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<p>This research concerns exploiting knowledge of the user's environment (i.e., context information) to enrich a user's communication making it more personal, by ensuring that the user receives only relevant messages and calls in his/her current context, and to facilitate more opportunities for communication interactions with people that are in the same context and that share the same interests as this user. We describe in this licentiate thesis the concepts of context-addressed messaging and context-aware session control that enable users to: (1) send messages to others based on their context, rather than their network address and (2) to initiate, adapt, and terminate user's communication sessions based on this user's current context, respectively. These concepts address questions such as: how to discover, select, and switch to an optimal communication means to meet varying user, contextual, communication, and device resource requirements and preferences. A key to solving these problems is to create a representation of the user's context-dependent preferences and to process the user's context-dependent preferences which are part of context triggers. These context triggers can initiate a communication event upon a particular context update. Additionally, in order to provide the described context-aware communication functions, these mechanisms need timely access to the acquired (desired) context information. This in turn raises a plethora of other questions, such as how to discover sensors that provide the desired context information; how to acquire raw context data from these sensors; how to abstract, process, and model this data to become "understandable" to applications and system components; and how to distribute this context to applications that are running on different nodes.</p><p> </p><p>This research is split into three different parts. The first part concerns investigating and implementing context management functions. As part of this research we propose a novel approach for context synthesis using context operators. We also propose a design architecture for context-aware middleware that mediates between the sensors and applications, and that is able to share and retrieve context from other nodes in the network. The second part of our research concerns our proposed mechanism for context-addressed messaging. To implement this mechanism we designed our own message format, called the Common Profile for Context-Addressed Messaging (CPCAM) that is able to use any high level context to compose a context-based address. Additionally, we proposed to use context-based filtering to find the correct message recipients and determine if this message is relevant to these potential message recipients in their current context, as well as to deliver this message to the recipients' preferred device that is adapted using their preferred communication means. At the end of this second part we design context-addressed messaging system operations on top of a SIP and SIMPLE-based network infrastructure. The third part of our research describes context-aware session control mechanisms using context switch and context trigger constructs. A context-switch selects an action from a set of context-dependent actions upon an incoming communication event based on the receiver's current context. In contrast, a context trigger initiates an action based on a context update and the user's preferences that are specified in this updated context. This part illustrates in several examples the context-aware session control mechanisms, i.e. the initiation of a communication session based on the match of a user's preferences and current context, as well as adaptation and (if necessary) termination of an ongoing communication session based upon the user's context-dependent preferences.</p><p> </p><p>The research leading to this licentiate has created network and system level models necessary for implementation of a context-addressed communication system that would enable users to easily design their own personalized, context-aware communication services. The necessary constructs and properties of these models are designed and analyzed in the thesis, as well as in conference papers and other documents published in the process of doing the research for this thesis. A number of remaining open issues and challenges have been outlined as part of the future work.</p><p> </p> / EU FP6 MIDAS (Middleware Platform for Developing and Deploying Advanced Mobile Services) / EU FP6 MUSIC (Self-adapting Applications for Mobile Users In Ubiquitous Computing Environments)

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-04-17T21:35:20Z No. of bitstreams: 1 DanielAlencarDaCosta_TESE.pdf: 9198560 bytes, checksum: 463f875eda2671bd33beca615f72eef3 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-04-18T22:34:50Z (GMT) No. of bitstreams: 1 DanielAlencarDaCosta_TESE.pdf: 9198560 bytes, checksum: 463f875eda2671bd33beca615f72eef3 (MD5) / Made available in DSpace on 2017-04-18T22:34:50Z (GMT). No. of bitstreams: 1 DanielAlencarDaCosta_TESE.pdf: 9198560 bytes, checksum: 463f875eda2671bd33beca615f72eef3 (MD5) Previous issue date: 2017-02-08 / The timely delivery of addressed software issues (i.e., bug fixes, enhancements, and new features) is what drives software development. Previous research has investigated what impacts the time to triage and address (or fix) issues. Nevertheless, even though an issue is addressed, i.e., a solution is coded and tested, such an issue may still suffer delay before being delivered to end users. Such delays are frustrating, since end users care most about when an addressed issue is available in the software system (i.e, released). In this matter, there is a lack of empirical studies that investigate why addressed issues take longer to be delivered compared to other issues. In this thesis, we perform empirical studies to understand which factors are associated with the delayed delivery of addressed issues. In our studies, we find that 34% to 98% of the addressed issues of the ArgoUML, Eclipse and Firefox projects have their integration delayed by at least one release. Our explanatory models achieve ROC areas above 0.74 when explaining delivery delay.We also find that the workload of integrators and the moment at which an issue is addressed are the factors with the strongest association with delivery delay.We also investigate the impact of rapid release cycles on the delivery delay of addressed issues. Interestingly, we find that rapid release cycles of Firefox are not related to faster delivery of addressed issues. Indeed, although rapid release cycles address issues faster than traditional ones, such addressed issues take longer to be delivered.Moreover, we find that rapid releases deliver addressed issues more consistently than traditional ones. Finally, we survey 37 developers of the ArgoUML, Eclipse, and Firefox projects to understand why delivery delays occur. We find that the allure of delivering addressed issues more quickly to users is the most recurrent motivator of switching to a rapid release cycle.Moreover, the possibility of improving the flexibility and quality of addressed issues is another advantage that are perceived by our participants. Additionally, the perceived reasons for the delivery delay of addressed issues are related to decision making, team collaboration, and risk management activities. Moreover, delivery delay likely leads to user/developer frustration according to our participants. Our thesis is the first work to study such an important topic in modern software development. Our studies highlight the complexity of delivering issues in a timely fashion (for instance, simply switching to a rapid release cycle is not a silver bullet that would guarantee the quicker delivery of addressed issues).

This research concerns exploiting knowledge of the user's environment (i.e., context information) to enrich a user's communication making it more personal, by ensuring that the user receives only relevant messages and calls in his/her current context, and to facilitate more opportunities for communication interactions with people that are in the same context and that share the same interests as this user. We describe in this licentiate thesis the concepts of context-addressed messaging and context-aware session control that enable users to: (1) send messages to others based on their context, rather than their network address and (2) to initiate, adapt, and terminate user's communication sessions based on this user's current context, respectively. These concepts address questions such as: how to discover, select, and switch to an optimal communication means to meet varying user, contextual, communication, and device resource requirements and preferences. A key to solving these problems is to create a representation of the user's context-dependent preferences and to process the user's context-dependent preferences which are part of context triggers. These context triggers can initiate a communication event upon a particular context update. Additionally, in order to provide the described context-aware communication functions, these mechanisms need timely access to the acquired (desired) context information. This in turn raises a plethora of other questions, such as how to discover sensors that provide the desired context information; how to acquire raw context data from these sensors; how to abstract, process, and model this data to become "understandable" to applications and system components; and how to distribute this context to applications that are running on different nodes.   This research is split into three different parts. The first part concerns investigating and implementing context management functions. As part of this research we propose a novel approach for context synthesis using context operators. We also propose a design architecture for context-aware middleware that mediates between the sensors and applications, and that is able to share and retrieve context from other nodes in the network. The second part of our research concerns our proposed mechanism for context-addressed messaging. To implement this mechanism we designed our own message format, called the Common Profile for Context-Addressed Messaging (CPCAM) that is able to use any high level context to compose a context-based address. Additionally, we proposed to use context-based filtering to find the correct message recipients and determine if this message is relevant to these potential message recipients in their current context, as well as to deliver this message to the recipients' preferred device that is adapted using their preferred communication means. At the end of this second part we design context-addressed messaging system operations on top of a SIP and SIMPLE-based network infrastructure. The third part of our research describes context-aware session control mechanisms using context switch and context trigger constructs. A context-switch selects an action from a set of context-dependent actions upon an incoming communication event based on the receiver's current context. In contrast, a context trigger initiates an action based on a context update and the user's preferences that are specified in this updated context. This part illustrates in several examples the context-aware session control mechanisms, i.e. the initiation of a communication session based on the match of a user's preferences and current context, as well as adaptation and (if necessary) termination of an ongoing communication session based upon the user's context-dependent preferences.   The research leading to this licentiate has created network and system level models necessary for implementation of a context-addressed communication system that would enable users to easily design their own personalized, context-aware communication services. The necessary constructs and properties of these models are designed and analyzed in the thesis, as well as in conference papers and other documents published in the process of doing the research for this thesis. A number of remaining open issues and challenges have been outlined as part of the future work. / EU FP6 MIDAS (Middleware Platform for Developing and Deploying Advanced Mobile Services) / EU FP6 MUSIC (Self-adapting Applications for Mobile Users In Ubiquitous Computing Environments)

In this qualitative research study, I use case studies to analyze the rhetorical understanding students have about online audiences, including how this understanding informs writerly choices, primarily in digital, self-sponsored writing. In this study I found that, while anxieties about online writing do exist, there are also many benefits for online writers that cause these anxieties to lessen. In addition, findings indicated that participants didn't always know how to correctly interpret and capitalize on audience feedback, which causes challenges, but these participants also claimed rhetorical power once they entered community spaces they cared about and better understood their purpose and roles as writers in those spaces. These findings contribute to composition pedagogy because they suggest areas for growth in the high school classroom, such as learning how to manage multiple audiences, how to best interpret feedback, and how to claim authority as young writers in unfamiliar rhetorical situations.

A wireless local area network (WLAN) provides high bandwidth to users in a limited geographical area. This network faces certain challenges and constraints that are not imposed on their wired counterparts. They are: frequency allocation, interference and reliability, security, power consumption, human safety, mobility, connection to wired LAN,service area, handoff and roaming, dynamic configuration and the throughput. But the wireless medium relies heavily on the features of MAC protocol and the MAC protocol is the core of medium access control for WLANs. The available MAC protocols all have their own merits and demerits. In our research works, we propose a hybrid MAC protocol forWLAN. In the design, we have combined the merits of the TDMA and CDMA systems to improve the throughput of the WLAN in a picocellular environment. We have used the reservation and polling methods of MAC protocols to handle both the low and high data traffics of the mobile users. We have strictly followed the standards specified by IEEE 802.11 for WLANs to implement the designed MAC protocol. We have simulated the hybrid TDMA/CDMA based MAC protocols combined with RAP (Randomly Addressed Polling) for Wireless Local Area Networks. We have developed a closed form mathematical expressions analytically for this protocol. We have also studied the power control aspects in this environment and we derived a closed form mathematical expressions analytically for this power control technique. This hybrid protocol is capable of integrating different types of traffic (like CBR,VBR and ABR services) and compiles with the requirements of next-generation systems.The lower traffic arrival is dealt with the Random Access and the higher traffic arrival is with the Polling methods. This enables us to obtain higher throughput and lowmean delay performance compared to the contention-reservation-based MAC schemes. The protocol offers the ability to integrate different types of services in a flexible way by the use of multiple slots per frame, while CDMA allows multiple users to transmit simultaneously using their own codes. The RAP uses an efficient "back-off" algorithm to improve throughput at higher arrival rates of user's data. The performance is evaluated in terms of throughput, delay, and rejection rate using computer simulation. A detailed simulation is carried out regarding the maximum number of users that each base station can support on a lossy channel. This work has analyzed the desired user's signal quality in a single cell CDMA (Code Division Multiple Access) system in the presence of MAI (Multiple Access Interference). Earlier power control techniques were designed to assure that all signals are received with equal power levels. Since these algorithms are designed for a imperfect control of power, the capacity of the system is reduced for a given BER (Bit-Error Rate). We proposed an EPCM (Efficient Power Control Mechanism) based system capacity which is designed for the reverse link (mobile to base station) considering the path loss, log-normal shadowing and Rayleigh fading. We have simulated the following applications for the further improvement of the performance of the designed MAC protocol:Designed protocol is tested under different traffic conditions. The protocol is tested for multimedia traffic under application oriented QoS requirements. Buffer Management and resource allocation. Call Admission Control (hand-offs, arrival of new users). The adaptability to the variable nature of traffic.The propagation aspects in the wireless medium. The proposed MAC protocol has been simulated and analysed by using C++/MATLAB Programming in IBM/SUN-SOLARIS UNIX environment. The results were plotted using MATLAB software. All the functions of the protocol have been tested by an analysis and also by simulation. Call admission control function of the protocol has been tested by simulation and analysis in a multimedia wireless network topology and from analysis we found that at low traffic the throughput is high and at high traffic the throughput is kept constant at a reasonable high value. The simulation results also justify/ coordinate the analysis results. Dynamic channel allocation function of the protocol was tested and analysed and the coordinated results show that at low traffic, high throughput and at high traffic the throughput is constant. Buffer management function of the protocol simulation shows the results that the packet loss can be controlled to a minimum by adjusting the buffer threshold level at any traffic conditions. Maintenance of data transfer during the hand-offs function was simulated and the results show that the blocked calls are less during low traffic and at high traffic the blocked calls can be kept constant at low value. Thus, the proposed model aimed at having high throughput, high spectral efficiency, low delay, moderate BER and moderate blocking probability. We have considered a pico cell with a maximum of several users and studied the power efficiency of combined channel coding and modulation with perfect power controlled CDMA system. Thus our simulation of the "software radio" has flexibility in choosing the proper channel coders dynamically depending upon the variations of AWGN channel.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / A utilizaÃÃo de vetores de bits à prÃtica corrente na representaÃÃo de conjuntos por endereÃamento direto com o intuito de reduzir o espaÃo de memÃria necessÃrio e melhorar o desempenho de aplicaÃÃes com uso de tÃcnicas de paralelismo em bits. Nesta dissertaÃÃo, examinamos implementaÃÃes para representaÃÃo de conjuntos por endereÃamento direto. A estrutura bÃsica nessas implementaÃÃes à o vetor de bits. No entanto, alÃm dessa estrutura bÃsica, implementamos tambÃm duas variaÃÃes. A primeira delas consiste em uma estratificaÃÃo de vetores de bits, enquanto a segunda emprega uma tabela de dispersÃo. As operaÃÃes associadas Ãs estruturas implementadas sÃo a inclusÃo ou remoÃÃo de um elemento do conjunto e a uniÃo ou interseÃÃo de dois conjuntos. Especial atenÃÃo à dada ao uso de paralelismo em bits nessas operaÃÃes. As implementaÃÃes das diferentes estruturas nesta dissertaÃÃo utilizam uma interface e uma implementaÃÃo abstrata comuns, nas quais as operaÃÃes sÃo especificadas e o paralelismo em bits à explorado. A diferenÃa entre as implementaÃÃes està apenas na estrutura utilizada. Uma comparaÃÃo experimental à realizada entre as diferentes estruturas utilizando algoritmos enumerativos para o problema de conjunto independente mÃximo. Duas abordagens sÃo utilizadas na implementaÃÃo de algoritmos enumerativos para o problema de conjunto independente mÃximo, ambas explorando o potencial de paralelismo em bits na representaÃÃo do grafo e na operaÃÃo sobre subconjuntos de vÃrtices. A primeira delas à um algoritmo do tipo {em branch-and-boound} proposto na literatura e a segunda emprega o mÃtodo das bonecas russas. Em ambos os casos, o uso de paralelismo em bits proporciona ganhos de eficiÃncia quando empregado no cÃlculo de limites inferiores baseados em cobertura por cliques. Resultados de experimentos computacionais sÃo apresentados como forma de comparaÃÃo entre os dois algoritmos e como forma de avaliaÃÃo das estruturas implementadas. Esses resultados permitem concluir que o algoritmo baseado no mÃtodo das bonecas russas à mais eficiente quanto ao tempo de execuÃÃo e quanto ao consumo de memÃria. AlÃm disso, os resultados experimentais mostram tambÃm que o uso de estratificaÃÃo e tabelas de dispersÃo permitem ainda maior eficiÃncia no caso de grafos com muito vÃrtices e poucas arestas. / The use of bit vectors is a usual practice for represent sets by direct addressing with the aim of reduce memory consumed and improve efficiency of applications with the use of bit parallel techniques. In this text, we study implementations for represent sets by direct addressed. The basic structure in this implementations is the bit vector. Besides that basic implementation, we implement two variations also. The first one is a stratification of the bit vector, while the second uses a hash table. The operations linked to the implemented structure are include and remove an element and the union and intersection of two sets. Especial attention is given to the use of bit parallel in this condition. The implementation of the different structures in this work use an base interface and a base abstract class, where the operations are defined and the bit parallel is used. An experimental comparative between this structures is carry out using enumerative algorithms for the maximum stable set problem. Two approaches are used in the implementation of the enumerative algorithms for the maximum stable set problem, both using the bit parallel in the representation of the graph and on the operations with subsets of vertices. The first one is a known branch-and-bound algorithm and the second uses the Russian dolls method. In both cases, the use of bit parallel improve efficiency when the lower bounds are calculated based in a clique cover of the vertices. The results of computational experiments are presented as comparison between the two algorithms and as an assessment of the structures implemented. These results show that the algorithm based on the method Russian Dolls is more efficient regarding runtime and the memory consumed. Furthermore, the experimental results also show that the use stratification and hash tables also allow more efficiency in the case of sparse graphs.

En s'appuyant sur les développements conceptuels apportés à la théorie de l'activité par la psychologie du travail, cette recherche se propose d'explorer la genèse et les fonctions des instruments dans la conduite des activités des sujets malades. La recherche s'appuie sur l'analyse de quatorze entretiens conduits auprès de personnes affectées par une ou plusieurs maladies chroniques sévères. Elle explore comment le sujet malade chronique déploie des " agir sur soi " au travers de ses activités. Elle démontre comment le sujet s’approprie et utilise pour ce faire, des artefacts et des instruments, élabore des stratégies et met en place des dispositifs pour étayer son travail quotidien et sa présence au monde. En s'appuyant sur les concepts de la théorie instrumentale élargie (Rabardel), sur l'activité médiatisée (Vygotski) et sur l’activité au service du maintien de soi en vie en santé (Tourette-Turgis), l'analyse des matériaux identifie trois catégories d'instruments (matériels, non matériels et mixtes) utilisés par les participants de l'étude. Ces instruments semblent remplir des fonctions d'organisateurs d'activités et de transformations des activités et des sujets. / Based on the conceptual developments brought to the theory of the activity by occupational psychology, this research explores the genesis and the functions of the instruments used by the subjects living with a chronic disease in their daily life given that patient ‘s participation in their own care is conceived as a work. The research is based on analysis of fourteen interviews conducted with people affected by one or more severe chronic diseases. It explores and analyses different situations describing how the subject affected by a chronic disease creates, invents different means to « act on oneself » in order to stay alive . This research describes how participants living with one or several chronic diseases use artefacts, tools, instruments , strategies to maintain active the multiple dimensions of their involvement with the world. Using different conceptual frameworks of research on work such as extended instrumental theory ( Rabardel), mediated activity ( Vygotski), the patient’s work ( Tourette-Turgis), content analysis of interviews shows three different categories of instruments ( material, intangible, mixted ) used by the participants of the study. These instruments seem to fulfill the functions of organizers of activities and transformations of the activities and the subjects.

Telemetry system, Optimisation, Sensoric networks, Smart Grid, Internet of Things, Sensors, Information security, Cryptography, Cryptography algorithms, Cryptosystem, Confidentiality, Integrity, Authentication, Data freshness, Non-Repudiation.