conversational agent. This prediction, carried out for each user turn in the dialog, makes it possible to adapt the system dynamically to the user’s needs. We have evaluated our proposal developing a context-aware system adapted to patients suffering from chronic pulmonary diseases, and provide a detailed discussion of the positive influence of our proposal in the success of the interaction, the information and services provided, as well as the perceived quality.  相似文献   

20.
基于本体的上下文感知系统   总被引:1,自引:0,他引:1       下载免费PDF全文
王曙宁  俞建新 《计算机工程》2007,33(11):42-43,49
普适计算自20世纪90年代中期被提出以后得到了普遍的关注。上下文感知作为实现普适计算的关键技术已成为重要的研究课题。在分析上下文感知系统以及组成模块的基础上,借鉴软件方法学中的快速原型模型思想,通过本体标记语言OWL给出了系统中感应模块搭建的实例。  相似文献   

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