## Search

Now showing items 151-160 of 179

#### Homogenization of nonisothermal immiscible incompressible two-phase flow in porous media

(Journal article; Peer reviewed, 2018-03-15)

In this paper, we consider nonisothermal two-phase flows through heterogeneous porous media with periodic microstructure. Examples of such models appear in gas migration through engineered and geological barriers for a deep repository for radioactive waste, thermally enhanced oil recovery and geothermal systems. The mathematical model is given by a coupled system of two-phase flow equations, and an ...

#### Asymptotic Behaviour of Ground States for Mixtures of Ferromagnetic and Antiferromagnetic Interactions in a Dilute Regime

(Journal article; Peer reviewed, 2018-04-30)

We consider randomly distributed mixtures of bonds of ferromagnetic and antiferromagnetic type in a two-dimensional square lattice with probability
1−p
1−p
and p, respectively, according to an i.i.d. random variable. We study minimizers of the corresponding nearest-neighbour spin energy on large domains in
Z
2
Z2
. We prove that there exists
p
0
p0
such that for
p≤
p
0
p≤p0
such ...

#### Steady States, Fluctuation-Dissipation Theorems and Homogenization for Reversible Diffusions in a Random Environment

(Journal article; Peer reviewed; Tidsskriftartikkel, 2018-04-02)

Prolongating our previous paper on the Einstein relation, we study the motion of a particle diffusing in a random reversible environment when subject to a small external forcing. In order to describe the long time behavior of the particle, we introduce the notions of steady state and weak steady state. We establish the continuity of weak steady states for an ergodic and uniformly elliptic environment. ...

#### Pointwise estimates for heat kernels of convolution-type operators

(Journal article; Peer reviewed; Tidsskriftartikkel, 2018-04-16)

We study the large‐time behaviour of the fundamental solution of parabolic equations with an elliptic part being non‐local convolution‐type operator. We assume that this operator is a generator of a Markov jump process, and that its convolution kernel decays at least exponentially at infinity. The fundamental solution shows rather different asymptotic behaviour depending on whether | x | ≲ t , or t ...

#### Resolvent bounds for jump generators

(Journal article; Peer reviewed; Tidsskriftartikkel, 2016-12-02)

The paper deals with jump generators with a convolution kernel. Assuming that the kernel decays either exponentially or polynomially, we prove a number of lower and upper bounds for the resolvent of such operators. In particular we focus on sharp estimates of the resolvent kernel for small values of the spectral parameter. We consider two applications of these results. First we obtain pointwise ...

#### Feasibility of Computational Fluid Dynamics for Analyzing Airflow around Porous Fences

(Journal article; Peer reviewed, 2019-01-19)

This article presents using the computational fluid dynamics (CFD) modeling to analyze the flow around porous fences. The feasibility of applying 2D and 3D models was assessed with respect to corresponding wind tunnel experiments. Comparisons between the flow structures on leeward of the fence as predicted by CFD models and the wind tunnel measurements were discussed. Velocity values for the two ...

#### A value chain analysis for bioenergy production from biomass and biodegradable waste: a case study in Northern Norway

(Peer reviewed; Chapter, 2018-09-12)

During the past decades, the concerns of the depletion of fossil fuels and global warming
caused by excess GHG emissions have become the most important driving force for the
development and utilization of renewable energy resources. The successful experiences
from the EU-28 have proved that bioenergy production from biomass and biodegradable
waste is the most reliable and promising solution in ...

#### Modeling and Attitude Control of Satellites in Elliptical Orbits

(Peer reviewed; Chapter, 2018-11-05)

The attitude determination and control system (ADCS) for spacecraft is responsible for determining its orientation using sensor measurements and then applying actuation forces to change the orientation. This chapter details the different components required for a complete attitude determination and control system for satellites moving in elliptical orbits. Specifically, the chapter details the orbital ...

#### Fuel cell technology application for Dubai rail systems

(Peer reviewed; Chapter, 2018-06-11)

Heat engines, such as internal combustion engines, have significant adverse effects on the environment due to their heat and harmful emissions. In addition, they are dependent on energy from fossil resources, which are depleting rapidly and they are not being properly utilized due to the relatively low efficiency of heat engines usually expressed by Carnot's efficiency. The low temperature direct ...

#### Utilizing fuel cell technology for Dubai Roads and Transport Authority (RTA)

(Peer reviewed; Chapter, 2018-06-11)

The need for developing environmentally friendly and sustainable energy sources is globally evident. This is due to two main reasons: Fossil fuels will continue to supply energy demands for only a few more decades and the amount of pollution generated due to fossil fuels is exceeding acceptable limits. One very promising clean energy converter is the fuel cell (FC). Fuel cells have the ability to ...