Refine
Language
- English (3)
Has Fulltext
- yes (3)
Keywords
- Distortion measure (1)
- Lattice Boltzmann method (1)
- Level Set method (1)
- free surface (1)
- human visual system (1)
- multiphase flow (1)
Faculty / Organisational entity
Designing exotic structures in low dimensions is key in today’s quest to tailor novel quantum states
in materials with unique symmetries. Particularly intriguing materials in this regard are low
dimensional aperiodic structures with non-conventional symmetries that are otherwise forbidden
in translation symmetric crystals. In our work, we focus on the link between the structural and
electronic properties of aperiodically ordered aromatic molecules on a quasicrystalline surface,
which has largely been neglected so far. As an exemplary case, we investigate the self-assembly and
the interfacial electronic properties of the nano-graphene-like molecule coronene on the bulk
truncated icosahedral (i) Al–Pd–Mn quasicrystalline surface using multiple surface sensitive
techniques. We find an aperiodically ordered coronene monolayer (ML) film on the i-Al–Pd–Mn
surface that is characterized by the same local motifs of the P1 Penrose tiling model as the bare
i-Al–Pd–Mn surface. The electronic valence band structure of the coronene/i-Al–Pd–Mn system
is characterized by the pseudogap of the bare i-Al–Pd–Mn, which persists the adsorption of
coronene confirming the quasiperiodic nature of the interface. In addition, we find a newly formed
interface state of partial molecular character that suggests an at least partial chemical interaction
between the molecule and the quasicrystalline surface. We propose that this partial chemical
molecule–surface interaction is responsible for imprinting the quasicrystalline order of the surface
onto the molecular film.
Within this paper we review image distortion measures. A distortion measure is a criterion that assigns a "quality number" to an image. We distinguish between mathematical distortion measures and those distortion measures in-cooperating a priori knowledge about the imaging devices ( e.g. satellite images), image processing algorithms or the human physiology. We will consider representative examples of different kinds of distortion measures and are going to discuss them.
A Lattice Boltzmann Method for immiscible multiphase flow simulations using the Level Set Method
(2008)
We consider the lattice Boltzmann method for immiscible multiphase flow simulations. Classical lattice Boltzmann methods for this problem, e.g. the colour gradient method or the free energy approach, can only be applied when density and viscosity ratios are small. Moreover, they use additional fields defined on the whole domain to describe the different phases and model phase separation by special interactions at each node. In contrast, our approach simulates the flow using a single field and separates the fluid phases by a free moving interface. The scheme is based on the lattice Boltzmann method and uses the level set method to compute the evolution of the interface. To couple the fluid phases, we develop new boundary conditions which realise the macroscopic jump conditions at the interface and incorporate surface tension in the lattice Boltzmann framework. Various simulations are presented to validate the numerical scheme, e.g. two-phase channel flows, the Young-Laplace law for a bubble and viscous fingering in a Hele-Shaw cell. The results show that the method is feasible over a wide range of density and viscosity differences.