Examensarbetets mål var att skapa en modell för oljedegenerering, för implementering i lastbilens styrsystem. En modell som är lämplig för implementering måste vara enkel nog för att kunna hanteras av styrsystemet och samtidigt tillförlitlig nog för att varken över- eller underskatta oljebytesintervallet allt för mycket. Onödigt täta oljebyten medför ökade kostnader för ny olja och produktionsbortfall medan för glesa oljebyten kan orsaka allvarliga skador på motorn med tillhörande kostnader. Modellen delades upp i fyra delmodeller svarandes mot dom olika processer som styr oljedegenereringen; bränsleutspädning, kemisk degradering, sotinblandning och kondensbildning. Delmodellerna skapades med utgångspunkt i publicerade studier av dom olika förloppen varefter dom implementerades i Matlab och jämfördes med mätdata som fanns tillgängliga på Scania. Då det varmöjligt jämfördes olika modifieringar av modellerna för att undersöka vilken som gav bäst överrensstämmelse med mätdata. Bränsleutspädning, sotbildning och vattenutspädning är relativt väl förstådda förlopp och deras beroende av olika parametrar är välkänt. Oljans kemiska degradering är ett betydligt mer komplicerat förlopp som beror av ett flertal olika faktorer och som därför är betydligt svårare att modellera. Av dom fyra delmodeller som skapades gav modellen för bränsleutspädning bäst överrensstämmelse då den jämfördes med mätdata. Data fanns endast tillgängliga för bränslets avdunstning ur oljesumpen och det är därför okänt hur väl modellen för inflödet stämmer. Då modellen för inflöde är kraftigt förenklad finns det anledning att misstänka att överrensstämmelsen inte är allt för god. Modellen för oljedegradering gick inte att verifiera med tillgängliga data och ytterligare försök är nödvändiga. Det konstaterades att oljetemperaturen är viktig för degraderingstakten, men att en modell baserad enbart på temperaturen inte är tillräcklig. Inte heller vattenutspädningsmodellen kunde verifieras. För detta kommer det att krävas direkt mätning av varje delflöde i modellen, vilket kommer att möjliggöra en noggrann verifiering med endast ett fåtal mätningar. Den modell för oljesotbildning som fanns tillgänglig på Scania bedömdes vara tillräckligt bra och ingen ytterligare utveckling av denna modell har gjorts. Modellen har endast dokumenterats kortfattat. / The aim of this thesis project was to create a model of engine oil deterioration, suitable for implementation in the engine control unit. To this end, the model has to be sufficiently simple not to unnecessarily waste limited computing power and yet exact enough not to over- or underestimate the oil change interval too much. Too frequent oil changes mean an unnecessary extra cost for new oil and loss of availability while too long oil change intervals may damage the engine, at an even greater cost. The model was divided into four sub-models, one for each of the processes that cause oil deterioration, i.e. dilution by fuel, chemical degradation, soot contamination and dilution by water. The models created were based on publicized scientific studies of the various processes. In order to validate the models they were implemented in Matlab and compared with experiment data. Various modification attempts were made and the resulting models were evaluated based on their correspondence with measurements. Dilution by fuel, dilution by water and soot contamination are all processes whose causes and dynamics are relatively well known. Oil degradation on the other hand is a complex process that depends on a large number of factors which makes it very complicated to model. This is especially problematic as oil degradation usually is limiting for oil change intervals. Out of the four sub-models that were created, the model for fuel dilution gave the best correspondence with measurements. However data was only available for the part of the model handling evaporation and thus it is unknown how well the model for fuel influx performs. As the model is very simple there is reason to believe that the correspondence between the modelled influx and the actual influx is not very good. The model for oil degradation could not be validated using the available data and further experiments are necessary. However it was concluded from the data available that a model based only on oil temperature, as was first intended, will not be sufficient. The water dilution model was reasonably accurate in predicting average water concentrations, but missed short term variations completely. In order to fully validate the model, further experiments, where the various rates of condensation are measured, will be necessary. The model for oil-soot already available at Scania was considered sufficient and no further work has been done on this model. A short description of the model has been included for completeness.

The purpose of this thesis was to investigate the possibilities of enhancing the temporal and spatial coherence of parametric devices in the mid-infrared spectrum by exploiting inherent coherence selection of Bessel beams. Several optical parametric oscillators (OPO) were constructed and characterized for various types of resonators and pump lasers. In the first part of this work an OPO was constructed out of a periodically poled KTP (PPKTP) crystal within a stable resonator. It was pumped by a Q-switched Nd:YAG laser in transversal and longitudinal single mode operation. The OPO was pumped at 1064 nm and operated at signal wavelength of 1595.9 nm with a bandwidth at FWHM of 0.2 nm and idler wavelength 3192.9 nm and bandwidth of 0.5nm at FWHM. The stable resonator was constructed out of a curved input coupler and a planar output coupler to generate a spatially coherent beam. The beam quality factor of the OPO was measured to M2=1.3 and M2=1.7 in the horizontal and the vertical direction respectively. In the second part of this work conical beams, and hence noncollinear phase matching, was used. This was done to improve and study the temporal and spatial coherence of the generated beam if the OPO is pumped by a laser operating in multiple transversal and longitudinal modes. Using noncollinear phase matching provides a possibility of generating a highly coherent signal (or idler) wave when using a pump laser which operates in multiple transversal and longitudinal modes. Usually, such pump laser makes it difficult to generate highly coherent beams since the properties, such as bandwidth and beam quality factor, of the pump laser are transferred to the generated waves. So called multimode lasers, which operate in multiple modes, can be considered inexpensive and reliable while providing high pulse energies, and they are therefore attractive as pump sources for nonlinear processes. Throughout this second part a Q-switched Nd:YAG laser operating in multiple transversal and longitudinal modes at a wavelength 1064 nm was used. Optical parametric generation (OPG) was used to compare the effects between pumping with a Gaussian wave, and collinear phase matching, and pumping with a conical, a Bessel beam and hence noncollinear phase matching. Thereafter, optical parametric oscillation was studied with collinear and noncollinear phase matching using a Fabry-Perot cavity. The OPO pumped by a Q-switched Gaussian beam, and hence using collinear phase matching had a signal wave at 1596.3 nm and a bandwidth at FWHM of 4 nm. The OPO pumped by a conical beam, hence a Bessel beam and noncollinear phase matching, had a signal wave at 1596.5 nm and a bandwidth at FWHM of 0.2 nm. Both OPOs had a beam quality factor M2~2 in horizontal and vertical direction.

In this thesis the isomerization process of the Merocyanine 540 fluorophore is studied. The presence of that process, when the dye is attached to the lipid membrane, was not reported before, and thus become a main interest of this work. For the further investigation: the reaction of the isomerization dynamics to the different properties of the membrane was studied. The influence of such membrane’s parameters as the size, polarity and fluidity were checked. It was revealed that the isomerization of the MC 540 is present inside the lipid membranes, and its dynamics is changed with the membrane’s polarity and viscosity. So the MC 540 could be in use as a probe for the investigation ofthe membrane’s properties. The isomerization process was studied with the help of the fluorescence correlation spectroscopy (FCS) which is a powerful technique for the single molecule studies.

Natural killer (NK) cells are lymphocytes of the innate immune system responsible for lysing tumor and virally-infected cells. Investigating NK cell heterogeneity can inform the development of more efficacious immunotherapeutic treatments. Cell motility is an essential aspect of NK cell function. Moreover, the cell migration behavior within cell populations displays a marked heterogeneity. For some time it has been clear that cell-matrix interactions can radically alter the behavior of certain types of cells. (1) However, conventional studies of cell migration have relied on flat (2-D) surfaces, and thus do not take this potentially game-changing third dimension into account. Still, migration studies using ECM-mimicking biomaterials such as collagen and Matrigel may employ volume imaging, but often fail to quantify and analyze the vertical direction of migration. This project used silicon microchip-based technology, extracellular matrixlike type I collagen hydrogel, and fluorescence laser scanning confocal microscopy to study the migration behavior of single cells in 3-D. NK and targetcells were embedded in a collagen gel matrix deposited inside sub-mm scale microwells. The microwell provides natural barriers to cell migration, and so ensures that the cells remain confined within the imaging volume. The entire volume of the microwell was scanned for two hours by time-lapse fluorescence microscopy. A total of N  = 14 NK cell migration trajectories were quantified using fluorescence centroid measurements. Results suggest that NK cells retain their cytotoxicity when embedded in the collagen matrix used for the 3-D migration assay. The average migration speed of the studied NK cells in three dimensions was found to be 3.7 ± 0.5μm/min (mean± SEM). Additionally, the NK cells exhibited a directional bias in migration, slightly preferring horizontal migration over vertical migration. In conclusion, this assay readily lends itself to short-term imaging of the migration behavior and cell-cell interactions of NK and target cells embedded in collagen gel in microwells. This microwell-gel system shows promising prospects for future applications at the interface of immunology and engineering. / NK-celler är lymfocyter tillhörande det ospecifika immunförsvaret vars uppgift är att uppsöka och avdöda tumör- och virusinfekterade celler. Genom att undersöka heterogeniteten inom NK-cellspopulationer öppnas en möjlighet att förbättra effektiviteten hos immunoterapeutiska behandlingar. Cellmotilitet är en viktig aspekt av NK-cellers funktion. Därutöver uppvisar cellmigrationsbeteendet inom cellpopulationer en märkbar heterogenitet. Det har under en tid stått klart att cell-matris-interaktioner kan ha en genomgripande effekt på beteendet hos vissa celltyper.(1) Emellertid grundar sig traditionella studier av cellmigration på användandet av tvådimensionella, plana ytor, och frånser på detta vis den potentiellt avgörande effekt som den tredje dimensionen kan ha på resultatet. Likväl kan studier som använder extracellulär matrix-liknande biomaterial, såsom kollagen och Matrigel, och som därutöver drar nytta av volymsavbildning för cellmigration ändå ofta bortse från att kvantifiera och analysera cellmigrationen i vertikalled. Detta projekt använde kiselbaserad mikrochipteknologi, extracellulär matrixliknande hydrogel typ I kollagen, samt fluorescensmikroskopi för att undersöka cellmigrationbeteendet hos enskilda NK-celler i 3-D. NK- och målceller bäddades in i en kollagenmatris vilken i sin tur gjöts in i en mindre än millimeterstor mikrobrunn. Mikrobrunnen utgör en naturlig barriär för cellmigration och kan således försäkra att cellerna stannar inuti avbildningsvolymen. Hela mikrobrunnens volym avbildades under två timmar med hjälp av tidsfördröjd fluorescensmikroskop. En tidsserie av mätningarna sammanställdes sedan. Totalt sammanställdes och kvantifierades N  = 14 NK-cellers cellmigrationsbanor genom att uppskatta cellernas fluorescenta mittpunkter i den återskapade 3-D-volymen. Resultaten ger vid handen att NK-celler behåller sin cytotoxiska förmåga när de är inbäddade i 3-D-matrisen som används i mikrobrunnsuppsättningen. Den tredimensionella medelhastigheten för cellmigrationen hos de undersökta cellerna var 3.7±0.5 μm/min (medelvärde±standardfelet). Därutöver uppvisade NK-cellerna en bias i den genomsnittliga riktningen hos cellmigrationen, där horisontell cellmigration föredrogs framför vertikal cellmigration. Avslutningsvis kan sägas att denna experimentella uppsättning utan större problem kan användas för korttidsavbildning av cellmigrationsbeteende och cell-cell-interaktioner hos NK- och målceller inbäddade i en mikrobrunnsingjuten kollagenmatris. Detta mikrobrunn-gel-baserade system uppvisar lovande möjligheter för framtida tillämpningar i gränsytan mellan immunologi och ingenjörskonst.

The main objective of this master thesis was assessing and evaluating the production of mixed U-Zr nitride fuel powders directly from metallic U-Zr binary alloys, instead of using separate nitride powders. Another secondary objective, if the main one was fulfilled at all, was assessing if it is easier to get the two nitrides in solid solution when obtained from the alloyed materials than when mixed from two nitride powders. Both objectives have been fulfilled by the experiments performed, and they are covered through the pages of this document. Mixed powders can indeed be produced directly from alloys. Therefore, when this procedure is used, many troublesome operations that involve the handling of radioactive and very atmosphere sensitive powders are omitted, which makes the job at the nuclear fuel production laboratories much easier. In addition, at least in one occasion, the mixed powder produced after the synthesis had the two nitrides forming solid solution. This very promising feature could be considerably helpful for the pressing and sintering of pellets if the solid solution from the powder was not affected by those processes. Very long diffusion controlled processes that need heat treatment at very high temperatures could be avoided if the solid solution lasted after sintering the pellets from the synthesized powders.

In this thesis the growth patterns of certain bacterial colonies are studied through numerical simulations of a continuous model, describing the growth of the colony. The objective was to construct a mathematical model capable of recreating observed growth patterns and thus try to gain some insight into the dynamics of bacterial growth. The model constructed in this thesis consists of a set of reaction-diffusion equations describing the evolution of the bacterial colony viewed as a continuous body rather than many individual bacteria. This approach was partially successful, in the sense that similar patterns to those observed in experiments were indeed observed in the simulations. On the other hand, the model was found inadequate in the sense that it could not satisfactory account for the initial rapid expansion of the colony in combination with the fact that the expansion is severely diminished after a few days. From the results it could be concluded that in order to get a satisfactory description of the complete evolution of the bacterial colonies studied here a more sophisticated theory for the diffusion processes is needed. The main conclusion is that the changes in the growth patterns are most likely due to genetic changes, or ’mutations’, in some bacteria causing the mutated bacteria to diffuse faster. There is an upper bound for the mutation frequency in order to get the patterns seen in experiments. The biological mechanism behind this phenomenon could be that the bacteria that mutate lose their pili enabling them to diffuse faster.

In this diploma project the so-called fixed beam moving stage (FBMS) module in the Raith 150 electron beam lithography system has been evaluated for making large area zone plate exposures. The project goal, besides the evaluation of the module, has been to find an exposure recipe for exposing zone plates with diameter up to 500 μm. The zone plates fabricated with this method will be used for synchrotron and x-ray free electron laser applications. The thesis starts with a short introduction to zone plate properties and fabrication procedures. Then the work where FBMS exposed zone plates are compared with normal write field exposures of 75 μm diameter zone plates is described. The conclusion is that for these small diameters, major problems with wobbly zones occur for the FBMS patterns. However, for larger diameters the pattern typically looks better. The final result with large area exposures are excellent zone plate patterns with 500 μm diameter and 100 nm outermost zone width. The total exposure time was 2 h 15 min. This relatively short time indicate that it will be practically possible to use the Raith system for these large area exposures.

The molten core-concrete interaction (MCCI) is treated as one of the important phenomena that may lead to the late containment failure by basemat penetration in a hypothetical severe accident of light water reactors (LWRs). The earlier research has showed that heat transfer limitation exists for the coolability of ex-vessel corium by atop water flooding due to crust formation on the melt/water interface that will isolate melt from water. However, several cooling mechanisms were identified in a series of intense investigations. A code (CORQUENCH) was developed and updated to incorporate the newly identified cooling mechanisms for the better predictions of cavity erosion and corium cooling behaviors. A description about such cooling mechanisms (i.e., bulking cooling, water ingression, eruption and crust breach) and the concrete ablation models implemented in the code is presented in this thesis. The technical work in the thesis includes two parts: first, the verification and validation of the code were performed against the CCI tests from the OECD/MCCI projects; and then a reactor-scale simulation was carried out for MCCI and ex-vessel corium coolability of a reference PWR with LCS concrete. The calculations of CCI tests have a plausible agreement with the experimental data. The calculation predicts an optimistic result for the reactor case, and a fast quenching achieved at about 145 minutes. In addition, a sensitivity study was also conducted on several important parameters, i.e., concrete type, corium composition, water flooding time, atmosphere pressure, concrete ablation temperature, initial temperature, decay power, cavity geometry, concrete decomposition model and melt upper heat transfer model. An attempt to explain the physics of the different predicted phenomena is presented as well. Finally, comparative calculations were performed by the other codes (ASTEC and FinCCI) for the same reactor-scale configuration. Discrepancies are found in the results. Some suggestions are proposed to improve the CORQUENCH code.

Heavy liquid metal (HLM - lead or lead bismuth eutectic) is considered as a candidate coolant for next-generation fast reactor and accelerate-driven systems (ADS), due to its favorable chemical, thermo-physical and neutronic properties in comparison with sodium which has been used as coolant in fast breeder reactors (FBRs). To perform design-base-accident analysis for the HLM-cooled reactors, the well-known transient thermal-hydraulic analysis codes (e.g., RELAP5 and TRACE) are being applied to the reactors with the new coolant. Since these codes were originally developed for light water reactors (LWRs), validations are necessary to ensure the codes to count all influences of the thermo-physical properties of HLM. In this thesis, the TRACE code is employed to simulate the transients performed on the TALL test facility which is a medium-size loop for thermal-hydraulic study of lead bismuth eutectic (LBE). The objectives of the present work are two-fold: i) to interpret the transients performed on the test facility; ii) to qualify the capabilities of the TRACE code for HLM-cooled system by using the experimental data and then perform separate-effect study beyond the experimental conditions. The transients related to safety issues such as loss of heat sink, loss of primary pump, loss of both primary/secondary pumps, overpower and accelerator trip are chosen in the simulations. In addition, the operational transients, the startup and the shut-down of the system are also simulated, respectively. Two configurations of the facility are considered: Configuration-A with a core tank, and Configuration-B with a fuel rod simulator. The separate-effect study is conducted to investigate the effects of coolant inventory, LBE flow resistance and mass flowrate in the secondary loop on natural circulation in the primary loop. Generally speaking, for all the cases analyzed in the present study, the calculation results have a good agreement with the experimental data for the primary side (LBE) parameters (e.g., variations in temperature and mass flowrate). Specifically, the simulation for the transient loss of heat sink indicates the same tendency as in the experiment in term of temperature: it is rising at the inlet and outlet of the core simulator, as well as at those of the intermediate heat exchanger. The temperature keeps going up till the resumption of the heat sink as a protective measure, and then it decreases sharply at the very beginning and gradually returns to steady-state conditions. For the transient loss of primary pump, the temperature level is elevated and a significant natural circulation in the primary loop obtained. The simulation well reproduces the establishing process of natural circulation and final flowrate, but it overestimates the peak temperature. Such simulation outcome II applies to the transient ―loss of both primary and secondary pumps‖, except for a further elevated temperature. The calculation results of the transients startup and overpower are perfectly matching the experimental data, especially when approaching the final steady state, while the transients of shutdown and heater trip are underestimated in their final temperatures but the trends are well captured in both the transients. In general, the transient time to a steady state or the maximum temperature level of Configuration-B is much shorter than that of Configuration-A, mainly because of the larger inventory of LBE in Configuration-A. The separate-effect study also shows that the LBE inventory in the primary loop plays a mitigative role in the transients. For the loss of primary pump transient, decrease in primary flow resistance and increase in secondary flowrate all contributes to passive safety. Keywords: Heavy metal liquid, transient thermal-hydraulics, safety analysis, TRACE

The so-called three-band Hubbard model is generally believed to be a good model for fermions on a CuO 2 lattice and to contain key features allowing to understand high-temperature superconductivity in the cuprates. A simpler and more popular model is the one-band Hubbard model. In this thesis,an extended one-band Hubbard model is derived from the three-band model. First, some mathematical background is given, as well as an introduction to Hubbard-like models. Then, to derive the extended one-band Hubbard model, the CuO 2 lattice is divided into clusters of one Cu and two O sites, and a variant of the Feshbach method is used to replace each such cluster by a single lattice site. To nd a suitable one-band model, all Hamiltonian matrix elements are matched between the two models. Finally, dierent sets of three-band parameters are considered, and it is studied how this aects the parameters in the extended one-band Hubbard model.