Magnetic bearings for vibration control

A survey is presented on the research of the Institute of Mechanics of the ETH in the field of vibration control with magnetic bearings. It shows a method for modelling an elastic rotor so that it can be represented by a low order model amenable to control techniques. It deals with the control law and spill-over effects, and it also discusses experimental results for an active resonance damper

Landau level splitting due to graphene superlattices

The Landau level spectrum of graphene superlattices is studied using a tight-binding approach. We consider non-interacting particles moving on a hexagonal lattice with an additional one-dimensional superlattice made up of periodic square potential barriers, which are oriented along the zig-zag or along the arm-chair directions of graphene. In the presence of a perpendicular magnetic field, such systems can be described by a set of one-dimensional tight-binding equations, the Harper equations. The qualitative behavior of the energy spectrum with respect to the strength of the superlattice potential depends on the relation between the superlattice period and the magnetic length. When the potential barriers are oriented along the arm-chair direction of graphene, we find for strong magnetic fields that the zeroth Landau level of graphene splits into two well separated sublevels, if the width of the barriers is smaller than the magnetic length. In this situation, which persists even in the presence of disorder, a plateau with zero Hall conductivity can be observed around the Dirac point. This Landau level splitting is a true lattice effect that cannot be obtained from the generally used continuum Dirac-fermion model.Comment: 12 pages, 9 figure

Injuries to the distal tibial epiphysis

No Abstract

Monte Carlo Simulation of Deffuant opinion dynamics with quality differences

In this work the consequences of different opinion qualities in the Deffuant model were examined. If these qualities are randomly distributed, no different behavior was observed. In contrast to that, systematically assigned qualities had strong effects to the final opinion distribution. There was a high probability that the strongest opinion was one with a high quality. Furthermore, under the same conditions, this major opinion was much stronger than in the models without systematic differences. Finally, a society with systematic quality differences needed more tolerance to form a complete consensus than one without or with unsystematic ones.Comment: 8 pages including 5 space-consuming figures, fir Int. J. Mod. Phys. C 15/1

Nonlinear Phenomena in Canonical Stochastic Quantization

Stochastic quantization provides a connection between quantum field theory and statistical mechanics, with applications especially in gauge field theories. Euclidean quantum field theory is viewed as the equilibrium limit of a statistical system coupled to a thermal reservoir. Nonlinear phenomena in stochastic quantization arise when employing nonlinear Brownian motion as an underlying stochastic process. We discuss a novel formulation of the Higgs mechanism in QED.Comment: 8 pages, invited talk at the International Workshop ``Critical Phenomena and Diffusion in Complex Systems'', Dec. 5-7, 2006, Nizhni Novgorod, Russi

Conductivity in a symmetry broken phase: Spinless fermions with 1/d1/d corrections

The dynamic conductivity $\sigma(\omega)$ of strongly correlated electrons in a symmetry broken phase is investigated in the present work. The model considered consists of spinless fermions with repulsive interaction on a simple cubic lattice. The investigated symmetry broken phase is the charge density wave (CDW) with wave vector $Q=(\pi,\pi,\pi)^\dagger$ which occurs at half-filling. The calculations are based on the high dimensional approach, i.e. an expansion in the inverse dimension $1/d$ is used. The finite dimensionality is accounted for by the inclusion of linear terms in $1/d$ and the true finite dimensional DOS. Special care is paid to the setup of a conserving approximation in the sense of Baym/Kadanoff without inconsistencies. The resulting Bethe-Salpeter equation is solved for the dynamic conductivity in the non symmetry broken and in the symmetry broken phase (AB-CDW). The dc-conductivity is reduced drastically in the CDW. Yet it does not vanish in the limit $T \to 0$ due to a subtle cancellation of diverging mobility and vanishing DOS. In the dynamic conductivity $\sigma(\omega)$ the energy gap induced by the symmetry breaking is clearly discernible. In addition, the vertex corrections of order $1/d$ lead to an excitonic resonance lying within the gap.Comment: 23 pages, 19 figures included with psfig, Revtex; Physical Review B15, in press (October/November 1996) depending on the printer/screen driver, it might be necessary to comment out figures 3,4,5,10,11,12,19 and have them printed separatel

Management of Chronic Staphylococcal Osteomyelitis of the Temporal Bone: The Use of Hyperbaric Oxygen

Hyperbaric oxygen (HBO) is an effective adjunct in the management of selected otolaryngologic problems including radiation-induced necrosis of the temporal hone, malignant external otitis, mandibular osteoradionecrosis and refractory osteomyelitis, soft tissue head and neck necrotizing fasciitis, compromised skin flaps and grafts, acute air or gas embolism, and otologic barotrauma. We describe the management of a patient with insidious Staphylococcus aureus osteomyelitis of the temporal bone by the use of HBO preoperatively and postoperatively in conjunction with surgical debridement. The possible application of angiogenic agents and tetracycline hone-labeling in combination with HBO therapy in the management of refractory neurotologic disease is discussed

Aspects of the administrative law relationship between the taxpayer and the Commissioner for Inland Revenue

Bibliography: pages 133-135.There is an administrative law relationship between the taxpayer and the Commissioner for Inland Revenue, (hereinafter referred to as 'the Commissioner') The basis of this relationship is that the Commissioner is required to collect tax and the taxpayer is required to pay the tax. In exercising his powers under the Income Tax Act No. 58 of 1962 (hereinafter referred to as the Act), the Commissioner has been conferred with discretionary powers. In this thesis, this administrative law relationship is examined with specific reference to the means of regulating the exercise by the Commissioner of his discretionary powers. There are a number of ways in which the discretionary powers of the Commissioner may be regulated. Generally discretion may be regulated by 'rule based administrative action' (1). This means that discretionary power is exercised subject to internal rules which state how discretionary power must be exercised. Another method of regulating the exercise of discretionary power is subsumed under the category of 'adjudicative techniques of decision' (2). The essence of the latter category is that the affected person participates in the decision which affects him. The exercise of discretionary power may be regulated furthermore if the Minister who has responsibility for the Department is required to be responsible for and account publicly for the actions of his subordinate. In this thesis, examples of rule based administrative action and adjudicative techniques of decision are examined