This thesis examines how sleep modes can be used in next generation mobile broadband systems (BuNGee) to substantially improve energy efficiency. Such systems employ a high degree of overlapping small cells in order to deliver very high throughput density for 5G networks in dense areas. It is shown how by limited exchange of information between neighbouring base stations it is possible to maintain quality of service (QoS), over a range of traffic loads, while enabling inactive base stations to sleep. Dynamic distributed topology management schemes are used here to switch off the small cells at low traffic load levels, while the remaining local traffic can be forwarded by their adjacent cells. A novel analytical model is generated using multi-dimensional Markov processes and is used to predict the theoretical system performance and potential energy reduction when a set of parameters are varied. The parameters discussed include the traffic load thresholds to switch off/on a base station. This new model provides an understanding of how to obtain the maximum energy reduction while guaranteeing QoS by choosing suitable parameter values in such a network. Performance of distributed energy efficient topology management schemes with a sleep mechanism are compared against the system without topology management. Results show the schemes deliver a significant energy reduction in energy consumption in the network, which is 35%-70% depending on the strategies used. The corresponding simulation models are used to verify the analytical model. It is shown how traffic load based thresholds (used to switch on/off base stations) measured on adjacent base stations have a higher impact than the threshold on the base station itself. The latter threshold has very limited influence on the system energy efficiency. An energy efficient topology management scheme employing combined sleep modes with handover for a BuNGee system is investigated as a way of providing further improvements to energy efficiency. Performance is examined using both analytical and simulation based models. A key aspect of this scheme is that a base station can redeploy its traffic load to its neighbours and then switch off itself when the local traffic is at a low/medium level.

Η παρούσα διπλωματική εργασία έχει ως σκοπό την ανάπτυξη εφαρμογής σε iPhone για την προσομοίωση κβαντικών υπολογισμών. Για την υλοποίηση του γραφικού περιβάλλοντος της εφαρμογής αντί για τη native γλώσσα προγραμματισμού για iphone (objective c), καθώς και τα επίσημα εργαλεία της apple επιλέχθηκε η πλατφόρμα phonegap. Αρχικά μελετήθηκαν: πρώτον, οι βασικές έννοιες που διέπουν τους κβαντικούς υπολογιστές και δεύτερον, η χρήση και οι δυνατότητες των διάφορων προγραμματιστικών γλωσσών και εργαλείων. Στη συνέχεια δημιουργήθηκε η γραφική διεπαφή της εφαρμογής με το χρήστη και εν τέλει αναπτύχθηκε η βιβλιοθήκη η οποία εκτελεί τους κβαντικούς υπολογισμούς. / This diploma dissertation presents the development of an iPhone application that simulates the quantum calculation. Instead of using the native programming language for iPhone applications, Objective C, web technologies an PhoneGap where chosen. At first, the theory of quantum calculation was studied. Then the technologies available for developing mobile apps where studied and therefore PhoneGap and web technologies were chosen. Finally the app was developed in two parts, firstly the user interface and finally the library that executes the quantum calculation.

Σε αυτή τη διπλωματική θα ασχοληθούμε με κινητά τηλέφωνα νέας γενιάς και με εφαρμογές οι οποίες θα αξιολογούν ένα προϊόν ή μία υπηρεσία και θα επιστρέφουν το αποτέλεσμα με «επαύξηση» της πραγματικότητας στην οθόνη του χρήστη.

Ubiquitous mobile devices have become a necessity in today’s society, opening new opportunities for interaction and collaboration between geographically distributed people. With the increased use of mobile phones, people can collaborate while on the move. Collaborators expect technologies that would enhance their teamwork and respond to their individual needs. Workflow is a widely used technology that supports collaboration and can be adapted for a variety of collaborative scenarios. Although the originally computer-based workflow technology has expanded also on mobile devices, there are still research challenges in the development of user-focused device-oriented collaborative workflows. As opposed to desktop computers, mobile devices provide a different, more personalised user experience and are carried by their owners everywhere. Mobile devices can capture user context and behave as digitalised user complements. By integrating context awareness into the workflow technology, workflow decisions can be based on local, context information and therefore, be more adapted to individual collaborators’ circumstances and expectations. Knowing the current context of collaborators and their mobile devices is useful, especially in mobile peer-topeer collaboration where the workflow process execution can be driven by devices according to the situation. In mobile collaboration, team workers share pictures, videos, or other content. Monitoring and exchanging the information on the current state of the content processed on devices can enhance the overall workflow execution. As mobile devices in peer-to-peer collaboration are not aware of a global workflow state, the content state information can be used to communicate progress among collaborators. However, there is still a lack of integrating content lifecycles in process-oriented workflows. The aim of this research was therefore to investigate how workflow technology can be adapted for mobile peer-to-peer collaboration, in particular, how the level of context awareness in mobile collaborative workflows can be increased and how the extra content lifecycle management support can be integrated. The collaborative workflow technology has been adapted for mobile peerto- peer collaboration by integrating context and content awareness. In the first place, a workflow-specific context management approach has been developed that allows defining workflow-specific context models and supports the integration of context models with collaborative workflows. Workflow process has been adapted to make decisions based on context information. Secondly, extra content management support has been added to the workflow technology. A representation for content lifecycles has been designed, and content lifecycles have been integrated with the workflow process. In this thesis, the MobWEL workflow approach is introduced. The Mob- WEL workflow approach allows defining, managing and executing mobile context-aware content-centric workflows. MobWEL is a workflow execution language that extends BPEL, using constructs from existing workflow approaches, Context4BPEL and BPELlight, and adopting elements from the BALSA workflow model. The MobWEL workflow management approach is a technology-based solution that has been designed to provide workflow management support to a specific class of mobile applications.

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.

In this thesis we look into usability in the context of smartphone applications. We selected three research areas to investigate, namely Wireless Personal Area Networks, Context-awareness, and Remote Information Access. These areas are investigated through a series of experiments, which focuses on important aspects of usability within software applications. Additionally, we mainly use smartphone devices in the experiments. In experiment 1, Multi-Platform Bluetooth Remote Control, we investigated Wireless Personal Area Networks. Specifically, we implemented a system consisting of two clients, which were created for Java ME and Windows Mobile, and integrated with a server application installed on a Bluetooth-enabled laptop. For experiments 2 and 3, Context-aware Meeting Room and PainDroid: an Android Application for Pain Management, we looked closely at the research area of Contextawareness. The Context-aware Meeting Room was created to automatically send meeting participants useful meeting notes during presentations. In experiment 3, we investigated the use of on-device sensors for the Android platform, providing an additional input mechanism for a pain management application, where the accelerometer and magnetometer were used. Finally, the last research area we investigated was Remote Information Access, where we conducted experiment 4, Customised Android Home Screen. We created a system that integrated both a cloud-based server application and a mobile client running on the Android platform. We used the cloud-computing platform to provide context management features, such as the ability to store the user configuration that was automatically pushed to the mobile devices.

Smartphones are innovations that currently provide immense benefits and convenience to users in society. However, not all the users of society are accepting and using smart phones, more specifically, for this research study older adults (50+) are a demographic group displaying such an attitude. Currently, there is minimal knowledge of the reasons that older adults adopt and use smartphones. Bearing this in mind, this research study aimed to identify, examine and explain the adoption and usage of smartphones in the UK within the 50 years old and above population. For this purpose, a conceptual framework, a Model of Smartphone Adoption (MOSA) was formed drawing factors from the theories of Unified theory of Acceptance and Use of Technology (UTAUT), the Diffusion of Innovations theory (DoI) and Technology Acceptance Model 3 (TAM3). Seven variables from the theories were brought to consideration, which were Observability, Social influence, Compatibility, Effort expectancy, Facilitation conditions, Performance expectancy and Perceived enjoyment. For the research method, a quantitative approach was selected to examine and apply MOSA that involved the data collection method of an online questionnaire survey that resulted in 204 completed replies during the pilot phase of this research and 984 in the final phase. The collected data was analysed using SEM-PLS where the results found that six of the eight formed hypotheses were supported, and the factors of Compatibility, Effort expectancy, Facilitation condition, Performance expectancy and Perceived enjoyment were important for the adoption of smartphones. From these results, it was understood that older adults used smartphones because they have enough knowledge, time and money to use. They also think that smartphones are easy to use, provide benefits including enjoyment and are compatible with their lifestyles. In terms of usage, older adults frequently used the basic features of smartphones such as making a phone call, SMS, email, and browsing. Older adults are also likely to use their devices for seeking information about their health and for appointments with their doctors; however, from this research it was found that more than half of the 50 years old and above adults did not use smartphones for health and well-being purposes. The contributions of this research are viewed to be the identification and understanding of the factors that encourage or inhibit smartphones use within the older adult population. Secondly, this research can inform smartphone manufacturers and developers of factors pertinent for the design of computing devices and applications specific to silver surfers. Finally, this research can enlighten policy makers when forming decisions that encourage the adoption and use of smartphones within the older adult population. Regarding limitations, these existed in the form of finance and time. To overcome the limitations, this research recommends further studies that apply qualitative research and/or to provide a comparison between western and eastern countries.

Η ανίχνευση καθημερινών φυσικών δραστηριοτήτων είναι πολύ σημαντική σε εφαρμογές όπως η ανάπτυξη αυτοματοποιημένων συστημάτων. Οι αισθητήρες κίνησης προηγουμένως χρησιμοποιούνταν μόνο ως συμπληρωματικές είσοδοι ενώ τώρα χρησιμοποιούνται όλο και πιο συχνά ως η κύρια πηγή δεδομένων για αναγνώριση κάποιας καθημερινής κίνησης. Σε αυτή την εργασία, χρησιμοποιούνται τα επιταχυνσιόμετρα των κινητών τηλεφώνων με σκοπό να αναγνωρισθούν σε πραγματικό χρόνο τέσσερις καθημερινές δραστηριότητες: κάθισμα, περπάτημα, ξάπλωμα, τρέξιμο. Σε αυτή την εργασία, σχεδιάστηκαν 2 νέα υβριδικά πρωτόκολλα που συνδυάζουν δύο άλλες μεθόδους της βιβλιογραφίας με παραμετροποιημένο τρόπο. Στη συνέχεια, τα 2 αυτά πρωτόκολλα υλοποιήθηκαν μέσω της ανάπτυξης Android εφαρμογών. Σύμφωνα με τα αποτελέσματα της αξιολόγησης η οποία έγινε με πραγματικούς χρήστες, οι 2 υβριδικές μέθοδοι επιτυγχάνουν μεγάλη ακρίβεια (έως και 99%), ενώ διατηρούν την κατανάλωση μπαταρίας σε πολύ χαμηλά επίπεδα (μέση κατανάλωση μπαταρίας 874mW). / Detecting daily physical activities is very important in applications such as developing automated comfort scenarios for an individual. Motion smartphone sensors were previously used only as a complementary input whereas now, they are increasingly used as the primary data source for motion recognition. In this work, we use smartphone accelerometers to recognize online four daily human activities: sitting, walking, lying and running. We design two new hybrid protocols combining state of the art methods in a parameterized way. Then, we implement those protocols in the context of Android applications, which we develop. According to our experimental performance evaluation with real users, our hybrid methods achieve very high accuracy (even 99%), while keeping battery dissipation at very satisfactory levels (average energy consumption 874mW).

Στην παρούσα εργασία θα αξιολογηθούν κάποιες αυτόματες μέθοδοι διαχωρισμού ακουστικών βιοσημάτων τα οποία λαμβάνονται από συστοιχία πιεζοηλεκτρικών αισθητήρων σε χαμηλές συχνότητες. Πιο συγκεκριμένα αρχικά θα οριστεί το πρόβλημα το οποίο μας ζητείται να επιλύσουμε και θα γίνουν αναφορές στη διαδρομή των δύο σημαντικότερων μεθόδων διαχωρισμού , της PCA και της ICA. Εν συνεχεία θα γίνει αναφορά στα βιοσήματα τόσο ως προς την προέλευση όσο και ως προς τα σημαντικότερα χαρακτηριστικά τους , η γνώση των οποίων διευκολύνει κατά πολύ τόσο τη διαδικασία του διαχωρισμού όσο και την αξιολόγηση της τελευταίας. Σε επόμενο κεφάλαιο θα γίνει εκτενής αναφορά στους πιεζοηλεκτρικούς αισθητήρες και τον τρόπο με τον οποίο κωδικοποιούν τα βιοσήματα με στόχο την περαιτέρω επεξεργασία τους. Στο μεγαλύτερο τμήμα της εργασίας αυτής ωστόσο θα αναλυθούν οι δύο τεχνικές διαχωρισμού , PCA και ICA και θα γίνει νύξη στους σημαντικότερους αλγορίθμους των παραπάνω (FastICA). Τέλος, θα γίνει εφαρμογή των μεθόδων αυτών τόσο σε τεχνητά όσο και σε πραγματικά σήματα και ανάλυση των αποτελεσμάτων που θα εξαχθούν. / In this diploma thesis some automatic acoustic bio-signal separation techniques are going to be evaluated. The signals used are taken from an array of piezoelectric sensors at low frequencies. To be more specific we are going to set the problem and make a brief report of the main historical facts about PCA and ICA. Furthermore, we are going to analyze both the origin and the most significant characteristics of bio-signals. This knowledge is going to provide us with a much easier separation procedure and a robust evaluation. Additionally not only piezoelectric sensors are going to be analyzed but also PCA and ICA will be resolved too. Main algorithms of both techniques will be mentioned. In conclusion those methods will be applied both on artificial and real data in order to draw some useful conclusions.

This thesis assesses the speed of adaptation and adoption of computing systems from an adult first-time user perspective in South Africa, with the aim of determining if it could ultimately lead to the reduction of the existing digital gap. As is evident from the social, educational, and economical gap for some observers, the reality of the existence of the digital gap in South Africa is undeniable. Constant non-targeted progress is made toward addressing imbalances, which seem to be more visible as the number of constant and permanent users is visibly increasing. These observed phenomena are mostly noticed amongst urban, educated, younger, middle-class citizens. The forgotten “missing middle” are left to fend for themselves. These are people who are still outside the digital drive the world is experiencing based on their schooling grade, geographical location, income level, and age. They were not in school when computer literacy was introduced, and they were too poor to teach themselves how to use a computer, too remote to observe the digital drive, and too old to learn from their peers. As citizens, their welfare matters, and when assessing the penetration of ICT in the country, their numbers also matter. One cannot ignore their presence and the difficulties and frustration that they experience when coming into contact with a computing system for the first time. The researcher is of the view that the presence of a computing system may not simply translate to the closure of the digital gap. In other words, people may gain access to a computer, but without computing usability skills or Internet connectivity it may not add value to their daily activities. Closing the digital gap in South Africa can be seen as political propaganda, but the reality is, how do we measure and assess it? It comes down to users, and in this particular case, attention is turned to the “missing middle”, here referred to as the adult first-time user. This is simply someone who is over the age of 18 years, lives in a rural community in South Africa, never completed school, and is using a computer for the first time. The researcher used a handheld tablet system as a tool to assess the participants’ adequacy in terms of the rate at which they complete tasks by developing mathematical equations which were placed together within an assessment metric that was later used to determine user proficiency, as well as their adaptation and user experience in order to determine if the participant can later adopt the device and take advantage of it. By so doing, the metric will comprise variables such as the user movement time, task completion success rate, task completion speed, user satisfaction, user reaction time, user completion rate per activity, time-based efficiency, and the assessment of the level of frustration any adult first-time user may experience while interacting with the system for the first time. The term “digital gap” may not be new to the ICT sphere, but no one has taken the step towards assessing it. The digital gap is no longer the absence of computing systems in many communities but rather the presence of inadequate user experience, which has not been properly measured and documented. The user experience metric (UXM) that was developed in this study provided the researcher with the opportunity to reassess the issue of systems adaptation, adoption, and usability by adult first-time users. This research is particularly driven by sound interaction design principles, user adaptation, and usability and user experience / Ph. D. (Information Systems) / School of Computing