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  • Pukkila, Eero (2022)
    Etuuspohjaisen eläkejärjestelyn laskennan tavoitteena on selvittää eläkevakuutuksen ottajan säästö- ja eläkesuunnitelmien yhteensopivuus ottaen samalla huomioon sopimukseen kuuluvat turvat ja muut kulut. Vapaaehtoisiin eläkesopimuksiin tehtyjen lakimuutosten seurauksena tällainen laskenta on monimutkaistunut huomattavasti 2000-luvun aikana ja vanhoille järjestelmille luodut laskentamallit eivät aina suoriudu toivotulla nopeudella. Tämän tutkielman aiheena on Profit Software Oy:n Profit Life & Pension -vakuutustenhallintajärjestelmän optimointi edellä kuvatun laskennan osalta.
  • Kilpinen, Salla (2018)
    Tämä pro gradu -tutkielma käsittelee Eukleideen algoritmia ja joitakin sen sovelluksista ja yleistyksistä. Eukleides Aleksandrialainen oli kreikkalainen matemaatikko (n. 300 eaa), joka kirjoitti muun muassa teoksen Alkeet. Alkeet on erityisesti geometrian kokonaisteos, mutta se sisältää myös jonkin verran lukuteoriaa, muun muassa Eukleideen algoritmin. Tämä algoritmi on yksi vanhimmista algoritmeista, jotka ovat yleisessä käytössä. Tutkielmassa esitellään Eukleideen algoritmi, jonka avulla voidaan selvittää kahden luvun suurin yhteinen tekijä ja Diofantoksen yhtälöt, jotka ovat kokonaislukukertoimisia kahden tai useamman muuttujan polynomiyhtälöitä. Tutkielman lopussa esitellään muutamia Eukleideen algoritmin sovelluksia ja algoritmin yleistyksiä muille kuin kokonaisluvuille.
  • Tikka, Sauli (2017)
    Tutkielmassa pyritään vastaamaan kysymykseen siitä, minkä ulottuvuuden euklidiseen avaruuteen voidaan määritellä bilineaarinen binäärioperaatio siten, että euklidinen avaruus varustettuna tällä laskutoimituksella on jakoalgebra. Työssä ei pyritä täydelliseen vastaukseen vaan päätavoitteena on antaa kysymykseen välttämätön ehto: avaruuden ulottuvuuden täytyy olla luvun kaksi potenssi. Tutkielman johdannossa esitellään ongelma ja annetaan esimerkki siitä, että kolmiulotteisessa avaruudessa ei jakoalgebran rakennetta voida saavuttaa. Työn ensimmäisessä varsinaisessa luvussa esitellään tarpeellinen määrä kategoriateoriaa, jotta algebralliselle topologialle tyypilliset kategorioihin ja funktoreihin liittyvät argumentit joita tutkielmassa käytetään, ovat perusteltuja. Lisäksi määritellään niin kutsuttu Hom-funktori ja esitellään sen perusominaisuuksia. Kyseisen funktorin soveltaminen, dualisointi, johtaa yksinkertaisella tavalla yleisen ketjukompleksin kohomologiaryhmiin. Tässä kohtaa työtä tulee selväksi, että dualisaatio säilyttää lukuisia homologiateoriasta tunnettuja ominaisuuksia ja konstruktioita. Luvun työläin ja tärkein osuus on universaalin kerrointeoreeman todistus. Kyseinen lause selvittää yhteyden kohomologia- ja homologiaryhmien välille ja antaa tavan laskea ketjukompleksin kohomologia- ryhmät sen homologiaryhmien avulla. Luvun loppupuolella esitellään yleisen kohomologiateorian aksiomaattinen määritelmä, jota tarvitaan myöhemmin tutkielmassa sekä tutustutaan tavallisimpiin kohomologiateorioihin. Näitä ovat muun muassa singulaarinen kohomologia ja solukohomologia. Kohomologiaryhmien perustietoihin tutustumisen jälkeen tutkielman neljännessä luvussa aletaan käsittelemään kohomologiaryhmille määriteltyä uutta laskutoimitusta, kuppituloa. Tämä on keskeinen käsite kohomologiateorian kannalta sillä se on varsinaisesti ensimmäinen täysin uusi asia verrattuna homologiateoriaan. Osoitetaan, että kuppitulo määrittelee kohomologiaryhmien porrastettun kertolaskun ja että varustamalla kohomologiaryhmistä muodostettu suora summa tällä laskutoimituksella lopputuloksena on porrastettu rengas, avaruuden kohomologiarengas. Muutaman valottavan esimerkin ja kuppitulon luonnolliseksi toteamisen jälkeen, näytetään että kuppitulo on antikommutatiivinen laskutoimitus jos kerroinrengas on kommutatiivinen. Tutkielman viimeisessä luvussa on kenties työn raskaimmat laskut. Luvun alkupuoli painottuu kahden avaruuden muodostaman tulojoukon kohomologiarenkaan laskemiseen. Künnethin kaava näyttää, että tietyin oletuksin kahden avaruuden kohomologiarenkaiden tensoritulolta tuloavaruuden kohomologiarenkaalle määritelty ristitulokuvaus on rengasisomorfismi. Lopulta laskemme projektiivisen avaruuden kohomologiarenkaan. Soveltamalla tätä tietoa ja Künnethin kaavaa jakoalgebran määräävän bilineaarisen binäärioperaation indusoimaan kohomologiakuvaukseen, saadaan vastaus johdannossa esitettyyn kysymykseen.
  • Kortelainen, Oskar (2018)
    Detta arbete är min Pro Gradu avhandling inom matematik och avhandlingen är gjord som en litteraturstudie. I denna avhandling presenteras den Euklidiska geometrin genom att introducera Euklides fem postulat. Det femte postulatet, parallellpostulatet, behandlas närmare eftersom det länge var kontroversiellt och dess relation till de övriga postulaten var oklar. I denna avhandling behandlas även bristerna i de Euklidiska postulaten på grund av att Euklides har baserat en del av sina bevis endast på gurer samt gjort antaganden som ej explicit bevisats. Det mest kända systemet för den Euklidiska geometrin där alla axiom är explicit formulerade är formulerad av David Hilbert. Hilbert formulerade 16 stycken axiom som indelas i fem grupper: incidensaxiomen, ordningsaxiomen, kontinuitetsaxiomen, kongruensaxiomen och parallellaxiomet. Denna avhandling bygger upp och presenterar den Hyperboliska geometrin genom att presentera några av matematikerna som arbetade med att ställa upp den Hyperboliska geometrin. Detta gjorde de genom att anta att de fyra första postulaten av Euklides gäller. Dessutom presenteras det Hyperboliska axiomet som är negationen av Euklides parallellpostulat och samtidigt det femte antagandet för den Hyperboliska geometrin. I avhandlingen tas det även upp tre stycken olika modeller för den Hyperboliska geometrin. Modellerna som tas upp är: Kleins modell samt Poincarés halvplansmodell och cirkelmodell. Till sist i avhandlingen bevisas det att den sistnämnda modellen är konsistent genom att använda oss av metoden med inversioner i cirklar. Med hjälp av denna metod kan det bevisas att de sex kongruensaxiomen som gäller för den Euklidiska geometrin också gäller för Poincarés cirkelmodell. Avhandlingen avslutas med en diskussion om vad konsistensen av modellen betyder.
  • Auvo, Markus (2022)
    As everyday life becomes digital, more and more daily things are done online. In particular, the increased use of mobile devices has accelerated this development. People are increasingly leaving information online about themselves that can be used to identify a person. On 25 May 2018, the European Union’s General Data Protection Regulation, the GDPR, was repealed in the European Union, repealing the previous European Union Data Protection Directive. The GDPR sets out how personal information should be stored and who can process it. The thesis examined how the introduction of GDPR has affected the customer data storage solutions and IT processes of Finnish SMEs during 2018-2020. The companies were examined in three phases: before, during and after the introduction of the GDPR. The study looked at the number of data breaches in the EU and the penalties imposed for them, and compared the situation in Finland. In addition, Finnish SMEs were interviewed for the dissertation. The interview was conducted as a questionnaire interview with 15 companies. The thesis found that Finland did not stand out in any way among other EU countries in GDPR violations. The answers received as a result of the survey revealed that there has been a clear variation in the interpretation of the content of the GDPR in Finland, which has affected the measures taken by companies. Based on the survey, the measures have also been influenced by the organization and organizational culture. However, the reliability of the results is affected by the small sample size.
  • Pakarinen, Antti (2013)
    Tämän Pro Gradu –tutkielman tarkoituksena oli selvittää Euran Vaaniin pohjavesialueen rajojen muutostarve. Tutkimus oli osana laajempaa ympäristöministeriön ja maa –ja metsätalousministeriön hanketta, jonka tarkoituksena on luoda yhtenäinen ja selkeä ohjeistus hienoainespeitteisten akviferien pohjavesialueiden rajaamiselle. Kenttätyöt tehtiin kesällä 2011. Tutkimusmenetelminä olivat raekokoanalyysi kuiva- ja märkäseulonnalla ja hiukkasmittarilla, ionikromatografia, massaspektrometria, veden stabiilien isotooppien määritys ja rakennetulkinta. Tutkimusten perusteella Vaaniin pohjavesialueen nykyiset rajat eivät ole toimivia pohjaveden suojelun kannalta. Nykyisen pohjavesialueen ulkopuolisilta alueilta, joiden vedenjohtavuusarvot mahdollistavat pohjaveden muodostumisen, on hydraulinen yhteys harjuun. Vedenjohtavuusarvojen perusteella tutkimusalue voidaan jakaa kolmeen eri luokkaan, jotka ovat muodostumisalue (K > 10-6 ms-1), vettä osittain läpäisevä alue (10-7 < K < 10-6 ms-1) ja vettä läpäisemätön alue (K < 10-7 ms-1). Rakennetulkinnan perusteella hyvin vettä johtavat kerrokset ovat jatkuvia Vaaniin ja Euran keskustan välisellä osuudella. Harjun morfologia on vaihtelevaa eivätkä muutokset näy maanpinnalla aluilla, joilla harju on hienoainessedimenttien peittämä. Pohjaveden päävirtaussuunnat Kauttualta kohti Vaaniita ja jokilaakson reunoilta harjuun. Pohjaveden redox-oloissa tapahtuu muutos Mölsin alueen hapettavista oloista pelkistäviksi kohti Vaaniin vedenottamoa ja samanaikaisesti kemiallinen koostumus muuttuu jonkin verran. Veden stabiilien isotooppien perusteella pohjaveden osuus jokivedestä on noin 5 – 8 %. Vaaniin pohjavesialueen rajoja on tutkimusten perusteella syytä muuttaa. Ehdotetaan kahta muutosvaihtoehtoa. Ensimmäisessä pohjavesialueen rajoja siirretään itään ja länteen siten, että muodostumisalueeksi lukeutuvat moreenikumpareet ovat pohjavesialueella. Toisessa vaihtoehdossa pohjavesi- ja muodostumisalueiksi rajataan alueet, joiden vedenjohtavuusarvot mahdollistavat pohjaveden muodostumisen. Peitteisten akviferien pohjavesialueiden rajauksissa tulisi tutkimusten perusteella ottaa huomioon myös harjualueen ulkopuoliset alueet, joilta voi olla hydraulinen yhteys harjuun. Muodostumisalueen rajauksissa käytetään perusteena, että muodostumisalueeksi rajaan alue, jonka vedenjohtavuusarvo vastaa hienon hiekan vedenjohtavuutta tai on sitä suurempi. Tutkimusten perusteella määritelmää suositellaan muutettavaksi siten, että rajaksi otetaan vedenjohtavuusarvo 10-6 ms-1, koska se ei ota kantaa sedimentin laatuun.
  • Paakkanen, Elias (2022)
    Tässä työssä on tutkittu Euroopan ja Pohjois-Atlantin talvi-ilmaston muuttumista 30-vuotisjaksojen 1961–1990 ja 1991–2020 välillä. Aineistona on käytetty Euroopan keskipitkien sääennusteiden keskuksen (ECMWF) kehittämää ERA5-uusanalyysidataa, jossa on assimiloitu havaintoja sääennustusmallin tuottamaan alkuarvauskenttään. Karttakuvat on piirretty niin ikään ECMWF:n kehittämällä ohjelmistolla, Metviewillä. Lämpötilan muutoksen pystyleikkauskuvan piirtämiseen on puolestaan käytetty Pythonin numpy- ja matplotlib.pyplot -kirjastoja. Työssä on tarkasteltu ilmanpaineessa, suihkuvirtauksessa, lämpötilassa, pystyliikkeissä, kosteudessa ja sademäärässä tapahtuneita muutoksia. Ennen varsinaisia tuloksia tutkielmassa on selitetty meteorologisiin suureisiin liittyvää fysikaalista teoriaa: miten paine, lämpötila ja tiheys ovat riippuvaisia toisistaan, kuinka geostrofinen tuuli syntyy sekä mitkä tekijät vaikuttavat sateen syntyyn. Kaikissa tarkasteltavissa suureissa on havaittu muutoksia. Lämpötilat ovat nousseet lähes koko Euroopan ja Pohjois-Atlantin alueella: eniten Pohjois-Euroopassa ja Pohjoisella jäämerellä sekä vähemmän Etelä-Euroopassa. Ilmanpaine on noussut Pohjois-Euroopassa ja Pohjois-Atlantin pohjoisosassa sekä laskenut Etelä-Euroopassa ja Pohjois-Atlantin eteläosassa. 250 hPa:n painepinnan Pohjois-Atlantin keskimääräinen suihkuvirtausmaksimi on voimistunut ja liikahtanut hieman pohjoisemmaksi. Sademäärät ja ilman sisältämän vesihöyryn määrä ovat kasvaneet Pohjois-Euroopassa ja pienentyneet Etelä-Euroopassa. Nousu- ja laskuliikkeet ovat monin paikoin voimistuneet. Muutosten tilastollisen merkitsevyyden tutkimiseen on käytetty Studentin kaksisuuntaista t-testiä. Alatroposfäärin lämpötilan muutos on eniten tilastollisesti merkitsevä, mutta muidenkin suureiden muutoksissa tilastollista merkitsevyyttä havaittiin laajalti. Tämä on loogista, sillä lämpötilan muutokset ovat kytköksissä myös muiden suureiden muutoksiin. Aiheesta on tehty myös aiemmin tutkimuksia, joiden tulokset ovat pääosin yhteensopivia tämän työn tulosten kanssa. Ainoastaan 500 hPa:n painepinnan geopotentiaalikorkeuden trendissä oli pientä eroavaisuutta. Tässä tutkielmassa muutosten tilastollinen merkitsevyys oli suurempaa kuin aiemmissa tutkimuksissa.
  • Paajanen, Juuso (2018)
    Konvektio on merkittävä säähän vaikuttava tekijä. Konvektio täytyy tuntea hyvin, että voidaan rakentaa toimivia sää- ja ilmastomalleja. Ala- ja keskitroposfäärin kosteus vaikuttaa merkittävästi konvektioon. Eräs suure kosteuden tutkimisessa on suhteellinen kosteus. Kosteutta voi tutkia helposti alueilla, joilta on saatavilla luotausdataa. Kaikkialta ei ole saatavilla luotausdataa, joten tarvitaan numeerisia malleja havaintojen lisäksi. Euroopan keskipitkien sääennusteiden keskuksen uusanalyysien avulla voidaan tutkia alueita, joilta luotausdataa ei ole saatavilla. Vertailin tässä työssä luotausten ja uusanalyysien välistä suhteellista kosteutta. Vertailuun valitsin kaksi asemaa trooppiselta Tyyneltämereltä, Aganan ja Pago Pagon. Tarkasteluväli on kahdeksan vuotta. Laskin keskiarvot kahdeksan vuoden ajalta kaikille kuukausille sekä vuodenaikakeskiarvot ajanhetkille 00 UTC ja 12 UTC. Suoritin vertailun neljällä eri painetasolla: 850 hPa, 800 hPa, 700 hPa ja 600 hPa. Keskiarvojen lisäksi laskin myös keskihajonnat kuukausille ja vuodenajoille. Laskut suoritin Matlabilla, jolla piirsin myös tulokset histogrammeihin. Tulokset osoittavat, että erot luotausten ja uusanalyysien välillä ovat pienet. Erot ovat yleisesti muutaman prosentin luokkaa. Keskihajonnat ovat suurempia luotauksissa kuin uusanalyyseissä. Luotauksia käytetään uusanalyyseissä syöttötietoina. Tulosten perusteella ei voida sanoa, että uusanalyysien suhteellinen kosteus vastaa todellisia arvoja muuallakin kuin luotausasemien kohdalla. Tutkimuksessa käytin vain kahta asemaa kahdeksan vuoden ajalta, joten tämän työn perusteella uusanalyysejä ei voi pitää täysin luotettavina, mutta vähintään suuntaa antavina.
  • Halonen, Liisa (2019)
    The Structural Funds of the European Union includes both strong and soft governance of the Union. In strong governance the state reforms their legal system and institutions functions based on the obligations of the Structural Funds. Soft governance, in contrast, is focused on the inhabitants of the unions, who then are governed indirectly by transmitting them the union´s values and by inciting. This thesis deals with the soft governance that is included in the Structural Funds. Additionally, the focus is on the innovation funding share of the Structural Funds. The theory framework of the thesis is governmentality literature, which states that governing consists of rationality and technology of government. Rationality means transmitting values and mindsets, and technology of government means the practical tool to do this. In the Structural Funds the distribution of funding forms the technology of government. There are several kinds of these technologies. This thesis focuses on the technologies of agency and productivity, as well as, transmitting regimes of practices. The Structural Funds program of Finland and the areal plans for the term 2014-2020 form the study material. The first part of the study is content-based, and it examines what kind of actors and what kind of acting the Structural Funds target. The second part of the study is theory-bounded, and it combines the results of the first part with the technologies presented in the governmentality literature. A new feature of this thesis is the division of actors into second and third parties. The second parties are the distributors of the funding, all of whom the European Union can govern directly, that is, using strong governing. The third parties are those actors who have the possibility to apply for the funding, but whom the Union cannot control directly. The only possibility to affect their acts is to induce, which is soft governing. The purpose of this division is to make clearer the difference between the two modes of government, strong and soft, in the second part of the study. The distributors of funding and their actions were not very visible in the study material. Both the distributors and their actions were referred mostly in general terms, if any. The most important actions required from the applying participants were to internationalise, specialise, and innovate, although innovation was also a defining feature when choosing the study material and therefore an obvious study result. All of these three actions were seen in the study material only in a positive light, although a lot of research has done where innovations have cut down those actions the Structural Funds are developed at the beginning: jobs and decreasing the differences between areas. In the study material the emphasis on the individual's responsibility, especially, in matters of obtaining training and skills represented the technology of agency. However, this was much more common in the programme documents related to the Social Fund than to the Regional Development Fund. The participants in these projects supported by the Social Fund should also benefit the companies that were funded by the Regional Development Fund. Ultimately, all the required features and results of the projects are the result of people's activities. The technology of performance was strongly present in the study material. The distribution of the funding is entirely based on the existence of predetermined numerical objectives and the funding applications must demonstrate how they can meet these objectives. Transmitting the regimes of practices was represented in the material by the presence of regions as subjects and the participation of the public organizations, along with the companies, in the project funding competitions.
  • Kokkonen, Maija (2019)
    European Union is a notable political actor that strives for governing and producing EU territory through spatial policies and planning. So far, spatial planning has been a technology to govern the terrestrial environment, but now marine space is seen as the new frontier of spatial planning. In 2014, EU has given a directive of maritime spatial planning (MSP), which aims to that every coastal member state had established spatial planning practices to their national marine areas by 2021 according to EU’s spatial agendas. The MSP has been looked at as a managerial tool helping to enhance the ecological condition of the seas, but not as a policy that produces spatiality. In this research, EU’s MSP policy is used as to research Europeanization of space in ‘EU’rope. The aim of this research is to interpret how understanding of ’EU’rope as a territorial entity is shaped through the structure of the maritime spatial planning policy and the meanings attached to it, in order to create a perception of the future development of EU and marine areas in general. The research is conducted from a social constructionist approach as an interpretive policy analysis. The concept of policy integration is in-built to MSP and is used as an indicator to Europeanization in this study. The policy integration effort is seen to steer social networks of actors that create the MSP in practice. Therefore, semi-structured theme interviews were conducted to the actors carrying out the MSP process in Finland. These actors’ understanding of the Finnish MSP is seen to construct ‘EU’ropean space in and through the domestic MSP process. Accordance with the hermeneutic traditions, comprehensive contextualization is conducted in this research in order to understand the maritime spatial planning policy. The research suggests that the spatiality and territoriality of marine areas produces different kind of planning practices than is seen in the terrestrial environment. The EU’s MSP policy is a policy tool for the EU territory, but at the same time, it is used as a tool to carry out domestic regional objectives as well. In Finland, the coastal Regions have benefitted from MSP and gained more power over the Finnish marine territories and the MSP may be used as to reinforce Regional planning. By adopting MSP policy, EU has changed the spatial governance structure of marine Europe. It has transformed heterogenic marine areas in Europe into single entity in order to be spatially governable by EU. These spaces have therefore been submitted under larger decision-making processes than before and EU is able to harness the national marine territories for the benefit of the whole Europe, and mainly due increasing economic growth in the territory. By means of policy integration efforts, the MSP creates new kinds of socio-spatial dimensions to Europe in where political bargaining over domestic marine spaces becomes a norm for the domestic maritime spatial planners. The research suggests that the territorial policy integration efforts reinforce the objectives of the EU directive in transnational collaboration, and this new platform of negotiation can be predicted to unify neighbouring domestic planning practices and goals in some extent.
  • Lee, Hei Shing (2021)
    In atmospheric sciences, measurements provided by remote-sensing instruments are crucial in observing the state of atmosphere. The associated uncertainties are important in nearly all data analyses. Random uncertainties reported by satellite instruments are typically estimated by inversion algorithms (ex-ante). They can be incomplete due to simplified or incomplete modelling of atmospheric processes used in the retrievals, and thus validating random uncertainties is important. However, such validation of uncertainties (or their estimates from statistical analysis afterwards, i.e. ex-post) is not a trivial task, because atmospheric measurements are obtained from the ever-changing atmosphere. This Thesis aims to explore the structure function method – an important approach in spatial statistics – and apply it to total ozone column measurements provided by the nadir-viewing satellite instrument TROPOMI. This method allows us to simultaneously perform validation of reported ex-ante random uncertainties and to explore of local-scale natural variability of atmospheric parameters. Two-dimensional structure functions of total ozone column have been evaluated based on spatial separations in latitudinal and longitudinal directions over selected months and latitude bands. Our results have indicated that the ex-post random uncertainties estimated agree considerably well with the reported ex-ante random uncertainties, which are within 1-2 DU. Discrepancies between them are very small in general. The morphology of ozone natural variability has also been illustrated: ozone variability is minimal in the tropics throughout the year, whereas in middle latitudes and polar regions they attain maxima in local spring and winter. In every scenario, the ozone structure functions are anisotropic with a stronger variability in the latitudinal direction, except at specific seasons in polar regions where isotropic behaviour is observed. Our analysis has demonstrated that the structure function method is a remarkable and promising tool for validating random uncertainties and exploring natural variability. It has a high potential for applications in other remote sensing measurements and atmospheric model data.
  • Karis, Peter (2020)
    This thesis presents a user study to evaluate the usability and effectiveness of a novel search interface as compared to a more traditional solution. InnovationMap is a novel search interface by Khalil Klouche, Tuukka Ruotsalo and Giulio Jacucci (University of Helsinki). It is a tool for aiding the user to perform ‘exploratory searching’; a type of search activity where the user is exploring an information space unknown to them and thus cannot form a specific search phrase to perform a traditional ‘lookup’ search as with the conventional search interfaces. In this user study InnovationMap is compared against TUHAT, a search portal that is currently in use at the University of Helsinki for searching for research works and research personnel from the university databases. The user evaluation is conducted as a qualitative within-subject study using volunteer users from the University of Helsinki. Each participant uses both systems in an alternating order over the course of two sessions. During the two sessions the volunteer user carries out information finding tasks defined in the experiment design, answers to a SUS (System Usability Scale) questionnaire and participates in a semi-structured interview. The answers from the assigned tasks are then evaluated and scored by field experts. The combined results from these methods are then used to formulate an educated assessment of the usability, effectiveness and future development potential of the InnovationMap search system.
  • Vierinen, Taavi (2023)
    A geopolymer waste form containing gasified ion exchange resin loaded with stable analogues of radionuclides (e.g., Sr, Co, Ni, Cr, Cs) was studied using semi-dynamic batch leaching experiments. The experiments were conducted for 180 days using an alkaline groundwater simulant in a glove box with controlled N2 atmosphere with < 10 ppm CO2 and O2. The experiments were conducted to investigate the leaching behavior of the geopolymer in conditions relevant to a low- and intermediate-level waste repository. The leaching results of the geopolymers showed leaching of cesium, sodium, aluminum, and silicon from the geopolymer, while potassium and calcium in the leachant sorbed to the geopolymer. The leaching and sorption rates were at their highest for the first 28 days of the experiment, before slowing down to a steady state which were maintained until the end of the experiment. This suggests that the geopolymers immobilized the waste analogues effectively with exception of cesium which had leached by 55 wt% of the initial fraction by day 180. The leaching indices of sodium, aluminum, silicon, and cesium were determined as: 9.9 ± 0.38, 10.1 ± 0.47, 10.5 ± 0.40, and 9.1 ± 0.30 respectively. The leaching indices are well above 6, which is considered a minimum value for WAC of cementitious waste forms by USNRC. The solid phase analysis of the geopolymer samples showed both presence of calcium rich secondary phases and increasing calcium concentration in the bulk matrix on the leachant contact surface of the geopolymer. It was concluded that the secondary phases consisted of CaCO3 minerals.
  • Holopainen, Ida (2021)
    Traditional parametric statistical inference methods, such as maximum likelihood and Bayesian inference, cannot be used to learn parameter estimates if the likelihood is intractable, for example due to the complexity of the studied phenomenon. This can be overcome by using likelihood-free inference that is used with simulator-based models to learn parameter estimates. Also, traditional methods used in the estimation of uncertainties related to the parameter estimates typically require a likelihood function, and that is why these methods cannot be applied in likelihood-free inference. In this thesis, we present a novel way to compute confidence sets for parameter estimates obtained from likelihood-free inference using Jensen—Shannon divergence. We consider two test statistics that are based on mean Jensen—Shannon divergence and propose hypothesised asymptotic distributions for them. We test whether these hypothesised distributions can be used in the computation of confidence sets for parameter estimates obtained from likelihood-free inference, and we evaluate the produced confidence sets by studying their frequentist behaviour that is summarised with coverage probabilities. We compare this frequentist behaviour between Jensen —Shannon divergence estimates and confidence sets obtained from grid evaluation of Monte Carlo estimates and from Bayesian optimisation for likelihood-free inference (BOLFI) to the ones obtained from maximum likelihood inference with Wald’s and log likelihood-ratio confidence sets using three different models. We also use a simulator- based model with intractable likelihood to study the proposed confidence sets with BOLFI. In order to study the influence of observations on the parameter estimates and their confidence sets, we conducted these experiments with varying the number of observations. We show that Jensen—Shannon divergence based confidence sets meet the expected frequentist behaviour.
  • Aula, Kasimir (2019)
    Air pollution is considered to be one of the biggest environmental risks to health, causing symptoms from headache to lung diseases, cardiovascular diseases and cancer. To improve awareness of pollutants, air quality needs to be measured more densely. Low-cost air quality sensors offer one solution to increase the number of air quality monitors. However, they suffer from low accuracy of measurements compared to professional-grade monitoring stations. This thesis applies machine learning techniques to calibrate the values of a low-cost air quality sensor against a reference monitoring station. The calibrated values are then compared to a reference station’s values to compute error after calibration. In the past, the evaluation phase has been carried out very lightly. A novel method of selecting data is presented in this thesis to ensure diverse conditions in training and evaluation data, that would yield a more realistic impression about the capabilities of a calibration model. To better understand the level of performance, selected calibration models were trained with data corresponding to different levels of air pollution and meteorological conditions. Regarding pollution level, using homogeneous training and evaluation data, the error of a calibration model was found to be even 85% lower than when using diverse training and evaluation pollution environment. Also, using diverse meteorological training data instead of more homogeneous data was shown to reduce the size of the error and provide stability on the behavior of calibration models.
  • Hou, Jian (2014)
    Pichia pastoris and Saccharomyces cerevisiae are two important fungi in both research and industrial applications of protein production and genetic engineering due to the inherent ability. For example, S.cerevisiae can produce important proteins from wide ranged sugar from ligno-cellulose to methanol. Accurate genome-scale metabolic networks (GMNs) of the two fungi can improve biotechnological production efficiency, drug discovery and cancer research. Comparison of metabolic networks between fungi brings a new way to study the evolutionary relationship between them. There are two basic steps for modeling metabolic networks. The first step is to construct a draft model from existing model or softwares such as the pathway tool software and InterProScan. The second step is model simulation in order to construct a gapless metabolic network. There are two main methods for genome-wide metabolic network reconstruction: constraint-based methods and graph-theoretical pathway finding methods. Constraints-based methods used linear equations to simulate the growth under your model with different constraints. Graph-theoretical pathway finding methods use graphic approach to construct the gapless model so that each metabolite can be acquired from either nutritions or the products of other gapless reactions. In my thesis, a new method designed by Pitkänen [PJH+ 14] is used to reconstruct the metabolic networks of Pichia pastoris and Saccharomyces cerevisiae. Five experiments were developed to evaluate the accuracy of the CoReCo method. The first experiment was to analyze the quality of the GMNs of Pichia pastoris and Saccharomyces cerevisiae by comparing with the existing model. The second and third experiments tested the stability of CoReCo constructed under random mutation and random deletion of the protein sequence simulating noisy input data. The next two experiments were done by considering different number of phylogenetic neighbors in the phylogenetic tree. The last experiment tested the effect of the two main parameters (acceptance and rejection thresholds) when CoReCo filled the reaction gaps in the final step.
  • Joswig, Niclas (2021)
    Simultaneous Localization and Mapping (SLAM) research is gaining a lot of traction as the available computational power and the demand for autonomous vehicles increases. A SLAM system solves the problem of localizing itself during movement (Visual Odometry) and, at the same time, creating a 3D map of its surroundings. Both tasks can be solved on the basis of expensive and spacious hardware like LiDaRs and IMUs, but in this subarea of visual SLAM research aims at replacing those costly sensors by, ultimately, inexpensive monocular cameras. In this work I applied the current state-of-the-art in end-to-end deep learning-based SLAM to a novel dataset comprising of images recorded from cameras mounted to an indoor crane from the Konecranes CXT family. One major aspect that is unique about our proposed dataset is the camera angle that resembles a classical bird’s-eye view towards the ground. This orientation change coming alongside with a novel scene structure has a large impact on the subtask of mapping the environment, which is in this work done through monocular depth prediction. Furthermore, I will assess which properties of the given industrial environments have the biggest impact on the system’s performance to identify possible future research opportunities for improvement. The main performance impairments I examined, that are characteristic for most types of industrial premise, are non-lambertian surfaces, occlusion and texture-sparse areas alongside the ground and walls.
  • Joswig, Niclas (2021)
    Simultaneous Localization and Mapping (SLAM) research is gaining a lot of traction as the available computational power and the demand for autonomous vehicles increases. A SLAM system solves the problem of localizing itself during movement (Visual Odometry) and, at the same time, creating a 3D map of its surroundings. Both tasks can be solved on the basis of expensive and spacious hardware like LiDaRs and IMUs, but in this subarea of visual SLAM research aims at replacing those costly sensors by, ultimately, inexpensive monocular cameras. In this work I applied the current state-of-the-art in end-to-end deep learning-based SLAM to a novel dataset comprising of images recorded from cameras mounted to an indoor crane from the Konecranes CXT family. One major aspect that is unique about our proposed dataset is the camera angle that resembles a classical bird’s-eye view towards the ground. This orientation change coming alongside with a novel scene structure has a large impact on the subtask of mapping the environment, which is in this work done through monocular depth prediction. Furthermore, I will assess which properties of the given industrial environments have the biggest impact on the system’s performance to identify possible future research opportunities for improvement. The main performance impairments I examined, that are characteristic for most types of industrial premise, are non-lambertian surfaces, occlusion and texture-sparse areas alongside the ground and walls
  • Noordsij, Dennis (2015)
    Application of machine learning methods for the analysis of functional neuroimaging signals, or 'brain-function decoding', is a highly interesting approach for better understanding of human brain functions. Recently, Kauppi et al. presented a brain-function decoder based on a novel feature extraction approach using spectral LDA, which allows both high classification accuracy (the authors used sparse logistic regression) and novel neuroscientific interpretation of the MEG signals. In this thesis we evaluate the performance of their brain-function decoder with additional classification and input feature scaling methods, providing possible additional options for their spectrospatial decoding toolbox SpeDeBox. We find the performance of their brain-function decoder to validate the potential of high frequency rhythmic neural activity analysis, and find that the logistic regression classifier provides the highest classification accuracy when compared to the other methods. We did not find additional benefits in applying prior input feature scaling or reduction methods.
  • Bortolussi, Federica (2022)
    The exploration of mineral resources is a major challenge in a world that seeks sustainable energy, renewable energy, advanced engineering, and new commercial technological devices. The rapid decrease in mineral reserves shifted the focus to under-explored and low accessibility areas that led to the use of on-site portable techniques for mineral mapping purposes, such as near infrared hyperspectral image sensors. The large datasets acquired with these instruments needs data pre-processing, a series of mathematical manipulations that can be achieved using machine learning. The aim of this thesis is to improve an existing method for mineralogy mapping, by focusing on the mineral classification phase. More specifically, a spectral similarity index was utilized to support machine learning classifiers. This was introduced because of the inability of the employed classification models to recognize samples that are not part of a given database; the models always classified samples based on one of the known labels of the database. This could be a problem in hyperspectral images as the pure component found in a sample could correspond to a mineral but also to noise or artefacts due to a variety of reasons, such as baseline correction. The spectral similarity index calculates the similarity between a sample spectrum and its assigned database class spectrum; this happens through the use of a threshold that defines whether the sample belongs to a class or not. The metrics utilized in the spectral similarity index were the spectral angler mapper, the correlation coefficient and five different distances. The machine learning classifiers used to evaluate the spectral similarity index were the decision tree, k-nearest neighbor, and support vector machine. Simulated distortions were also introduced in the dataset to test the robustness of the indexes and to choose the best classifier. The spectral similarity index was assessed with a dataset of nine minerals acquired from the Geological Survey of Finland retrieved from a Specim SWIR camera. The validation of the indexes was assessed with two mine samples obtained with a VTT active hyperspectral sensor prototype. The support vector machine was chosen after the comparison between the three classifiers as it showed higher tolerance to distorted data. With the evaluation of the spectral similarity indexes, was found out that the best performances were achieved with SAM and Chebyshev distance, which maintained high stability with smaller and bigger threshold changes. The best threshold value found is the one that, in the dataset analysed, corresponded to the number of spectra available for each class. As for the validation procedure no reference was available; because of this reason, the results of the mine samples obtained with the spectral similarity index were compared with results that can be obtained through visual interpretation, which were in agreement. The method proposed can be useful to future mineral exploration as it is of great importance to correctly classify minerals found during explorations, regardless the database utilized.