Mining Cell Transition Data

Cell transition data is obtained from a cellular phone that switches its current serving cell tower. The data consists of a sequence of transition events, which are pairs of cell identifiers and transition times. The focus of this thesis is applying data mining methods to such data, developing new algorithms, and extracting knowledge that will be a solid foundation on which to build location-aware applications. In addition to a thorough exploration of the features of the data, the tools and methods developed in this thesis provide solutions to three distinct research problems. First, we develop clustering algorithms that produce a reliable mapping between cell transitions and physical locations observed by users of mobile devices. The main clustering algorithm operates in online fashion, and we consider also a number of offline clustering methods for comparison. Second, we define the concept of significant locations, known as bases, and give an online algorithm for determining them. Finally, we consider the task of predicting the movement of the user, based on historical data. We develop a prediction algorithm that considers paths of movement in their entirety, instead of just the most recent movement history. All of the presented methods are evaluated with a significant body of real cell transition data, collected from about one hundred different individuals. The algorithms developed in this thesis are designed to be implemented on a mobile device, and require no extra hardware sensors or network infrastructure. By not relying on external services and keeping the user information as much as possible on the user s own personal device, we avoid privacy issues and let the users control the disclosure of their location information.

Kestävästi vaihtuva muoti : Kestävän muodin mahdollisuudet ja haasteet vaatesuunnittelijan näkökulmasta

The concept of sustainable fashion covers not only the ecological and ethical matters in fashion and textile industries but also the cultural and social affairs, which are equally intertwined in this complex network. Sustainable fashion does not have one explicit or well-established definition; however, many researchers have discussed it from different perspectives. This study provides an overview of the principals, practices, possibilities, and challenges concerning sustainable fashion. It focuses particularly on the practical questions a designer faces. The aim of this study was to answer the following questions: What kind of outlooks and practices are included in sustainable fashion? How could the principles of sustainable fashion be integrated into designing and making clothes? The qualitative study was carried out by using the Grounded Theory method. Data consisted mainly of academic literature and communication with designers who practice sustainable fashion. In addition to these, several websites and journalistic articles were used. The data was analyzed by identifying and categorizing relevant concepts using the constant comparative method, i.e. examining the internal consistency of each category. The study established a core category, around which all other categories are integrated. The emerged concepts were organized into a model that pieces together different ideas about sustainable fashion, namely, when the principles of sustainable development are applied to fashion practices. The category named Considered Take and Return is the core of the model. It consists of various design philosophies that form the basis of design practice, and thus it relates to all other categories. It is framed by the category of Attachment and Appreciation, which reflects the importance of sentiment in design practice, for example the significance of aesthetics. The categories especially linked to fashion are Materials, Treatments of Fabrics and Production Methods. The categories closely connected with sustainable development are Saving Resources, Societal Implications, and Information Transparency. While the model depicts separate categories, the different segments are in close interaction. The objective of sustainable fashion is holistic and requires all of its sections to be taken into account.

Local numerical modelling of magnetoconvection and turbulence - implications for mean-field theories

During the last decades mean-field models, in which large-scale magnetic fields and differential rotation arise due to the interaction of rotation and small-scale turbulence, have been enormously successful in reproducing many of the observed features of the Sun. In the meantime, new observational techniques, most prominently helioseismology, have yielded invaluable information about the interior of the Sun. This new information, however, imposes strict conditions on mean-field models. Moreover, most of the present mean-field models depend on knowledge of the small-scale turbulent effects that give rise to the large-scale phenomena. In many mean-field models these effects are prescribed in ad hoc fashion due to the lack of this knowledge. With large enough computers it would be possible to solve the MHD equations numerically under stellar conditions. However, the problem is too large by several orders of magnitude for the present day and any foreseeable computers. In our view, a combination of mean-field modelling and local 3D calculations is a more fruitful approach. The large-scale structures are well described by global mean-field models, provided that the small-scale turbulent effects are adequately parameterized. The latter can be achieved by performing local calculations which allow a much higher spatial resolution than what can be achieved in direct global calculations. In the present dissertation three aspects of mean-field theories and models of stars are studied. Firstly, the basic assumptions of different mean-field theories are tested with calculations of isotropic turbulence and hydrodynamic, as well as magnetohydrodynamic, convection. Secondly, even if the mean-field theory is unable to give the required transport coefficients from first principles, it is in some cases possible to compute these coefficients from 3D numerical models in a parameter range that can be considered to describe the main physical effects in an adequately realistic manner. In the present study, the Reynolds stresses and turbulent heat transport, responsible for the generation of differential rotation, were determined along the mixing length relations describing convection in stellar structure models. Furthermore, the alpha-effect and magnetic pumping due to turbulent convection in the rapid rotation regime were studied. The third area of the present study is to apply the local results in mean-field models, which task we start to undertake by applying the results concerning the alpha-effect and turbulent pumping in mean-field models describing the solar dynamo.