Design Of Context-aware Systems Research Articles

A baseline for context-aware system for safety messages dissemination in VANETs

Vehicular ad-hoc networks (VANETs) are mobile networks with highly dynamic contexts of operation. The design and application of context-aware systems could be critical to enhance the performance of protocols deployed in VANETs, which depend on both network and traffic conditions, to detect hostile communication environments, as well as to offer a novel way to make decisions in real-time. In this paper, we present a baseline study for the design of a context-aware system for dissemination of safety messages in VANETs. We model a realistic vehicular intersection and perform extensive simulations to evaluate two well-known dissemination mechanisms, namely the Slotted 1-persistence and the Traffic Adaptive Data Dissemination (TrAD) Protocol, with a set of parameters according to different operation scenarios. We show how the dissemination mechanisms’ performance could be improved, or worsened, by choosing a different set of parameter values. By characterizing the operation scenarios, it is possible to adequate the parameters of the dissemination mechanism with the values that work best in a given context, improving in this way the general performance of the dissemination mechanisms under study.

Context-Aware System Design for Remote Health Monitoring: An Application to Continuous Edema Assessment

Designing remote health monitoring systems requires a multi-faceted perspective that takes into account requirements and contexts imposed by the medical application, technology, and end-user. We study such a design perspective in the context of remote and real-time edema monitoring. Edema (accumulation of fluid in certain soft-tissues) is regarded as one of the most important symptoms for systematic diseases such as heart failure. Monitoring edema allows patients and caregivers to understand the state of sickness and effectiveness of the treatments. This article proposes a novel low-power context-aware and real-time wearable platform capable of continuous assessment of ankle edema in remote settings. Our system keeps track of changes in subject’s ankle circumference as well as current body posture. An examination of our system with 15 subjects demonstrates the effectiveness and reliability of the proposed force-sensitive-resistor-based edema sensor (with an $R^2$ of 0.87 for our regression model and intraclass correlation of 0.97) as well as an over 96 percent accuracy in activity monitoring that provide the means to perform reliable data validation on ankle circumference measurements in a continuous manner. Furthermore, we devise a novel derivative-free power optimization approach to maximize the battery lifetime resulting in improvement in battery lifetime by a factor of 2.13.

Enhanced multiclass SVM with thresholding fusion for speech-based emotion classification

As an essential approach to understanding human interactions, emotion classification is a vital component of behavioral studies as well as being important in the design of context-aware systems. Recent studies have shown that speech contains rich information about emotion, and numerous speech-based emotion classification methods have been proposed. However, the classification performance is still short of what is desired for the algorithms to be used in real systems. We present an emotion classification system using several one-against-all support vector machines with a thresholding fusion mechanism to combine the individual outputs, which provides the functionality to effectively increase the emotion classification accuracy at the expense of rejecting some samples as unclassified. Results show that the proposed system outperforms three state-of-the-art methods and that the thresholding fusion mechanism can effectively improve the emotion classification, which is important for applications that require very high accuracy but do not require that all samples be classified. We evaluate the system performance for several challenging scenarios including speaker-independent tests, tests on noisy speech signals, and tests using non-professional acted recordings, in order to demonstrate the performance of the system and the effectiveness of the thresholding fusion mechanism in real scenarios.

Going Mobile

Travel behavior is becoming inherently dynamic and socially connected because of the increasing use of mobile technologies; as such, the concept of context is becoming increasingly important in travel and tourism and particularly within today’s technology-supported mobile environment. This article builds upon existing literature describing recent developments in context-aware system design with the aim of defining the notion of context as it relates to the mobile technological environment for tourism. As part of this effort, a conceptual framework is proposed to describe the structure and fundamental properties of context, and several implications are discussed for tourism research and the design of mobile systems.

Development of context-aware workflow systems based on Petri Net Markup Language

The Petri Net Markup Language (PNML) is originally an XML-based interchange format for Petri nets. Individual companies may specify their process models in Petri nets and exchange the Petri nets with other companies in PNML. This paper aims to demonstrate the capabilities of PNML in the development of applications instead of an industrial interchange format only. In this paper, we apply PNML to develop context-aware workflow systems. In existing literature, different methodologies for the design of context-aware systems have been proposed. However, workflow models have not been considered in these methodologies. Our interests in this paper are to propose a methodology to automatically generate context-aware action lists for users and effectively control resource allocation based on the state of the workflow systems. To achieve these objectives, we first propose Petri net models to describe the workflows. Next, we propose models to capture resource activities. Finally, the interactions between workflows and resources are combined to obtain a model for the whole processes. Based on the combined model, we propose architecture to automatically generate context-aware graphical user interface to guide the users and control resource allocation in workflow systems. We demonstrate our design methodology using a health care example.

Inference of Human Intentions in Smart Home Environments

Most of context models have limited capability in involving human intention for system evolvability and self-adaptability. Human intention in context aware systems can evolve at any time; however, context aware systems based on these context models can provide only standard services that are often insufficient for specific user needs. Consequently, evolving human intentions result in changes in system requirements. Moreover, an intention must be analyzed from tangled relations with different types of contexts. In the past, this complexity has prevented researchers from using computational methods for analyzing or specifying human intention in context aware system design. The authors investigated the possibility for inferring human intentions from contexts and situations, and deploying appropriate services that users require during system run-time. This paper presents an inference ontology to represent stepwise inference tasks, and then evaluate contexts surrounding a user who accesses PCs through a case study of the smart home environment.

Bringing context-aware access to the web through spoken interaction

The web has become the largest repository of multimedia information and its convergence with telecommunications is now bringing the benefits of web technology to hand-held devices. To optimize data access using these devices and provide services which meet the user needs through intelligent information retrieval, the system must sense and interpret the user environment and the communication context. In addition, natural spoken conversation with handheld devices makes possible the use of these applications in environments in which the use of GUI interfaces is not effective, provides a more natural human-computer interaction, and facilitates access to the web for people with visual or motor disabilities, allowing their integration and the elimination of barriers to Internet access. In this paper, we present an architecture for the design of context-aware systems that use speech to access web services. Our contribution focuses specifically on the use of context information to improve the effectiveness of providing web services by using a spoken dialog system for the user-system interaction. We also describe an application of our proposal to develop a context-aware railway information system, and provide a detailed evaluation of the influence of the context information in the quality of the services that are supplied.

Injecting Self-Organisation into Pervasive Service Ecosystems

Pervasive service ecosystems are a new paradigm for the design of context-aware systems featuring adaptivity and self-awareness. A theoretical and practical framework has been proposed for addressing these scenarios, taking primary inspirations from natural ecosystems and grounding upon two basic abstractions: “live semantic annotations” (LSAs), which are descriptions stored in infrastructure nodes and wrapping data, knowledge, and activities of humans, devices, and services; and “eco-laws”, acting as system rules evolving the population of LSAs as if they were molecules subject to chemical-like reactions. In this paper, we aim at deepening how self-organisation can be injected in pervasive service ecosystems in terms of spatial structures and algorithms for supporting the design of context-aware applications. To this end, we start from an existing classification of self-organisation patterns, and systematically show how they can be supported in pervasive service ecosystems, and be composed to generate a self-organising emergent behaviour. A paradigmatic crowd steering case study is used to demonstrate the effectiveness of our approach.

Modeling and simulation to assist context aware system design

In this paper we present a modelling and visualization design approach for context-aware systems, specifically focusing on applications that support location tracking and that exhibit their behaviour as actuations in the deployment environment. The design tool addresses two key challenges in the design cycle for ubiquitous computing systems. Firstly, facilitating cost-effective, repeatable and easily (re-)configurable experiments that support thorough testing of the target deployment space, including outlier test scenarios. Secondly, supporting an iterative design cycle, using traceability of the causal relationships between context and exhibited system behaviour. The aim is to identify potentially problematic behaviour in the system under test, which can be provided as feedback to lead informed redesign of the prototype system. In this paper we present initial experiments using this tool to test a simple automatic lighting application. We discuss the results and the implications of the findings from these experiments for the models used to drive this design tool.

A Quality Framework for the Storage and Retrieval of Context

Much current work in the field of context-aware systems focuses on application-specific solutions and ad-hoc approaches, and the lack of conceptual models for the design of context-aware systems hinders the development of more general and complex systems. Furthermore, it is often unclear what the consequences of early design decisions are for the quality of the final implementation, making the design difficult and leading to mistakes only to be discovered when the system is already implemented. In this article we present a classification of the architectural aspects of developing context-aware systems. We furthermore give a quality framework that describes the consequences of the architectural aspects on the quality of the context-aware system. We demonstrate the usefulness of the framework by modeling the architecture of a context-aware system.

Intelligibility and Accountability: Human Considerations in Context-Aware Systems

This essay considers the problem of defining the context that context-aware systems should pay attention to from a human perspective. In particular, we argue that there are human aspects of context that cannot be sensed or even inferred by technological means, so context-aware systems cannot be designed simply to act on our behalf. Rather, they will have to be able to defer to users in an efficient and nonobtrusive fashion. Our point is particularly relevant for systems that are constructed such that applications are architecturally isolated from the sensing and inferencing that governs their behavior. We propose a design framework that is intended to guide thinking about accommodating human aspects of context. This framework presents four design principles that support intelligibility of system behavior and accountability of human users and a number of human-salient details of context that must be accounted for in context-aware system design.

Context-Aware Technology: A Phenomenological Perspective

Context-aware systems are currently to a large extent designed from a systems perspective. Research on these technologies has so far mostly been focused on exploring what can be built and less on how it will show up in people's lives. The existing theory and practice in human-computer interaction has mainly evolved from work on graphical user interfaces, and additional theory is required to enable user-centered design of context-aware systems. Interaction with such systems is to a larger extent physical, and an appropriate theory consequently needs to account for the user's bodily nature. We have found the phenomenology of Merleau-Ponty to be a good starting point for the development of such theory. With its first-person focus on the lived body and its relation to the environment, it provides a conceptual framework well suited for understanding context-aware systems from the user's perspective. The perspective moves the focus from seeing a context-aware system as an artifact "sensing" information, to seeing it as an interactive system with a physical user interface. This makes the distinction between foreground and background interaction a property not of the system, but of the situation. A consequence of this philosophical standpoint is that context can never be a property of the world, but that context rather is the horizon within which the user makes sense of the world. The phenomenological perspective enables a systematic exploration of the design space for context-aware systems-as they appear to the user. It further enables an analysis of the requirements for a seamless integration between screen-based and context-aware systems. The essay ends by pointing to the need for making the technology available in a form that can be easily utilized by interaction designers.