Changes In User's Context Research Articles

Context-aware System for Dynamic Privacy Risk Inference

With the rapid expansion of smart cyber–physical systems and environments, users become more and more concerned about their privacy, and ask for more involvement in the protection of their data. However, users may not be necessarily aware of the direct and indirect privacy risks they take to properly protect their privacy. In this paper, we propose a context-aware semantic reasoning system, denoted as the Privacy Oracle, capable of providing users with a dynamic overview of the privacy risks taken as their context evolves. To do so, the system continuously models, according to a proposed Semantic User Environment Modeling (SUEM) ontology, the knowledge (received by the system) about the user of interest and his surrounding cyber–physical environment. In parallel, it performs continuous reasoning over modeled information, by relying on set of privacy rules, in order to dynamically infer the privacy risks taken by the user. To validate our approach, we developed a prototype based on the semantic web tools such as OWL API, SWRL API and the inference engine Pellet. We evaluated the system performance by considering multiple use cases. Our experimental results show that the Privacy Oracle can assist users by dynamically detecting their incurred privacy risks, and by tracking, in real-time, the evolution of those risks as user context changes.

Novel activity classification and occupancy estimation methods for intelligent HVAC (heating, ventilation and air conditioning) systems

Reductions in HVAC (heating, ventilation and air conditioning) energy consumption can be achieved by limiting heating in the winter or cooling in the summer. However, the resulting low thermal comfort of building occupants may lead to an override of the HVAC control, which revokes its original purpose. This has led to an increased interest in modeling and real-time tracking of location, activity, and thermal comfort of building occupants for HVAC energy management. While thermal comfort is well understood, it is difficult to measure in real-time environments where user context changes dynamically. Encouragingly, plethora of sensors available on smartphone unleashes the opportunity to measure user contexts in real-time. An important contextual information for measuring thermal comfort is Metabolism rate, which changes based on current physical activities. To measure physical activity, we develop an activity classifier, which achieves 10% higher accuracy compared to Support Vector Machine and k-Nearest Neighbor. Office occupancy is another contextual information for energy-efficient HVAC control. Most of the phone based occupancy estimation techniques will fail to determine occupancy when phones are left at desk while sitting or attending meetings. We propose a novel sensor fusion method to detect if a user is near the phone, which achieves more than 90% accuracy. Determining activity and occupancy our proposed algorithms can help maintaining thermal comfort while reducing HVAC energy consumptions.

Dynamic framework for building highly-localized mobile web DTN applications

Proximity-based mobile applications are increasing in popularity. Such apps engage users while in proximity of places of interest (malls, bus stops, restaurants, theatres), but remain closed or unused after the user goes away. Since the number of ‘places of interest’ is constantly growing and can be large, it is impractical to install a large number of corresponding native applications on the phone when each app engages the user for only a small period of time.In this paper, we propose a dynamic framework for deploying highly-localized mobile web applications. Such web applications are deployed locally to users in proximity, and can be opened in the browser. Communication in the web app is performed over the Delay-Tolerant Network of mobile users, removing the need of an Internet connection. DTN protocols can be dynamically added or removed at run-time, allowing each application to use a protocol best suited to its needs. After usage, the web application is closed either manually by the user, or automatically when the user goes away from the place of interest.To restrict deployment of web apps to only those users in a relevant context (e.g.: people walking nearby a store), and to automatically switch off DTN protocols when user context changes, we have extended the framework to be ‘context-aware’, using the low-power barometer sensor on the phone to detect when the user is idle, walking, or in vehicle. Applications can specify which protocols to run in these user contexts, and when to switch them off, reducing power consumption.We have implemented the framework on Android. Our analysis of the framework show that the memory and performance overhead incurred is small. Using this framework, we have written a simple DTN web application for bus-stops to help the physically challenged. Using real-device measurements, we show that adding context awareness to the framework can reduce power consumption by at least 53%.

Security Issues in Pervasive Computing: A Healthcare Scenario

In the past few years, pervasive computing applications have grown tremendously because of recent developments in portable, low-cost, lightweight devices with faster short range and low power wireless communications networks. Pervasive computing environment consists of various small, frequently mobile, handheld and portable smart devices connected to an ad-hoc network structure. These devices are fully efficient in sensing the environment around them and reacting intelligently to the changes in user context in order to simplify the user activities. Security issues increase in pervasive computing environments as it provides a user access to computing resources and services from any location and at any point of time. Pervasive computing has become an essential in healthcare because of so many small devices used. The security plays an essential role in this regard. A wide range of research has been carried in pervasive computing. This paper elaborates the security issues in pervasive computing specially in the healthcare field.