Non-isothermal transport of multi-phase fluids in porous media. The entropy production

We derive the entropy production for transport of multi-phase fluids in a non-deformable, porous medium exposed to differences in pressure, temperature, and chemical potentials. Thermodynamic extensive variables on the macro-scale are obtained by integrating over a representative elementary volume (REV). Using Euler homogeneity of the first order, we obtain the Gibbs equation for the REV. From this we define the intensive variables, the temperature, pressure and chemical potentials and, using the balance equations, derive the entropy production for the REV. The entropy production defines sets of independent conjugate thermodynamic fluxes and forces in the standard way. The transport of two-phase flow of immiscible components is used to illustrate the equations.Comment: 25 pages, 7 figures, Talk at Interpore, New Orleans, 201

Non-isothermal transport of multi-phase fluids in porous media. Constitutive equations

We develop constitutive equations for multi-component, multi-phase, macro-scale flow in a porous medium exposed to temperature-, composition-, and pressure -gradients. The porous medium is non-deformable. We define the pressure and the composition of the representative elementary volume (REV) in terms of the volume and surface averaged pressure and the saturation, and the respective driving forces from these variables. New contributions due to varying porosity or surface tension offer explanations for non-Darcy behavior. The interaction of a thermal and mechanical driving forces give thermal osmosis. An experimental program is suggested to verify Onsager symmetry in the transport coefficients.Comment: 22 pages, 2 figure

Evaluering av NTNU Technology Transfer

Med dette presenteres resultatene fra en evaluering av NTNU Technology Transfer AS (TTO), som er gjennomført på oppdrag av NTNU. Utgangspunktet for oppdraget, var NTNUs ønske om å få en helhetlig analyse av TTOs rolle innenfor NTNUs strategi for nyskaping, og som kunne brukes i en pågående prosess med videreutvikling av denne strategien. Av denne grunn er det lagt vekt på å diskutere hvilke muligheter det er for å utvikle aktiviteten i TTO, både ved en bedre tilrettelegging av rammebetingelsene for virksomheten, og ved en utvikling av virksomhetens strategi

RSA-kryptering med diskusjon om bruk av det i skolen

Masteroppgaven gir en grunnleggende introduksjon av RSA kryptering, og angrep på RSA kryptering. Vi presenterer, modulær aritmetikk, tallteorien som er nødvendig for å forstå RSA kryptering, og en generell innføring i hva kryptografi er, og introduserer ulike prinsipper for kryptering. Vi ser på de matematiske prinsippene bak RSA-systemet, og viser hvorfor det er ’sikkert’. Vi ser på måter for å oppnå suksessfulle ’real life’ angrep på RSA-systemet. Tilslutt sees det på hvordan dette passer inn i undervisningen i skolen

Explosion Loading on Equipment from CFD Simulations

PresentationExplosion studies using computational fluid dynamics (CFD) are performed on daily basis among safety consultants all over the world. The purpose of the explosion studies is usually to give guidance on required design strength of equipment, piping, blast walls or buildings. One key element is to translate the results from an explosion simulation, into actual forces on equipment. Major weaknesses exist in the current approaches for estimation of loads on small and medium sized equipment. Hansen et al. (2014) demonstrated how loads on rectangular equipment could be estimated by combining free field form drag and pressure gradient. In the current work it is discussed how best to estimate loads onto other types of equipment including cylindrical pipes, pipe bundles and other shapes, and some comparisons and validation against large scale experiments are also included. The main findings of this work are the more accurate guidance on how best to extract explosion loads from simulations, including discussons on appropriate drag coefficients

Preferences for urban building materials: Does building culture background matter?

publishedVersio

The ecology of medical care in Norway: wide use of general practitioners may not necessarily keep patients out of hospitals

Background. Our aim was to investigate the pattern of self reported symptoms and utilisation of health care services in Norway. Design and methods. With data from the cross-sectional Tromsø Study (2007-8), we estimated population proportions reporting symptoms and use of seven different health services. By logistic regression we estimated differences according to age and gender. Results. 12,982 persons aged 30-87 years participated, 65.7% of those invited. More than 900/1000 reported symptoms or health problems in a year as well as in a month, and 214/1000 and 816/1000 visited a general practitioner once or more in a month and a year, respectively. The corresponding figures were 91/1000 and 421/1000 for specialist outpatient visits, and 14/1000 and 116/1000 for hospitalisations. Physiotherapists were visited by 210/1000, chiropractors by 76/1000, complementary and alternative medical providers by 127/1000, and dentists by 692/1000 in a year. Women used most health care services more than men, but genders used hospitalisations and chiropractors equally. Utilisation of all services increased with age, except chiropractors, dentists and complementary and alternative medical providers. Conclusions. Almost the entire population reported health related problems during the previous year, and most residents visited a general practitioner. Yet there were high rates of inpatient and outpatient specialist utilisation. We suggest that wide use of general practitioners may not necessarily keep patients out of specialist care and hospitals