Thermal modelling of commercial lithium-ion batteries

The accelerating adoption of electrical technologies in vehicles over the recent years has led to an increase in the research on electrochemical energy storage systems, which are among the key elements in these technologies. The application of electrochemical energy storage systems for instance in hybrid electrical vehicles (HEVs) or hybrid mobile working machines allows tolerating high power peaks, leading to an opportunity to downsize the internal combustion engine and reduce fuel consumption, and therefore, CO2 and other emissions. Further, the application of electrochemical energy storage systems provides an option of kinetic and potential energy recuperation. Presently, the lithium-ion (Li-ion) battery is considered the most suitable electrochemical energy storage type in HEVs and hybrid mobile working machines. However, the intensive operating cycle produces high heat losses in the Li-ion battery, which increase its operating temperature. The Li-ion battery operation at high temperatures accelerates the ageing of the battery, and in the worst case, may lead to a thermal runaway and fire. Therefore, an appropriate Li-ion battery cooling system should be provided for the temperature control in applications such as HEVs and mobile working machines. In this doctoral dissertation, methods are presented to set up a thermal model of a single Li-ion cell and a more complex battery module, which can be used if full information about the battery chemistry is not available. In addition, a non-destructive method is developed for the cell thermal characterization, which allows to measure the thermal parameters at different states of charge and in different points of cell surface. The proposed models and the cell thermal characterization method have been verified by experimental measurements. The minimization of high thermal non-uniformity, which was detected in the pouch cell during its operation with a high C-rate current, was analysed by applying a simplified pouch cell 3D thermal model. In the analysis, heat pipes were incorporated into the pouch cell cooling system, and an optimization algorithm was generated for the estimation of the optimalplacement of heat pipes in the pouch cell cooling system. An analysis of the application of heat pipes to the pouch cell cooling system shows that heat pipes significantly decrease the temperature non-uniformity on the cell surface, and therefore, heat pipes were recommended for the enhancement of the pouch cell cooling system.

Secondary Aural Symptoms in Relation to Cranio-Cervical and General Disorders

The present thesis comprises two study populations. The first study sample (SS1) consisted of 411 adults examined and interviewed at three annual visits. The second study sample (SS2) consisted of 1720 adults who filled in a mailed questionnaire about secondary otalgia, tinnitus and fullness of ears. In the second phase of the SS2, 100 subjects with otalgia were examined and interviewed by specialist in stomatognathic physiology and otorhinolaryngology. In the third phase, 36 subjects participated in a randomized, controlled and blinded trial of effectiveness of occlusal appliance on secondary otalgia, facial pain, headache and treatment need of temporomandibular disorders (TMD). The standardized prevalence of recurrent secondary otalgia was 6%, tinnitus 15% and fullness of ears 8%. Aural symptoms were more frequent among young than old subjects. They were associated with other, simultaneous aural symptoms, TMD pain, head and neck region pain, and visits to a physician. The subjects with aural symptoms more often had tenderness on palpation of masticatory muscles and clinical signs of temporomandibular joint than the subjects without. 85% of the subjects reporting secondary otalgia had cervical spine or temporomandibular disorder or both. In SS1, the final model of secondary otalgia included active need treatment for TMD, elevated level of stress symptoms, and bruxism. In SS2, the final models of aural symptoms included associated aural symptoms, young age, TMD pain, headache and shoulder ache. Stabilization splint more effectively alleviated secondary otalgia and active treatment need for TMD than a palatal control splint. In patients with aural pain, tinnitus or fullness of ears, it is important to first rule out otologic and nasopharyngeal diseases that may cause the symptoms. If no explanation for aural symptoms is found, temporomandibular and cervical spine disorders should be rouled out to minimize unnecessary visits to a physician.

Growth, yield and secondary metabolite production of Drosera species cultivated in peat beds in Finland

Tiivistelmä

Factors affecting the snow and wind induced damage of a montane secondary forest in northeastern China

Abstract

Type II aromatic polyketide biosynthetic tailoring enzymes: diversity and adaptation in Streptomyces secondary metabolism.

Members of the bacterial genus Streptomyces are well known for their ability to produce an exceptionally wide selection of diverse secondary metabolites. These include natural bioactive chemical compounds which have potential applications in medicine, agriculture and other fields of commerce. The outstanding biosynthetic capacity derives from the characteristic genetic flexibility of Streptomyces secondary metabolism pathways: i) Clustering of the biosynthetic genes in chromosome regions redundant for vital primary functions, and ii) the presence of numerous genetic elements within these regions which facilitate DNA rearrangement and transfer between non-progeny species. Decades of intensive genetic research on the organization and function of the biosynthetic routes has led to a variety of molecular biology applications, which can be used to expand the diversity of compounds synthesized. These include techniques which, for example, allow modification and artificial construction of novel pathways, and enable gene-level detection of silent secondary metabolite clusters. Over the years the research has expanded to cover molecular-level analysis of the enzymes responsible for the individual catalytic reactions. In vitro studies of the enzymes provide a detailed insight into their catalytic functions, mechanisms, substrate specificities, interactions and stereochemical determinants. These are factors that are essential for the thorough understanding and rational design of novel biosynthetic routes. The current study is a part of a more extensive research project (Antibiotic Biosynthetic Enzymes; www.sci.utu.fi/projects/biokemia/abe), which focuses on the post-PKS tailoring enzymes involved in various type II aromatic polyketide biosynthetic pathways in Streptomyces bacteria. The initiative here was to investigate specific catalytic steps in anthracycline and angucycline biosynthesis through in vitro biochemical enzyme characterization and structural enzymology. The objectives were to elucidate detailed mechanisms and enzyme-level interactions which cannot be resolved by in vivo genetic studies alone. The first part of the experimental work concerns the homologous polyketide cyclases SnoaL and AknH. These catalyze the closure of the last carbon ring of the tetracyclic carbon frame common to all anthracycline-type compounds. The second part of the study primarily deals with tailoring enzymes PgaE (and its homolog CabE) and PgaM, which are responsible for a cascade of sequential modification reactions in angucycline biosynthesis. The results complemented earlier in vivo findings and confirmed the enzyme functions in vitro. Importantly, we were able to identify the amino acid -level determinants that influence AknH and SnoaL stereoselectivity and to determine the complex biosynthetic steps of the angucycline oxygenation cascade of PgaE and PgaM. In addition, the findings revealed interesting cases of enzyme-level adaptation, as some of the catalytic mechanisms did not coincide with those described for characterised homologs or enzymes of known function. Specifically, SnoaL and AknH were shown to employ a novel acid-base mechanism for aldol condenzation, whereas the hydroxylation reaction catalysed by PgaM involved unexpected oxygen chemistry. Owing to a gene-level fusion of two ancestral reading frames, PgaM was also shown to adopt an unusual quaternary sturucture, a non-covalent fusion complex of two alternative forms of the protein. Furthermore, the work highlighted some common themes encountered in polyketide biosynthetic pathways such as enzyme substrate specificity and intermediate reactivity. These are discussed in the final chapters of the work.

Lipase-catalyzed Approaches towards Secondary Alcohols: Intermediates for Enantiopure Drugs

The use of enantiopure intermediates for drug synthesis is a trend in pharmaceutical industry. Different physiological effects are associated with the enantiomers of chiral molecules. Thus, the safety profile of a drug based on an enantiopure active pharmaceutical ingredient is more reliable. Biocatalysis is an important tool to access enantiopure molecules. In biocatalysis, the advantage of selectivity (chemo-, regio- and stereoselectivity) is combined with the benefits of a green synthesis strategy. Chemoenzymatic syntheses of drug molecules, obtained by combining biocatalysis with modern chemical synthesis steps usually consists of fewer reaction steps, reduced waste production and improved overall synthetic efficiency both in yields and enantio- and/or diastereoselectivities compared with classical chemical synthesis. The experimental work together with the literature review clearly indicates that lipase catalysis is highly applicable in the synthesis of enantiopure intermediates of drug molecules as the basis to infer the correct stereochemistry. By lipase catalysis, enantiopure secondary alcohols used as intermediates in the synthesis of Dorzolamide, an antiglaucoma drug, were obtained. Enantiopure _-hydroxy nitriles as potential intermediates for the synthesis of antidepressant drugs with 1-aryl-3- methylaminopropan-1-ol structure were also obtained with lipases. Kinetic resolution of racemates was the main biocatalytic approach applied. Candida Antarctica lipase B, Burkholderia cepacia lipase and Thermomyces lanuginosus lipase were applied for the acylation of alcohols and the alcoholysis of their esters in organic solvents, such as in diisopropyl ether and tert-butyl methyl ether. Candida Antarctica lipase B was used under solvent free conditions for the acylation of ethyl 3-hydroxybutanoate.

Akkujen ja superkondensaattorien yhteiskäyttö energiavarastoina ja niiden verkkoon liittäminen ajoneuvoissa

Ajoneuvojen tiukentuneet päästörajoitukset, sekä ajoneuvojen kokonaishyötysuhteen parantamisen tarve ohjaavat ajoneuvovalmistajia kehittämään uusia ratkaisuja. Energiavarastojen käyttö ajoneuvoissa on yleistynyt ja niiden käytöllä voidaan saada huomattava energiasäästö. Tässä kandidaatintyössä on esitelty erilaisia energiavarastoja ja niiden verkkoon liittämistä. Pääpaino työssä on akkujen ja superkondensaattorien rinnankytkennässä. Energiavarastot pyritään kytkemään mahdollisimman vähällä tehoelektroniikalla verkkoon. Esimerkkitapaukseksi on otettu litium-ioni akkujen ja superkondensaattorien rinnankytkentä vaihtojännitteeseen pelkällä invertterillä.

Middle school mediocrity : quality and inequality in secondary education

Centrala teman i min avhandling är parallellskolesystem, linjedelning och segregering i högstadier och gymnasier. Det finns stora skillnader mellan länder gällande den årskurs då eleverna sorteras in i olika nivåer genom skilda klasser eller skolor. I Tyskland och Nederländerna till exempel delas eleverna upp före högstadiet medan Sverige och Finland har enhetsskolor på högstadienivå. Jag argumenterar att parallellskolesystem har en positiv effekt på elevernas testresultat i årskurserna före linjedelningen. Eleverna har incitament att jobba hårdare för att komma på i den akademiska linjen. Jag undersöker incitamentseffekter empiriskt, och hittar mönster konsistenta med incitamentseffekter både i brittisk och i internationell data. Det andra bidraget i avhandlingen är metodologiskt. Nationalekonomer brukar behandla testresultat från t.ex. IQ-tester eller internationella PISA-undersökningar som om absoluta nivån på poängantalen har betydelse i sig. I verkligheten antyder de endast en rangordning. Jag visar att normalfördelade testresultat i många fall ligger tillräckligt nära dess pengavärde på arbetsmarknaden för att ändå kunna tolkas som absoluta.

Pragmatic competence of Finnish learners of English: Meaning in interaction in secondary and upper secondary schools

Tutkin pro gradu -tutkielmassani englannin kielen oppijoiden pragmaattista kompetenssia. Tarkoitukseni oli selvittää, miten suomalaiset yläkoululaiset ja lukiolaiset osaavat käyttää englannin kieltä erilaisissa kommunikaatiotilanteissa. Tutkielmani voidaan sijoittaa välikielen pragmatiikan tutkimukseen. Halusin selvittää, millä tasolla suomalaisten oppijoiden pragmaattinen kompetenssi on ja kehittyykö se yläkoulun ja lukion välillä. Lisäksi tutkin, vaikuttavatko oppimisympäristö ja oppimismahdollisuudet oppijoiden kykyyn käyttää englannin kieltä. Toisin sanoen vertasin englantipainotteisilla luokilla olevia oppilaita formaalin opetuksen oppijoihin sekä tutkin, vaikuttavatko englanninkieliset vapaa-ajan aktiviteetit ja oppijoiden mahdolliset oleskelut englanninkielisissä maissa heidän pragmaattiseen kompetenssiinsa. Tutkimukseni kohderyhmä koostui yläkoulun kahdeksasluokkalaisista ja lukion toisen vuosikurssin opiskelijoista. Testasin neljä eri ryhmää, joissa oli sekä formaalissa opetuksessa olevia oppijoita (yksi ryhmä kahdeksasluokkalaisia ja yksi ryhmä toisen vuosikurssin opiskelijoita) että kielipainotteisten luokkien oppijoita (yksi ryhmä kahdeksasluokkalaisia ja yksi ryhmä toisen vuosikurssin opiskelijoita). Arvioin kohderyhmäni pragmaattista kompetenssia monivalintatestillä, jossa testattiin oppijoiden kykyä käyttää ja ymmärtää implikaatioita, tilannekohtaisia rutiineja sekä puheakteja. Taustakysymysten avulla selvitin, kuinka usein oppijat käyttivät englantia vapaa-aikanaan ja olivatko he vierailleet englanninkielisissä maissa. Tutkimustulokseni osoittavat, että suomalaisten yläkoululaisten ja lukiolaisten pragmaattinen kompetenssi oli korkea. Pragmaattinen kompetenssi kehittyi kahdeksasluokkalaisten ja lukion toisen vuosikurssin välillä. Kehitys oli suurempaa formaalissa opetuksessa kuin kielipainotteisilla luokilla. Englantipainotteisilla luokilla olevat oppilaat suoriutuivat testistä paremmin kuin formaalin opetuksen oppilaat. Tosin erot olivat tilastollisesti merkitseviä vain yläkoulussa. Tutkimuksessani siis päättelin, että vieraskielinen opetus vaikutti enemmän nuorempiin oppijoihin. Eri oppimismahdollisuudet osoittautuivat haastaviksi analysoida. Tulokset osoittivat, että vain englanninkielisessä maassa oleskelulla oli vaikutusta oppijoiden pragmaattiseen kompetenssiin. Kysyttäessä vapaa-ajan aktiviteettien merkitystä oppijat kuitenkin kertoivat, että ne auttoivat heitä testiin vastaamisessa enemmän kuin englanninopetuksessa käydyt asiat. Kouluissa tulisikin jatkossa painottaa yhä enemmän vuorovaikutteista kieltenopetusta.

Battery Cell Modeling for Battery Management System

Usage of batteries as energy storage is emerging in automotive and mobile working machine applications in future. When battery systems become larger, battery management becomes an essential part of the application concerning fault situations of the battery and safety of the user. A properly designed battery management system extends one charge cycle of battery pack and the whole life time of the battery pack. In this thesis main objectives and principles of BMS are studied and first order Thevenin’s model of the lithium-titanate battery cell is built based on laboratory measurements. The battery cell model is then verified by comparing the battery cell model and the actual battery cell and its suitability for use in BMS is studied.

Understanding and improving quality of secondary school education : conceptions among teachers in Tanzania

Temat för studien handlar om gymnasielärares uppfattningar om kvalitet och om hur kvalitet kan utvecklas i gymnasieutbildningen in Tanzania. Studien är till sin karaktär kvalitativ och består av utprövade semistrukturerade intervjuer med sammanlagt trettio lärare som arbetar i fyra gymnasieskolor både i urbana och rurala miljöer. Lärarna har varierande arbetserfarenhet och undervisar i olika ämnen. Huvudfokus har gällt identifieringen av variationer i lärares uppfattningar om kvalitet. På basen av två forskningsfrågor avslöjar analysen uppfattningar av hur lärare förstår och önskar utveckla kvaliteten på gymnasieutbildningen. Resultaten visar att lärare förstår kvaliteten på utbildningen i sina skolor som försök att möta skolans och samhällets mål, som individuella prestationer och förmågor som att inneha kompetenser och som att möta utmaningar inom utbildning, Identifierade uppfattningar var baserade på lärarnas personliga kunskap, arbetsmiljön och varierande omständigheter som rådde i deras skolor. Uppfattningar om en förbättring av kvaliteten i gymnasieutbildningen innefattade utveckling av lärares motivation, skolmiljön, arbetet i klassrum, kvaliteten på lärares kunskaper och färdigheter och undervisningsmaterial. Ambitionen bakom studien ar att erbjuda en plattform för strategier för att förbättra kvaliteten på gymnasieutbildningen. Resultaten strävar till att ge en fördjupad insikt i uppfattningar hos en utvald grupp av lärare som arbetar under samma villkor inom gymnasieskolor I Tanzania. Av den här anledningen är den genererade kunskapen därför relevant för att belysa lärares uppfattningar även utanför den studerade gruppen av respondenter.