Thesis (MBA)--Stellenbosch University, 2014. / Factors influencing the adoption of smartphones are not known in South Africa. Smartphone adoption globally is currently measured as being around forty-seven percent of all mobile phone users, with an expectation that it will be around the fifty per cent mark by 2017. Most of this growth will come from markets that are highly price-sensitive, and low-cost smartphones will allow users to shift from feature phones to smartphones, or they may skip the step of buying a feature phone altogether and upgrade directly to a smartphone. With one of the fastest growing smartphone adoption rates in the world. Primary data was collected using an online survey tool, and four hundred and twenty-six responses to the survey were collected. The survey instrument was designed to collect information regarding the smartphone attributes and features that are most pertinent to the smartphone purchasing decision. The research also profiled how consumers were currently using their mobile devices from a time and frequency perspective. This was done through descriptive and inferential statistical analysis of the sample data. The research adopted the Technology Acceptance Model (TAM) with three added constructs from the literature, being Entertainment, Security and Privacy, and Social Networking. The objective of the research, therefore, was to test the relationship of these constructs in relation to smartphone adoption by the sample collected. Inspection of the data was done through multiple logistic regression on respondent’s current adoption status of smartphones. Only PU (Perceived Usefulness) was measured to be significant after inferential statistical analysis, but this proved to have only minor influence on the overall multiple regression equation of the research. Entertainment was statistically not significant in the research, but was measured as very close to significance whenusing a confidence level alpha of 0.05. The application of the TAM model with added constructs proved to be successful, although the added constructs did not result in significance of the associated sample data. Respondents indicated that smartphone features such as battery life and the affordability of data were the most important to them in the decision of purchasing a smartphone. The descriptive data did reveal differing adoption trends among different race groups within South Africa, and it is recommended that this phenomenon be explored in further detail in future research.

La planification tactique consiste à élaborer des plans de production afin de répondre au mieux à la demande, à un moindre coût. Traditionnellement, cette planification est divisée en trois plans principaux : le Plan Industriel et Commercial (PIC), le Plan Directeur de Production (PDP) et le Calcul des Besoins Net (CBN). Pour élaborer ces différents plans, des modèles mathématiques dits de " lot-sizing " ont été développés. Cependant, les mécanismes de fusion/acquisition entre entreprises ont considérablement complexifié cette planification en y intégrant les aspects multi-site inhérents au concept de chaîne logistique et il n'existe pas, à notre connaissance, de modèle du domaine et de modèle mathématique de référence pour cette problématique. Dans cette thèse, nous proposons un modèle générique de connaissance pour la planification multi-site à partir duquel un modèle mathématique générique peut être obtenu. Ce dernier permet, par instanciation, de retrouver les principaux modèles de la littérature. Nous proposons également des méthodes d'optimisation efficaces pour l'élaboration des plans de production (PIC, PDP et CBN) dans un contexte mono et multi-site : - Nous nous intéressons à l'obtention du PIC et du PDP dans un contexte mono-site au travers de la résolution du Capacitated Lot Sizing Problem (CLSP) grâce à des métaheuristiques et des bornes inférieures. Par cette technique, nous améliorons des résultats de la littérature. - Nous proposons un modèle mathématique pour la planification d'une chaîne logistique de type " flowshop hybride " obtenu par instanciation du modèle mathématique générique ainsi qu'une méthode d'optimisation efficace pour déterminer les PDPs et CBNs pour cette chaîne logistique. Nous abordons ensuite les problèmes de faisabilité des plans de production ainsi déterminés au niveau opérationnel en utilisant différents couplages entre modèles mathématiques ou modèles de simulation, ce qui permet d'assurer la synchronisation verticale des plans. Enfin, dans le cadre d'un contrat industriel, nous nous intéressons à la mise en place d'une politique de gestion de stock à demande différenciée. Après avoir étudié la faisabilité d'une telle mise en oeuvre dans un contexte industriel, nous avons conçu les algorithmes et développé l'application permettant de calculer les seuils de rationnement de chaque client afin de mener un test grandeur nature de cette politique.

The overall aim of the thesis has been to introduce Personal Mobile Grids (PMGrids) as a novel paradigm in grid computing that scales grid infrastructures to mobile devices and extends grid entities to individual personal users. In this thesis, architectural designs as well as simulation models for PM-Grids are developed. The core of any grid system is its resource scheduler. However, virtually all current conventional grid schedulers do not address the non-clairvoyant scheduling problem, where job information is not available before the end of execution. Therefore, this thesis proposes a honeybee inspired resource scheduling heuristic for PM-Grids (HoPe) incorporating a radical approach to grid resource scheduling to tackle this problem. A detailed design and implementation of HoPe with a decentralised self-management and adaptive policy are initiated. Among the other main contributions are a comprehensive taxonomy of grid systems as well as a detailed analysis of the honeybee colony and its nectar acquisition process (NAP), from the resource scheduling perspective, which have not been presented in any previous work, to the best of our knowledge. PM-Grid designs and HoPe implementation were evaluated thoroughly through a strictly controlled empirical evaluation framework with a well-established heuristic in high throughput computing, the opportunistic scheduling heuristic (OSH), as a benchmark algorithm. Comparisons with optimal values and worst bounds are conducted to gain a clear insight into HoPe behaviour, in terms of stability, throughput, turnaround time and speedup, under different running conditions of number of jobs and grid scales. Experimental results demonstrate the superiority of HoPe performance where it has successfully maintained optimum stability and throughput in more than 95% of the experiments, with HoPe achieving three times better than the OSH under extremely heavy loads. Regarding the turnaround time and speedup, HoPe has effectively achieved less than 50% of the turnaround time incurred by the OSH, while doubling its speedup in more than 60% of the experiments. These results indicate the potential of both PM-Grids and HoPe in realising futuristic grid visions. Therefore considering the deployment of PM-Grids in real life scenarios and the utilisation of HoPe in other parallel processing and high throughput computing systems are recommended.

A mobile ad hoc network (MANET) is a collection of mobile platforms or nodes that come together to form a network capable of communicating with each other, without the help of a central controller. To avail the maximum potential of a MANET, it is of great importance to devise a routing scheme, which will optimize upon the performance of a MANET, given the high rate of random mobility of the nodes. In a MANET individual nodes perform the routing functions like route discovery, route maintenance and delivery of packets from one node to the other. Existing routing protocols flood the network with broadcasts of route discovery messages, while attempting to establish a route. This characteristic is instrumental in deteriorating the performance of a MANET, as resource overhead triggered by broadcasts is directly proportional to the size of the network. Bounded-dynamic source routing (B-DSR), is proposed to curb this multitude of superfluous broadcasts, thus enabling to reserve valuable resources like bandwidth and battery power. B-DSR establishes a bounded region in the network, only within which, transmissions of route discovery messages are processed and validated for establishing a route. All route discovery messages reaching outside of this bounded region are dropped, thus preventing the network from being flooded. In addition B-DSR also guarantees loop-free routing and is robust for a rapid recovery when routes in the network change.

<p>Modern sensing apps require continuous and intense computation on data streams. Unfortunately, mobile devices are failing to keep pace despite advances in hardware capability. In contrast to powerful system-on-chips that rapidly evolve, battery capacities merely grow. This hinders the potential of long-running, compute-intensive sensing services such as image/audio processing, motion tracking and health monitoring, especially on small, wearable devices. </p><p>In this thesis, we present three pieces of work that target at improving the energy efficiency for mobile sensing. (1) In the first work, we study heterogeneous mobile processors that dynamically switch between high-performance and low-power cores according to tasks' performance requirements. We benchmark interactive mobile workloads and quantify the energy improvement of different microarchitectures. (2) Realizing that today's users often carry more than one mobile devices, in the second work, we extend the resource boundary of individual devices by prototyping a distributed framework that coordinates multiple devices. When devices share common sensing goals, the framework schedules sensing and computing tasks according to devices' heterogeneity, improving the performance and latency for compute-intensive sensing apps. (3) In the third work, we study the power breakdown of motion sensing apps on wearable devices and show that traditional offloading schemes cannot mitigate sensing’s high energy costs. We design a framework that allows the phone to take over sensing and computation by predicting the wearable's sensory data, when motions of the two devices are highly correlated. This allows the wearable to offload without communicating raw sensing data, resulting in little performance loss but significant energy savings.</p> / Dissertation

M.Sc. / Grid computing is a technology concerned with harvesting idle resources of geographically distributed and interconnected computers. It solves problems regarded as too complex or large to be solved by a single computer. Furthermore, economic grid computing is becoming the most dominant form of grid computing. It enables some form of payment to occur between resource producers and resource consumers in grid computing. Mobile devices and mobile telecommunication services, a relatively new field of technology, are rapidly increasing in popularity, size, strength and application. At the end of 2006, there were approximately 2.7 billion global active mobile users utilising mobile devices and mobile telecommunication services [Aho07]. At the end of 2007 this number had grown to 3.3 billion mobile users, more than half a billion additional mobile users in a period of one year [McN07]. With such large numbers, grid computing can benefit from the clustering of mobile devices forming a mobile grid computing model. However, there are many inherent disadvantages concerning mobile devices, such as low processing capabilities, unpredictable network connections and battery utilisation. Such hurdles must be addressed and solved if a mobile computing infrastructure or architecture is ever to be considered. This dissertation proposes the implementation of an economic mobile computing solution: Mobile Agents for Global Mobile Device Grid Infrastructure Enterprises, or MAGGIE. MAGGIE is concerned with harvesting idle mobile device resources by implementing the supply and demand economic model, aiming to create a healthy competitive economic market environment. MAGGIE implements agent and mobile agent technology to compensate for the hurdles introduced by mobile devices and mobile device software development platforms. It is targeted at both Sun Microsystems’s J2ME MIDP 2.0 and Microsoft’s .NET Compact Framework, enabling lower-end and higher-end mobile devices to contribute mobile computing services and resources for utilisation by other mobile device users. The primary goal of MAGGIE is to produce an architecture as generic as possible regarding the development and implementation of MAGGIE services. MAGGIE allows third-party application developers to seamlessly implement an array of MAGGIE services, without indepth prior knowledge of the architecture and technical aspects of MAGGIE. Finally, MAGGIE’s capabilities are demonstrated by implementing a distributed mobile chess service known as the MAGGIE Chess Service. The MAGGIE Chess Service enables a collection of distributed mobile devices in determining the best move originating from a chessboard position.

Devido à sua constante evolução, associada ao surgimento contínuo de novas tecnologias, a computação tem se tornado cada vez mais presente no cotidiano das pessoas, sendo utilizada não só no meio acadêmico e corporativo, mas também no entretenimento e no auxílio às atividades pessoais, entre outros. Nesse contexto, vem ocorrendo um grande avanço em termos de redução de custo e de aumento da variedade de dispositivos do tipo Personal Digital Assistants (PDAs). Esse avanço aumenta a demanda por aplicações que explorem esses equipamentos, mas são poucas as ferramentas que auxiliam no desenvolvimento dessas aplicações. O objetivo da presente pesquisa foi investigar o desenvolvimento de aplicações para dispositivos móveis, especificamente para PDAs, com independência de plataforma. A abordagem adotada foi a extensão da ferramenta MCards, um construtor de aplicações para PDAs, com o propósito de permitir a geração de aplicações para dispositivos móveis com a utilização da tecnologia J2ME (Java 2 Micro Edition). Para tanto, foi necessário, inicialmente, um entendimento do protótipo disponível da ferramenta MCards realizado através da aplicação de um processo de Engenharia Reversa na ferramenta MCards, baseando-se no modelo FUSION-RE/I. Foram executadas, também, manutenções na ferramenta com a finalidade de corrigir imperfeições e problemas de execução e de melhorar suas funcionalidades. Após o processo de Engenharia Reversa e manutenção da ferramenta, foi implementado e incorporado à ferramenta MCards o módulo de geração de aplicações J2ME. O módulo de geração de aplicações J2ME transforma a especificação abstrata, gerada pela manipulação do usuário no editor visual da ferramenta MCards, em código para a tecnologia J2ME com a utilização do perfil CDC / Personal Profile, compilando o código gerado para dar origem aos arquivos da aplicação J2ME que serão utilizados para instalação no dispositivo móvel. / Mobile devices such as Personal Digital Assistants (PDAs) have grown up and number and models, while their cost has been continuously decreasing. Although this scenario indicates that there is a demand for tools that support the development of applications for mobile devices, the literature does not report platform-independent tools. The aim of this research was to investigate the development of applications for mobile devices in a platform-independent way. We have elected to extend an existing prototype tool that supported the development of Palm OS applications, MCards, so that it supported the development of applications using J2ME (Java 2 Micro Edition). We first carried out a reverse engineering process, using FUSION-RE/I, which lead to the understanding of the prototype along with the production of a new, more stable and documented version. We then investigated the process of application generation for the J2ME platform and proposed an extension to MCards that supported both Palm OS and J2ME. In the extended version, the J2ME module transforms an abstract specification, generated with the MCards visual editor, in J2ME code using the CDC/Personal profile. As a result, the extended MCards tool supports the development of applications for the two most common platforms for mobile devices, Palm Os, Pocket PC and Symbian OS.

Os sistemas de modelagem de distribuição provável de espécie são utilizados para identificar regiões onde há maior probabilidade de uma determinada espécie viver, baseado nas características ambientais de localizações onde é conhecido que há presença daquela espécie. Estes sistemas requerem computação de alto desempenho devido à grande quantidade de dados que precisam ser processados para se gerar um modelo com a distribuição provável. Um momento importante do processo de modelagem de distribuição de espécies é a coleta dos dados, no qual os pesquisadores vão a campo para identificar alguns pontos de presença ou ausência, no entanto este processo é feito de forma ainda manual. Este trabalho apresenta uma proposta de automação deste processo por meio da utilização de dispositivos móveis e arquitetura SOA. Historicamente, os sistemas que utilizam arquiteturas orientadas a serviço não consideram fortemente as limitações inerentes aos dispositivos móveis, tais como poder de processamento, capacidade de armazenamento e duração da bateria. A falta de uma infra-estrutura de referência para estes sistemas pode ser apontada como uma das causas deste problema. Assim, é proposta uma infra-estrutura de desenvolvimento para sistemas móveis que utilizam uma arquitetura orientada a serviços voltada à experiência do usuário. Esta infra-estrutura tem especial atenção a como as restrições dos sistemas móveis influenciam tanto a arquitetura de software quanto a apresentação dos serviços para o usuário final. Disserta-se sobre fatores e questões relevantes ao projeto de sistemas de natureza móvel sugerindo a sua consideração durante a elaboração de projetos semelhantes. São propostos também um conjunto de métricas para avaliação do desempenho para a realização de experimentos com o objetivo de validar os aspectos de usabilidade e arquitetura, além de identificar modificações na infra-estrutura proposta. / Species distribution modeling system are used to identify regions where there is the probability to a species survive, based on the environmental characteristics where there is for sure presence of a species. Those systems require high performance computation due the large amount of data that are processed in order to create the distribution model. An important moment of the modeling process is the data collecting, when the researchers go field to identify the localizations of presence or absence, but this process is still done manually. This paper presents a proposal for automating this process through the use of mobile devices and SOA architecture. Historically, systems using service oriented architectures do not consider strongly the limitations of mobile devices such as processing power, storage capacity and duration of battery. The lack of an infrastructure of reference for these systems can be considered one of the causes of this problem. Thus, we propose an infrastructure development for mobile systems using a service-oriented architecture focused on user experience. This infrastructure has special attention to the restrictions of mobile systems influence both the software architecture as the presentation of services to the end user. Mobile related issues are discussed suggesting its consideration during the development of similar projects. Also, it is proposed a set of metrics for performance evaluation to carry out experiments aimed at validating the architecture and usability aspects, and identify changes in the proposed infrastructure.

Aplicações que demandam uma sincronização entre usuários móveis requerem um mecanismo para a difusão (multicast) de mensagens entre dispositivos móveis. Em alguns casos, o multicast deve ser atômico, isto é, ou todos os elementos do grupo processam a mensagem difundida, ou nenhum deles. O AM2C é um protocolo para multicast atômico em Computação Móvel. Entretanto, o principal problema do AM2C é sua falta de escalabilidade, uma vez que este protocolo faz uma difusão para todas as estações-base na rede fixa. Esta dissertação descreve o projeto, implementação, simulação e avaliação dos protocolos AM2C e iAM2C, onde o segundo protocolo é uma variante escalável do primeiro. As implementações e simulações foram feitas usando o ambiente MobiCS - Mobile Computing Simulator, que é uma ferramenta para o teste e a análise de desempenho de protocolos distribuídos em redes móveis. A dissertação apresenta uma comparação detalhada dos protocolos para diferentes configurações de rede e diversos padrões de migração dos hosts móveis. / Applications that demand some synchronization among mobile users require a mechanism for reliable delivery of multicast messages to a group of mobile hosts. In some cases, the multicast must be atomic, i.e., either all or none of the mobile hosts accept each message. The AM2C is a protocol for atomic multicast in Mobile Computing. However, the main problem of AM2C is its lack of scalability, since it is based on broadcasts to all base stations in the fixed network. This work describes the project, implementation, simulation and evaluation of the protocols AM2C and iAM2C, where the second protocol is a scalable variant of the first. The implementations and simulations were performed using MobiCS - Mobile Computing Simulator, that is a tool for testing and doing performance analysis of distributed protocols in mobile networks. This work presents a detailed comparison of the protocols for different network configurations and various patterns of mobile hosts migrations.

Mobile health (mHealth) can be defined as the practice of medicine and public health supported by mobile computing technologies, such as mobile phones, PDAs, tablets, sensors and other wireless devices. Particularly in the case of mobile phones, there has been a significant increase in the number of lines, equipment, and network infrastructure in Low- and Middle-Income Countries (LMIC), allowing the adoption of mHealth systems efficiently. There are now several cases of systems for data collection focused on primary care, health surveillance and epidemiological research, which were adopted in these countries. Such systems provide health care managers information with higher quality and in a shorter time, which in turn improves their ability to plan actions and respond to emergencies. However, security is not included among the main requirements of such systems. Aiming to address this issue, we developed a survey about mHealth applications and research initiatives in Brazil, which shows that a reasonable number of papers only briefly (13%) or simply do not mention (40%) their security requirements. This survey also provides a discussion about the current state-of-art of Brazilian mHealth researches, including the main types of applications, target users, devices employed and the research barriers identified. After that, we present the SecourHealth, a security framework for mHealth data collection applications. SecourHealth was designed to cope with six main security requirements: support user registration and authentication mechanisms; treat network disconnections and delays; provide a secure data storage - even in case of possible theft or loss of equipment; allow secure data exchange between the device and server; enabling device sharing between users (i.e., health workers); and allow trade-offs between security, performance and usability. This thesis also describes in detail the framework modeling and development steps showing how it was integrated into an application for the Android platform. Finally, we benchmarked the cryptographic algorithms implemented, when compared to the overhead of using HTTPS protocol. / Saúde Móvel (mHealth) pode ser definida como a prática médica e a saúde pública suportadas por tecnologias de computação móvel, como: telefones celulares, PDAs, tablets, sensores e outros dispositivos sem fio. Particularmente no caso dos celulares, há um aumento expressivo no número de linhas, aparelhos, e na infraestrutura de rede em países de média e baixa renda (Low- Middle- Income Countries, LMIC), permitindo a adoção de sistemas mHealth de maneira eficiente. Existem, hoje, vários casos de sistemas de coleta de dados voltadas à atenção primária, vigilância (em saúde) e pesquisas epidemiológicas adotados nesses países. Tais sistemas fornecem aos gestores de saúde uma informação de melhor qualidade em menor tempo, que por sua vez melhoram a capacidade de planejamento e resposta a emergências. Contudo, nota-se um relaxamento no cumprimento de requisitos de segurança nestes sistemas. Com base nisso, foi feito um levantamento de aplicações e iniciativas de pesquisa em mHealth no Brasil, no qual se constatou que um número razoável de trabalhos mencionam fracamente (13%) ou não menciona (40%) os requisitos de segurança. Este levantamento também discute sobre o estado atual das pesquisas de mHealth no Brasil, os principais tipos de aplicações, os grupos de usuários, os dispositivos utilizados e as barreiras de pesquisa identificadas. Em seguida, este trabalho apresenta o SecourHealth, um framework de segurança voltado ao desenvolvimento de aplicações de mhealth para coleta de dados. O SecourHealth foi projetado com base em seis requisitos principais de segurança: suportar o registro e a autenticação do usuário; tratar a desconexão e os atrasos na rede; prover o armazenamento seguro de dados prevendo possibilidades de furto ou perda dos aparelhos; fazer transmissão segura de dados entre o aparelho e o servidor; permitir o compartilhamento de dispositivos entre os usuários (e.g., agentes de saúde); e considerar opções de compromisso entre segurança, desempenho e usabilidade. O trabalho também descreve com detalhes as etapas de modelagem e desenvolvimento do framework - que foi integrado a uma aplicação para a plataforma Android. Finalmente, é feita uma análise do desempenho dos algoritmos criptográficos implementados, considerando o overhead pelo simples uso do protocolo HTTPS.