A generalized 1D particle transport method for convection diffusion reaction model

This work is devoted to the development of numerical method to deal with convection diffusion dominated problem with reaction term, non - stiff chemical reaction and stiff chemical reaction. The technique is based on the unifying Eulerian - Lagrangian schemes (particle transport method) under the framework of operator splitting method. In the computational domain, the particle set is assigned to solve the convection reaction subproblem along the characteristic curves created by convective velocity. At each time step, convection, diffusion and reaction terms are solved separately by assuming that, each phenomenon occurs separately in a sequential fashion. Moreover, adaptivities and projection techniques are used to add particles in the regions of high gradients (steep fronts) and discontinuities and transfer a solution from particle set onto grid point respectively. The numerical results show that, the particle transport method has improved the solutions of CDR problems. Nevertheless, the method is time consumer when compared with other classical technique e.g., method of lines. Apart from this advantage, the particle transport method can be used to simulate problems that involve movingsteep/smooth fronts such as separation of two or more elements in the system.

Air des Bijoux

Oopperasta Faust.

Quantification of Proteins and Cells: Luminometric Nonspecific Particle-Based Methods

New luminometric particle-based methods were developed to quantify protein and to count cells. The developed methods rely on the interaction of the sample with nano- or microparticles and different principles of detection. In fluorescence quenching, timeresolved luminescence resonance energy transfer (TR-LRET), and two-photon excitation fluorescence (TPX) methods, the sample prevents the adsorption of labeled protein to the particles. Depending on the system, the addition of the analyte increases or decreases the luminescence. In the dissociation method, the adsorbed protein protects the Eu(III) chelate on the surface of the particles from dissociation at a low pH. The experimental setups are user-friendly and rapid and do not require hazardous test compounds and elevated temperatures. The sensitivity of the quantification of protein (from 40 to 500 pg bovine serum albumin in a sample) was 20-500-fold better than in most sensitive commercial methods. The quenching method exhibited low protein-to-protein variability and the dissociation method insensitivity to the assay contaminants commonly found in biological samples. Less than ten eukaryotic cells were detected and quantified with all the developed methods under optimized assay conditions. Furthermore, two applications, the method for detection of the aggregation of protein and the cell viability test, were developed by utilizing the TR-LRET method. The detection of the aggregation of protein was allowed at a more than 10,000 times lower concentration, 30 μg/L, compared to the known methods of UV240 absorbance and dynamic light scattering. The TR-LRET method was combined with a nucleic acid assay with cell-impermeable dye to measure the percentage of dead cells in a single tube test with cell counts below 1000 cells/tube.

Recovery and refining of manganese as by-product from hydrometallurgical processes

The consumption of manganese is increasing, but huge amounts of manganese still end up in waste in hydrometallurgical processes. The recovery of manganese from multi-metal solutions at low concentrations may not be economical. In addition, poor iron control typically prevents the production of high purity manganese. Separation of iron from manganese can be done with chemical precipitation or solvent extraction methods. Combined carbonate precipitation with air oxidation is a feasible method to separate iron and manganese due to the fast kinetics, good controllability and economical reagents. In addition the leaching of manganese carbonate is easier and less acid consuming than that of hydroxide or sulfide precipitates. Selective iron removal with great efficiency from MnSO4 solution is achieved by combined oxygen or air oxidation and CaCO3 precipitation at pH > 5.8 and at a redox potential of > 200 mV. In order to avoid gypsum formation, soda ash should be used instead of limestone. In such case, however, extra attention needs to be paid on the reagents mole ratios in order to avoid manganese coprecipitation. After iron removal, pure MnSO4 solution was obtained by solvent extraction using organophosphorus reagents, di-(2-ethylhexyl)phosphoric acid (D2EHPA) and bis(2,4,4- trimethylpentyl)phosphinic acid (CYANEX 272). The Mn/Ca and Mn/Mg selectivities can be increased by decreasing the temperature from the commonly used temperatures (40 –60oC) to 5oC. The extraction order of D2EHPA (Ca before Mn) at low temperature remains unchanged but the lowering of temperature causes an increase in viscosity and slower phase separation. Of these regents, CYANEX 272 is selective for Mn over Ca and, therefore, it would be the better choice if there is Ca present in solution. A three-stage Mn extraction followed by a two-stage scrubbing and two-stage sulfuric acid stripping is an effective method of producing a very pure MnSO4 intermediate solution for further processing. From the intermediate MnSO4 some special Mn- products for ion exchange applications were synthesized and studied. Three types of octahedrally coordinated manganese oxide materials as an alternative final product for manganese were chosen for synthesis: layer structured Nabirnessite, tunnel structured Mg-todorokite and K-kryptomelane. As an alternative source of pure MnSO4 intermediate, kryptomelane was synthesized by using a synthetic hydrometallurgical tailings. The results show that the studied OMS materials adsorb selectively Cu, Ni, Cd and K in the presence of Ca and Mg. It was also found that the exchange rates were reasonably high due to the small particle dimensions. Materials are stable in the studied conditions and their maximum Cu uptake capacity was 1.3 mmol/g. Competitive uptake of metals and acid was studied using equilibrium, batch kinetic and fixed-bed measurements. The experimental data was correlated with a dynamic model, which also accounts for the dissolution of the framework manganese. Manganese oxide micro-crystals were also bound onto silica to prepare a composite material having a particle size large enough to be used in column separation experiments. The MnOx/SiO2 ratio was found to affect significantly the properties of the composite. The higher the ratio, the lower is the specific surface area, the pore volume and the pore size. On the other hand, higher amount of silica binder gives composites better mechanical properties. Birnesite and todorokite can be aggregated successfully with colloidal silica at pH 4 and with MnO2/SiO2 weight ratio of 0.7. The best gelation and drying temperature was 110oC and sufficiently strong composites were obtained by additional heat-treatment at 250oC for 2 h. The results show that silica–supported MnO2 materials can be utilized to separate copper from nickel and cadmium. The behavior of the composites can be explained reasonably well with the presented model and the parameters estimated from the data of the unsupported oxides. The metal uptake capacities of the prepared materials were quite small. For example, the final copper loading was 0.14 mmol/gMnO2. According to the results the special MnO2 materials are potential for a specific environmental application to uptake harmful metal ions.

Katupölyn torjunta hiekoitushiekan poistossa kaupunkiympäristössä

Katupölyn torjumisessa hiekoitushiekan poistossa kaupunkiympäristössä tutkittiin, miten katujen talvikunnossapidon toimenpiteet ja talven hiekoitushiekkojen poistotyö vaikuttavat yhdyskuntailman hengitettävien hiukkasten PM10 -katupölyn määrään ja selvitettiin nykyiset käytännöt sekä uusia menetelmiä vähentää katupölyn määrää. Tutkimus on tehty Lappeenrannan kaupungin teknisen toimen katujen kunnossapidon tulosalueelle. Hankkeessa keskityttiin löytämään uusi ja tehokkaampi työmenetelmä sekä työjärjestys hiekanpoistoon, jotta työnaikaisen katupölyn määrä saataisiin minimoitua. Tehokkaita menetelmiä tutkimuksen perusteella olivat katujen ennalta kastelua ja työnaikainen pölynsidonta suolaliuoksella katupölyn vähentämiseen sekä oikean menetelmän käyttö. Pölynsidonta suolaliuoksella osoittautui tehokkaaksi akuutin katupölyn vähentämiskeinoksi. Pölynsidonta ei kuitenkaan poista katupölyä ja puhdistus tulee tehdä myöhemmin. Kadunvarren lumessa on suuria hiekoitushiekan kiintoainespitoisuuksia ja lumen poisviennillä voidaan saavuttaa hyötyjä katupölyongelman kannalta. Hiekoituspäivien lukumäärä on myös suoraan verrannollinen katupölyn määrään. Hiekoituksen ohella myös nastarenkaiden käyttö lisää katupölypäästöjä kaupunkialueilla. Nastarenkaiden vaikutusta katupölyn määrään ei selvitetty tässä tutkimuksessa tarkemmin, koska nastarenkaiden käyttökiellon voidaan olettaa lisäävän liikennetapaturmia sekä myös liukkaudentorjunnan tarvetta, eli hiekoitusta.

Theoretical Analysis and Numerical Simulation of Spectral Radiative Properties of Combustion Gases in Oxy/Air-Fired Combustion Systems

Energy efficiency is one of the major objectives which should be achieved in order to implement the limited energy resources of the world in a sustainable way. Since radiative heat transfer is the dominant heat transfer mechanism in most of fossil fuel combustion systems, more accurate insight and models may cause improvement in the energy efficiency of the new designed combustion systems. The radiative properties of combustion gases are highly wavelength dependent. Better models for calculating the radiative properties of combustion gases are highly required in the modeling of large scale industrial combustion systems. With detailed knowledge of spectral radiative properties of gases, the modeling of combustion processes in the different applications can be more accurate. In order to propose a new method for effective non gray modeling of radiative heat transfer in combustion systems, different models for the spectral properties of gases including SNBM, EWBM, and WSGGM have been studied in this research. Using this detailed analysis of different approaches, the thesis presents new methods for gray and non gray radiative heat transfer modeling in homogeneous and inhomogeneous H2O–CO2 mixtures at atmospheric pressure. The proposed method is able to support the modeling of a wide range of combustion systems including the oxy-fired combustion scenario. The new methods are based on implementing some pre-obtained correlations for the total emissivity and band absorption coefficient of H2O–CO2 mixtures in different temperatures, gas compositions, and optical path lengths. They can be easily used within any commercial CFD software for radiative heat transfer modeling resulting in more accurate, simple, and fast calculations. The new methods were successfully used in CFD modeling by applying them to industrial scale backpass channel under oxy-fired conditions. The developed approaches are more accurate compared with other methods; moreover, they can provide complete explanation and detailed analysis of the radiation heat transfer in different systems under different combustion conditions. The methods were verified by applying them to some benchmarks, and they showed a good level of accuracy and computational speed compared to other methods. Furthermore, the implementation of the suggested banded approach in CFD software is very easy and straightforward.

Mikä on air-fligt-periaate?

kuv., 14 x 22 cm

Mikä on air-fligt-periaate?

kuv., 14 x 22 cm

Utilization of Particle Image velocimetry in PPOOLEX condensation experiments

Particle Image Velocimetry, PIV, is an optical measuring technique to obtain velocity information of a flow in interest. With PIV it is possible to achieve two or three dimensional velocity vector fields from a measurement area instead of a single point in a flow. Measured flow can be either in liquid or in gas form. PIV is nowadays widely applied to flow field studies. The need for PIV is to obtain validation data for Computational Fluid Dynamics calculation programs that has been used to model blow down experiments in PPOOLEX test facility in the Lappeenranta University of Technology. In this thesis PIV and its theoretical background are presented. All the subsystems that can be considered to be part of a PIV system are presented as well with detail. Emphasis is also put to the mathematics behind the image evaluation. The work also included selection and successful testing of a PIV system, as well as the planning of the installation to the PPOOLEX facility. Already in the preliminary testing PIV was found to be good addition to the measuring equipment for Nuclear Safety Research Unit of LUT. The installation to PPOOLEX facility was successful even though there were many restrictions considering it. All parts of the PIV system worked and they were found out to be appropriate for the planned use. Results and observations presented in this thesis are a good background to further PIV use.

Microstructural and environmental effects on the mechanical properties of porous particle-polymer composites

Papper kan anses vara ett av de mest använda materialen i det dagliga livet. Tidskrifter, tidningar, böcker och diverse förpackningar är några exempel på pappersbaserade produkter. Papperets egenskaper måste anpassas till användningsändamålet. En tidskrift kräver t.ex. hög ljushet, opacitet och en slät yta hos papperet, medan dessa egenskaper är mindre viktiga för en dagstidning. Allt tryckpapper behöver vissa mekaniska egenskaper för att tåla vidarebearbetning såsom kalandrering, tryckning och vikning. Man kan bestryka papper för att förbättra dess optiska egenskaper och tryckbarhetsegenskaper. Vid bestrykning appliceras en dispersion av mineralpigment och polymerbindemedel som ett tunt lager på papperets yta. Bestrykningsskiktet kan ses som ett komplext, poröst kompositmaterial som även bidrar till papperets mekaniska egenskaper och dess processerbarhet i diverse konverteringsoperationer. Kravet på framställning av förmånligt papper med tillräckliga styrkeegenskaper ställer allt högre krav på optimeringen av pappersbestrykningsskiktets egenskaper och produktionskostnader. Målet med detta arbete var att förstå sambandet mellan pigmentbestrykningsskiktets mikrostruktur och dess makroskopiska, mekaniska egenskaper. Resultaten visar att adhesionen i gränsytan mellan pigment och bindemedel är kritisk för bestrykningsskiktets förmåga att bära mekanisk belastning. Polära vätskor är vanliga i tryckfärger och kan, eftersom de påverkar syra/bas-interaktionerna mellan pigment och latexbindemedel, försvaga denna adhesion. Resultaten tyder på att ytstyrkan hos bestruket papper kan höjas genom användning av bifunktionella dispergeringsmedel för mineralpigment. Detta medför inbesparingar i pappersproduktionen eftersom mängden bindemedel, den dyraste komponenten i bestrykningsskiktet, kan minskas.

Air policing turvallisuuspoliittisena kysymyksenä Suomessa

Tutkimuksessa tarkastellaan air policingia turvallisuuspoliittisena kysymyksenä Suomessa, Islannin ilmavalvontahankkeen kautta. Tavoitteena oli selvittää Islannin ilmavalvonnasta käydyn julkisen keskustelun perusteella, miten air policing näyttäytyy Suomen turvallisuuspolitiikassa. Air policingilla tarkoitetaan vieraan suvereenin valtion ilmatilan koskemattomuuden valvontaa ja turvaamista rauhan aikana. Suomen turvallisuuspolitiikassa air policing on aiemmin käyttämätön työväline. Tutkimuksessa analysoitiin Suomessa käytyä julkista keskustelua Islannin ilmavalvonnasta. Keskustelua tutkittiin puolustusvoimien lakisääteisten tehtävien ja Suomen sotilaallisen liittoutumattomuuden näkökulmista. Tarkastelujen perusteella tehtiin johtopäätöksiä air policingista Suomen turvallisuuspoliittisena kysymyksenä. Tutkimuksen aineisto koostui Islannin ilmavalvontaa käsittelevistä Helsingin Sanomien, Uuden Suomen, Kylkiraudan ja Sotilasaikakauslehden kirjoituksista, eduskunnan täysistuntojen pöytäkirjoista sekä keskeisten turvallisuuspoliittisten päättäjien lausunnoista. Tarkasteltava ajanjakso oli vuoden 2009 alusta vuoden 2012 loppuun. Tutkimusmenetelmä oli sisällönanalyysi. Islannin ilmavalvonnasta käyty julkinen keskustelu koostui lyhyestä jaksosta vuonna 2009 sekä vilkkaasta ja laaja-alaisesta keskustelusta vuonna 2012. Tärkeimpiä sisältöteemoja olivat Nato ja Suomen liittoutumattomuus sekä pohjoismainen yhteistyö. Keskustelussa muodostui vastakkainasettelu, jossa toinen mielipide kannatti ja toinen vastusti Suomen osallistumista Islannin ilmavalvontaan. Puolustusvoimien lakisääteisiä tehtäviä käsiteltiin julkisuudessa vähän. Sen sijaan Suomen sotilaallinen liittoutumattomuus oli keskustelun ytimessä. Islannin ilmavalvontahankkeen kriitikot katsoivat osallistumisen vaarantavan Suomen liittoutumattomuuden Islannin Nato-jäsenyyden vuoksi. Hankkeen kannattajat perustelivat osallistumisen olevan osan tiivistyvää pohjoismaista puolustusyhteistyötä. Suomen ylin turvallisuuspoliittinen johto on ollut valmis ottamaan käyttöön air policingin Islannin ilmavalvontahankkeen yhteydessä. Kysymys on osoittautunut poliittisesti vaikeaksi, eikä konsensusta ole saavutettu. Maaliskuussa 2013 näyttää siltä, että mahdollinen osallistuminen Islannin ilmavalvontaan toteutuu harjoitusmuotoisena, jolloin siinä ei ole kyse varsinaisesta air policingista.

Effect of additives, precursors and process conditions on particle morphology

The objective of the thesis was to develop methods to manufacture and control calcium carbonate crystal nucleation and growth in precipitation process. The work consists of experimental part and literature part that addresses theory of nucleation, crystallization and precipitation. In the experimental part calcium carbonate was precipitated using carbonization reaction. Precipitation was carried out in presence of known morphology controlling agents (anionic polymers and sodium silicate) and by using different operation conditions. Formed material was characterized using SEM images, and its thermal stability was assessed. This work demonstrates that carbon dioxide feeding rate and concentrations of calcium hydroxide and additives can be used to control size, shape and amount of precipitating calcium carbonate.

[Air de Laodice]

Soitinnus: lauluääni (sopraano), piano.