Fully massive tadpoles at 5-loop : reduction and difference equations

Möller J. Fully massive tadpoles at 5-loop : reduction and difference equations. Bielefeld: Universität Bielefeld; 2012.Loop integrals are essential for the computation of predictions in quantum field theories like the Standard Model of elementary particle physics. For instance, in the case of anomalous dimensions of QCD or the pressure in thermal QCD we face so-called tadpole loop integrals. In this thesis we study an important subset of these integrals, the fully massive vacuum (bubble) integrals. For the first time, we consider fully massive tadpoles at the 5-loop level pioneering the way for future high-precision calculations. We have implemented a Laporta algorithm in the algebraic manipulator \texttt{FORM} using generalized recurrence relations, a combination of integration-by-parts and space-time dimensional identities. This enabled us to perform the reduction of fully massive tadpoles up to the 5-loop level to a basis of master integrals. We modified the implementation in such a way that difference equations are obtained for a large number of the yet unknown master integrals. We started to solve the system of difference equations by means of factorial series expansions

Boundary-Conforming Finite Element Methods for Twin-Screw Extruders using Spline-Based Parameterization Techniques

This paper presents a novel spline-based meshing technique that allows for usage of boundary-conforming meshes for unsteady flow and temperature simulations in co-rotating twin-screw extruders. Spline-based descriptions of arbitrary screw geometries are generated using Elliptic Grid Generation. They are evaluated in a number of discrete points to yield a coarse classical mesh. The use of a special control mapping allows to fine-tune properties of the coarse mesh like orthogonality at the boundaries. The coarse mesh is used as a 'scaffolding' to generate a boundary-conforming mesh out of a fine background mesh at run-time. Storing only a coarse mesh makes the method cheap in terms of memory storage. Additionally, the adaptation at run-time is extremely cheap compared to computing the flow solution. Furthermore, this method circumvents the need for expensive re-meshing and projections of solutions making it efficient and accurate. It is incorporated into a space-time finite element framework. We present time-dependent test cases of non-Newtonian fluids in 2D and 3D for complex screw designs. They demonstrate the potential of the method also for arbitrarily complex industrial applications

Influence of the bulk and surface morphology on adhesion of polystyrene-inter-poly-cross-2-ethylhexyl-methacrylate films and particles

The adhesion behavior of semi-interpenetrating polymer networks (semi-IPNs) of linear polystyrene (PS) in crosslinked poly-2-ethylhexylmethacrylate (EHMA) was studied by variation of the bulk and surface morphology, i.e., domain size, continuity, and concentration in the domains. Semi-IPNs were prepared by liquid-liquid demixing upon cooling of a homogeneous solution of PS in methacrylate monomer, followed by gelation of the PS-rich phase and UV polymerization of the methacrylate resin. Welding of films allowed the preparation of larger objects provided that (1) the samples were phase separated to a high degree and contained domains with a high PS concentration (>90%) and (2) polystyrene was present at the interface. For semi-IPN films, a linear dependence of the adhesion strength on the (crack healing time)1/4 was obtained. Based on these considerations, a process was developed to obtain melt-processable semi-IPN particles, by quenching droplets of the polymer solution into a cold liquid. These particles obtained a PS-rich skin layer and showed good adhesion after blending with a thermoplast

Towards early ice detection on wind turbine blades using acoustic waves

The study focuses on the early detection of ice using controlled acoustic waves propagating in the wind turbine blades. An experimental set-up with a cold climate chamber, a composite test object used in turbine blades and equipment for glaze and rime ice production has been developed. Controlled acoustic waves are generated by magnetostrictive Terfenol-D based actuator. The propagation of three orthogonally polarized acoustic waves was studied by means of 6 accelerometers positioned, 3 each, in 2 holders on the 8 m long composite test object. The results show that for the considered composite test object the formation of ice, the ice mass, icing areas and the temperature have a significant influence on controlled acoustic waves propagation w.r.t. Fourier transform, amplitude attenuation and RMS values as indicators concluding that the proposed acoustic wave technique is a promising approach for ice detection

Standortorientierung des ökologischen Landbaus zwischen Kostenführerschaft und Nischenproduktion

Site specific factors of different landscapes influence the farmers’ economic decision whether to produce organic bulk commodities or niche products for a small market. The verification of this hypothesis is based on standardized production processes of beef and goat cheese in two different model regions

Improving Visual Function after Mild Traumatic Brain Injury Using a Vision Therapy Program: Case Reports

This case report describes the outcome of vision therapy for three patients who were referred to therapy due to visual symptoms after mild traumatic brain injury (MTBI). The criterion for inclusion was a high score (>21p) on the Convergence Insufficiency Symptom Survey (CISS) scale. The vision therapy program (VTP) included both face-to-face sessions and home-based tasks. Cases #1 and #2 had a substantial CISS scale evaluation improvement, and case #2 normalized the CISS scale score from 36 to 19. All patients agreed that vision therapy helped them understand their own vision and changes in their vision, which helped their overall recovery after MTBI. Rehabilitation professionals have an important role in screening for vision impairments and treating functional vision challenges after mild traumatic brain injury