Browsing by Author "Turunen, Tuomas"
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- Analysis of multi-propeller marine applications by means of computational fluid dynamics
Insinööritieteiden korkeakoulu | Master's thesis(2014-05-19) Turunen, TuomasTyössä tarkastellaan laskentamenetelmiä, joiden avulla voidaan analysoida useampipotkurisia meritekniikan laitteita. Tavoitteena on luoda laskentatyökalu, jolla voidaan parantaa olemassa olevia laitteita ja arvioida uusien konseptien suorituskykyä ja siten suunnitella hyötysuhteeltaan nykyistä parempia tuotteita. Ensiksi käydään läpi tällä hetkellä saatavilla olevia laskentamenetelmiä ja arvioidaan niiden soveltuvuutta kirjallisuustutkimuksen avulla. Potkurin pyöriminen mallinnetaan MRF-menetelmällä sekä pyörivän hilan menetelmällä, jossa hilan eri osat on erotettu niin sanotulla liukuvalla pinnalla. Turbulenssi mallinnetaan RANS-tyyppisellä kaksiyhtälömallilla SST k-omega. Teoria, johon laskentamenetelmät perustuvat, käydään läpi ja mallien toimivuutta tutkitaan vertaamalla laskettuja tuloksia mittauksiin. Vertailutapauksia on kaksi. Ensimmäisessä tapauksessa on yksi potkuri avovesiolosuhteissa ja toisessa tapauksessa yksikkö, johon kuuluu vastakkain pyörivä potkuri (CRP). Laskenta tehdään avoimen lähdekoodin virtaussimulointiohjelmistolla OpenFOAM-2.2.x, jossa sovelletaan esitettyjä laskentamenetelmiä. Kaikki käytetyt menetelmät toimivat yksittäin, mutta edelleen tarvitaan jatkotutkimuksia, jotta saavutettaisiin tavoiteltu laskentatyökalu useampipotkuristen laitteiden analysoimiseen. - Diskretointimenetelmät OpenFOAMissa
School of Engineering | J Muu elektroninen julkaisu(2011) Turunen, TuomasTiivistelmä Tarkoituksena on koota OpenFOAMissa käytettävät diskretointimenetelmät ja niiden vaatimukset käyttäjän näkökulmasta. Lisäksi esitellään, miten eri menetelmien valitseminen vaikuttaa laskennan aikana ratkaistaviin yhtälöryhmiin. - Hilatiheyden määrittäminen ennen simulointia
School of Engineering | J Muu elektroninen julkaisu(2012) Turunen, TuomasTiivistelmä: Tarkoituksena on koota menetelmiä, joilla voi arvioida hilan tiheyden tarvetta seinien läheisyydessä ennen simuloinnin aloittamista. Pääkohdat: Tämä muistio esittelee joitakin menetelmiä dimensiottoman etäisyyden määrittämiseksi eri virtaustapauksissa ja vertailee niiden käyttökelpoisuutta. - Mice Reach Higher Visual Sensitivity at Night by Using a More Efficient Behavioral Strategy
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2020-01-06) Koskela, Sanna; Turunen, Tuomas; Ala-Laurila, PetriCircadian clocks predictively adjust the physiology of organisms to the day/night cycle. The retina has its own clock, and many diurnal changes in its physiology have been reported. However, their implications for retinal functions and visually guided behavior are largely unresolved. Here, we study the impact of diurnal rhythm on the sensitivity limit of mouse vision. A simple photon detection task allowed us to link well-defined retinal output signals directly to visually guided behavior. We show that visually guided behavior at its sensitivity limit is strongly under diurnal control, reaching the highest sensitivity and stability at night. The diurnal differences in visual sensitivity did not arise in the retina, as assessed by spike recordings from the most sensitive retinal ganglion cell types: ON sustained, OFF sustained, and OFF transient alpha ganglion cells. Instead, we found that mice, as nocturnal animals, use a more efficient search strategy for visual cues at night. Intriguingly, they can switch to the more efficient night strategy even at their subjective day after first having performed the task at night. Our results exemplify that the shape of visual psychometric functions depends robustly on the diurnal state of the animal, its search strategy, and even its diurnal history of performing the task. The results highlight the impact of the day/night cycle on high-level sensory processing, demonstrating a direct diurnal impact on the behavioral strategy of the animal. - Organizing Elective Interhospital Patient Transfers with Fixed-wing Aircraft in Finland
Perustieteiden korkeakoulu | Master's thesis(2023-10-11) Pyykönen, LottaThe ageing of the Finnish population is placing strain on healthcare costs and affecting the availability of healthcare professionals. Supply needs to be increased to meet the rising demand caused by the increasing number of pensioners. Supply can be increased either by adding more resources to the system or by improving productivity. The study explores the potential of using fixed-wing aircraft for long-distance elective interhospital patient transport to increase productivity in the Finnish healthcare system. Furthermore, the intervention’s leverage to the Finnish healthcare system and society is examined. A broad societal view on value-based healthcare is used to avoid sub-optimization when evaluating the viability of the intervention. The value creation process in elective interhospital transport can be described by resources used to create value and by outcomes that matter. Productivity, which is one of the outcomes that matter, is assessed by comparing the cost- and time-effectiveness of the intervention to ground ambulance operations. Other outcomes that matter is examined based on expert interviews. The findings indicate that fixed-wing aircraft are more time-effective after 120km but less cost-effective than the current solution. The greatest benefits of the solution’s time-effectiveness relate to equity and productivity. The solution can improve equity by making specialized treatment more accessible. Moreover, it can improve productivity by more efficient resource allocation, by balancing demand among hospitals and by helping the communication of centralization. However, even though the potential of the intervention has been recognized, further research is needed to mitigate the risks related to it such as financial and environmental risks. - Paradoxical Rules of Spike Train Decoding Revealed at the Sensitivity Limit of Vision
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2019-11-06) Smeds, Lina; Takeshita, Daisuke; Turunen, Tuomas; Tiihonen, Jussi; Westö, Johan; Martyniuk, Nataliia; Seppänen, Aarni; Ala-Laurila, PetriAll sensory information is encoded in neural spike trains. It is unknown how the brain utilizes this neural code to drive behavior. Here, we unravel the decoding rules of the brain at the most elementary level by linking behavioral decisions to retinal output signals in a single-photon detection task. A transgenic mouse line allowed us to separate the two primary retinal outputs, ON and OFF pathways, carrying information about photon absorptions as increases and decreases in spiking, respectively. We measured the sensitivity limit of rods and the most sensitive ON and OFF ganglion cells and correlated these results with visually guided behavior using markerless head and eye tracking. We show that behavior relies only on the ON pathway even when the OFF pathway would allow higher sensitivity. Paradoxically, behavior does not rely on the spike code with maximal information but instead relies on a decoding strategy based on increases in spiking. Smeds et al. combine retinal ganglion cell recordings with markerless tracking of mouse behavior in photon detection. They show that behavior relies on information presented as increased spiking activity rather than the spike code carrying the maximal information. - Retinal OFF ganglion cells allow detection of quantal shadows at starlight
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2022-07-11) Westö, Johan; Martyniuk, Nataliia; Koskela, Sanna; Turunen, Tuomas; Pentikäinen, Santtu; Ala-Laurila, PetriPerception of light in darkness requires no more than a handful of photons, and this remarkable behavioral performance can be directly linked to a particular retinal circuit—the retinal ON pathway. However, the neural limits of shadow detection in very dim light have remained unresolved. Here, we unravel the neural mechanisms that determine the sensitivity of mice (CBA/CaJ) to light decrements at the lowest light levels by measuring signals from the most sensitive ON and OFF retinal ganglion cell types and by correlating their signals with visually guided behavior. We show that mice can detect shadows when only a few photon absorptions are missing among thousands of rods. Behavioral detection of such “quantal” shadows relies on the retinal OFF pathway and is limited by noise and loss of single-photon signals in retinal processing. Thus, in the dim-light regime, light increments and decrements are encoded separately via the ON and OFF retinal pathways, respectively. - Standardi k-epsilon-mallin tarkastelu OpenFOAMissa
School of Engineering | J Muu elektroninen julkaisu(2011) Turunen, TuomasTiivistelmä: Standardi k-epsilon-mallissa hilassa olevissa vapaan virtauksen alueissa turbulenssi katoaa eikä välttämättä syty enää sen jälkeen. Tarkoituksena on muokata mallia siten, että turbulenssi ei katoa vapaan virtauksen alueella. Tarkoituksena on myös tutustua k-epsilon-mallin yhtälöihin ja niissä esiintyvien termien merkityksiin. - Tracking mouse eye movements at the sensitivity limit of vision
Perustieteiden korkeakoulu | Master's thesis(2020-01-20) Seppänen, Aarni - Tukirakenteen mekaaninen mallintaminen kudosteknologiassa
Sähkötekniikan korkeakoulu | Bachelor's thesis(2012) Nisén, Henrik