Effect of pore structure on capillary condensation in a porous medium

The Kelvin equation relates the equilibrium vapor pressure of a fluid to the curvature of the fluid-vapor interface and predicts that vapor condensation will occur in pores or irregularities that are sufficiently small. Past analyses of capillary condensation in porous systems with fractal structure have related the phenomenon to the fractal dimension of the pore volume distribution. Recent work, however, suggests that porous systems can exhibit distinct fractal dimensions that are characteristic of both their pore volume and the surfaces of the pores themselves. We show that both fractal dimensions have an effect on the thermodynamics that governs capillary condensation and that previous analyses can be obtained as limiting cases of a more general formulation.Mechanical Engineerin

Geometric Alignments of the Subgrid-Scale Force in the Atmospheric Boundary Layer

In recent years field experiments have been undertaken in the lower atmosphere to perform a priori tests of subgrid-scale (SGS) models for large-eddy simulations (LES). The experimental arrangements and data collected have facilitated studies of variables such as the filtered strain rate, SGS stress and dissipation, and the eddy viscosity coefficient. However, the experimental set-ups did not permit analysis of the divergence of the SGS stress (the SGS force vector), which is the term that enters directly in the LES momentum balance equations. Data from a field experiment (SGS2002) in the west desert of Utah, allows the calculation of the SGS force due to the unique 4×4 sonic anemometer array. The vector alignment of the SGS force is investigated under a range of atmospheric stabilities. The eddy viscosity model is likely aligned with the measured SGS force under near-neutral and unstable conditions, while its performance is unsatisfactory under stable condition

Development of a digital advisor to support the decision-making process of acquiring a car

This thesis explores how consumers behave in the process of acquiring a car and aspires to solve the main challenge that consumers are facing in the decision-making process. The mobility landscape is rapidly evolving and offering consumers more choices than ever before in meeting their transportation needs. The rise of sharing economy and the development of new technologies has facilitated the entrance of new business models and thereby new car ownership types. With the increased use of internet as an information source, much documentation is at the consumer’s disposal. Still, the number of alternatives may lead to confusion, stress and sub-optimal decision-making. The goal of the thesis is to develop a digital advisor that would provide the end-user with unbiased decision support for acquiring a private car. To achieve the described goal, the study was designed to collect data and test concepts through four phases, in line with design thinking. A theoretical review of the trends in the mobility market, environmental drivers, sharing economy, and the psychology of the decision-making processes was conducted to form the framework. The first phase of the thesis explored the car loan application process through testing current solutions and interviewing consumers. The results showed the car loan application process was not considered problematic for consumers, and that the main challenge was to search, navigate and evaluate information and thereby deciding on an ownership type. The second phase explored the consumers’ information search and decision-making process through interviews. This resulted in a simple prototype for a digital advisor that could solve the identified challenges in the process. The prototype was tested in the third phase, and the content of the digital advisor was defined together with consumers. The fourth and last phase resulted in a definition of the characteristics of each ownership type based on data collection through a survey.Denne masteroppgaven utforsker hvordan forbrukere oppfører seg i prosessen med å anskaffe en bil og ønsker å løse hovedutfordringen som forbrukerne står overfor i beslutningsprosessen. Mobilitetslandskapet er i rask utvikling og gir forbrukerne mange valgmuligheter for å dekke behovet for transport. Utviklingen av ny teknologi har bidratt til en vekst i delingsøkonomien, noe som har resultert i at nye forretningsmodeller har blitt til og tilført nye typer bilhold i markedet. Med den økte bruken av internett som informasjonskilde har forbrukeren tilgang på mye dokumentasjon. Derimot kan antallet alternativer føre til forvirring, stress og et suboptimalt beslutningsgrunnlag. Målet med oppgaven er å utvikle en digital rådgiver som vil gi sluttbrukeren upartisk beslutningsstøtte for å anskaffe bil. For å oppnå det beskrevne målet ble data samlet og konsepter testet gjennom fire faser, i tråd med Design thinking. En teoretisk gjennomgang av trendene i mobilitetsmarkedet, miljødrivere, delingsøkonomi og psykologien i beslutningsprosesser ble gjennomført for å danne rammeverket. Den første fasen av oppgaven utforsket søknadsprosessen for billån gjennom å teste nåværende løsninger og intervjue forbrukere. Resultatene viste at søknadsprosessen for billån ikke ble ansett som problematisk for forbrukerne, og at hovedutfordringen var å søke, navigere og evaluere informasjon og derved bestemme seg for typen bilhold. Den andre fasen utforsket forbrukernes informasjonssøk og beslutningsprosess gjennom intervjuer. Dette resulterte i en enkel prototype for en digital rådgiver som kunne løse de identifiserte utfordringene i prosessen. Prototypen ble testet i tredje fase, og innholdet i den digitale rådgiveren ble definert sammen med forbrukerne. Den fjerde og siste fasen resulterte i en definisjon av egenskapene til hver type bilhold, basert på datainnsamling gjennom en undersøkelse.This resulted in a simple prototype for a digital advisor that could solve the identified challenges in the process. The prototype was tested in the third phase, and the content of the digital advisor was defined together with consumers. The fourth and last phase resulted in a definition of the characteristics of each ownership type based on data collection through a survey.M-E

Similarity Scaling Over a Steep Alpine Slope

In this study, we investigate the validity of similarity scaling over a steep mountain slope (30-41 $$^\circ$$ ). The results are based on eddy-covariance data collected during the Slope Experiment near La Fouly (SELF-2010); a field campaign conducted in a narrow valley of the Swiss Alps during summer 2010. The turbulent fluxes of heat and momentum are found to vary significantly with height in the first few metres above the inclined surface. These variations exceed by an order of magnitude the well-accepted maximum 10% required for the applicability of Monin-Obukhov similarity theory in the surface layer. This could be due to a surface layer that is too thin to be detected or to the presence of advective fluxes. It is shown that local scaling can be a useful tool in these cases when surface-layer theory breaks down. Under convective conditions and after removing the effects of self-correlation, the normalized standard deviations of slope-normal wind velocity, temperature and humidity scale relatively well with $$z/\varLambda$$ , where $$z$$ is the measurement height and $$\varLambda (z)$$ the local Obukhov length. However, the horizontal velocity fluctuations are not correlated with $$z/\varLambda$$ under all stability regimes. The non-dimensional gradients of wind velocity and temperature are also investigated. For those, the local scaling appears inappropriate, particularly at night when shallow drainage flows prevail and lead to negative wind-speed gradients close to the surfac