Search

The environmental impacts of several scenarios for wood waste’s treatment were studied via life cycle assessment (LCA). The scenarios were modelled via both attributional and consequential approaches to LCA. The ALCA results indicate that producing insulation from wood waste appears to be a good alternative to incineration, whereas incineration outperforms the production of all the other recycled products studied (particle board, composite, bioethanol, biochar, and textile fibre). When the substituting products and marginal energy are considered in the CLCA, other recycled products too seem to show good environmental performance relative to incineration. Textile fibre from wood waste is a solid alternative to producing viscose and cotton, and if marginal energy with even smaller environmental impacts than biomass were used, other products could well become compelling alternatives.

New particle formation in the Arctic atmosphere is an important source of aerosol particles. Understanding the processes of Arctic secondary aerosol formation is crucial due to their significant impact on cloud properties and therefore Arctic amplification. We observed the molecular formation of new particles from low-volatility vapors at two Arctic sites with differing surroundings. In Svalbard, sulfuric acid (SA) and methane sulfonic acid (MSA) contribute to the formation of secondary aerosol and to some extent to cloud condensation nuclei (CCN). This occurs via ion-induced nucleation of SA and NH3 and subsequent growth by mainly SA and MSA condensation during springtime and highly oxygenated organic molecules during summertime. By contrast, in an ice-covered region around Villum, we observed new particle formation driven by iodic acid but its concentration was insufficient to grow nucleated particles to CCN sizes. Our results provide new insight about sources and precursors of Arctic secondary aerosol particles.

We compared observations of aerosol particle formation and growth in different parts of the planetary boundary layer at two different environments that have frequent new particle formation (NPF) events. In summer 2012 we had a campaign in Po Valley, Italy (urban background), and in spring 2013 a similar campaign took place in Hyytiälä, Finland (rural background). Our study consists of three case studies of airborne and ground-based measurements of ion and particle size distribution from ∼1 nm. The airborne measurements were performed using a Zeppelin inside the boundary layer up to 1000 m altitude. Our observations show the onset of regional NPF and the subsequent growth of the aerosol particles happening almost uniformly inside the mixed layer (ML) in both locations. However, in Hyytiälä we noticed local enhancement in the intensity of NPF caused by mesoscale boundary layer (BL) dynamics. Additionally, our observations indicate that in Hyytiälä NPF was probably also taking place above the ML. In Po Valley we observed NPF that was limited to a specific air mass.

New particle formation in the Arctic atmosphere is an important source of aerosol particles. Understanding the processes of Arctic secondary aerosol formation is crucial due to their significant impact on cloud properties and therefore Arctic amplification. We observed the molecular formation of new particles from low-volatility vapors at two Arctic sites with differing surroundings. In Svalbard, sulfuric acid (SA) and methane sulfonic acid (MSA) contribute to the formation of secondary aerosol and to some extent to cloud condensation nuclei (CCN). This occurs via ion-induced nucleation of SA and NH and subsequent growth by mainly SA and MSA condensation during springtime and highly oxygenated organic molecules during summertime. By contrast, in an ice-covered region around Villum, we observed new particle formation driven by iodic acid but its concentration was insufficient to grow nucleated particles to CCN sizes. Our results provide new insight about sources and precursors of Arctic secondary aerosol particles.

The purpose of the acoustic model in Automatic Speech Recognition system is to model the acoustic properties of the speech. Speech, however, has a lot of internal variation making development of a general acoustic model for all purposes an extremely difficult. Adaptation is used to tune the general acoustic models into a specific task, in order to improve the performance of the system. Maximum A Posteriori (MAP) adaptation is one of the most common acoustic model adaptation techniques in the speech recognition. MAP adaptation scheme in AaltoASR, Automatic Speech Recognition system of Aalto University, was implemented for this thesis. Implementation was tested with speaker adaptation and compared with constrained Maximum Likelihood Linear Regression (MLLR) adaptation to confirm that implementation functions properly. Results were the same as in previous studies, thus it was concluded that implementation is function correctly. Constrained MLLR adaptation performs better when the adaptation set is less than 10 minutes, otherwise MAP adaptation is superior. MAP implementation has other uses besides the adaptation. It successfully reduced the size of the acoustic model while improving the performance. MAP was also used to adapt colloquial language by giving more weight to the chosen corpus after Maximum Likelihood or discriminative training., Puheentunnistimen akustisella mallilla mallinnetaan puheen akustisia ominaisuuksia. Puhetta on kuitenkin monentyylistä ja puhe vaihtelee jopa puhujittain suuresti. Akustisen mallin täytyykin mallintaa puhetta laaja-alaisesti toimiakseen tyydyttävästi arkisissa olosuhteissa. Kaikkiin tilanteisiin soveltuvan akustisen mallin opettaminen ei kuitenkaan ole käytännössä mahdollista. Tästä syystä akustisia malleja viritetään tiettyihin olosuhteisiin esimerkiksi adaptaatiolla. Yksi yleisimmistä adaptaatiomenetelmistä on Maximum A Posteriori (MAP) adaptaatio. Tässä työssä esitellään MAP adaptaation implementoiti AaltoASR puheentunnistusjärjestelmään, ja tutkitaan mihin tarkoituksiin adaptaatiota voidaan soveltaa. MAP adaptaatiota verrattiin Constrained Maximum Likelihood Linear Regression (CMLLR) -adaptaatioon puhuja-adaptaatiokokeessa implementaation toimivuuden varmistamiseksi. Todettiin, että CMLLR adaptaatio suoriutuu paremmin, jos adaptointiaineiston määrä on alle 10 minuuttia. Aineiston ollessa yli 10 minuuttia MAP adaptaatio on puolestaan soveltuvampi valinta, sillä MAP hyötyy adaptointiaineiston kasvusta enemmän kuin CMLLR. Tulokset vastaavat aikaisempia tutkimuksia, joissa MAP ja CMLLR adaptaatiota on verrattu keskenään. Lisäksi huomattiin, että MAP implementointia voidaan käyttää myös akustisen mallin koon pienentämiseen sekä painottamaan tiettyä osaa opetusaineistosta tavallisen Maximum Likelihood tai diskriminatiivisen opetuksen jälkeen. Aineiston painottamismenetelmää testattin puhekielen adaptoimiseen.

Työssä tarkennettiin Suomessa keräämättä jäävän jäteöljyn määrää ja selvitettiin keräämättä jäävän jäteöljyn hyödyntämisen ympäristövaikutukset kolmella eri hyödyntämismenetelmällä. Keräämättä jäävän jäteöljyn määrää tarkennettiin aiemmin tehdyn esiselvityksen tulosten perusteella arvioimalla vielä öljyvahingoissa vuotanut öljymäärä, romuautojen sisältämän öljyn määrä sekä itse öljynsä vaihtavien markkinoilta keräämättä jäävä määrä. Elinkaariarvioinnilla vertailtiin keräämättä jäävän jäteöljyn hyödyntämisen potentiaalisia ympäristövaikutuksia kolmella eri hyödyntämismenetelmällä: 1. keskitetty keräys ja regenerointi, 2. keskitetty keräys ja poltto polttolaitoksessa sekä 3. hajautettu keräys ja pienpoltto moniöljypolttimella. Pienpoltto ei ole sallittua Suomessa, mutta sen ympäristövaikutuksia haluttiin vertailla muihin menetelmiin. Elinkaariarvioinnissa tutkitut vaikutusluokat olivat ilmastonmuutos, happamoituminen, myrkyllisyys ihmiselle, vesistöjen ekotoksisuus, maaperän ekotoksisuus sekä hiukkaset. Tutkimuksessa huomioitiin jäteöljyn kuljetuksessa ja keräyksessä sekä hyödyntämisprosesseissa tarvittavien polttoaineiden ja tärkeimpien kemikaalien valmistus ja kuljetus Suomeen sekä sähkön ja lämmön tuotanto. Elinkaariarvioinnin tulosten kannalta on merkittävää mitä jäteöljyn hyödyntämisellä korvataan. Jäteöljyn regenerointi korvaa voiteluaineiden perusöljyn primääristä tuotantoa, kun muissa tapauksissa jäteöljyn energiahyödyntäminen korvaa kevyen polttoöljyn tuotantoa ja energiahyödyntämistä. Perusöljyn primäärisen tuotannon välttämisestä saatavat hyvitykset ovat merkittävästi suuremmat kuin jäteöljyn regeneroinnista aiheutuvat päästöt, joten saavutetaan ympäristöhyötyjä. Energiahyödyntämisen suhteen taas kevyen polttoöljyn tuotannosta ja polttamisesta saatavat hyvitykset ovat samaa suuruusluokkaa jäteöljyn polttamisen kanssa, joten potentiaaliset ympäristöhyödyt ovat pienemmät. Toteutetun kevennetyn elinkaariarvioinnin tulosten perusteella potentiaalisilta ympärist, In this study the quantity of uncollected waste oil was estimated more specifically and the environmental impacts of its utilization were assessed. The quantity of uncollected waste oil estimated in the pre-report was further estimated with the amount of waste oil leaked in oil accidents, the amount of waste oil in scrap vehicles and the amount of oil in do it yourself oil changers -market. Life cycle assessment (LCA) was used to evaluate the potential environmental impacts of utilization of uncollected waste oil in three different utilization techniques: 1. centralized collection and regeneration 2. centralized collection and combustion in an incineration plant and 3. decentralized collection and small scale combustion in a space heater. Small scale combustion of waste oil is not allowed in Finland. Nevertheless its environmental impacts were assessed so it could be compared with other techniques. Impact categories used in the LCA were global warming, acidification, human toxicity, fresh water ecotoxicity, terrestrial ecotoxicity and particulate matter formation. Production and transportation to Finland of fuels and most relevant chemicals needed in transportation, collection and utilization processes were taken into account as well as the production of electricity and heat. The avoided processes that waste oil utilization is substituting have a significant effect on the results of the LCA. Regeneration of waste oil substitutes primary production of lubricant base oil. In the other cases energy recovery of waste oil substitutes energy production with light fuel oil and the production of light fuel oil. The avoided impacts of primary base oil production are significantly greater than impacts caused by regeneration and therefore environmental benefits are obtained. Instead in energy recovery the differ-ence between combustion of waste oil and combustion and production of light fuel oil is not that big and environmental benefits are smaller. According to the results o

Schobesberger, S., Vaananen, R., Leino, K., Virkkula, A., Backman, J., Pohja, T., Siivola, E., Franchin, A., Mikkila, J., Paramonov, M., Aalto, P.P., Krejci, R., Petaja, T. & Kulmala, M. 2013: Airborne measurements over the boreal forest of southern Finland during new particle formation events in 2009 and 2010. Boreal Env. Res. 18: 145-163. We conducted airborne observations of aerosol physical properties over the southern Finland boreal forest environment. The aim was to investigate the lower tropospheric aerosol (up to 4-km altitude) over an area of 250 by 200 km, in particular during new particle formation (NPF) events, and to address the spatial variability of aerosol number concentration and number size distribution. The regional NPF events, detected both airborne and at the ground, with air masses originating from the Arctic or northern Atlantic Ocean were studied throughout the boundary layer and throughout the area covered. Three suitable case studies are presented in more detail. In two of these studies, the concentrations of nucleation mode particles (3-10 nm in diameter) were found considerably higher (up to a factor of 30) in the upper parts of the planetary boundary layer compared to ground-based measurements during the nucleation events. The observed vertical variation can be connected to boundary layer dynamics and interactions between the boundary layer and the lower free troposphere, likely yielding high concentrations of newly formed aerosol particles. Our results suggest that nucleation does not necessarily occur close to the surface. In one presented case we found evidence of NPF occurring in a limited area above cloud, in the complete absence of a regional NPF event., AuthorCount:14