It is of interest to construct windows that can spread the transmitted light in a specified manner. The Kirchhoff approximation in the geometrical optical limit in combination with a chosen general form of the window surfaces yields the profile for the window surfaces, letting us specify how the light should be spread.The probability distribution function for the slopes of a window surface consisting of joined line segments was implemented in the simulation software Maxwell1D. Simulations show the feasibility of such windows. However they do not respond well when subject to light incident with another angle of incidence than the angle in mind.By using Snell's law to compensate for using a simpler system, the time needed for the simulations can be greatly reduced while simultaneously obtaining a higher accuracy in the results.

An inverse statistics analysis of one minute stock quotes from 492 large Europeancompanies has revealed the existence of a gain-loss asymmetry in thefollowing index. The gain-loss asymmetry differs from that observed for dailyclosure prices of the Dow Jones Industrial Average [38], as the probability ofthe optimal investment horizon for a gain is higher than that of a loss. Forindividual stocks, the gain-loss asymmetry was observed to only appear forsignificantly larger return-levels. To the best of our knowledge, this is thefirst time such an analysis has been performed on high-frequency data.A principal component analysis was done by performing an eigenvalue decompositionof the correlation matrix from a sliding time-window. The firstprincipal component was observed to describe the market excellently. Its correspondingeigenvalue was observed to be significantly larger than theoreticalpredictions from random matrix theory, implying that the eigenvalue carriesinformation common to all stocks. Using this eigenvalue as an index measuringthe collectivity in the market has revealed the existence of collectivetrends that appear to be stronger during falling than rising markets. Thishas been observed for two different datasets, the above described one minutestock quotes and daily closure prices from 29 stocks composing the DJIA lateFebruary 2008. The observation is in accordance with results of Balogh etal. [40], and provides further support to the speculation of Johansen et al.[37] that a difference in collective trends is the reason behind the gain-lossasymmetry observed in indexes and not for individual stocks for the samereturn-level.The key idea behind the fear factor model of Donangelo et al. [42] has beenstrongly supported by the observation that collective trends appear to bestronger during sharp index drops. As the collectivity increment has beenobserved to be dependent on the size of the index drop, it is suggested thatthe model should incorporate also individual fear factors for economic sectors,in addition to the global fear factor governing the market as a whole. Periodsexhibiting a rising index positively correlated to the strength of collectivityhas indicated the presence of an optimism factor that also should be incorporatedin the fear factor model [42], forcing stocks to rise synchronously.

Energivariasjon i fullt utviklet turbulens er studert. I en tidsserie for tur- bulens energi er det oppdaget en asymmetri mellom positive og negative energiendringer. Invers statistikk metode gir en mulighet til å studere denne asymmetrien nærmere.For analyse i denne oppgaven er turbulent strømning generert ved bruk av GOY skallmodell. Skallmodellen er en tilnærmingmodell til Navier-Stokes likninger for strømningens bevegelse. Modellen er tidligere vist å gi realistiske verdier for energi og hastighet for en turbulens strømning.Ved bruk av forward statistikk og invers statistikk på turbulens ener- gi er det funnet en asymmetri i energiendringen. Det er vist at en negativ energivariasjon høyst sannsynlig inntreffer før en positiv energivariasjon av samme størrelse. Tidsforskjellen er empirisk funnet til å følge sammenhen- gen δτδE ∼ δE0,749, hvor τδE er forventningstiden for en energivariasjon δE. I tillegg er det funnet en positiv trend i tidsserien for energi, som sier at ener- giendring etter korte tidsintervall høyst sannsynlig er positiv. Det er gjort et forsøk på å beskrive denne asymmetrien og opprinnelsen av dette fenomenet er drøftet.

The main focus of this master thesis work has been to image InAs emph{quantum dots} (QDs) using emph{atomic force microscopy} (AFM), to identify and evaluate various image processing methods used to estimate the volume of the InAs QDs. The InAs QDs studied in this thesis work, had been deposited on GaAs substrates, using solid-source emph{molecular beam epitaxy} (MBE) before the thesis work started. The total QD volume was determined for all samples, using eight different estimation methods. The purpose of estimating the total QD volume, was to compare the total volume to the deposited volume.Previous studies on similar samples, have indicated that the total volume can be larger than the deposited volume during MBE growth. This discrepancy is explained by incorporation of Ga from the substrate during growth. This was not observed in this thesis work. One possible explanation is that the samples have oxidized; resulting in a lower measured height.In addition, the relationship between atomic steps, defects and the appearance of large QDs were studied. parTwo series of samples were studied: one in which the QD growth temperature was varied and one in which the amount of deposited InAs was varied. The total QD volumes were found to increase with the QD growth temperature and the deposited InAs thickness. Square-shaped defects and contours of 2D islands were observed in nearly all samples. Higher/multiple terraces seem to be related to regions of higher QD density.

This thesis investigates the electrodeposition process of zinc-, copper-, silver-, and silver copperoxides at cathodic and anodic voltages. Silver copper oxide has been successfully electrodepositedon a substrate of PtSi from a pH 12 dilute solution of copper nitrate, silver nitrate and sodiumhydroxide at 0.9V vs a silver metal cathode. This film was confirmed to be polycrystalline AgCuO2by EDS and XRD studies. Zinc oxide and copper oxide were deposited on gold substrates from their respective nitrates. The zinc oxide deposition was confirmed polycrystalline in XRD and had a band gap between 3.2eV and 3.5eV measured by optical reflectance. The copper oxide appeared polycrystalline in SEM but only amorphous signal was achieved in XRD, the material had a band gap of around 2eV. Despite many attempts, clean silver oxide was not successfully deposited. These materials may all be suitable for solar cells applications.

In this thesis, clean and oxidized Pd(57)Cu(43)(100) single crystal surfaces were studied by LEED, STM and XPS in UHV conditions. The clean sample annealed to 300 degrees C has been found to either consist of ordered domains of Pd or Cu atoms forming a c(2 × 2) structure, or by a more disordered alloy c(2 × 2) structure of p4g symmetry. Small areas of (1 × 1) structure as well as screw dislocations and island- like formations are present on this surface. Annealing the clean sample to 600 degrees C causes Cu segregation to the surface as well as a shift towards higher binding energy of Pd 3d(5/2) core levels, and an almost defect- free surface with p(2 × 2) structure is seen. Oxidation at 300 degrees C of the surface annealed to 300 degrees C shows that a c(2 × 2) covers the whole surface for all oxygen dosages at 68L or above, and XPS spectra do not vary with oxygen dosage, hence the c(2 × 2) is inert in this case. For dosages of 1350L or above, oxide islands and a large number of defects could appear, depending on the preparation history of the sample. Oxidation at 300 degrees C and 600 degrees C of the Cu rich surface annealed to 600 degrees C reveals up to seven structures, which are p(2 × 2), c(2 × 2), (4 × 4)- like, hexagonal, maze- like, (2root(2) ×root(2))R45degrees missing row type and one more structure that could not be characterized. There is evidence that copper oxide phases are formed for the Cu rich surfaces annealed to 600 degrees C, but no bulk oxide was formed in any experiments. A detailed understanding of clean and oxidized Pd(57)Cu(43)(100) has been obtained at the atomic scale.

Vanntrevekst er den viktigste årsaken til aldring i polymerisk isolasjon i mellomspenningskabler. Sia vanntrær ikke dannes ved lav relativ fuktighet (R.H.), er det viktig å holde relativ fuktighet i isolasjonen lav så lenge som mulig. Dette kan gjøres ved å beskytte isolasjonen med ei kappe av to polymerer. For å beregne vanntransporten inn i isolasjonen, må kappematerialenes vanntransportegenskaper kjennes. For noen polymerer varierer vanntransportegenskapene med det hydrostatiske trykket og den relative fuktigheta (damptrykket). I denne oppgaven er det målt transportkoeffisienter for to kandidater til kappematerialer: én halvledende lineær lavdensitetspolyetylen (LLDPE) og én halvledende eterbasert termoplastisk polyuretan (TPU). Noen av prøvene har vært utsatt for strekking til 10 % statisk forlengelse og etterfølgende relaksasjon i forkant av forsøkene, for å finne ut om ei slik mekanisk påkjenning har noe å si for transportkoeffisientene. Det er gjort målinger av metningskonsentrasjoner ved 0,1 MPa og 30 MPa hydrostatisk trykk, og permeabilitetsmålinger ved forskjellige damptrykk. Konklusjonene om metningskonsentrasjonen i TPU ved 0,1 MPa og 30 MPa hydrostatisk trykk trekkes delvis på grunnlag av et tidligere arbeid. I tillegg har diffusjons- og løselighetskoeffisientene for ustrukket TPU blitt målt ved forskjellige damptrykk. Det er ikke funnet noen signifikant sammenheng mellom det hydrostatiske trykket og vannopptaket i noen av materialene, hverken med strukkede eller ustrukkede prøver. Det er heller ikke funnet at strekking har noen signifikant innvirkning på transportkoeffisientene, bortsett fra at strukket TPU viser en ca. 15 % større metningskonsentrasjon enn ustrukket TPU. Det er funnet at transportkoeffisientene i TPU varierer med damptrykket, men hverken diffusjons-, løselighets- eller permeabilitetskoeffisienten varierer mer enn med en faktor 3 mellom 20 % R.H. og 80 % R.H. For LLDPE er det ikke gjort like omfattende undersøkelser, men permeabilitetskoeffisienten i det materialet viser ingen damptrykkavhengighet.

We have performed modified Gurson model calibrations to the steel alloys Weldox 460E, Weldox 700E and Weldox 900E through finite element method (FEM) simulations of various tensile material tests performed, and used these material models to perform FEM simulations of impact of blunt tool steel projectiles on target plates made out of these steel alloys. The purpose of these FEM simulations was to study the dependence of target plate steel alloy on the ballistic limit velocity of the projectile resulting from the modified Gurson model. It was found that the modified Gurson model is able to reproduce the dependence seen in experiments, but that it is strongly dependent on a certain model parameter related to the shear stress dependence on material damage. We have also discovered potential problems, and possible solutions, regarding the calibration of these material models and the use of them in the FEM impact simulations carried out.