Context information brings new opportunities for efficient and effective applications and services on mobile devices. Many existing work exploit the context dependency of mobile usage for specific applications, and show significant, quantified, performance gains by utilizing context. In order to be practical, such works often pay careful attention to the energy and processing costs of context awareness while attempting to maintain reasonable accuracy. These works also have to deal with the challenges of multiple sources of context, which can lead to a sparse training data set. Even with the abundance of such work, quantifying context-dependency and the relationship between context-dependency and performance achievements remains an open problem, and solutions to manage the and challenges of context awareness remain ad-hoc. To this end, this dissertation methodologically quantifies and measures the context dependency of three principal types of mobile usage in a methodological, application agnostic yet practical manner. The three usages are the websites the user visits, the phone numbers they call, and the apps they use, either built-in or obtained by the user from the App Store . While this dissertation measures the context dependency of these three principal types of mobile usage, its methodology can be readily extended to other context-dependent mobile usage and system resources. This dissertation further presents SmartContext, a framework to systematically optimize the energy cost of context awareness by selecting among different context sources, while satisfying the system designer’s cost-accuracy tradeoffs. Finally, this thesis investigates the collective effect of social context on mobile usage, by separating and comparing LiveLab users based on their socioeconomic groups. The analysis and findings are based on usage and context traces collected in real-life settings from 24 iPhone users over a period of one year. This dissertation presents findings regarding the context dependency of three principal types of mobile usage; visited websites, phone calls, and app usage. The methodology and lessons presented here can be readily extended to other forms of context and context-dependent usage and resources. They guide the development of context aware systems, and highlight the challenges and expectations regarding the context dependency of mobile usage.

Security awareness is becoming an increasingly valuable characteristic due to the increased digitization of society. The commonality of constantly connected devices, such as smartphones and tablets, along with the threat of malware and cyber-attacks has sparked an interest in creating a system with the purpose of training people in security awareness. This thesis aims to show the presence of patterns in mobile device usage, and explore the possibility of using pattern detection as a means to predict riskful actions on mobile devices as a step to evaluate the prediction approach for use in the training system.A survey has been conducted by gathering usage data from a number of participants through the use of a logging application. This data was then analyzed using artificial neural networks provided by the open source FANN library in search for patterns preluding certain events. The results lend support to the claim that patterns exist in the way mobile devices are used, but the usefulness of FANN as a tool for finding these patterns was shown to be questionable.

Mojawapo ya matokeo ya utandawazi ni kuwapo kwa simu za kiganjani na matumizi yake. Siku hizi nchini Tanzania mawasiliano ya simu yamekuwako kwa wingi kuliko ilivyokuwa tangu wakati wa uhuru hadi katikati ya miaka ya tisini. Lugha ya Kiswahili inayotumika katika simu hizi ni ya kiutandawazi na pengine si rahisi kuiona nje ya wigo huu wa kiutandawazi ambao pia unajumuisha mawasiliano kwa barua pepe, na maongezi katika tovuti. Suala kubwa tunalolijadili katika makala hii ni changamoto zinazoletwa na lugha hii katika Isimujamii, hasa kuchanganya msimbo (lugha) na kubadili misimbo (lugha) (code mixing and code switching). Kwahiyo mwelekeo wa makala hii ni utafiti wa matumizi ya lugha hii tandawazi kwa kuangalia simu za viganjani na athari yake katika nadharia za isimujamii. Madhumuni yetu ni kuangalia matumizi ya lugha ya Kiswahili katika simu za viganjani.

Mojawapo ya matokeo ya utandawazi ni kuwapo kwa simu za kiganjani na matumizi yake. Siku hizi nchini Tanzania mawasiliano ya simu yamekuwako kwa wingi kuliko ilivyokuwa tangu wakati wa uhuru hadi katikati ya miaka ya tisini. Lugha ya Kiswahili inayotumika katika simu hizi ni ya kiutandawazi na pengine si rahisi kuiona nje ya wigo huu wa kiutandawazi ambao pia unajumuisha mawasiliano kwa barua pepe, na maongezi katika tovuti. Suala kubwa tunalolijadili katika makala hii ni changamoto zinazoletwa na lugha hii katika Isimujamii, hasa kuchanganya msimbo (lugha) na kubadili misimbo (lugha) (code mixing and code switching). Kwahiyo mwelekeo wa makala hii ni utafiti wa matumizi ya lugha hii tandawazi kwa kuangalia simu za viganjani na athari yake katika nadharia za isimujamii. Madhumuni yetu ni kuangalia matumizi ya lugha ya Kiswahili katika simu za viganjani.