An investigation of the dynamic characteristics of a bolted-rotor system

A Jeffcott rotor consists of a disc at the centre of an axle supported at its end by bearings. A bolted Jeffcott rotor is formed by two discs, each with a shaft on one side. The discs are held together by spring loaded bolts near the outer edge. When the rotor turns there is tendency for the discs to separate on one side. This effect is more marked if the rotor is unbalanced, especially at resonance speeds. The equations of motion of the system have been developed with four degrees of freedom to include the rotor and bearing movements in the respective axes. These equations which include non-linear terms caused by the rotor opening, are subjected to external force such from rotor imbalance. A simulation model based on these equations was created using SIMULINK. An experimental test rig was used to characterise the dynamic features. Rotor discs open at a lateral displacement of the rotor of 0.8 mm. This is the threshold value used to show the change of stiffness from high stiffness to low stiffness. The experimental results, which measure the vibration amplitude of the rotor, show the dynamic behaviour of the bolted rotor due to imbalance. Close agreement of the experimental and theoretical results from time histories, waterfall plots, pseudo-phase plots and rotor orbit plot, indicated the validity of the model and existence of the non-linear jump phenomenon.

Die Sprache des Wahnsinns. Harald Kaas und sein Erzählband ‘Uhren und Meere’:Harald Kaas and his short story collection 'watches and seas'

This essay examines the only book published by the late Harald Kaas. His collection of short stories Uhren und Meere (1979), dealing with depictions of psycho-pathological states of mind, gained Kaas a short-lived notoriety as he himself was a certified schizophrenic possessing first-hand experience of psychiatric treatment. This essay sets out to investigate whether or to what extent the stories in Uhren und Meere can be understood as a document of the language of madness. It concludes that despite the biographical dimension of his schizophrenic experience, Kaas’s texts fail to voice an as it were unadulterated language of madness. However, when read in conjunction with his quasi-poetological interview statements, it is possible to determine the very nature of madness as a collapse of a logical system of language. Meaning that language cannot actively be used to express madness, while at the same time madness can express itself in a language that we necessarily fail to understand. The language of madness manifests itself as the madness of language.

Creating lift versus building the base:current trends in marketing dynamics

Markets are dynamic by nature, and marketing efforts can be directed to stimulate, reduce, or to utilize these dynamics. The field of marketing dynamics aims at modeling the effects of marketing actions and policies on short-term performance (“lift”) and on long-term performance (“base”). One of the core questions within this field is: “How do marketing efforts affect outcome metrics such as revenues, profits, or shareholder value over time?” Developments in statistical modeling and new data sources allow marketing scientists to provide increasingly comprehensive answers to this question. We present an outlook on developments in modeling marketing dynamics and specify research directions.