Communicative Purposes of Press Releases Announcing Reduction in Workforce

Tämä tutkielma käsittelee kaupallisten yhtiöiden julkaisemia lehdistötiedotteita, joissa ilmoitetaan henkilöstövähennyksistä. Erityisenä tutkimuskohteena ovat lehdistötiedotteiden informatiiviset ja promotionaaliset päämäärät ja tarkoitukset sekä näiden päämäärien ja tarkoitusten ilmentyminen tekstin retorisen rakenteen, valittujen retoristen strategioiden sekä leksikaalisten ja kieliopillisten valintojen kautta. Tutkimuksen aineisto koostuu 50 englanninkielisestä lehdistötiedotteesta, jotka sisältävät ilmoituksen henkilöstövähennyksistä. Lehdistötiedotteet kerättiin yritysten verkkosivuilta. Tutkimuksen teoreettisena viitekehityksenä toimivat soveltavan kielentutkimuksen alalla erityisesti ammattikielentutkimuksessa (ESP, English for Specific Purposes) laajalti käytetty Swalesin (1990) tekstilajia (genre) koskeva määritelmää ja Bhatian (1993) kehittämä geneerisen analyysin malli. Ennen aineiston kielitieteellistä analysointia tutkimuksessa perehdyttiin Bhatian (1993) mallin mukaisesti lehdistötiedotteiden historiaan, kohdeyleisöihin, diskurssiyhteisöön ja sen tuottamiin muihin tekstilajeihin, aikaisempiin lehdistotiedotteita käsitteleviin kielitieteellisiin tutkimuksiin sekä erityisesti yritysten henkilövähennyksiin liittyvään tilannekontekstiin. Kielitieteellisessä analyysissä tutkittavista teksteistä tunnistettiin kahdeksan retorista vaihetta (move), jotka olivat tyypillisiä tutkituille teksteille. Kunkin retorisen vaiheen yksittäiset ilmentymät koottiin yhteen erillisiksi aineistoiksi, joista pyrittiin tunnistamaan kullekin vaiheelle tyypilliset retoriset strategiat sekä toistuvat leksikaaliset ja kieliopilliset valinnat. Tutkimuksessa todettiin, että vaikka tutkittujen lehdistötiedotteiden pääasiallinen tarkoitus oli yhtiön toiminnasta tiedottaminen, niillä oli myös promotionaalinen päämäärä, joka ilmeni mm. pyrkimyksenä välittää yhtiöstä mahdollisimman positiivinen kuva eri kohdeyleisöille, erityisesti sijoittajille. Tämän positiivisen kuvan välittämiseen käytettyjä keinoja olivat mm. odotettavissa olevien saavutusten korostaminen, ulkoisten tekijöiden nimeäminen nykyisen tilanteen aiheuttajaksi, passiivin käyttö sekä erilaiset yrityksen julkisen kuvan säilyttämiseen pyrkivät (face-saving) strategiat.

Model based analysis of the post-combustion calcium looping process for carbon dioxide capture

This thesis presents a one-dimensional, semi-empirical dynamic model for the simulation and analysis of a calcium looping process for post-combustion CO2 capture. Reduction of greenhouse emissions from fossil fuel power production requires rapid actions including the development of efficient carbon capture and sequestration technologies. The development of new carbon capture technologies can be expedited by using modelling tools. Techno-economical evaluation of new capture processes can be done quickly and cost-effectively with computational models before building expensive pilot plants. Post-combustion calcium looping is a developing carbon capture process which utilizes fluidized bed technology with lime as a sorbent. The main objective of this work was to analyse the technological feasibility of the calcium looping process at different scales with a computational model. A one-dimensional dynamic model was applied to the calcium looping process, simulating the behaviour of the interconnected circulating fluidized bed reactors. The model incorporates fundamental mass and energy balance solvers to semi-empirical models describing solid behaviour in a circulating fluidized bed and chemical reactions occurring in the calcium loop. In addition, fluidized bed combustion, heat transfer and core-wall layer effects were modelled. The calcium looping model framework was successfully applied to a 30 kWth laboratory scale and a pilot scale unit 1.7 MWth and used to design a conceptual 250 MWth industrial scale unit. Valuable information was gathered from the behaviour of a small scale laboratory device. In addition, the interconnected behaviour of pilot plant reactors and the effect of solid fluidization on the thermal and carbon dioxide balances of the system were analysed. The scale-up study provided practical information on the thermal design of an industrial sized unit, selection of particle size and operability in different load scenarios.

Towards sustainable Iron- and steelmaking with economic optimization

The iron and steelmaking industry is among the major contributors to the anthropogenic emissions of carbon dioxide in the world. The rising levels of CO2 in the atmosphere and the global concern about the greenhouse effect and climate change have brought about considerable investigations on how to reduce the energy intensity and CO2 emissions of this industrial sector. In this thesis the problem is tackled by mathematical modeling and optimization using three different approaches. The possibility to use biomass in the integrated steel plant, particularly as an auxiliary reductant in the blast furnace, is investigated. By pre-processing the biomass its heating value and carbon content can be increased at the same time as the oxygen content is decreased. As the compression strength of the preprocessed biomass is lower than that of coke, it is not suitable for replacing a major part of the coke in the blast furnace burden. Therefore the biomass is assumed to be injected at the tuyere level of the blast furnace. Carbon capture and storage is, nowadays, mostly associated with power plants but it can also be used to reduce the CO2 emissions of an integrated steel plant. In the case of a blast furnace, the effect of CCS can be further increased by recycling the carbon dioxide stripped top gas back into the process. However, this affects the economy of the integrated steel plant, as the amount of top gases available, e.g., for power and heat production is decreased. High quality raw materials are a prerequisite for smooth blast furnace operation. High quality coal is especially needed to produce coke with sufficient properties to ensure proper gas permeability and smooth burden descent. Lower quality coals as well as natural gas, which some countries have in great volumes, can be utilized with various direct and smelting reduction processes. The DRI produced with a direct reduction process can be utilized as a feed material for blast furnace, basic oxygen furnace or electric arc furnace. The liquid hot metal from a smelting reduction process can in turn be used in basic oxygen furnace or electric arc furnace. The unit sizes and investment costs of an alternative ironmaking process are also lower than those of a blast furnace. In this study, the economy of an integrated steel plant is investigated by simulation and optimization. The studied system consists of linearly described unit processes from coke plant to steel making units, with a more detailed thermodynamical model of the blast furnace. The results from the blast furnace operation with biomass injection revealed the importance of proper pre-processing of the raw biomass as the composition of the biomass as well as the heating value and the yield are all affected by the pyrolysis temperature. As for recycling of CO2 stripped blast furnace top gas, substantial reductions in the emission rates are achieved if the stripped CO2 can be stored. However, the optimal recycling degree together with other operation conditions is heavily dependent on the cost structure of CO2 emissions and stripping/storage. The economical feasibility related to the use of DRI in the blast furnace depends on the price ratio between the DRI pellets and the BF pellets. The high amount of energy needed in the rotary hearth furnace to reduce the iron ore leads to increased CO2 emissions.

Characterization of Leaf-Type Ferredoxin-NADP+ Oxidoreductase (FNR) Isoforms in Arabidopsis thaliana

Life on earth is based on sunlight, which is captured in chemical form by photosynthetic reactions. In the chloroplasts of plants, light reactions of photosynthesis take place at thylakoid membranes, whereas carbon assimilation reactions occur in the soluble stroma. The products of linear electron transfer (LET), highly-energetic ATP molecules, and reducing power in the form of NADPH molecules, are further used in the fixation of inorganic CO2 molecules into organic sugars. Ferredoxin-NADP+ oxidoreductase (FNR) catalyzes the last of the light reactions by transferring electrons from ferredoxin (FD) to NADP+. In addition to LET, FNR has been suggested to play a role in cyclic electron transfer (CET), which produces ATP without the accumulation of reducing equivalents. CET is proposed to occur via two putative routes, the PGR5- route and the NDH-route. In this thesis, the leaf-type FNR (LFNR) isoforms LFNR1 and LFNR2 of a model organism, Arabidopsis thaliana, were characterized. The physiological roles of LFNRs were investigated using single and double mutant plants. The viability of the single mutants indicates functionality of both isoforms, with neither appearing to play a specific role in CET. The more severe phenotype of low-temperature adapted fnr2 plants compared to both wild-type (WT) and fnr1 plants suggests a specific role for LFNR2 under unfavorable growth conditions. The more severe phenotype of the fnr1 x fnr2 (F1 generation) plants compared to single mutants reflects down-regulated photosynthetic capacity, whereas slightly higher excitation pressure indicates mild over-excitation of electron transfer chain (ETC). However, induction of CET and various photoprotective mechanisms enable adaptation of fnr1 x fnr2 plants to scarcity of LFNR. The fnr1 fnr2 plants (F2 generation), without detectable levels of LFNR, were viable only under heterotrophic conditions. Moreover, drought stress induced acceleration of the rate of P700 + re-reduction in darkness was accompanied by a concomitant up-regulation of the PGR5-route specific components, PGR5 and PGRL1, demonstrating the induction of CET via the PGR5-route. The up-regulation of relative transcriptional expression of the FD1 gene indicates that the FD1 isoform may have a specific function in CET, while no such role could be defined for either of the LFNR isoforms. Both the membrane-bound and soluble LFNR1 and LFNR2 each appear as two distinct spots after 2D-PAGE with different isoelectric points (pIs), indicating the existence of post-translational modifications (PTMs) which do not determine the membrane attachment of LFNR. The possibility of phosphorylation and glycosylation PTMs were excluded, but all four LFNR forms were shown to contain acetylated lysine residues as well as alternative N-termini. N-terminal acetylation was shown to shift the pI of both LFNRs to be more acidic. In addition, all four LFNR forms were demonstrated to interact both with FD1 and FD2 in vitro

Wind Turbine Direct-Drive Permanent-Magnet Generator with Direct Liquid Cooling for Mass Reduction

Today’s electrical machine technology allows increasing the wind turbine output power by an order of magnitude from the technology that existed only ten years ago. However, it is sometimes argued that high-power direct-drive wind turbine generators will prove to be of limited practical importance because of their relatively large size and weight. The limited space for the generator in a wind turbine application together with the growing use of wind energy pose a challenge for the design engineers who are trying to increase torque without making the generator larger. When it comes to high torque density, the limiting factor in every electrical machine is heat, and if the electrical machine parts exceed their maximum allowable continuous operating temperature, even for a short time, they can suffer permanent damage. Therefore, highly efficient thermal design or cooling methods is needed. One of the promising solutions to enhance heat transfer performances of high-power, low-speed electrical machines is the direct cooling of the windings. This doctoral dissertation proposes a rotor-surface-magnet synchronous generator with a fractional slot nonoverlapping stator winding made of hollow conductors, through which liquid coolant can be passed directly during the application of current in order to increase the convective heat transfer capabilities and reduce the generator mass. This doctoral dissertation focuses on the electromagnetic design of a liquid-cooled direct-drive permanent-magnet synchronous generator (LC DD-PMSG) for a directdrive wind turbine application. The analytical calculation of the magnetic field distribution is carried out with the ambition of fast and accurate predicting of the main dimensions of the machine and especially the thickness of the permanent magnets; the generator electromagnetic parameters as well as the design optimization. The focus is on the generator design with a fractional slot non-overlapping winding placed into open stator slots. This is an a priori selection to guarantee easy manufacturing of the LC winding. A thermal analysis of the LC DD-PMSG based on a lumped parameter thermal model takes place with the ambition of evaluating the generator thermal performance. The thermal model was adapted to take into account the uneven copper loss distribution resulting from the skin effect as well as the effect of temperature on the copper winding resistance and the thermophysical properties of the coolant. The developed lumpedparameter thermal model and the analytical calculation of the magnetic field distribution can both be integrated with the presented algorithm to optimize an LC DD-PMSG design. Based on an instrumented small prototype with liquid-cooled tooth-coils, the following targets have been achieved: experimental determination of the performance of the direct liquid cooling of the stator winding and validating the temperatures predicted by an analytical thermal model; proving the feasibility of manufacturing the liquid-cooled tooth-coil winding; moreover, demonstration of the objectives of the project to potential customers.

CO2:n adsorptio Loviisan voimalaitoksen päästöilmasta 14C-päästöjen määrittämiseksi

Tämän kandidaatintyön tavoitteena oli selvittää mahdollisuuksia 14C:n kemiallisten muotojen eriyttämiseen käyttäen Loviisan voimalaitoksella olemassa olevaa näytteenkeräyslaitteistoa. Lisäksi tarkoituksena oli selvittää parhaiten tähän käyttötarkoitukseen soveltuva zeoliittityyppiä tyypeistä 4A, 5A ja 13X. Työn kirjallisessa osassa käsitellään ydinvoimalaitoksen C14-päästöjä keskittyen pääosin Loviisan VVER-laitokseen. Adsorption osalta esitellään kaupallisesti käytettyjä adsorptiomateriaaleja ja paneudutaan adsorptioon fysikaalisena ja kemiallisena ilmiönä. Lisäksi esitellään kahden desorptiomenetelmän perusperiaatteet. Kirjallisen osan lopussa kootaan tutkimukseen vaikuttavia tekijöitä ja esitellään aiemmin käytössä ollut näytteenkeräyslaitteisto. Kokeellisessa osassa esitellään työssä käytetyt laitteistot. Lisäksi on kuvattu mittausten suoritus nestetuikelaskurilla. Tämän jälkeen työssä esitellään mittaustuloksien käsittely ja näin saadut tulokset.

Utilization of steelmaking waste materials for production of calcium carbonate (CaCO3)

The steel industry produces, besides steel, also solid mineral by-products or slags, while it emits large quantities of carbon dioxide (CO2). Slags consist of various silicates and oxides which are formed in chemical reactions between the iron ore and the fluxing agents during the high temperature processing at the steel plant. Currently, these materials are recycled in the ironmaking processes, used as aggregates in construction, or landfilled as waste. The utilization rate of the steel slags can be increased by selectively extracting components from the mineral matrix. As an example, aqueous solutions of ammonium salts such as ammonium acetate, chloride and nitrate extract calcium quite selectively already at ambient temperature and pressure conditions. After the residual solids have been separated from the solution, calcium carbonate can be precipitated by feeding a CO2 flow through the solution. Precipitated calcium carbonate (PCC) is used in different applications as a filler material. Its largest consumer is the papermaking industry, which utilizes PCC because it enhances the optical properties of paper at a relatively low cost. Traditionally, PCC is manufactured from limestone, which is first calcined to calcium oxide, then slaked with water to calcium hydroxide and finally carbonated to PCC. This process emits large amounts of CO2, mainly because of the energy-intensive calcination step. This thesis presents research work on the scale-up of the above-mentioned ammonium salt based calcium extraction and carbonation method, named Slag2PCC. Extending the scope of the earlier studies, it is now shown that the parameters which mainly affect the calcium utilization efficiency are the solid-to-liquid ratio of steel slag and the ammonium salt solvent solution during extraction, the mean diameter of the slag particles, and the slag composition, especially the fractions of total calcium, silicon, vanadium and iron as well as the fraction of free calcium oxide. Regarding extraction kinetics, slag particle size, solid-to-liquid ratio and molar concentration of the solvent solution have the largest effect on the reaction rate. Solvent solution concentrations above 1 mol/L NH4Cl cause leaching of other elements besides calcium. Some of these such as iron and manganese result in solution coloring, which can be disadvantageous for the quality of the PCC product. Based on chemical composition analysis of the produced PCC samples, however, the product quality is mainly similar as in commercial products. Increasing the novelty of the work, other important parameters related to assessment of the PCC quality, such as particle size distribution and crystal morphology are studied as well. As in traditional PCC precipitation process, the ratio of calcium and carbonate ions controls the particle shape; a higher value for [Ca2+]/[CO32-] prefers precipitation of calcite polymorph, while vaterite forms when carbon species are present in excess. The third main polymorph, aragonite, is only formed at elevated temperatures, above 40-50 °C. In general, longer precipitation times cause transformation of vaterite to calcite or aragonite, but also result in particle agglomeration. The chemical equilibrium of ammonium and calcium ions and dissolved ammonia controlling the solution pH affects the particle sizes, too. Initial pH of 12-13 during the carbonation favors nonagglomerated particles with a diameter of 1 μm and smaller, while pH values of 9-10 generate more agglomerates of 10-20 μm. As a part of the research work, these findings are implemented in demonstrationscale experimental process setups. For the first time, the Slag2PCC technology is tested in scale of ~70 liters instead of laboratory scale only. Additionally, design of a setup of several hundreds of liters is discussed. For these purposes various process units such as inclined settlers and filters for solids separation, pumps and stirrers for material transfer and mixing as well as gas feeding equipment are dimensioned and developed. Overall emissions reduction of the current industrial processes and good product quality as the main targets, based on the performed partial life cycle assessment (LCA), it is most beneficial to utilize low concentration ammonium salt solutions for the Slag2PCC process. In this manner the post-treatment of the products does not require extensive use of washing and drying equipment, otherwise increasing the CO2 emissions of the process. The low solvent concentration Slag2PCC process causes negative CO2 emissions; thus, it can be seen as a carbon capture and utilization (CCU) method, which actually reduces the anthropogenic CO2 emissions compared to the alternative of not using the technology. Even if the amount of steel slag is too small for any substantial mitigation of global warming, the process can have both financial and environmental significance for individual steel manufacturers as a means to reduce the amounts of emitted CO2 and landfilled steel slag. Alternatively, it is possible to introduce the carbon dioxide directly into the mixture of steel slag and ammonium salt solution. The process would generate a 60-75% pure calcium carbonate mixture, the remaining 25-40% consisting of the residual steel slag. This calcium-rich material could be re-used in ironmaking as a fluxing agent instead of natural limestone. Even though this process option would require less process equipment compared to the Slag2PCC process, it still needs further studies regarding the practical usefulness of the products. Nevertheless, compared to several other CO2 emission reduction methods studied around the world, the within this thesis developed and studied processes have the advantage of existing markets for the produced materials, thus giving also a financial incentive for applying the technology in practice.

Pre- and postnatal nutrition – target for allergy risk reduction

A rapid increase in allergic diseases in Western societies has led to the conclusion that our modern lifestyle is a risk factor for immune dysregulation. Potential culprits and benefactors are searched among early dietary and microbial exposures, which may act to program later allergic disease. The aim of this thesis was to investigate the role of early maternal and child nutrition in reducing the risk of child allergy. The study population comprised of 256 mother – child pairs from families with a history of allergy participating in a randomized controlled dietary counseling and probiotic intervention (Lactobacillus rhamnosus GG and Bifidobacterium lactis Bb12) study from early pregnancy onwards. The dietary counseling aimed for a diet complying with dietary recommendations for pregnant and lactating women, with special attention to fat quality. Maternal dietary counseling was reflected in cord blood fatty acids suggesting better essential fatty acid status in infants in the counseling group. Dietary counseling with probiotics or placebo had no effect on child allergy risk, but associations between maternal diet during pregnancy and breastfeeding and child allergic outcomes were found in secondary analyses. During pregnancy, milk intake was related to decreased and cheese intake to increased risk of child atopic eczema. During breastfeeding, intake of vitamin C was related to increased risk of asthma and intake of egg was related to decreased risk of atopic eczema. The timing of introduction of complementary foods to infant’s diet was not associated with risk of atopic eczema, when adjusted with parental opinion of child allergic symptoms (i.e., potential reverse causality). In conclusion, the results demonstrate that infant fatty acid supply can be modified via maternal dietary changes. In addition, interesting associations of maternal diet with child allergy risk were discovered. However, no difference in the incidence of allergic diseases with dietary counseling was observed. This suggests that more potent dietary interventions might be necessitated to induce clinical risk reduction of allergy. Highrisk families can safely adhere to dietary recommendations for pregnant and lactating women, and the results support the current conception that no additional benefit is gained with delaying introduction of complementary feeding.

Reduction of nitrogen oxide emissions in lime kiln

Different nitrogen oxide removal technologies for rotary lime kiln are studied in this thesis, the main focus being in commercial technologies. Post-combustion methods are investigated in more detail as potential possible NOx removal with combustion methods in rotary lime kiln is more limited or primary methods are already in use. However, secondary methods as NOx scrubber, SNCR or SCR technologies are not listed as the Best Available Technologies defined by European Union. BAT technologies for NOx removal in lime kiln are (1) Optimised combustion and combustion control, (2) Good mixing of fuel and air, (3) Low-NOx burner and (4) Fuel selection/low-N fuel. SNCR method is the most suitable technique for NOx removal in lime kiln when NOx removal from 50 % to 70 % is required in case primary methods are already in use or cannot be applied. In higher removal cases ammonia slip is an issue in SNCR. By using SCR better NOx reduction can be achieved but issues with catalyst materials are expected to arise because of the dust and sulphur dioxide which leads to catalyst poison formation in lower flue gas temperatures. NOx scrubbing has potential when simultaneous NOx and SO2 removal is required. The challenge is that NO cannot be scrubbed directly, but once it is oxidized to NO2 or further scrubbing can be performed as the solubility of NO2 is higher. Commercial installations have not been made regarding SNCR, SCR or NOx scrubbing regarding rotary lime kiln. For SNCR and SCR the closest references come from cement industry.

Unequal Teeth Widths for Torque Ripple Reduction in Permanent Magnet Synchronous Machines With Fractional-Slot Non-Overlapping Windings

Permanent magnet synchronous machines with fractional-slot non-overlapping windings (FSPMSM), also known as tooth-coil winding permanent magnet synchronous machines (TCW PMSM), have been under intensive research during the latest decade. There are many optimization routines explained and implemented in the literature in order to improve the characteristics of this machine type. This paper introduces a new technique for torque ripple minimization in TCW PMSM. The source of torque harmonics is also described. The low order torque harmonics can be harmful for a variety of applications, such as direct drive wind generators, direct drive light vehicle electrical motors, and for some high precision servo applications. The reduction of the torque ripple harmonics with the lowest orders (6th and 12th) is realized by machine geometry optimization technique using finite element analysis (FEA). The presented optimization technique includes the stator geometry adjustment in TCW PMSMs with rotor surface permanent magnets and with rotor embedded permanent magnets. Influence of the permanent magnet skewing on the torque ripple reduction and cogging torque elimination was also investigated. It was implemented separately and together with the stator optimization technique. As a result, the reduction of some torque ripple harmonics was attained.

Cost Reduction of Permanent Magnet Synchronous Machines

Electrical machine drives are the most electrical energy-consuming systems worldwide. The largest proportion of drives is found in industrial applications. There are, however many other applications that are also based on the use of electrical machines, because they have a relatively high efficiency, a low noise level, and do not produce local pollution. Electrical machines can be classified into several categories. One of the most commonly used electrical machine types (especially in the industry) is induction motors, also known as asynchronous machines. They have a mature production process and a robust rotor construction. However, in the world pursuing higher energy efficiency with reasonable investments not every application receives the advantage of using this type of motor drives. The main drawback of induction motors is the fact that they need slipcaused and thus loss-generating current in the rotor, and additional stator current for magnetic field production along with the torque-producing current. This can reduce the electric motor drive efficiency, especially in low-speed, low-power applications. Often, when high torque density is required together with low losses, it is desirable to apply permanent magnet technology, because in this case there is no need to use current to produce the basic excitation of the machine. This promotes the effectiveness of copper use in the stator, and further, there is no rotor current in these machines. Again, if permanent magnets with a high remanent flux density are used, the air gap flux density can be higher than in conventional induction motors. These advantages have raised the popularity of PMSMs in some challenging applications, such as hybrid electric vehicles (HEV), wind turbines, and home appliances. Usually, a correctly designed PMSM has a higher efficiency and consequently lower losses than its induction machine counterparts. Therefore, the use of these electrical machines reduces the energy consumption of the whole system to some extent, which can provide good motivation to apply permanent magnet technology to electrical machines. However, the cost of high performance rare earth permanent magnets in these machines may not be affordable in many industrial applications, because the tight competition between the manufacturers dictates the rules of low-cost and highly robust solutions, where asynchronous machines seem to be more feasible at the moment. Two main electromagnetic components of an electrical machine are the stator and the rotor. In the case of a conventional radial flux PMSM, the stator contains magnetic circuit lamination and stator winding, and the rotor consists of rotor steel (laminated or solid) and permanent magnets. The lamination itself does not significantly influence the total cost of the machine, even though it can considerably increase the construction complexity, as it requires a special assembly arrangement. However, thin metal sheet processing methods are very effective and economically feasible. Therefore, the cost of the machine is mainly affected by the stator winding and the permanent magnets. The work proposed in this doctoral dissertation comprises a description and analysis of two approaches of PMSM cost reduction: one on the rotor side and the other on the stator side. The first approach on the rotor side includes the use of low-cost and abundant ferrite magnets together with a tooth-coil winding topology and an outer rotor construction. The second approach on the stator side exploits the use of a modular stator structure instead of a monolithic one. PMSMs with the proposed structures were thoroughly analysed by finite element method based tools (FEM). It was found out that by implementing the described principles, some favourable characteristics of the machine (mainly concerning the machine size) will inevitable be compromised. However, the main target of the proposed approaches is not to compete with conventional rare earth PMSMs, but to reduce the price at which they can be implemented in industrial applications, keeping their dimensions at the same level or lower than those of a typical electrical machine used in the industry at the moment. The measurement results of the prototypes show that the main performance characteristics of these machines are at an acceptable level. It is shown that with certain specific actions it is possible to achieve a desirable efficiency level of the machine with the proposed cost reduction methods.

Production of magnesium carbonates from serpentinites for CO2 mineral sequestration : optimisation towards industrial application

Global warming is one of the most alarming problems of this century. Initial scepticism concerning its validity is currently dwarfed by the intensification of extreme weather events whilst the gradual arising level of anthropogenic CO2 is pointed out as its main driver. Most of the greenhouse gas (GHG) emissions come from large point sources (heat and power production and industrial processes) and the continued use of fossil fuels requires quick and effective measures to meet the world’s energy demand whilst (at least) stabilizing CO2 atmospheric levels. The framework known as Carbon Capture and Storage (CCS) – or Carbon Capture Utilization and Storage (CCUS) – comprises a portfolio of technologies applicable to large‐scale GHG sources for preventing CO2 from entering the atmosphere. Amongst them, CO2 capture and mineralisation (CCM) presents the highest potential for CO2 sequestration as the predicted carbon storage capacity (as mineral carbonates) far exceeds the estimated levels of the worldwide identified fossil fuel reserves. The work presented in this thesis aims at taking a step forward to the deployment of an energy/cost effective process for simultaneous capture and storage of CO2 in the form of thermodynamically stable and environmentally friendly solid carbonates. R&D work on the process considered here began in 2007 at Åbo Akademi University in Finland. It involves the processing of magnesium silicate minerals with recyclable ammonium salts for extraction of magnesium at ambient pressure and 400‐440⁰C, followed by aqueous precipitation of magnesium in the form of hydroxide, Mg(OH)2, and finally Mg(OH)2 carbonation in a pressurised fluidized bed reactor at ~510⁰C and ~20 bar PCO2 to produce high purity MgCO3. Rock material taken from the Hitura nickel mine, Finland, and serpentinite collected from Bragança, Portugal, were tested for magnesium extraction with both ammonium sulphate and bisulphate (AS and ABS) for determination of optimal operation parameters, primarily: reaction time, reactor type and presence of moisture. Typical efficiencies range from 50 to 80% of magnesium extraction at 350‐450⁰C. In general ABS performs better than AS showing comparable efficiencies at lower temperature and reaction times. The best experimental results so far obtained include 80% magnesium extraction with ABS at 450⁰C in a laboratory scale rotary kiln and 70% Mg(OH)2 carbonation in the PFB at 500⁰C, 20 bar CO2 pressure for 15 minutes. The extraction reaction with ammonium salts is not at all selective towards magnesium. Other elements like iron, nickel, chromium, copper, etc., are also co‐extracted. Their separation, recovery and valorisation are addressed as well and found to be of great importance. The assessment of the exergetic performance of the process was carried out using Aspen Plus® software and pinch analysis technology. The choice of fluxing agent and its recovery method have a decisive sway in the performance of the process: AS is recovered by crystallisation and in general the whole process requires more exergy (2.48–5.09 GJ/tCO2sequestered) than ABS (2.48–4.47 GJ/tCO2sequestered) when ABS is recovered by thermal decomposition. However, the corrosive nature of molten ABS and operational problems inherent to thermal regeneration of ABS prohibit this route. Regeneration of ABS through addition of H2SO4 to AS (followed by crystallisation) results in an overall negative exergy balance (mainly at the expense of low grade heat) but will flood the system with sulphates. Although the ÅA route is still energy intensive, its performance is comparable to conventional CO2 capture methods using alkanolamine solvents. An energy‐neutral process is dependent on the availability and quality of nearby waste heat and economic viability might be achieved with: magnesium extraction and carbonation levels ≥ 90%, the processing of CO2‐containing flue gases (eliminating the expensive capture step) and production of marketable products.

Characterization of amine-based CO2 adsorbent for Direct Air Capture

Direct air capture technologies extract CO2 from air at a concentration of as low as 400ppm. The captured CO2 can be used for the production of synthetic methane or liquid fuels. In the literature survey of this thesis, results related to direct air capture by using solid sorbents are presented and critically discussed. In the experimental part, a proprietary amine functionalized resin is characterized for direct air capture. Structural comparison is also made to a commercial resin of similar type. Based on the literature survey, the most important parameters in direct air capture process are low adsorption and desorption temperatures, good cyclic stability in dry and humid conditions, high CO2 outlet purity and a high working capacity. Primary amine functionalized solid sorbents are found to often have good qualities for direct air capture, but overall process performance is rarely studied exhaustively. Based on FTIR spectra, both resin adsorbents are found to be consisted of polystyrene functionalized with primary amine, and capture CO2 by forming carbamate. The commercial resin is more porous, has a slightly higher particle size and contains fewer impurities. Important physical parameters are gained of the proprietary resin, such as internal porosity and median particle size. The resin’s amine group is found to endure thermal treatment reasonably well. CO2 adsorption capacity gained by thermal gravimetry from 400ppm CO2 is highest at 25oC, and is found to be reasonable compared to values presented in literature. Thus, the resin is stated to exhibit promising qualities for direct air capture.

Variance reduction properties of dynamic hedging models - empirical evidence from BRICS countries

This Master’s Thesis analyses the effectiveness of different hedging models on BRICS (Brazil, Russia, India, China, and South Africa) countries. Hedging performance is examined by comparing two different dynamic hedging models to conventional OLS regression based model. The dynamic hedging models being employed are Constant Conditional Correlation (CCC) GARCH(1,1) and Dynamic Conditional Correlation (DCC) GARCH(1,1) with Student’s t-distribution. In order to capture the period of both Great Moderation and the latest financial crisis, the sample period extends from 2003 to 2014. To determine whether dynamic models outperform the conventional one, the reduction of portfolio variance for in-sample data with contemporaneous hedge ratios is first determined and then the holding period of the portfolios is extended to one and two days. In addition, the accuracy of hedge ratio forecasts is examined on the basis of out-of-sample variance reduction. The results are mixed and suggest that dynamic hedging models may not provide enough benefits to justify harder estimation and daily portfolio adjustment. In this sense, the results are consistent with the existing literature.

Alternative electron transfer routes involved in photoprotection of cyanobacteria

In oxygenic photosynthesis, the highly oxidizing reactions of water splitting produce reactive oxygen species (ROS) and other radicals that could damage the photosynthetic apparatus and affect cell viability. Under particular environmental conditions, more electrons are produced in water oxidation than can be harmlessly used by photochemical processes for the reduction of metabolic electron sinks. In these circumstances, the excess of electrons can be delivered, for instance, to O2, resulting in the production of ROS. To prevent detrimental reactions, a diversified assortment of photoprotection mechanisms has evolved in oxygenic photosynthetic organisms. In this thesis, I focus on the role of alternative electron transfer routes in photoprotection of the cyanobacterium Synechocystis sp. PCC 6803. Firstly, I discovered a novel subunit of the NDH-1 complex, NdhS, which is necessary for cyclic electron transfer around Photosystem I, and provides tolerance to high light intensities. Cyclic electron transfer is important in modulating the ATP/NADPH ratio under stressful environmental conditions. The NdhS subunit is conserved in many oxygenic phototrophs, such as cyanobacteria and higher plants. NdhS has been shown to link linear electron transfer to cyclic electron transfer by forming a bridge for electrons accumulating in the Ferredoxin pool to reach the NDH-1 complexes. Secondly, I thoroughly investigated the role of the entire flv4-2 operon in the photoprotection of Photosystem II under air level CO2 conditions and varying light intensities. The operon encodes three proteins: two flavodiiron proteins Flv2 and Flv4 and a small Sll0218 protein. Flv2 and Flv4 are involved in a novel electron transport pathway diverting electrons from the QB pocket of Photosystem II to electron acceptors, which still remain unknown. In my work, it is shown that the flv4-2 operon-encoded proteins safeguard Photosystem II activity by sequestering electrons and maintaining the oxidized state of the PQ pool. Further, Flv2/Flv4 was shown to boost Photosystem II activity by accelerating forward electron flow, triggered by an increased redox potential of QB. The Sll0218 protein was shown to be differentially regulated as compared to Flv2 and Flv4. Sll0218 appeared to be essential for Photosystem II accumulation and was assigned a stabilizing role for Photosystem II assembly/repair. It was also shown to be responsible for optimized light-harvesting. Thus, Sll0218 and Flv2/Flv4 cooperate to protect and enhance Photosystem II activity. Sll0218 ensures an increased number of active Photosystem II centers that efficiently capture light energy from antennae, whilst the Flv2/Flv4 heterodimer provides a higher electron sink availability, in turn, promoting a safer and enhanced activity of Photosystem II. This intertwined function was shown to result in lowered singlet oxygen production. The flv4-2 operon-encoded photoprotective mechanism disperses excess excitation pressure in a complimentary manner with the Orange Carotenoid Protein-mediated non-photochemical quenching. Bioinformatics analyses provided evidence for the loss of the flv4-2 operon in the genomes of cyanobacteria that have developed a stress inducible D1 form. However, the occurrence of various mechanisms, which dissipate excitation pressure at the acceptor side of Photosystem II was revealed in evolutionarily distant clades of organisms, i.e. cyanobacteria, algae and plants.