62 hasil untuk "W. Mathis"
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The Long Road to Entertainment Radio Broadcasting in Germany
In 2023, the 100th birthday of “Unterhaltungs-Rundfunk” (Entertainment Radio Broadcasting) in Germany was celebrated with numerous special exhibitions and contributions in the press, radio and television. In this context, details on the historical development of this communication medium were also…
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Egbert von Lepel and the Invention of the Spark-Gap Transmitter
…this medium, were carried out more than ten years earlier (Pungs, 1922; Mathis, 2019; Titze and Mathis, 2020; Mathis and Titze, 2021). One of the pioneers of this technology was the German Egbert von Lepel, who developed in 1907 a new concept of wireless transmitters that was also suitable for use…
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100 Years of Wireless Telephony in Germany: Experimental Radio Transmission from Eberswalde and Königs Wusterhausen
In this contribution, we examine the development of radio technology before 1921 and the emergence of the broadcasting concept during the World War I. We consider in detail the experiments in the transmitter stations located in Eberswalde and Königs Wusterhausen and numerous sources in order to…
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Realisierung eines verzerrungsarmen Open-Loop Klasse-D Audio-Verstärkers mit SB-ZePoC
…Maß reduziert werden. Durch das von der Forschungsgruppe um Prof. Mathis vorgestellte SB-ZePoC Verfahren (Zero Position Coding with Separated Baseband) wird diese Art der Signalverzerrung durch Generierung eines separierten Basisbands verhindert. Deshalb können auch niedrige Schaltfrequenzen…
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Berechnung der auftretenden lokalen Kräfte auf der magnetischen Beschichtung eines magnetischen Rasterkraftmikroskops
Die numerische Berechnung entstehender Kraftwirkungen auf Körper aufgrund magnetischer Wechselwirkungen zwischen diesen, ist in Bezug auf die mechanische Deformation dieser Körper ein noch nicht vollständig gelöstes Problem. In dieser Arbeit wird ein Vergleich vorhandener Kraftberechnungsmethoden…
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Simulating circuits with impasse points
In this paper circuits with impasse points, i.e. with jumps in their configuration space will be analyzed. These non-regularized circuits exhibit a fold in their configuration space, which can lead to difficulties during the simulation with standard circuit simulators like SPICE. The former…
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Analysis and Simulation of Reduced FIR Filters
High order FIR filters employ model reduction techniques, in order to decrease power consumption and time delay. During reduction high order FIR filters are converted into low order IIR filters preserving stability and phase linearity as main features. Matlab simulations of an audio system with…
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Test signal generation for analog circuits
In this paper a new test signal generation approach for general analog circuits based on the variational calculus and modern control theory methods is presented. The computed transient test signals also called test stimuli are optimal with respect to the detection of a given fault set by means of a…
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Numerical modelling of nonlinear electromechanical coupling of an atomic force microscope with finite element method
In this contribution, an atomic force microscope is modelled and in this context, a non-linear coupled 3-D-boundary value problem is solved numerically using the finite element method. The coupling of this system is done by using the Maxwell stress tensor. In general, an iterative weak coupling is…
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Order reduction of hierarchical interconnected dynamical systems
The simulation of large scale nonlinear dynamical interconnected systems, as they arise in all modern engineering disciplines, is a usual task. Due to the high complexity of the considered systems, the principle of thinking in hierarchical structures is essential and common among engineers…
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Eine selbstkonsistente Carleman Linearisierung zur Analyse von Oszillatoren
…Systeme auf, sodass diese Methode nicht angewendet werden kann Mathis(2000). Carleman hat gezeigt, dass nichtlineare Differentialgleichungen mit polynomiellen Nichtlinearitäten in ein unendliches System von linearen Differentialgleichungen transformiert werden können Carleman(1932). Wird das…
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Transformation of passive electrical networks with distributed PWL-sources using a Model Order Reduction
In modeling of distributed systems with distributed sources large networks with RLC-elements and independent sources arise. This high complexity leads to a high effort in simulations. Therefore model reduction can be used to reduce these networks, preserving the behavior at the observed nodes in…
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Adapting the range of validity for the Carleman linearization
In this contribution, the limitations of the Carleman linearization approach are presented and discussed. The Carleman linearization transforms an ordinary nonlinear differential equation into an infinite system of linear differential equations. In order to transform the nonlinear differential…
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Discretization analysis of bifurcation based nonlinear amplifiers
Recently, for modeling biological amplification processes, nonlinear amplifiers based on the supercritical Andronov–Hopf bifurcation have been widely analyzed analytically. For technical realizations, digital systems have become the most relevant systems in signal processing applications. The…
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Increasing the time resolution of a pulse width modulator in a class D power amplifier by using delay lines
In this paper, we present a method to increase the time resolution of a pulse width modulator by using delay lines. The modulator is part of an open loop class D power amplifier, which uses the ZePoC algorithm to code the audio signal which is amplified in the class D power stage. If the time…
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Modellierung von Quanteneffekten in einem ladungsbasierten MOS-Transistor-Modell zur Simulation von nanoskalierten CMOS-Analogschaltungen
Aufgrund der fortschreitenden Miniaturisierung der Bauelemente in CMOS-Schaltungen und den dadurch erreichten Strukturgrößen nehmen quantenmechanische Effekte zunehmenden Einfluss auf die Funktion von Transistoren und damit auf die gesamte Schaltung. Unter Einbeziehung der Energiequantisierung an…
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Automated parametrical antenna modelling for ambient assisted living applications
In this paper a parametric modeling technique for a fast polynomial extraction of the physically relevant parameters of inductively coupled RFID/NFC (radio frequency identification/near field communication) antennas is presented. The polynomial model equations are obtained by means of a three-step…
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A first approach to the distortion analysis of nonlinear analog circuits utilizing X-parameters
In this contribution a first approach to the distortion analysis of nonlinear 2-port-networks with X-parameters1 is presented. The X-parameters introduced by Verspecht and Root (2006) offer the possibility to describe nonlinear microwave 2-port-networks under large signal conditions. On the basis…
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A design approach for integrated CMOS LC-tank oscillators using bifurcation analysis
Electrical oscillators play a decisive role in integrated transceivers for wired and wireless communication systems. In this context the study of fully integrated differential VCOs has received attention. In this paper formulas for investigations of the stability as well as the amplitude of CMOS LC…
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Entwurfskonzept einer Car2Car-Multiband-Dachantenne
Due to the vastly increasing use of wireless services in the car, such as WiFi, Car2Car and LTE, the requirements on bandwidth and radiation pattern of the roof antenna systems become more challenging. In this work, a design concept for multi-band roof antenna systems is presented. We aim to get a…