Dissertations / Theses on the topic 'Context-aware architecture'

Master of Philosophy (Architecture)
Context-aware computing is a mobile computing paradigm in which applications can discover, use, and take advantage of contextual information, such as the location, tasks and preferences of the user, in order to adapt their behaviour in response to changing operating environments and user requirements. A problem that arises is the inability to respond to contextual information that cannot be classified into any known context. Many context-aware applications require all discovered contextual information to exactly match a type of context, otherwise the application will not react responsively. The ability to learn and recall contexts based on the contextual information discovered has not been very well addressed by previous context-aware applications and research. The aim of this thesis is to develop a component middleware technology for mobile computing devices for the discovery and capture of contextual information, using the situated reasoning concept of constructive memory. The research contribution of this thesis lies in developing a modified architecture for context-aware systems, using a constructive memory model as a way to learn and recall contexts from previous experiences and application interactions. Using a constructive memory model, previous experiences can be induced to construct potential contexts, given a small amount of learning and interaction. The learning process is able to map the many variations of contextual information currently discovered by the user with a predicted type of context based on what the application has stored and seen previously. It only requires a small amount of contextual information to predict a context, something common context-aware systems lack, as they require all information before a type of context is assigned. Additionally, some mechanism to reason about the contextual information being discovered from past application interactions will be beneficial to induce contexts for future experiences.

Thesis (S.M.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 1999.
Includes bibliographical references (p. 83-84).
How many times have you gone to the grocery store but left your shopping list on the refrigerator door? Wouldn't it be more efficient to have a reminder to buy groceries and the shopping list delivered to you when you were in the vicinity of the store? How many times have you suddenly thought of something you must do or have just had a great idea that you want to write down, or record, for future reference? Wouldn't it be useful to record that thought and be reminded of it when in the relevant place and time? Information delivery utopia would be to receive the exact amount of data we need (no more, no less), when and where we need it, and in a gratifying format, for example, in a pleasant voice or well-structured text. Although we are still far away from this goal, a partial solution to the information overload is to create systems which deliver timely information when the user is in the relevant context. This thesis describes comMotion, a context-aware communication system for a mobile or wearable computing platform. A behaviour-learning agent automatically learns the salient locations in the user's life. Once these places have been determined, location specific to-do lists, electronic Post-it notes or reminders, and subscription requested information can be delivered to the user at the right place and time. The user interacts with the system through a visual and/or speech interface.
by Natalia Marmasse.
S.M.

Thesis: S.M., Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2014.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 95-100).
Current biological research workflows make use of disparate, poorly integrated systems that cause large mental burden on the scientist leading to mistakes on often long, complex and costly experimental procedures. The lack of open tools to assist in the collection of distributed experimental conditions and data is largely responsible making protocols difficult to debug and laboratory practice hard to learn. In this thesis, we describe an open Protocol Descriptor Language (PDL) and system to enable a context-rich, quantitative approach to biological research. We detail the development of a closed-loop pipetting technology and a wireless, sample temperature sensor that integrate with our Protocol Description platform enabling novel, real-time experimental feedback to the researcher thereby reducing mistakes and increasing overall scientific reproducibility.
by Charles Fracchia.
S.M.

Context-aware computing aims at making mobile devices sensitive to the social and physical settings in which they are used. A necessary requirement to achieve this goal is to enable those devices to establish a shared understanding of the desired settings. Establishing a shared understanding entails the need to manipulate sensed data in order to capture a real world situation wholly, conceptually, and meaningfully. Quite often, however, the data acquired from sensors can be inexact, incomplete, and/or uncertain. Inexact sensing arises mostly due to the inherent limitation of sensors to capture a real world phenomenon precisely. Incompleteness is caused by the absence of a mechanism to capture certain real-world aspects; and uncertainty stems from the lack of knowledge about the reliability of the sensing sources, such as their sensing range, accuracy, and resolution. The thesis identifies a set of criteria for a context-aware system to capture dynamic real-world situations. On the basis of these criteria, a distributed architecture is designed, implemented and tested. The architecture consists of Primitive Context Servers, which abstract the acquisition of primitive contexts from physical sensors; Aggregators, to minimise error caused by inconsistent sensing, and to gather correlated primitive contexts pertaining to a particular entity or situation; a Knowledge Base and an Empirical Ambient Knowledge Component, to model dynamic properties of entities with facts and beliefs; and a Composer, to reason about dynamic real-world situations on the basis of sensed data. Two additional components, namely, the Event Handler and the Rule Organiser, are responsible for dynamically generating context rules by associating decision events ? signifying a user?s activity ? with the context in which those decision events are produced. Context-rules are essential elements with which the behaviour of mobile devices can be controlled and useful services can be provided. Four estimation and recognition schemes, namely, Fuzzy Logic, Hidden Markov Models, Dempster-Schafer Theory of Evidence, and Bayesian Networks, are investigated, and their suitability for the implementation of the components of the architecture of the thesis is studied. Subsequently, fuzzy sets are chosen to model dynamic properties of entities. Dempster-Schafer?s combination theory is chosen for aggregating primitive contexts; and Bayesian Networks are chosen to reason about a higher-level context, which is an abstraction of a real-world situation. A Bayesian Composer is implemented to demonstrate the capability of the architecture in dealing with uncertainty, in revising the belief of the Empirical Ambient Knowledge Component, in dealing with the dynamics of primitive contexts and in dynamically defining contextual states. The Composer could be able to reason about the whereabouts of a person in the absence of any localisation sensor. Thermal, relative humidity, light intensity properties of a place as well as time information were employed to model and reason about a place. Consequently, depending on the variety and reliability of the sensors employed, the Composer could be able to discriminate between rooms, corridors, a building, or an outdoor place with different degrees of uncertainty. The Context-Aware E-Pad (CAEP) application is designed and implemented to demonstrate how applications can employ a higher-level context without the need to directly deal with its composition, and how a context rule can be generated by associating the activities (decision events) of a mobile user with the context in which the decision events are produced.

Thesis (S.M.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2003.
Includes bibliographical references (p. 83-88).
The thesis presents a novel situationally-aware multimodal spoken language system called Fuse that performs speech understanding for visual object selection. An experimental task was created in which people were asked to refer, using speech alone, to objects arranged on a table top. During training, Fuse acquires a grammar and vocabulary from a "show-and-tell" procedure in which visual scenes are paired with verbal descriptions of individual objects. Fuse determines a set of visually salient words and phrases and associates them to a set of visual features. Given a new scene, Fuse uses the acquired knowledge to generate class-based language models conditioned on the objects present in the scene as well as a spatial language model that predicts the occurrences of spatial terms conditioned on target and landmark objects. The speech recognizer in Fuse uses a weighted mixture of these language models to search for more likely interpretations of user speech in context of the current scene. During decoding, the weights are updated using a visual attention model which redistributes attention over objects based on partially decoded utterances. The dynamic situationally-aware language models enable Fuse to jointly infer spoken language utterances underlying speech signals as well as the identities of target objects they refer to. In an evaluation of the system, visual situationally-aware language modeling shows significant , more than 30 %, decrease in speech recognition and understanding error rates. The underlying ideas of situation-aware speech understanding that have been developed in Fuse may may be applied in numerous areas including assistive and mobile human-machine interfaces.
by Niloy Mukherjee.
S.M.

This dissertation studies the context-aware application with its proposed algorithms at client side. The required context-aware infrastructure is discussed in depth to illustrate that such an infrastructure collects the mobile user’s context information, registers service providers, derives mobile user’s current context, distributes user context among context-aware applications, and provides tailored services. The approach proposed tries to strike a balance between the context server and mobile devices. The context acquisition is centralized at the server to ensure the usability of context information among mobile devices, while context reasoning remains at the application level. Hence, a centralized context acquisition and distributed context reasoning are viewed as a better solution overall. The context-aware search application is designed and implemented at the server side. A new algorithm is proposed to take into consideration the user context profiles. By promoting feedback on the dynamics of the system, any prior user selection is now saved for further analysis such that it may contribute to help the results of a subsequent search. On the basis of these developments at the server side, various solutions are consequently provided at the client side. A proxy software-based component is set up for the purpose of data collection. This research endorses the belief that the proxy at the client side should contain the context reasoning component. Implementation of such a component provides credence to this belief in that the context applications are able to derive the user context profiles. Furthermore, a context cache scheme is implemented to manage the cache on the client device in order to minimize processing requirements and other resources (bandwidth, CPU cycle, power). Java and MySQL platforms are used to implement the proposed architecture and to test scenarios derived from user’s daily activities. To meet the practical demands required of a testing environment without the impositions of a heavy cost for establishing such a comprehensive infrastructure, a software simulation using a free Yahoo search API is provided as a means to evaluate the effectiveness of the design approach in a most realistic way. The integration of Yahoo search engine into the context-aware architecture design proves how context aware application can meet user demands for tailored services and products in and around the user’s environment. The test results show that the overall design is highly effective,providing new features and enriching the mobile user’s experience through a broad scope of potential applications.

Thesis (S.M.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2002.
Includes bibliographical references (leaves 116-120).
In the present thesis I create and use wireless power as an alternative to replace wiring and batteries in certain new scenarios and environments. Two specific scenarios will be highlighted and discussed that motivated this research: The Interactive Electromechanical Necklace and the Wireless-Batteryless Electronic Sensors. The objective is to wirelessly gather energy from one RF source and convert it into usable DC power that is further applied to a set of low-power-demanding electronic circuits. This idea improves the accomplishments of Radio Frequency Identification (RFID) tags systems. The RF-to-DC conversion objective is accomplished by designing and characterizing an element commonly known as a Rectenna, which consists of an antenna and an associated rectification circuitry. The rectenna is fully characterized in this dissertation and it is used for powering electronic lights, sounds, transmitters, and different types of sensors as well. The wireless power transmission system is presented in the first place with the development of a special set of wearable beads for an interactive necklace. These beads allow physical interaction between the necklace and electronic elements placed in the environment. This scenario demonstrates that passive electronics without batteries are possible. Next I also design and implement low-power sensors that will use the energy delivered from the rectennas to perform active tasks. The switching sensor provides visual/audio feedback to the user when there's a change in the state of the sensed object (i.e. LEDs lit when a stapler runs out of staples); the humidity sensor permits monitoring the humidity in the soil of a flower pot. The sensor actively transmits the information of any of two possible stages (dry soil/humid soil) to its environment. This scenario extends the capabilities of common RFID tags, where not only they transmit information but also can react to their environment in an active fashion.
by Jorge Ulises Martinez Araiza.
S.M.

The continuous technical progress in mobile device built-in modules and embedded sensing techniques creates opportunities for context-aware mobile applications. The context-aware computing paradigm exploits the relevant context as implicit input to characterise the user and physical environment and provide a computing service customised to the contextual situation. However, heterogeneity in techniques, complexity of contextual situation, and gap between raw sensor data and usable context keep the techniques from truly integration for extensive use. Studies in this area mainly focus on feasibility demonstration of the emerging techniques, and they lack general architecture support and appropriate service customisation strategy. This investigation aims to provide general system architecture and technical approaches to deal with the heterogeneity problem and efficiently utilise the dynamic context towards proactive computing service that is customised to the contextual situation. The main efforts of this investigation are the approaches to gathering, handling, and utilising the dynamic context information in an efficient way and the decision making and optimisation methods for computing service customisation. In brief, the highlights of this thesis cover the following aspects: (1) a hierarchical context-aware computing architecture supporting interoperable distribution and further use of context; (2) an in-depth analysis and classification of context and the corresponding context acquisition methods; (3) context modelling and context data representation for efficient and interoperable use of context; (4) a rule-based service customisation strategy with a rule generation mechanism to supervise the service customisation. In addition, feasibility demonstration of the proposed system and contribution justification of this investigation are conducted through case studies and prototype implementations. One case study uses mobile built-in sensing techniques to improve the usability and efficiency of mobile applications constrained by resource limitation, and the other employs the mobile terminal and embedded sensing techniques to predict users’ expectations for home facility automatic control. Results demonstrate the feasibility of the proposed context handling architecture and service customisation methods. It shows great potential for employing the context of the computing environment for context-aware adaptation in pervasive and mobile applications but also indicates some underlying problems for further study.

To provide users with personalized adaptive services only using the accessible computing resources in a cloud environment, context aware applications need to assimilate both the accessed and derived context, i.e. a combination of more than one sensed data and information in the environment. Context data dependency, dependency that arises between the context data producer and consumer, may get introduced in a system due to numerous reasons. But as the number of context dependencies for a service increases, the more complex the system becomes to manage. The thesis addresses issues of how to identify context dependencies, represent such context dependencies and then reduce them in a system. In the first part of the thesis, we present two efficient approaches to determine context dependency relations among various services in ubiquitous computing environment to help better analyse the pervasive services. One approach is based on graph theory, and we have used the topological sort to determine the context dependencies. The second approach is based on solving constraint networks which determines whether an entity is affected when the state of a certain other entity has its state changed, i.e. determining the dynamic nature of context dependency. In the second part of the thesis, we present a mode for representation of context dependencies within a system. Our model that represents context dependencies is based on set theory and first-order predicate logic. The context dependency representation model also represents alternative sources for context acquisition that can be utilized in a case in which the preferred context producers are not available to service the desired context to the relevant context consumer any more. Further, we try to reduce the context dependencies by presenting the idea of profile context, which is based on the proposal of an open framework for context acquisition, management and distribution. This heuristic approach is based on the idea of utilizing mobile nodes in an ad hoc overlay network with more resources than the context producer itself to store various contextual information under the banner of profile context, and further, provide profile context instead of each context individually based on the queries the nodes receive from the context consumers. Bringing together the context information and context updates from various sources, support for context aware decisions can be implemented efficiently in a mobile environment by addressing the issues of context dependency using profile context

Desktops, laptops, smartphones, tablets, and the Kinect, oh my! With so many devices available to the average consumer, the limitations and pitfalls of each interface are becoming more apparent. Swimming in devices, users often have to stop and think about how to interact with each device to accomplish the current tasks at hand. The goal of this thesis is to minimize user cognitive effort in handling multiple devices by creating a context aware hybrid interface. The context aware system will be explored through the hybridization of gesture and touch interfaces using a multi-touch coffee table and the next-generation Microsoft Kinect. Coupling gesture and touch interfaces creates a novel multimodal interface that can leverage the benefits of both gestures and touch. The hybrid interface is able to utilize the more intuitive and dynamic use of gestures, while maintaining the precision of a tactile touch interface. Joining these two interfaces in an intuitive and context aware way will open up a new avenue for design and innovation.

De nos jours, la façon d'utiliser les applications mobiles dans le domaine des transports offre de nouveaux défis liés aux spécificités de l'environnement, comme la forte mobilité des terminaux, leur répartition, ou encore le réseau instable de communication. La plupart des applications existantes ont des contraintes de fonctionnement qui les rendent inadaptées si les conditions d'exécution évoluent rapidement. Cela rend intéressant l'utilisation d'un cadre unifié de conception et d'exécution, capable de gérer ces applications. Nos travaux portent, dans un premier temps, sur une étude des applications mobiles et de leur comportement, en fonction du contexte d'exécution. Nous considérons le cas des applications dédiées aux transports, conçues pour accompagner et assister un usager dans son déplacement (navigation, sécurité routière, applications des moyens de transports, etc.). Nous identifions les éléments du contexte propres aux applications fortement mobiles et les modélisons. Dans un second temps, nous proposons un cadre dynamique et sensible au contexte, permettant le déploiement de nouveaux services " à la volée " ainsi que leur adaptation pour une meilleure utilisation des ressources dans des milieux très évolutifs. Nous nous focalisons sur le côté réactif, permettant d'adapter le comportement des applications à leurs nouvelles conditions d'utilisation. Les applications sont décomposées en services de base avec un couplage lâche pour une plus grande flexibilité. Nous utilisons une architecture orientée service, qui permet la réutilisation des services communs à plusieurs applications mais aussi la gestion du contexte au travers de services équivalents mais capables de fonctionner dans des conditions différentes.Nous montrons, grâce au prototype de notre plateforme CATS (Context-Aware Transportation Services), d'abord la faisabilité d'une plateforme à services sur des terminaux portables. Nous testons ensuite plusieurs scénarios afin de démontrer la réactivité des adaptations aux changements de contexte. Dans cette thèse nous proposons une vue d'ensemble sur la création et la gestion des applications sensibles au contexte pour le domaine des transports. Le but de notre démarche est d'assurer le bon fonctionnement de l'ensemble des applications d'un utilisateur, malgré les changements dynamiques du contexte.

Computer Architecture is entering an era where hundreds of Processing Elements (PE) can be integrated onto single chips even as decades-long, steady advances in instruction, thread level parallelism are coming to an end. And yet, conventional methods of parallelism fail to scale beyond 4-5 PE's, well short of the levels of parallelism found in the human brain. The human brain is able to maintain constant real time performance as cognitive complexity grows virtually unbounded through our lifetime. Our underlying thesis is that contextual categorization leading to simplified algorithmic processing is crucial to the brains performance efficiency. But, since the overheads of such reorganization are unaffordable in real time, we also observe the critical role of sleep and dreaming in the lives of all intelligent beings. Based on the importance of dream sleep in memory consolidation, we propose that it is also responsible for contextual reorganization. We target mobile device applications that can be personalized to the user, including speech, image and gesture recognition, as well as other kinds of personalized classification, which are arguably the foundation of intelligence. These algorithms rely on a knowledge database of symbols, where the database size determines the level of intelligence. Essential to achieving intelligence and a seamless user interface however is that real time performance be maintained. Observing this, we define our chief performance goal as: Maintaining constant real time performance against ever increasing algorithmic and architectural complexities. Our solution is a method for Malleable Contextual Partitioning (MCP) that enables closer personalization to user behavior. We conceptualize a novel architectural framework, the Dream Architecture for Lateral Intelligence (DALI) that demonstrates the MCP approach. The DALI implements a dream phase to execute MCP in ideal MISD parallelism and reorganize its architecture to enable contextually simplified real time operation. With speech recognition as an example application, we show that the DALI is successful in achieving the performance goal, as it maintains constant real time recognition, scaling almost ideally, with PE numbers up to 16 and vocabulary size up to 220 words.
Master of Science

This thesis deals with Context Aware Services, Smart Environments, Context Management and solutions for Devices and Service Interoperability. Multi-vendor devices offer an increasing number of services and end-user applications that base their value on the ability to exploit the information originating from the surrounding environment by means of an increasing number of embedded sensors, e.g. GPS, compass, RFID readers, cameras and so on. However, usually such devices are not able to exchange information because of the lack of a shared data storage and common information exchange methods. A large number of standards and domain specific building blocks are available and are heavily used in today's products. However, the use of these solutions based on ready-to-use modules is not without problems. The integration and cooperation of different kinds of modules can be daunting because of growing complexity and dependency. In this scenarios it might be interesting to have an infrastructure that makes the coexistence of multi-vendor devices easy, while enabling low cost development and smooth access to services. This sort of technologies glue should reduce both software and hardware integration costs by removing the trouble of interoperability. The result should also lead to faster and simplified design, development and, deployment of cross-domain applications. This thesis is mainly focused on SW architectures supporting context aware service providers especially on the following subjects: - user preferences service adaptation - context management - content management - information interoperability - multivendor device interoperability - communication and connectivity interoperability Experimental activities were carried out in several domains including Cultural Heritage, indoor and personal smart spaces – all of which are considered significant test-beds in Context Aware Computing. The work evolved within european and national projects: on the europen side, I carried out my research activity within EPOCH, the FP6 Network of Excellence on “Processing Open Cultural Heritage” and within SOFIA, a project of the ARTEMIS JU on embedded systems. I worked in cooperation with several international establishments, including the University of Kent, VTT (the Technical Reserarch Center of Finland) and Eurotech. On the national side I contributed to a one-to-one research contract between ARCES and Telecom Italia. The first part of the thesis is focused on problem statement and related work and addresses interoperability issues and related architecture components. The second part is focused on specific architectures and frameworks: - MobiComp: a context management framework that I used in cultural heritage applications - CAB: a context, preference and profile based application broker which I designed within EPOCH Network of Excellence - M3: "Semantic Web based" information sharing infrastructure for smart spaces designed by Nokia within the European project SOFIA - NoTa: a service and transport independent connectivity framework - OSGi: the well known Java based service support framework The final section is dedicated to the middleware, the tools and, the SW agents developed during my Doctorate time to support context-aware services in smart environments.

This thesis proposed solutions to some shortcomings to current eLearning architectures. The proposed DeLC architecture supports context-aware and adaptable provision of eLearning services and electronic content. The architecture is fully distributed and integrates service-oriented development with agent technology. Central to this architecture is that a node is our unit of computation (known as eLearning node) which can have purely service-oriented architecture, agent-oriented architecture or mixed architecture. Three eLeaerning Nodes have been implemented in order to demonstrate the vitality of the DeLC concept. The Mobile eLearning Node uses a three-level communication network, called InfoStations network, supporting mobile service provision. The services, displayed on this node, are to be aware of its context, gather required learning material and adapted to the learner request. This is supported trough a multi-layered hybrid (service- and agent-oriented) architecture whose kernel is implemented as middleware. For testing of the middleware a simulation environment has been developed. In addition, the DeLC development approach is proposed. The second eLearning node has been implemented as Education Portal. The architecture of this node is poorly service-oriented and it adopts a client-server architecture. In the education portal, there are incorporated education services and system services, called engines. The electronic content is kept in Digital Libraries. Furthermore, in order to facilitate content creators in DeLC, the environment Selbo2 was developed. The environment allows for creating new content, editing available content, as well as generating educational units out of preexisting standardized elements. In the last two years, the portal is used in actual education at the Faculty of Mathematics and Informatics, University of Plovdiv. The third eLearning node, known as Agent Village, exhibits a purely agent-oriented architecture. The purpose of this node is to provide intelligent assistance to the services deployed on the Education Pportal. Currently, two kinds of assistants are implemented in the node - eTesting Assistants and Refactoring eLearning Environment (ReLE). A more complex architecture, known as Education Cluster, is presented in this thesis as well. The Education Cluster incorporates two eLearning nodes, namely the Education Portal and the Agent Village. eLearning services and intelligent agents interact in the cluster.

The design of a common architecture that can support multiple data-flow patterns (or contexts) embedded in complex control flow structures, in applications like multimedia processing, is particularly challenging when the target platform is a Field Programmable Gate Array (FPGA) with a heterogeneous mixture of device primitives. This thesis presents scheduling and mapping algorithms that use a novel area cost metric to generate resource aware context adaptable architectures. Results of a rigorous analysis of the methodology on multiple test cases are presented. Results are compared against published techniques and show an area savings and execution time savings of 46% each.

Considering that irrigation occupies the major percentage of consumed water in agriculture and that Brazil intends to expand considerably its irrigated area in the coming decades, there is a growing need in improving the irrigation water management, mostly in regions with limited availability of water or occurrences of hydric deficiency periods. Therefore, the increase of technologies for performing irrigation using environmental information is becoming important because they enable the maximization of water and energy consumption, maintaining or even improving the yield and quality of agricultural production. This work proposes a context-aware remote sensing architecture for irrigation and its contributions are: (a) the development of two prototypes of a moisture and precipitation meter based on the proposed architecture using open hardware technologies; (b) the development of a context taxonomy that defines the types of information that can be used in the prototype s architecture; and (c) a comparison between two different types of soil moisture sensors. For the validation of the architecture, two case studies were realized to verify the correct functioning of the architecture components, as well as a data collection was performed to make the comparison between a resistive low-cost sensor produced at the Federal University of Santa Maria, and a high-accuracy and high-cost frequency domain reflectometry (FDR) sensor (CS616 - Campbell Scientific, United States). The results obtained from the analyzed data were satisfactory, where it was verified that the architecture is viable, meeting the requirements to which it has proposed. In addition, the comparison performed showed a determination coefficient of up to 95 % between the low-cost resistive soil moisture sensors and the soil moisture sensors CS616 of Campbell R .
Considerando que a irrigação ocupa a maior porcentagem da água consumida na agricultura, e que o Brasil pretende expandir consideravelmente a sua área irrigada nas próximas décadas, há uma crescente necessidade de melhorar o manejo da água de irrigação, principalmente em regiões com reduzida disponibilidade de água ou ocorrência de períodos de deficiência hídrica. Por isso, o incremento de tecnologias na realização da irrigação utilizando-se de informações referentes ao ambiente, estão tornando-se importantes por permitirem a maximização do uso da água e energia, mantendo, ou mesmo melhorando, o rendimento e a qualidade da produção agrícola. Este trabalho propõe uma arquitetura de sensoriamento remoto sensível ao contexto para irrigação, e suas contribuições são: (a) o desenvolvimento de dois protótipos de um medidor de umidade e pluviometria baseados na arquitetura proposta utilizando tecnologias open hardware; (b) o desenvolvimento de uma taxonomia de contextos que define os tipos de informações que podem ser utilizadas na arquitetura dos protótipos; e (c) uma comparação entre dois tipos distintos de sensores de umidade do solo. Para a validação da arquitetura, foram realizados dois estudos de caso para verificar o correto funcionamento dos componentes da arquitetura, bem como a coleta de dados para efetuar a comparação entre um sensor resistivo de baixo custo produzido na Universidade Federal de Santa Maria, e um sensor de alta precisão e custo que utiliza a técnica de reflectometria no domínio da frequência (FDR) (CS616 - Campbell Scientific, Estados Unidos). Os resultados obtidos com os dados analisados foram satisfatórios, onde verificou-se que a arquitetura atende aos requisitos aos quais se propôs. Além disso, a comparação realizada apresentou coeficientes de determinação de até 95% entre os sensores resistivos de umidade do solo de baixo custo e os sensores de umidade do solo CS616 da Campbell R .

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 2004.
Includes bibliographical references (leaves 59-60).
Architectural interior spaces provide a rich syntax for context-aware modeling. In a wireless wide area network (WAN), an urban environment can be geographically tessellated into a series of polygons reflecting the radio transmission range of each wireless access point (AP). By using these APs as spatial aggregation units in a relational database, logical assumptions about short-term behavioral patterns can be modelled; this paper describes a method to capture, encode, and interpret context-aware cues. These cues are then utilized by an intranet web server to produce context-aware output, information that fits the client's short-term activity landscape and intentions. The method does not require any special client-side software and preserves the user's anonymity as it derives the client's physical location implicitly. Such a framework permits a new type of context-aware web interaction based upon the logical "common sense" patterns that are specific to architectural interior spaces at a given time.
by Napier Sandford Fuller.
S.M.

In this dissertation, we propose service-oriented sensor-actuator networks (SOSANETs) as a new paradigm for building the next generation of customizable, open, interoperable sensor-actuator networks. In SOSANETs, nodes expose their capabilities to applications in the form of service profiles. A node's service profile consists of a set of services (i.e., sensing and actuation capabilities) that it provides and the quality of service (QoS) parameters associated with those services (delay, accuracy, freshness, etc.). SOSANETs provide the benefits of both application-specific SANETs and generic SANETs. We first define a query model and an architecture for SOSANETs. The proposed query model offers a simple, uniform query interface whereby applications specify sensing and actuation queries independently from any specific deployment of the underlying SOSANET. We then present uRACER (Reliable Adaptive serviCe-driven Efficient Routing), a routing protocol suite for SOSANETs. uRACER consists of three routing protocols, namely, SARP (Service-Aware Routing Protocol), CARP (Context-Aware Routing Protocol), and TARP (Trust-Aware Routing Protocol). SARP uses an efficient service-aware routing approach that aggressively reduces downstream traffic by translating service profiles into efficient paths. CARP supports QoS by dynamically adapting each node's routing behavior and service profile according to the current context of that node, i.e. number of pending queries and number and type of messages to be routed. Finally, TARP achieves high end-to-end reliability through a scalable reputation-based approach in which each node is able to locally estimate the next hop of the most reliable path to the sink. We also propose query optimization techniques that contribute to the efficient execution of queries in SOSANETs. To evaluate the proposed service-oriented architecture, we implemented TinySOA, a prototype SOSANET built on top of TinyOS with uRACER as its routing mechansim. TinySOA is designed as a set of layers with a loose interaction model that enables several cross-layer optimization options. We conducted an evaluation of TinySOA that included a comparison with TinyDB. The obtained empirical results show that TinySOA achieves significant improvements on many aspects including energy consumption, scalability, reliability and response time.
Ph. D.

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Dey et al. [10] define context as the information set that can be used to characterize the status of an entity (e.g. person, place or object relevant to the user-application interaction). Perera et al. [36] propose a context information life cycle in 4 phases: acquisition, modeling, reasoning and dissemination. Context modeling consists in representing the real world in computing and, according to Bettini et al. [2], a good information context modeling mitigates the complexity of context-aware applications. In the context of this work, a systematic review demonstrated that the literature has focused on context information modeling, but with less emphasis on the architectural project. The main problem addressed on this work is the creation and evaluation of architectural projects that work together on the context modeling phase of a Semantic Context-Aware System (SCAS), which uses ontologies as main information modeling technique. This work proposes an architectural solution to two relevant services of the ontology-based context modeling phase: the former represents context information collected through sensors, and the latter aggregates context information represented by the former for a same individual or entity. Both architectural designs were built using well-known architectural styles and design patterns, as well as were evaluated against architectural designs of similar projects. As a result, the main contributions include the architectural designs of ontology-based services for context representation and aggregation as references for the development of SCAS in terms of the context modeling phase.
Contexto é o conjunto de informações que pode ser utilizado para caracterizar a situação de uma entidade (pessoa, lugar ou objeto relevante para a interação usuário-aplicação) [10]. Perera et al. [36] propõem um ciclo de vida para a informação de contexto composto por 4 etapas: aquisição, modelagem, raciocínio e disseminação. A etapa de modelagem de contexto consiste em representar o mundo real na computação. Segundo Bettini et. al. [2] “uma boa modelagem de informação de contexto reduz a complexidade das aplicações sensíveis a contexto”. Um Sistema Sensível ao Contexto Semântico (SSCS) é um sistema computacional que utiliza ontologias que, segundo Gruber [15], é “uma especificação explícita de uma conceitualização”, e consistem em uma das formas de modelar as informações de contexto. Como resultado de uma revisão sistemática feita pelo autor deste trabalho evidenciou que na literatura o foco dos trabalhos tem sido na modelagem da informação de contexto com menor enfoque no uso de projeto arquitetural. Com base nisso, o principal problema endereçado neste trabalho é a criação e avaliação dos projetos arquiteturais que trabalhem em conjunto na modelagem do ciclo de vida de contexto em SSCS. Objetiva-se elaborar uma solução arquitetural para sistemas sensíveis ao contexto semântico baseado em ontologias. Propôs-se neste trabalho o projeto arquitetural para o software de representação ontológica de contexto e para o software de agregação ontológica de contexto. O primeiro representa as informações coletadas através de sensores e o segundo agrega as informações representadas para um mesmo indivíduo ou entidade. Realizou-se, assim, a avaliação dos projetos arquiteturais propostos e explana-se sobre os resultados obtidos, comparando-os com outros projetos existentes na literatura. Com a obtenção dos resultados propostos, espera-se contribuir com a literatura, apresentando projetos arquiteturais e avaliações destes, auxiliando, assim, o desenvolvimento de SSCS no que se refere à modelagem do ciclo de vida de contexto.

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2008.
Title from title screen (site viewed Nov. 25, 2008). PDF text: xiii, 173 p. : ill. ; 2 Mb. UMI publication number: AAT 3315261. Includes bibliographical references. Also available in microfilm and microfiche formats.

碩士
國立政治大學
資訊管理研究所
94
With the popularity of the Wireless LAN, mobile workers are able to access various services or resources with seamless roaming, as well as mobile VPN, just via their handheld devices. Not only for the corporations but the Internet Service Providers(ISP), a secure and trusted remote access is required. User identity should be authenticated in advance, and the service providers grant or deny mobile users the access to resources according to their statuses. Besides, a usage-based accounting and billing is crucial to provide commercialized services within WLAN, and to benefit those service providers. As a result, a AAA architecture designed for coordinating the authentication, authorization and accounting between different administrative networks is required with urgent need. The objective of this research is to provide a context-aware based AAA architecture which adopts context as the design principle to define access control policies. So the system can detect the changing contexts of mobile workers, re-authenticate user identity, adjust dynamically service permissions in the light of context-based access control policies, and bill the user taking into account the contexts efficiently. In this research, we take examples of roaming services and VPN to describe how the architecture works.

This thesis deals with the problem of interaction with context-aware mobile applications in digitally augmented physical spaces. The term "mobile application" is used as an umbrella term for any piece of software that can run on a mobile device in order to support a human task. “Context-aware” refers to the ability of such applications to use information about the environment or the user to adapt their behaviour accordingly. A "physical hyperlink" is a mechanism that associates a physical object or point in space with digital information/service(s). The term “digitally augmented physical space” refers here to a physical space where digital information relevant to points or artefacts can be accessed (e.g. by means of physical hyperlinks). In the last two decades mobile devices and applications have developed tremendously. With them, on one hand new ways appeared to support human tasks and on the other hand new research challenges emerged. A key factor is the continuous change of environment and context of use. This is very different to a classic desktop computer application, in which the external environment is hardly changing, as the user and the computer do not change location during interaction. In the world of mobile computing the environment and the context of use are changing, at a faster rate. One of the most widely spread mobile devices, the mobile phone, evolved into a powerful mobile computing device. These advanced devices are now ubiquitously spread and already billions of people carry and use them daily. New services and uses are emerging with every step of evolution of this technology. However these rapidly emerging and evolving technologies and services result in a generally heterogeneous environment that affects user experience. The advances in mobile technology permitted devices to be equipped with sensors and hardware that allow on one hand the acquisition of information from the environment and on the other hand interaction with objects like physical hyperlinks, that permit direct access to information related to physical artefacts. In the frame of this thesis a conceptual framework (MobiAct framework) and a service oriented architecture (MobiAct architecture) have been defined. The MobiAct framework deals with the interaction with context-aware mobile applications in a digitally augmented physical space. The MobiAct framework has as a goal to identify the main concepts that come into play while interacting with context-aware applications in digitally augmented physical spaces. MobiAct architecture is an innovative solution for delivering context-aware mobile services in digitally augmented physical spaces. The MobiAct architecture has MobiAct framework as the underlying base. The architecture aims at enabling a uniform and consistent user experience across spaces and contexts and at facilitating the design and development of context-aware mobile services by providing ready functionality for common tasks. Finally a set of software architectural patterns relevant to designing mobile context-aware applications have been identified. These patterns provide a set of building blocks to facilitate the design and development of similar systems. The road towards designing MobiAct conceptual architecture and framework for interacting with context-aware mobile applications included the development and evaluation of several prototypes mainly targeted at public and semi-public environments. These prototypes contributed in a great degree towards exploring and studying context-aware mobile applications and interaction with digitally augmented physical spaces using physical hyperlinks and subsequently defining the requirements for the architecture. To avoid binding the architecture to capabilities of a certain platform, the prototypes involved different devices and platforms. The prototypes and applications developed included educational games and a guide for a museum, an application to support users of a library and a shopping assistant aimed at a supermarket environment. The findings of these efforts contributed in the definition of the MobiAct architecture that has been evaluated through a software architecture analysis method based on scenarios and discussions involving representative stakeholders as well as an evaluation team
Αυτή η διατριβή πραγματεύεται το πρόβλημα της αλληλεπίδρασης μεταξύ χρηστών και εφαρμογών φορητών συσκευών με επίγνωση του πλαισίου, σε ψηφιακά επαυξημένους φυσικούς χώρους. Ο όρος "εφαρμογή φορητής συσκευής", ή “φορητή εφαρμογή”, χρησιμοποιείται ως όρος που περικλείει κάθε λογισμικό που μπορεί να εκτελεστεί σε μια φορητή συσκευή έτσι ώστε να υποστηρίξει μια ανθρώπινη εργασία (task). Ο όρος "πλαισιογνωστικός" αναφέρεται στη δυνατότητα τέτοιων εφαρμογών να χρησιμοποιήσουν πληροφορίες σχετικές με το άμεσο περιβάλλον ή με το χρήστη ώστε να προσαρμόσουν τη συμπεριφορά τους κατάλληλα. Ένας "φυσικός υπερσύνδεσμος" είναι ένας μηχανισμός που συσχετίζει ένα φυσικό αντικείμενο ή σημείο στο χώρο με ψηφιακή πληροφορία ή ψηφιακή υπηρεσία. Ο όρος "ψηφιακά επαυξημένος χώρος" αναφέρεται σε ένα φυσικό χώρο από όπου είναι προσβάσιμη ψηφιακή πληροφορία που σχετίζεται με σημεία ή αντικείμενα του χώρου (π.χ. μέσω φυσικών υπερσυνδέσμων). Τις τελευταίες δύο δεκαετίες οι φορητές συσκευές και εφαρμογές έχουν εξελιχθεί εντυπωσιακά. Μαζί τους εμφανίστηκαν νέοι τρόποι υποστήριξης ανθρώπινων εργασιών και παράλληλα παρουσιάστηκαν και νέα ερευνητικά προβλήματα. Ένας σημαντικός παράγοντας είναι η συνεχής αλλαγή του περιβάλλοντος στο οποίο γίνεται η χρήση και του πλαισίου επίγνωσης της χρήσης. Αυτό διαφέρει πολύ από τις κλασικές εφαρμογές υπολογιστών, όπου το εξωτερικό περιβάλλον αλλάζει ελάχιστα καθώς ο χρήστης και ο υπολογιστής δεν μεταβάλλουν τη θέση τους στη διάρκεια της αλληλεπίδρασης. Στον κόσμο των φορητών υπολογιστών το περιβάλλον και το πλαίσιο επίγνωσης αλλάζουν με γρηγορότερο ρυθμό. Μια από τις πιο ευρέως διαδεδομένες φορητές συσκευές, το κινητό τηλέφωνο, εξελίχθηκε σε μια ισχυρή φορητή υπολογιστική συσκευή. Αυτές οι εξελιγμένες συσκευές είναι σήμερα διάχυτες και δισεκατομμύρια ανθρώπων τις κουβαλούν και χρησιμοποιούν καθημερινά. Νέες υπηρεσίες και χρήσεις εμφανίζονται με κάθε βήμα εξέλιξης αυτής της τεχνολογίας. Ωστόσο αυτές οι ταχέως εμφανιζόμενες και εξελισσόμενες τεχνολογίες και υπηρεσίες καταλήγουν να δημιουργήσουν ένα γενικώς ετερογενές περιβάλλον, πράγμα το οποίο επηρεάζει την εμπειρία της χρήσης τους. Οι εξελίξεις στη φορητή τεχνολογία επέτρεψαν στις συσκευές αυτές να εξοπλισθούν με αισθητήρες και υλικό το οποίο επιτρέπει τη συλλογή πληροφοριών από το περιβάλλον και επίσης την αλληλεπίδραση με αντικείμενα όπως είναι οι φυσικοί υπερσύνδεσμοι, οι οποίοι επιτρέπουν την άμεση πρόσβαση σε πληροφορία που σχετίζεται με τα φυσικά αντικείμενα. Στο πλαίσιο αυτής της εργασίας ορίστηκε ένα εννοιολογικό πλαίσιο (πλαίσιο εργασίας MobiAct) και μια υπηρεσιοκεντρική αρχιτεκτονική (service oriented architecture) (αρχιτεκτονική MobiAct). Το πλαίσιο εργασίας MobiAct αφορά την αλληλεπίδραση με πλαισιογνωστικές φορητές εφαρμογές σε ψυφιακά επαυξημένους φυσικούς χώρους. Η αρχιτεκτονική MobiAct έχει ως στόχο τον εντοπισμό των βασικών σημείων της αλληλεπίδρασης με πλαισιογνωστικές εφαρμογές σε ψηφιακά επαυξημένους φυσικούς χώρους. Η αρχιτεκτονική MobiAct είναι μια πρωτοποριακή λύση για την παροχή πλαισιογνωστικών υπηρεσιών σε ψηφιακά επαυξημένους φυσικούς χώρους. Η βάση της αρχιτεκονικής MobiAct είναι το πλαίσιο εργασίας MobiAct. Η αρχιτεκτονική στοχεύει στην πραγμάτωση μιας ομοιόμορφης και συνεπούς εμπειρίας χρήστη διαμπάξ σε διάφορους φυσικούς χώρους και πλαίσια επίγνωσης και στη διευκόλυνση της ανάπτυξης πλαισιογνωστικών φορητών υπηρεσιών (μέσω της παροχής λειτουργικότητας για εργασίες που επαναλαμβάνονται συχνά). Τέλος έχει εντοπιστεί ένα σύνολο αρχιτεκτονικών προτύπων για το σχεδιασμό φορητών πλαισιογνωστικών εφαρμογών. Αυτά τα πρότυπα συγκροτούν μια ομάδα καλουπιών που διευκολύνουν το σχεδιασμό και την ανάπτυξη παρεμφερών συστημάτων. Η πορεία προς το σχεδιασμό του πλαισίου και της αρχιτεκτονικής MobiAct για την αλληλεπίδραση με φορητές πλαισιογνωστικές εφαρμογές συμπεριέλαβε το σχεδιασμό και την ανάπτυξη αρκετών πρωτοτύπων τα οποία στόχευαν κυρίως σε δημόσια ή ημι-δημόσια περιβάλλοντα. Αυτά τα πρωτότυπα συνέβαλαν σε μεγάλο βαθμό στην εξερεύνηση και στη μελέτη των πλαισιογνωστικών φορητών εφαρμογών και της αλληλεπίδρασης με ψηφιακά επαυξημένους φυσικούς χώρους μέσω φυσικών υπερσυνδέσμων και τελικά στον ορισμό των απαιτήσεων για την αρχιτεκτονική. Για την αποφυγή της υπερβολικής συσχέτισης της αρχιτεκτονικής με τις δυνατότητες μιας συγκεκριμένης πλατφόρμας, τα πρωτότυπα συμπεριέλαβαν διάφορες συσκευές και πλατφόρμες. Τα πρωτότυπα και οι εφαρμογές που αναπτύχθηκαν περιλαμβάνουν εκπαιδευτικές εφαρμογές και έναν πλοηγό για ένα μουσείο, μια εφαρμογή για την υποστήριξη των επισκεπτών μιας βιβλιοθήκης καθώς και έναν βοηθό αγορών σε περιβάλλον σούπερ μάρκετ. Τα ευρήματα αυτών των προσπαθειών συνέβαλλαν στον ορισμό της αρχιτεκτονικής MobiAct η οποία αξιολογήθηκε χρησιμοποιώντας μια μεθοδολογία ανάλυσης αρχιτεκτονικών λογισμικού που βασίζεται σε σενάρια και συζητήσεις με αντιπροσωπευτικούς συμμετόχους καθώς και με μια ομάδα αξιολόγησης.

碩士
國立東華大學
資訊工程學系
103
With the rapid development of mobile devices and micro-electro-mechanical systems, our living world is filled with sensors. With their help, we can discover the status of users and their surroundings when need. Following the expansion of such devices and sensors, the technology of context-awareness grows fast. We can see many context-aware services or applications nowadays. And with the push of Internet of Things in recent years, there will be more and more things that can provide context information in our daily life. This will certainly bring out more context-aware applications, and smart home is one of the most popular among them. However, when developing a context-aware system or application, a developer needs to handle different kinds of context information. Contexts need to be processed to properly describe the whole situation, and then the developer can use them in his application. To simplify the processing works, we propose a three-layered tuple space architecture for context storing, combination and abstraction, and then implemented it with JavaSpaces. We provide several APIs and class libraries based on JavaSpaces to help developing context-aware applications. We also provide a modular architecture and a development flow for developing applications with our implementation. Finally, we developed three different smart home applications to assess the usefulness of the architecture we proposed, and to evaluate the performance of the system.

This thesis explores the field of context-aware information systems (CAIS). We present an approach called Compose, Learn, and Discover (CLD) to incorporate CAIS into the user daily workflow. The CLD approach is self-adjusting. It enables users to personalise the information views for different situations. The CAIS learns about the usage of the information views and recalls the right view in the right situation. We illustrate the CLD approach through an application in the health care field using the Clinical Document Architecture (CDA). In order to realise the CLD approach, we introduce Semantic Composition as a new paradigm to personalise information views. Semantic Composition leverages the type information in the domain model to simplify the user-interface composition process. We also introduce a pattern discovery mechanism that leverages data-mining algorithms to discover correlations between user information needs and different situations.