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  • Lindström, Annika (2016)
    The aeolian silty deposits found in Lammi region are commonly known as Lammi Loess. The term is established even though there are no extensive research done with modern sedimentological methods and some of the previous research on the topic are questioning the completely aeolian nature of these deposits. The purpose of this research was to determine how silty deposits known as Lammi loess fit into the definitions of loess, what type of surface textures can be detected from the deposits grains and in what extent and manner Lammi loess occurs in the Lammi region. The loess deposits of Lammi were studied using field observations and grain size analyses. The sediments grain surface textures were analyzed using scanning electron microscope (SEM). The aim of this study was to achieve an extensive understanding of the deposits properties and occurrences in the Lammi region, and also of the typical surface textures of the grains. 18 sediment samples from ten different locations in Lammi was used as material for the study. In addition one dune sample was used as a point of comparison. The locations were situated at 117-166 m asl. (meters above sea level) and majority of them were located mainly below the highest shore of the Baltic Ice Lake (162 m asl.). Lammi loess is moderately sorted aeolian deposit, consisting mainly of coarse silt and fine sand. The deposits were formed when sediments uncovered by the drop of waterlevel in the Baltic basin were exposed to aeolian activity. The source material of these deposits are local and deposition occurred rather quickly. Lammi loess occurs as rather small and local deposits on the slopes of deltas and hills. The formations are more focused on the north-west slopes. Lammi loess has several characteristics typical for loass, but as a whole it is very individualistic formation with properties that are between loess and coversands. The Lammi loess deposits resemble loess in regards of their texture, color, porosity and skewness, but the distribution of sand sized grains matches that of coversands. Some of the studied sediments were either completely or partially deposited in water.
  • Tiainen, Tony (2016)
    Tässä työssä valmistettiin sarja pinta-funktionalisoitavia ja lämpöherkkiä mikrogeelipartikkeleita lääkeainekuljettajiksi. Partikkelit syntetisoitiin dispersiopolymeroinnilla vinyylikaprolaktaamista (VCL), metakryylihaposta (MAA) ja vinyylibentsyyliatsidista (VBA) käyttäen N, N'-bis(akryyli)kystamiinia silloittajana. Komponentit valittiin niiden funktionaalisuuksien ja bioyhteensopivuuden vuoksi, VBA sisällytettiin partikkeleihin sen liittämisreaktioihin sopivan atsidiryhmän takia. Monomeerisuhteita vaihdeltiin parhaimman lopputuloksen aikaansaamiseksi. Partikkeleiden atsidiryhmien reaktiivisuutta testattiin ATRP menetelmällä valmistetuilla alkyyni-pääteryhmäisillä PDMAEMA-ketjuilla. Ne liitettiin partikkeleihin käyttäen kuparikatalysoitua atsidi-alkyyni sykloadditiota (CuAAC). Partikkelien kemiallista rakennetta selvitettiin NMR- ja IR-analyyseillä. Partikkelien koko mitattiin lämpötilan funktiona dynaamisella valonsironnalla. Oikean reagenssisuhteen ja reaktio-olosuhteiden löydyttyä partikkeleita syntetisoitiin onnistuneesti. Niiden todettiin olevan stabiileja vesiliuoksessa ja niiden todettiin muuttavan kokoaan lämpötilan funktiona. Atsidiryhmien reaktiivisuus todettiin havaitsemalla PDMAEMA IR- ja NMR-spektristä intensiivisen puhdistuksen jälkeen.
  • Missonen, Reetta (2019)
    Tässä työssä tutkittiin RAFT-polymeroinnilla syntetisoidun lämpöherkän poly(etyleeniglykoli)- b-poly(vinyylibentsyylimetyyliammoniumtriflaatin) (PEG93-PVBTMA62-OTf) liuoskäyttäytymistä ja aggregoitumista eri LiOTf-konsentraatioilla. Polymeerin hydrofobinen pääteryhmä poistettiin onnistuneesti radikaalireaktiolla, ja myös muokatun polymeerin faasikäyttäytymistä LiOTf-vesiliuoksessa tutkittiin ja verrattiin alkuperäiseen polymeeriin. Myös homopolymeeri PVBTMA-OTf polymeroitiin RAFT-menetelmällä, ja sen faasimuutoksen lämpötiloja mitattiin eri LiOTf-konsentraatiolla. Tutkimusmenetelminä käytettiin UV-Vis-spektrometriaa, NMR-spektroskopiaa ja dynaamista valonsirontaa. Alkuperäisellä polymeerillä (PEG93-PVBTMA62-OTf) havaittiin sekä alemman- (LCST), että ylemmän kriittisen liuoslämpötilan (UCST) –tyypin faasimuutos vesiliuoksessa, johon oli lisätty OTf-ioneja. Lisätyn suolan määrällä on suuri merkitys havaittuihin samentumispisteisiin. Polymeerin pääteryhmällä ei havaittu olevan suurta merkitystä liuoskäyttäytymiseen, erot alkuperäisen ja muokatun lohkokopolymeerin samentumispisteiden lämpötilojen välillä olivat korkeintaan muutamia asteita. Homopolymeerillä havaittiin ainoastaan UCST-tyypin faasimuutos, joten LCST-faasimuutos on vahvasti riippuvainen PEG-lohkosta.
  • Mononen, Marko (2014)
    Tämän tutkielman tarkoituksena on tutkia miten lämpökameraa voitaisiin käyttää hyödyksi fysiikan opetuksessa. Lämpökamera avaa mielenkiintoisen tavan lähestyä fysiikan ilmiöitä uudella, visuaalisella tavalla. Lämpökameroiden hankintahinnat alkavat olla jo tarpeeksi alhaisia koulujen hankittavaksi, joten niiden käyttäminen fysiikan opetuksessa on kiinnostava aihe. Tutkimuksen kontekstiksi on valittu energian käsitteen lähestyminen lämmön avulla. Tutkielmassa perehdytään aluksi hahmottavaan lähestymistapaan, jonka ajatusmaailman pohjalle lämpökameralla tehdyt mittaukset ja kokeet rakentuvat. Samalla perehdytään myös tyypillisiin lämpöopin virhe-, ennakko- ja intuitiivisiin käsityksiin. Lisäksi käydään läpi miten oppiminen ja käsitteellinen muutos tapahtuu. Tämän jälkeen perehdytään lyhyesti lämpökameraan ja sen taustalla olevaan teoriaan kirjallisuuden pohjalta. Varsinaisessa tutkimusosassa tutkitaan lämpökameran käyttämistä mittalaitteena, jonka jälkeen hahmottavan lähestymistavan pohjalta pohditaan energian käsitteenmuodostuksen kulkua ja mielekästä tapaa lähestyä energian laajaa käsitettä. Kun käsitteenmuodostusprosessi on jäsennetty, siirrytään itse energian käsitettä hahmottavien kokeiden ja mittausten pariin. Tutkimus toteutettiin tutustumalla lämpökameraan ja tutkimalla millaisiin mittauksiin se soveltuu. Tämän jälkeen suunniteltiin kokeita, jotka soveltuvat energian käsitteen hahmottamiseen. Tutkimuksen pohjalta voidaan sanoa, että lämpökamera on hyvä työkalu lämpöilmiöiden kokeelliseen tutkimukseen ja sen avulla voidaan tehdä monipuolisia mittauksia
  • Tenhunen, Sini (2019)
    Tässä työssä perehdytään Suomessa talvisin suuria lämpötilan ennustevirheitä aiheuttaviin tilanteisiin ja pyritään löytämään yhteyksiä ECMWF:n säämallin mallimuuttujien ja suurten ennustevirheiden välille, jotta ECMWF:n sääennusteita voitaisiin jatkokäsitellä Ilmatieteen laitoksella esimerkiksi koneoppimismenetelmin. Yleisesti ECMWF:n sääennusteet toimivat Suomen alueella hyvin, mutta talvella heikkotuulisissa ja selkeissä pakkastilanteissa ennusteiden laatu heikkenee huomattavasti. Työssä todetaan, että ECMWF:n säämallin kahden metrin lämpötilalaskentaan on tehty rajoituksia, jotka heikentävät säämallin kykyä ennustaa lämpötiloja stabiileissa olosuhteissa. Työssä tehdään data-analyysia käyttäen Ilmatieteen laitokselle tallennettuja vuosien 2013-2017 ECMWF:n sääennustedatasta saatavilla olevia mallimuuttujia. Ennusteita verrataan Suomen alueelta valittuun 90 havaintoaseman joukkoon, jotka on jaoteltu Ilmatieteen laitoksen tilastoiman 30 vuoden keskilämpötilan mukaan kolmeen alueeseen. Aluksi mallimuuttujien ja ennustevirheiden välisiä yhteyksiä eri alueilla tutkitaan lineaaristen korrelaatioiden avulla, jonka jälkeen korrelaatiotuloksia ja empiirisiä havaintoja hyväksikäyttäen valitaan lupaavimmat mallimuuttujat tiheysfunktioanalyysiin. Tiheysfunktioanalyysissa piirretään jakaumia erilaisille ennustevirheille ja pyritään löytämään tilanteita, joissa jollakin alueella tietynlainen ennustevirheen suuruus näyttäisi liittyvän tietynlaisiin ennustettuihin mallimuuttujan arvoihin. Oletuksena on, että yliennustustilanteet erottuisivat tiheysfunktiokuvista parhaiten, sillä suurimmat ja tyypillisimmät lämpötilan ennustevirheet ovat talvisin yliennustevirheitä, jolloin säämallin ennustama lämpötila on lämpimämpi kuin havaittu lämpötila. Tuloksena kuitenkin nähdään, että eroavaisuuksia eri lämpötilavirheiden välillä näkyy paljon odotettua vähemmän ja vain muutamien mallimuuttujien kohdalla hieman selkeämmin. Dataa ja havaintoaineistoa tarkemmin analysoitaessa havaitaan, että yliennustustilanteet tapahtuvat todennäköisemmin juuri kylmässä korkeapainesäässä, jossa taivas on pilvetön ja tuuli heikkoa. Tällöin siis empiirisesti havaittu ilmiö voidaan todeta myös data-analyysin keinoin. Vaikka jonkinlaista parannusta ECMWF:n ennusteeseen voidaan jatkokäsittelyllä tehdä, tulee pidempikantoinen ratkaisu kuitenkin itse säämallin kehityksestä. Jatkotoimenpiteenä voitaisiin suorittaa tarkempaa data-analyysia käyttämällä dataa luokittelevia tekoälyalgoritmeja, sekä suodattaa lämpötilavirheaikasarjaa ilmiökohtaisempaa tutkimusta varten.
  • Lehtinen, Johanna (2022)
    Climate change is going to bring a change for ecosystems and their abiotic and biotic processes. Relationship between climate and ecosystems is usually studied using macroclimatic data, but plants have been found to be more closely associated with changes in microclimates. Microclimates involve temperature, wind, radiation, and humidity conditions near the ground surface. Microclimates can change over short distances creating differences for areas general climatic conditions. Microclimates can help plants to survive in the edge of their dispersal area or create stronger variations in temperatures. Not much research conducted on microclimates in boreal ecosystems yet. The aim of this thesis is to illustrate how environmental variables affect temperatures in different seasons inside boreal biome. Microclimates are a combination of physical processes and environmental variables. Main physical processes are energy released and bound by changes in the state of water, heat flux between soil and air, and radiation balance. Environmental variables are key components on defining how physical processes occur in the area affecting the microclimatic temperatures. Topography creates change in the lapse rates via altitude variations, and slope curves and orientation change radiation and moisture conditions. Radiation and moisture conditions also vary according to the vegetation factors, for example in the forest where canopy cover and vegetation height create differences in physical processes. Water masses and mires affect the area’s moisture conditions and heat flux between air and water. Heat flux between air and soil on the other hand is affected by quality of soil and wind conditions. Wind currents affect the mixing of different layers of air and the cold air pooling together with local topography. Relative influence of the environmental variables was studied using 8 study areas located in different boreal climatic zones. Study sites included 50 to 100 temperature meters, covering different environmental conditions in the area. Temperature data were collected at a height of 15 cm above the ground over a two-year period. In this thesis explanatory variables where canopy cover, radiation, slope, wind, distance to forest edge, TWI, and water and wetland portions. GAM-models were generated for different temperature variables for different months and years. Explanation ability of the model was evaluated with bootstrap-method. Relative influence of the explanatory variables was examined by variable randomization. Models explanatory power was highest in the southern study areas and decreased slightly when moving to the northern sites. There was a positive correlation between model explanatory power and its stability. Based on this the results are more reliable in the southern sites and during the summer. Temperatures observed in microclimates followed the changes in the macroclimatic conditions. In the northern areas, the main environmental factors explaining temperature variations were mainly topographic variables such as slope, wind, and TWI. In the southern areas vegetation variables like canopy cover, distance to forest edge and wetland portion were more relevant in explaining the temperature variations. Results also suggest that topography driven wind conditions are an important variable in the northern areas. Wind was found to decrease temperatures in winter months and increase temperatures in summer. The influence of wind has not yet been taken into consideration in many previous studies, as it is affected by several different factors. Further research into the factors affecting microclimatic temperatures is important in order to determine more precisely the differences between the environmental factors influencing the temperatures and their relative significance in different years. However, the temperature variables occurring in the boreal zone can be explained by examining the topographic and vegetation variables.
  • Käkelä, Saara (2014)
    Due to global climate change there will be an increase in frequency of extreme temperatures. That will have an effect to species distribution regions. By adding extreme temperatures on a species distribution model based on the basic climatological variables we could improve the understanding of biological effect of climatic variability and extremes. The aim of this study is to develop a species distribution model for arctic-alpine and boreal vascular plant species and examine does the extremes improve predictions. The other question is, does vascular plant species from two different biogeographical distributions responds similarly to bioclimatic variables? A study area (26 000 square kilometre) is located in Northwestern Finland and it belongs to subarctic climate regime. A climate model is produced from the data of 61 climate stations from 1971–2000. Modeling was done with generalized additive model (GAM) by using geographical variables as explanatories (geographical location, elevation, the effect of the Arctic Ocean, lake and mire cover). Total sample of vascular plant species was 1182 of 1x1 km grids. The distribution model was done with three different statistical techniques (GLM, GAM, GBM). First a simple model was modeled with three baseline variables (a temperature of the coldest month, water balance, growing degree days) and then the extreme temperatures were added to compose a full model. The predictive power of the models was tested by calculating the area under the curve of a receiver operating characteristic plot (AUC) and the true skill statistic (TSS) for both models. Incorporating the extreme temperatures into the distribution model significantly improved the accuracy of distribution model of the both plant groups. The improvement was small but statistically significant. The relative importance of each predictor variable and the response of each bioclimatic variable to occurrence of species varied between the plant groups. The most significant explanatory variable to explain the arctic-alpine plant distribution is the temperature of the coldest month. The probability of occurrence increase with that variable as well as with water balance which is the second. The third significant variable is mean annual absolute minimum temperature (a negative response). For the boreal species the relative importance of climatic variables is more evenly distributed between predictor variables in the full model. The growing degree day is the most important variable (positive). Water balance (negative) and mean annual absolute maximum temperature (positive) have almost an equal variable importance. The main finding of the study is that the inclusion of extreme temperatures into distribution models of vascular plant species will improve occurrence predictions at the high-latitude study site. Secondly, arctic-alpine and boreal plant species have opposite responses on climate variables that have been used. The results could be solved in the planning of conservation areas and the climate change impact analyses.
  • Lindgren, Vilma (2019)
    Three rivers in Hannukainen, in the Kolari municipality in Finland lie in the vicinity of an old mining site planned to be re-opened for mining activities. The rivers are known to have considerable inputs of groundwater (GW) due to earlier studies, and vulnerable natural salmonid populations. Two thermal infrared (TIR) datasets were used in this study from the Hannukainen area to find GW discharge locations and the landscape geomorphological factors affecting their occurrence; a TIR set collected in 2016 with an unmanned aerial vehicle (UAV) and a TIR set from 2012–2013 containing classified GW discharge site information. The processing of the UAV data was described in detail and GW discharge sites were located manually in GIS. Discovered GW sites were classified into four categories: spring, diffuse seepage, relict channel and tributary confluence plume. Temperature profiles were created to examine the temperature changes along the rivers. The GW sites mostly caused only minor fluxes to the stream temperature, the main effect being on the landscape morphological features. Four landscape metrics were calculated from the GW discharge site TIR data 2012–2013 and open GIS data: channel sinuosity, gradient, terrain slope and entrenchment ratio (ER). The metrics were then statistically correlated with the GW discharge site locations. After the correlations ER was the only statistically significant metric indicating connections to the discharge site occurrences and counts. Low statistic model accuracy values and correlation coefficients were attained suggesting that a large part of the variance in the data remains unexplained by the metrics. There was a weak positive linear relationship between ER and the discharge site occurrences and counts, which means that more open valleys are more prone to having an increased amount of GW discharge sites. As the correlation is weak, a large part of the effects on the discharge amounts come likely from other riverine processes. The results partly agree and partly differ from the few studies that used similar metrics. As used in this study the use of landscape metrics to predict the locations of GW discharge sites would be challenging and the reliability of results would be hard to ensure. More established methods for choosing, calculating and correlating the metrics are suggested. Also an inventory for metric values or value combinations representing the probable locations of GW discharge sites would be helpful in future studies.
  • Määttänen, Aino-Maija (2020)
    Climate change has the strongest impact on high-latitude ecosystems that are adapted to cool climates. In order to better understand and predict the changes in tundra vegetation observed on large scales as well as their feedbacks onto climate, it is necessary to look at what is happening at finer scales; even in individual plants. Technological developments over the past few decades have enabled the spread of cost-effective, light and small unmanned aerial vehicles (UAVs). As very high-resolution data (pixel size <10cm) becomes more and more available, the remote sensing methods used in environmental analysis become subject to a paradigm shift as algorithms and analyzes based on machine vision and learning turn out to be more common. Harnessing new methods is attractive because they allow flexible and highly automated data collection and the production of highly accurate remote sensing products from hard-to-reach areas such as the tundra. However, obtaining reliable results requires careful planning and testing of processing algorithms and parameters. This study looked at how accurately variables derived from aerial images collected with an off-the-shelf digital camera can map the vegetation structure on a landscape scale. In Kilpisjärvi, northern Fennoscandia, a total of ~ 10,000 aerial photographs were collected by drone covering an area of three hundred hectares. In addition, dominant vascular plants were identified from 1183 points in the area, as well as vegetation height. Aerial images were processed into dense three-dimensional point clouds by using SfM (Structure from Motion) method, which is based on computer vision and digital photogrammetry. From the point clouds terrain models and vegetation height models were interpolated. In addition, image mosaic covering the entire area was produced. Based on these data, predictive variables were calculated, which were used together with the terrain reference data in Geographical Object-Based Image Analysis (GEOBIA). The filtered ground points corresponded to observations throughout the region, and the produced elevation models strongly correlated with the ground reference data. The terrain model error was greatest in areas with tall vegetation. Changes in lighting conditions and vegetation during aerial image surveys posed challenges in both phases of object-based analysis: segmentation and classification. but overall accuracy improved from 0.27 to 0.54 when topography, vegetation height and texture variables were added to the classifier and the number of target classes was reduced. Methods based on machine vision and learning can produce important information about vegetation structure, vegetation height, in a landscape. However, more research is needed to determine the best algorithms and parameters in a tundra environment where environmental conditions change rapidly and vegetation is heterogeneous and mixed, causing differences between aerial images and difficulties in analyses.
  • Hallenberg, Sami (Helsingin yliopistoHelsingfors universitetUniversity of Helsinki, 2012)
    Tässä pro gradu -tutkielmassa käsitellään langattoman IEEE 802.11 -lähiverkon eli WLANin tietoturvaa. Siihen kuuluu laitteiden todentaminen, datan salaus, lähetysten muuttumattomuus eli eheys ja verkon saatavuus. WLANin kolme eri tietoturvaprotokollaa, WEP, WPA ja WPA2, täyttävät tietoturvan eri osa-alueille asetettuja tavoitteita hyvin vaihtelevasti. WEP on vanhin ja kaikilta osin puutteellinen. Epävirallinen ja väliaikaiseksi tarkoitettu WPA takaa jo luotettavan todennuksen, mutta on muilta osin puutteellinen. WPA2 on standardoitu ja tarjoaakin WLANissa luotettavan todennuksen, salauksen ja eheyden. WPA2 ei kuitenkaan takaa verkon saatavuutta. Hyökkääjä voi palvelunestohyökkäyksillä estää verkon käyttöön oikeutettuja tahoja käyttämästä verkkoa. Vaarallisimmat palvelunestohyökkäykset WLANissa perustuvat joko radiohäirintään, yksittäisten lähetysten heikkoon todentamiseen tai suurella lähetysmäärällä tulvittamiseen. Palvelunestohyökkäyksillä voidaan helposti lamaannuttaa verkon toiminta, eikä mikään yksittäinen keino torju kaikkia hyökkäyksiä. Tässä tutkielmassa käydään läpi erilaisia hyökkäyksiä ja niiden torjuntakeinoja. Esitän myös uuden ajatuksen sekvenssinumeroihin perustuvasta tulvituksen torjunnasta. Lähetyksissä säännönmukaisesti eteneviä sekvenssinumeroita on aiemmin käytetty vain väärennetyn lähettäjästä kertovan MAC-osoitteen havaitsemiseen, mutta niitä voidaan käyttää myös tulvitushyökkäyksen torjumiseen.
  • Mielikäinen, Taneli (2013)
    Läpivalaisukuvien orientointi on eräs rakennebiologian keskeisimmistä laskennallisista ongelmista. Siinä on tavoitteena selvittää joukolle identtisten kappaleiden läpivalaisukuvia läpivalaisusuunnat toistensa suhteen. Jos läpivalaisukuvien läpivalaisusuunnat tunnetaan, voidaan läpivalaisukuvista niiden avulla päätellä läpivalaisukuvia vastaava tiheysjakauma. Tässä tutkielmassa osoitetaan, että läpivalaisukuvien orientointi on yleisessä tapauksessa NP-kovaa, approksimointikelvotonta ja kiintoparametriratkeamatonta. Tämän jälkeen ongelmalle esitetään heuristisia ratkaisuja ja arvioidaan kokeellisesti niiden toimivuutta.
  • Heino, Roy Samuel (2014)
    Työssä esitellään Laplace-muunnoksena tunnettu integraalimuunnos. Se on yksi yleisimmin käytössä olevista integraalimuunnoksista, minkä taustat pohjautuvat Eulerin ja Lagrangen käänteistä Laplace-muunnosta muistuttaviin integraaleihin. Muunnos sai nimensä kehittäjänsä ranskalaisen matemaatikon Pierre-Simon Laplace (1749-1827) mukaan. Työn alussa esitellään Laplace-muunnoksen syntyyn liittyvää historiaa sekä palautetaan mieleen joitain esitietoja liittyen integraalin suppenemiseen ja jatkuvuuden käsitteeseen. Tämän jälkeen perehdytään varsinaiseen asiaan, eli Laplace-muunnoksen määritelmään ja sen ominaisuuksiin. Käydään läpi kuinka muodostuvat derivaatan ja integraalin Laplace-muunnokset sekä lopulta tutkitaan käänteisen Laplace-muunnoksen määritelmää ominaisuuksineen. Laplace-muunnos muuntaa t:n funktion f, s:n funktioksi F, minkä ratkaiseminen esimerkiksi osamurtohajotelman avulla on huomattavasti alkuperäistä helpompaa. Lopulta F(s) palautetaan käänteisen Laplace-muunnoksen avulla takaisin t:n funktioksi f, mikä on differentiaaliyhtälön ratkaisu. Käänteismuunnoksen ja kompleksisen Laplace-muunnoksen määrittelyssä käytän apuna Fourier'n muunnoksen teoriaa. Työssä käsitellään myös konvoluution sekä yksikköaskelfunktion käsitteitä ja niiden Laplace-muunnoksia. Tavoitteena on osoittaa kuinka kyseinen menetelmä helpottaa tietyntyyppisten differentiaaliyhtälöiden ratkaisemista. Varsinkin sähkötekniikassa ja elektroniikassa kyseinen integraalimuunnos on erittäin tärkeä työväline. Työn lopussa sovelletaan opittua erityyppisten differentiaaliyhtälöiden ratkaisuun sekä elektroniikan piirien, eritoten RLC-piirien yhteydessä ilmenevien differentiaaliyhtälöiden teoriaan.
  • Suhonen, Heli (2016)
    The topic of this Master's thesis (Pro Gradu) is the housing of families with children and their moving desires in the inner city. The objective of this thesis is to find out which factors would explain the increased number of children living in Helsinki inner city in the recent years. In national discussions, it has been considered why families with children stay in the inner city: is it a consequence of the global popularity of urban housing or is it due to the economic recession? In this thesis, these factors are examined through structural and cultural values. The effects of financial resources of families with children as well as the significance of the area's location and services are categorised as structural factors. The values of families with children related to housing and attitudes towards it, relationship with the neighbourhood as well as culture and recreation are counted as cultural factors. This thesis brings up the hopes and wishes of families with children concerning good living environment as well as ideas on what kind of living environment would best meet the children's needs and how it could be implemented through planning and design. Arabianranta is a new residential area favoured by families with children in the eastern inner city. The residents of Arabianranta are middle-class and have higher education. This thesis examines the housing selections, housing satisfaction and moving aspirations of 17 families with children living in Arabianranta through thematic interviews. Families are attracted to Arabianranta residential area by the new, affordable family apartments and the surrounding nature as well as the child-friendly environment of the area. Based on this thesis, families with children are happy with living in Arabianranta. The families who participated in the thesis were divided into three groups based on the research results: Urban residents living in self-owned apartments (47%), urban residents living in rental apartments (36%) and people planning to move elsewhere (17%). Urban families (83%) want to continue living in the inner city. They are willing to make compromises on the apartment's size rather than its location. Based on the research results, it can be stated that urban families feel that smooth day-to-day life and short commute are the most important reasons for living near the city centre. It is important to them that the children's days at day care do not become too long and that the family has time together in the evenings. Based on this thesis, the most significant reasons for the increasing amount of families with children in the inner city are the attractiveness of inner city areas and the popularity of urban way of living. Families with children see the inner city as a very attractive option, and people do not want to move away, if it is financially possible for them to remain in the area.
  • McCann, Robin (2022)
    Large deviations theory is a branch of probability theory which studies the exponential decay of probabilities for extremely rare events in the context of sequences of probability distributions. The theory originates from actuaries studying risk and insurance from a mathematical perspective, but today it has become its own field of study, and is no longer as tightly linked to insurance mathematics. Large deviations theory is nowadays frequently applied in various fields, such as information theory, queuing theory, statistical mechanics and finance. The connection to insurance mathematics has not grown obsolete, however, and these new results can also be applied to develop new results in the context of insurance. This paper is split into two main sections. The first presents some basic concepts from large deviations theory as well as the Gärtner-Ellis theorem, the first main topic of this thesis, and then provides a fairly detailed proof of this theorem. The Gärtner-Ellis theorem is an important result in large deviations theory, as it gives upper and lower bounds relating to asymptotic probabilities, while allowing for some dependence structure in the sequence of random variables. The second main topic of this thesis is the presentation of two large deviations results developed by H. Nyrhinen, concerning the random time of ruin as a function of the given starting capital. This section begins with introducing the specifics of this insurance setting of Nyrhinen’s work as well as the ruin problem, a central topic of risk theory. Following this are the main results, and the corresponding proofs, which rely to some part on convex analysis, and also on a continuous version of the Gärtner-Ellis theorem. Recommended preliminary knowledge: Probability Theory, Risk Theory.
  • Vepsäläinen, Mikko (Helsingin yliopistoUniversity of HelsinkiHelsingfors universitet, 2001)
  • Malkamäki, Aapo (2018)
    In mitochondria and many bacteria, the electron transport chain produces energy from foodstuff as a part of cell respiration. Complex IV, also known as Cytochrome c Oxidase, is the last protein complex in the electron transport chain. It couples electron transport with the transfer of protons across the inner mitochondrial membrane (or the cell membrane in bacteria). The pumped protons produce a proton-motive force, which drives adenosine triphosphate synthase to generate adenosine triphosphate molecules used as energy currency in many cellular functions. Dysfunction of complex IV may cause myopathies and other mitochondrial malfunctions, and therefore it is important to understand how this enzyme functions and is regulated. The work performed in this Thesis provides novel insights into the intricate function of the enzyme and reveals the importance of lipid-protein interactions that turn out to be critical in the enzyme function. These insights provide new ways to better understand how cardiolipin as a key lipid in mitochondrial membranes participates in proton uptake pathways, and whether cardiolipin also has an important role in complex IV dimerization. Six large-scale atomistic molecular dynamics simulations of complex IV were performed, including simulations of the dimeric as well as the monomeric complex IV. In each simulation, the membrane consisted of three kinds of primary lipids found in the inner mitochondrial membrane. All the simulations were two to three microseconds long, therefore representing the current state-of-the-art in membrane-protein simulations in this context. The simulation data show that the dimeric complex IV is stable. The data also reveal that there are fewer protein-protein ion pairs between complex IV monomers in the presence of cardiolipins at the interface, however cardiolipin could also function as glue forming charge-charge interactions with both of the monomers. Cardiolipin-complex IV interactions seem to have more significance compared to other lipid-complex IV interactions, favoring the earlier proposals that cardiolipins are possibly involved in proton uptake. The monomeric complex IV was observed to tilt 5-10 degrees with respect to the initial position of the protein and membrane normal, while for the dimeric complex IV no tilt was observed. The difference in tilt might work as a free energy barrier in dimerization. It is also suggested that cardiolipins between the monomers could reduce the possible free energy barrier in dimerization. Understanding of these microscopic aspects by means of molecular dynamics simulations may open up new avenues to target mitochondrial dysfunctions.
  • Wang, Liang (2013)
    Evaluation of large-scale network systems and applications is usually done in one of three ways: simulations, real deployment on Internet, or on an emulated network testbed such as a cluster. Simulations can study very large systems but often abstract out many practical details, whereas real world tests are often quite small, on the order of a few hundred nodes at most, but have very realistic conditions. Clusters and other dedicated testbeds offer a middle ground between the two: large systems with real application code. They also typically allow configuring the testbed to enable repeatable experiments. In this paper we explore how to run large BitTorrent experiments in a cluster setup. We have chosen BitTorrent because the source code is available and it has been a popular target for research. In this thesis, we first give a detailed anatomy on BiTorrent system, such as its basic components, logical architecture, key data structures, internal mechanisms and implementations. We illustrate how this system works by splitting the whole distribution process into small scenarios. Then we performed a series of experiments on our cluster with different combination of parameters in order to gain a better understanding of the system performance. We made our initial try in discussing 'How to design a rational experiment' formally. This issue did not receive as much attention as it should in the previous research work. Our contribution is two-fold. First, we show how to tweak and configure the BitTorrent client to allow for a maximum number of clients to be run on a single machine, without running into any physical limits of the machine. Second, our results show that the behavior of BitTorrent can be very sensitive to the configuration and we re-visit some existing BitTorrent research and consider the implications of our findings on previously published results. As we show in this paper, BitTorrent can change its behavior in subtle ways which are sometimes ignored in published works.
  • Pierce, Matthew (2015)
    This thesis provides a detailed exploration of numerous methods — some established and some novel — considered in the construction of a text-categorization system, for use in a large-scale, online news-monitoring system known as PULS. PULS is an information extraction (IE) system, consisting of a number of tools for automatically collecting named-entities from text. The system also has access to large training corpora in the business domain, where documents are annotated with associated industry-sectors. These assets are leveraged in the construction of a multi-label industry-sector classifier, the output of which is displayed on the web-based front-end of PULS, for new articles. Through review of background literature and direct experimentation with each stage of development, we illuminate many major challenges of multi-label classification. These challenges include: working effectively in a real-world scenario that poses time and memory restrictions; organizing and processing semi-structured, pre-annotated text corpora; handling large-scale data sets and label sets with significant class imbalances; weighing the trade-offs of different learning algorithms and feature-selection methods with respect to end-user performance; and finding meaningful evaluations for each system component. In addition to presenting the challenges associated with large-scale multi-label learning, this thesis presents a number of experiments and evaluations to determine methods which enhance overall performance. The major outcome of these experiments is a multi-stage, multi-label classifier that combines IE-based rote classification — with features extracted by the PULS system — with an array of balanced, statistical classifiers. Evaluation of this multi-stage system shows improvement over a baseline classifier and, for certain evaluations, over state-of-the-art performance from literature, when tested on a commonly-used corpus. Aspects of the classification method and their associated experimental results have also been published for international conference proceedings.
  • Wälchli, Ben (2020)
    High accuracy bonding of optical components is required for the manufacture of photonic integrated circuits. We propose and demonstrate a novel method of metal-to-metal thermocompression bonding. By using highly localized heating, we propose to avoid thermal drift during bonding and stresses due to thermal mismatch of bonded components. This is achieved by focusing an infrared laser through a silicon substrate and a purpose built thin film stack to heat the bonding interface. Samples with gold bonding pads are used to investigate bonding efficacy. We demonstrate melting of metal bonding pads. Shear testing suggests that the limiting factor in attained bond strength is the structure of the thin film stack under the bonding pad. A redesign of this stack is required in order to improve bond durability.
  • Käki-Mäkelä, Joni (2020)
    Tutkielmassa käydään läpi pelien perusrakennuspalikat, joiden laskennallinen tuottaminen on mahdollista erilaisten tekniikoiden avulla. Lisäksi tutkielmassa selvitetään, mikä on tekoälyn rooli peleissä, ja millaisia tekoälyjärjestelmiä peleissä on. Tutkielmassa tarkastellaan laskennallisen sisällöntuotannon ja tekoälyn eri tekniikoita eri perspektiiveistä. Lisäksi tehdään katsaus eri pelien ja pelimoottorien tarjoamiin tekoälyjärjestelmiin. Tutkielmassa on myös esitelty laskennallinen sisällöntuotanto, ja selvitetty miten talojen pohjapiirustuksia voidaan toteuttaa laskennallisesti. Tutkielmaa varten on toteutettu algoritmi talon pohjapiirustusten laskennalliseen tuotantoon ja arvioitu sen sopivuutta sisällöntuotannon keinona.