Browsing by Author "Virtanen, Antti"
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- An assessment of divergent approaches to the implementation of mandatory non-financial reporting in Finland and Sweden
School of Business | Master's thesis(2019) Virtanen, Antti - ELMFIRE predictions of the bootstrap current profile in the JET pedestal region
Perustieteiden korkeakoulu | Master's thesis(2020-03-17) Virtanen, AnttiMagnetic confinement of a plasma in a tokamak fusion reactor requires sufficient plasma current drive to sustain the magnetic field configuration. In present devices, the necessary current is mainly driven by external means. Non-inductive, self-generated plasma current called bootstrap current is considered critical in any future tokamak-based designs. The bootstrap current develops in a plasma due to the presence of a radial plasma pressure gradient. Consequently, significant bootstrap current drive arises in particular in a steep pedestal that forms in high confinement mode plasma scenarios. The bootstrap current also plays an important role in pedestal stability. In this thesis, the bootstrap current profile is studied in the pedestal region numerically with both neoclassical and turbulent simulations using plasma and magnetic parameters present in the JET tokamak. The simulations are performed with the gyrokinetic plasma simulation code ELMFIRE in the low-collisionality regime. The neoclassical simulation results are compared to two different analytical estimates. From the turbulence simulations, the effect of electrostatic instabilities on the bootstrap current profile is investigated by comparing the results to neoclassical predictions. The neoclassical bootstrap current simulations are found to agree with the analytical estimates within a few percent. No large deviation between the two analytical models is observed for the low-collisionality regime, and both models match the simulation results within numerical accuracy, even when approaching the limit where the neoclassical approximations start to break down. However, discrepancies as large as 20% between the numerical simulation and the analytical estimates by the models are introduced when the collision grid used by ELMFIRE is made sparser, resulting in inaccuracy in the collision operator. The turbulence simulations show a strong effect of turbulent fluctuations on the plasma current which reduces the current density in comparison to the neoclassical predictions. Computational restrictions prevent further quantitative investigations and analyses. - Ikäihmisten huomioiminen käyttäjäkeskeisessä suunnittelussa
Perustieteiden korkeakoulu | Bachelor's thesis(2020-05-26) Virtanen, Antti - Look at the cookies — Effects of dark patterns in web browser cookie dialogues
Perustieteiden korkeakoulu | Master's thesis(2024-08-19) Virtanen, AnttiThis master's thesis studies how use of dark patterns is able to affect user behavior. The push towards a heavily data-driven competition among businesses has made the ability to collect as much user data as possible extremely valuable for them. The browser cookies help collecting data, but it requires the user's consent is some legislations. A cookie consent dialog is a common way to gain this consent and dark patterns can be used to nudge this choice towards a favorable one. To study the effects of dark patterns, an experiment using eye tracking and custom data collection software was conducted. Participants were presented with extremely simple tasks that they completed answering on a dialogue taking resemblance from real cookie consent dialogues. Participants eye gaze and mouse pointer location were tracked during the experiment. Also, a background information survey on demography and web browsing habits were conducted. The key metrics we ended up looking were the task completion time and which button on the dialogue was first looked at. From the task completion times, the only comparison that really stood up was the one between the contexts of random words as button labels and the labels usually used in actual cookie dialogues. A change in visual button design did not result in any change. When looking at the gaze patterns, it was clear that participants tended to read the dialogue from left-to-right according to the English language. However, the approaches of participants were very different. It seems a users personal habituation is way more deciding than any small change in visual design for how the users observe a user interface. This definitely strengthens the theory that existing design convention could be the primary factor steering user decision when interacting with cookie consent dialogues. - Using video to characterize participant's behaviour in magnetoencephalography: optical-flow-based approach
Perustieteiden korkeakoulu | Bachelor's thesis(2017-04-12) Virtanen, Antti