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If a flexible rotor contacts its stator, the nonlinearities induced by
contact may result in a great variety of vibration phenomena. This article
presents experimental results gained at test rigs. Fundamental phenomena are
analyzed and discussed. First, a modular kit for rotordynamic experiments is
described. The kit allows customizing the properties of rotor and stator that
are relevant for the dynamic behavior. The system allows to specify target
values for natural frequencies, modal damping, clearance width, contact fric-
tion and others. Basic congurations based on this kit were used to study the
in
uence of mass, stiness and damping of both rotor and stator, contact fric-
tion and misalignment of the stator on the vibration of the rotor-stator system.
Extensions of the kit allowed the experimental investigation of systems with
a multitude of natural frequencies, highly
exible stators and even drop down
and overload incidents of rotors supported by active magnetic bearings. The
article also analyzes and explains the various vibration phenomena resulting
from contact. In particular, resonance diagrams from run-up and run-down
processes, orbit plots and frequency spectra are utilized to discuss the dynamic
characteristics. The motion types encountered include not only rotor syn-
chronous motions, but also multi frequency motions (forward and backward
whirl), sub- and super-harmonic motions, motions including sidebands as well
as chaotic motions. Emphasis is put on sensitive system parameters and on
existence and stability of the various types of motion.
Microelectrode arrays serve as an indispensable tool in electro-physiological research to study the electrical activity of neural cells, enabling measurements of single cell as well as network communication analysis. Recent experimental studies have reported that the neuronal geometry has an influence on electrical signaling and extracellular recordings. However, the corresponding mechanisms are not yet fully understood and require further investigation. Allowing systematic parameter studies, computational modeling provides the opportunity to examine the underlying effects that influence extracellular potentials. In this letter, we present an in silico single cell model to analyze the effect of geometrical variability on the extracellular electric potentials. We describe finite element models of a single neuron with varying geometric complexity in three-dimensional space. The electric potential generation of the neuron is modeled using Hodgkin-Huxley equations. The signal propagation is described with electro-quasi-static equations, and results are compared with corresponding cable equation descriptions. Our results show that both the geometric dimensions and the distribution of ion channels of a neuron are critical factors that significantly influence both the amplitude and shape of extracellular potentials.
Vulnerable road users (VRUs, i.e. cyclists and pedestrians) will play an important role in future traffic. To avoid accidents and achieve a highly efficient traffic flow, it is important to detect VRUs and to predict their intentions. In this article a holistic approach for detecting intentions of VRUs by cooperative methods is presented. The intention detection consists of basic movement primitive prediction, e.g. standing, moving, turning, and a forecast of the future trajectory. Vehicles equipped with sensors, data processing systems and communication abilities, referred to as intelligent vehicles, acquire and maintain a local model of their surrounding traffic environment, e.g. crossing cyclists.
Heterogeneous, open sets of agents (cooperating and interacting vehicles, infrastructure, e.g. cameras and laser scanners, and VRUs equipped with smart devices and body-worn sensors) exchange information forming a multi-modal sensor system with the goal to reliably and robustly detect VRUs and their intentions under consideration of real time requirements and uncertainties. The resulting model allows to extend the perceptual horizon of the individual agent beyond their own sensory capabilities, enabling a longer forecast horizon. Concealments, implausibilities and inconsistencies are resolved by the collective intelligence of cooperating agents.
Novel techniques of signal processing and modelling in combination with analytical and learning based approaches of pattern and activity recognition are used for detection, as well as intention prediction of VRUs. Cooperation, by means of probabilistic sensor and knowledge fusion, takes place on the level of perception and intention recognition. Based on the requirements of the cooperative approach for the communication a new strategy for an ad hoc network is proposed. The evaluation is done using real data gathered with a research vehicle, a research intersection with public traffic and mobile devices.
Cooperative Starting Intention Detection of Cyclists based on Smart Devices and Infrastructure
(2017)
Manipulation von Abgaswerten
(2017)
Dieses kleine Buch stellt Hintergründe zum Abgasskandal dar, z. B. welche Schadstoffe kritisch sind, wie Motorsteuergeräte, Abgasrückführung und Abgasnachbehandlung funktionieren, wie Manipulationen auf dem Prüfstand möglich sind, mit welchen Fahrzyklen getestet wird und in welchem rechtlichen und politischen Umfeld dies lange Zeit unbemerkt mit unterschiedlichen Konsequenzen in der EU und den USA geschehen konnte. Es werden Maßnahmen vorgestellt, mit denen Fahrzeuge auch real gesetzliche Grenzwerte einhalten können und wie Manipulationen zukünftig rechtlich und politisch verhindert werden können. Dem Leser werden durch Literaturhinweise zusätzliche Details erschlossen.