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The Global ETD Search service is a free service for researchers
to find electronic theses and dissertations. This service is
provided by the
Networked Digital Library of Theses and Dissertations.
Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
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Showing 81 to 90 of 93 (0.042 seconds)| 81 |
Návrh 10-ti kanálového equalizeru s optimalizací kmitočtové charakteristiky a spektrálním audio-analyzátorem / Design of 10-channel audio equalizer with optimization of frequency characteristic and spectral audio analyzerŠtěrba, Václav January 2013 (has links)
This work deals with the design of a 10-zones equalizer with optimized frequency characteristics with a spectrum audio analyzer. In this work the problem of processing audio signals using equalization for filtering the interference frequencies, correction of frequency cover signal boost or suppression of the required zones of the audible spectrum are also analyzed. The influence of subjective perception of sound intensity of the audio signals reproduction and its use in working with equalizer is discussed too. The work describes the principles and usage of the audio-analyzer as a tool for the optimization of the audio equalization setting when ensuring the appropriate listening conditions of music reproduction, spoken word, sounds, etc. It also focuses on the signal source for testing audio-chains, their generation and measurement using the audio analyzer. The equalizer equipment, audio-analyzer generator of reference signals equipment and power supply are designed as a single unit.
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Integrated Magnetic Components for RF ApplicationsHussaini, Sheena 03 June 2015 (has links)
No description available.
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NOVEL METHOD TO CONTROL ANTENNA CURRENTS BASED ON THEORY OF CHARACTERISTIC MODESElghannai, Ezdeen Ahmed January 2016 (has links)
No description available.
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Návrh elektronicky rekonfigurovatelných filtračních struktur s moderními aktivními prvky / Design of electronically reconfigurable filtering structures with modern active elementsPrát, Marek January 2018 (has links)
The aim of master's thesis was design of electronically reconfigurable filters. Adjustability of pole frequency or quality factor is possible. First part of thesis deals with theoretical analysis of filters, their operation modes, design of frequency filters using Signal-Flow graph method and parasitic analysis. The next part describes active elements used in thesis. In a third part, three reconfigurable filters are described and designed and their simulations and parasitic analysis are made. Last part deals with filter design in EAGLE and experimental measurement.
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Syntéza elektronicky rekonfigurovatelných kmitočtových filtrů / Synthesis of the electronically reconfigurable frequency filtersMichalička, Filip January 2020 (has links)
This diploma thesis deals with design of reconection-less electronically reconfigurable filter structures which have single input and single output using unconventional active elements, which have ability to adjust one of their parameter e.g. gain or transconductance. The first part describes basic parameters of frequency filters, the division of filters by frequency transfer response and used circuit elements, their operational modes, the principle of reconnection-less electronically reconfiguration and the circuit design method MUNV. Second part describes all active elements used in the proposal of filters, their properties and the implementation using existing transistor-level models. The third part contains the design of three reconnection-less electronically reconfigurable filters and the simulations results obtained from simulation programs OrCAD Capture and PSpice. The obtained results were compared with theoretical behaviour. This part also contains results of these analyses: sensitivity, parasitic, Monte Carlo and temperature to determine the behaviour in varied cases.
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Elektronicky rekonfigurovatelné kmitočtové filtry / Electronically reconfigurable frequency filtersGajdoš, Adam January 2016 (has links)
The aim of the thesis was design of reconnection-less and electronically reconfigurable filters of SISO type with non-traditional active elements. Adjustability of bandwidth or quality factor is also required. First part of the thesis deals with theoretical analysis of filters, their operation modes and design of frequency filters using Signal-flow graph method aswell. Last but not least, electronical reconfiguration of transfer function and parasitic analysis was discussed. Another part describes active elements used in the practical part of thesis. Behaviors and design of active elements using existing circuits (e.g. UCC,EL2082) are described and their transformation into the Signal-flow graph form too. In the practical part five reconnection-less and reconfigurable filters of SISO type was designed using SNAP program. Simulations were done using Orcad program with ideal and real simulation models of active elements. Last part deals with filter design in EAGLE and experimental measurement.
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Voltage Transients in the Field Winding of Salient Pole Wound Synchronous Machines : Implications from fast switching power electronicsFelicetti, Roberto January 2021 (has links)
Wound Field Synchronous Generators provide more than 95% of the electricity need worldwide. Their primacy in electricity production is due to ease of voltage regulation, performed by simply adjusting the direct current intensity in their rotor winding. Nevertheless, the rapid progress of power electronics devices enables new possibilities for alternating current add-ins in a more than a century long DC dominated technology. Damping the rotor oscillations with less energy loss than before, reducing the wear of the bearings by actively compensating for the mechanic unbalance of the rotating parts, speeding up the generator with no need for additional means, these are just few of the new applications which imply partial or total alternated current supplying of the rotor winding. This thesis explores what happens in a winding traditionally designed for the direct current supply when an alternated current is injected into it by an inverter. The research focuses on wound field salient pole synchronous machines and investigates the changes in the field winding parameters under AC conditions. Particular attention is dedicated to the potentially harmful voltage surges and voltage gradients triggered by voltage-edges with large slew rate. For this study a wide frequency band simplified electromagnetic model of the field winding has been carried out, experimentally determined and validated. Within the specific application of the fast field current control, the research provides some references for the design of the rotor magnetic circuit and of the field winding. Finally the coordination between the power electronics and the field winding properties is addressed, when the current control is done by means of a long cable or busbars, in order to prevent or reduce the ringing.
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Transient And Distributed Algorithms To Improve Islanding Detection Capability Of Inverter Based Distributed GenerationAl Hosani, Mohamed 01 January 2013 (has links)
Recently, a lot of research work has been dedicated toward enhancing performance, reliability and integrity of distributed energy resources that are integrated into distribution networks. The problem of islanding detection and islanding prevention (i.e. anti-islanding) has stimulated a lot of research due to its role in severely compromising the safety of working personnel and resulting in equipment damages. Various Islanding Detection Methods (IDMs) have been developed within the last ten years in anticipation of the tremendous increase in the penetration of Distributed Generation (DG) in distribution system. This work proposes new IDMs that rely on transient and distributed behaviors to improve integrity and performance of DGs while maintaining multi-DG islanding detection capability. In this thesis, the following questions have been addressed: How to utilize the transient behavior arising from an islanding condition to improve detectability and robust performance of IDMs in a distributive manner? How to reduce the negative stability impact of the well-known Sandia Frequency Shift (SFS) IDM while maintaining its islanding detection capability? How to incorporate the perturbations provided by each of DGs in such a way that the negative interference of different IDMs is minimized without the need of any type of communication among the different DGs? It is shown that the proposed techniques are local, scalable and robust against different loading conditions and topology changes. Also, the proposed techniques can successfully distinguish an islanding condition from other disturbances that may occur in power system networks. This work improves the efficiency, reliability and safety of integrated DGs, which presents a necessary advance toward making electric power grids a smart grid.
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Einfluss von additiven thermischen Belastungen auf das Langzeitverhalten von stromführenden Schraubenverbindungen mit verzinnten und vernickelten Leitern aus Aluminium und Kupfer in elektrisch angetriebenen FahrzeugenPoudeu, F.S.D., Beilner, M., Schlegel, S. 04 June 2024 (has links)
Zur Stromübertragung innerhalb von elektrischen Komponenten (zum Beispiel in der Batterie) im Fahrzeug werden bevorzugt Stromschienen eingesetzt. Diese werden aus Gründen der Austauschbarkeit und Reparaturfähigkeit über Schraubenverbindungen gefügt. Abhängig von den Leiter- und den Beschichtungswerkstoffen, den Montageparametern und den Belastungsbedingungen im Betrieb altern diese stromführenden Schraubenverbindungen zeitabhängig. Dadurch erhöhen sich der Verbindungswiderstand und die Verbindungstemperatur. Wenn die anwendungsspezifische Grenztemperatur an der Kontaktstelle erreicht ist, kann die Funktion der Schraubenverbindung beeinträchtigt werden oder ein Ausfall auftreten. In diesem Beitrag werden die Einflüsse der Belastungsarten abhängig von den Leiter- und Beschichtungswerkstoffen und von der Montagevorspannkraft auf das Verhalten von Schraubenverbindungen untersucht und gegenüber dargestellt. Darauf aufbauend wird die dominante Belastung hergeleitet. / Busbars are preferred for power transmission within the electrical components (for example in in the battery) in the vehicle. These are connected with bolts for reasons of interchangeability and reparability. Depending on the conductor and coating materials, the assembly parameters and the load conditions during operation, these current-carrying bolted connections age over time. This increases the connection resistance and the connection temperature. If the application-specific limit temperature is reached at the contact point, the function of the bolted connection can be impaired or failure can occur. In this article, the influences of the types of load depending on the conductor and coating materials and the assembly preload force on the behavior of current-carrying bolted connections are examined and compared. Based on this, the dominant load is derived.
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Reverberation Chamber Modeling Using Finite-Difference Time-Domain MethodPetit, Frédéric 12 1900 (has links)
Since the last few years, the unprecedented growth of communication systems involving the propagation of electromagnetic waves is particularly due to developments in mobile phone technology. The reverberation chamber is a reliable bench-test, enabling the study of the effects of electromagnetic waves on a specific electronic appliance. However, the operating of a reverberation chamber being rather complicated, development of numerical models are of utmost importance to determine the crucial parameters to be considered.This thesis consists in the modelling and the simulation of the operating principles of a reverberation chamber by means of the Finite-Difference Time-Domain method. After a brief study based on field and power measurements performed in a reverberation chamber, the second chapter deals with the different problems encountered during the modelling. The consideration of losses being a very important factor in the operating of the chamber, two methods of implementation of these losses are set out in this chapter. Chapter~3 consists in the analysis of the influence of the stirrer on the first eigenmodes of the chamber; the latter modes can undergo a frequency shift of several MHz. Chapter~4 shows a comparison of results issued from high frequency simulations and theoretical statistical results. The problem of an object placed in the chamber, resulting in a field disturbance is also tackled. Finally, in the fifth chapter, a comparison of statistical results for stirrers having different shapes is set out.
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