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Resonant Behaviour of Pulse Generators for the Efficient Drive of Optical Radiation Sources Based on Dielectric Barrier Discharges

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ISBN: 9783731500834 Year: Pages: 212 p. DOI: 10.5445/KSP/1000036098 Language: ENGLISH
Publisher: KIT Scientific Publishing
Subject: Technology (General)
Added to DOAB on : 2019-07-30 20:02:02
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Dielectric barrier discharge (DBD) excimer lamps emit vacuum-UV optical radiation. This work presents novel methods for efficiently operating DBDs with short, high-voltage pulses. Transformer-less systems utilising SiC power semiconductor switches are presented. Pulse frequencies of up to 3.1 MHz and peak inverter efficiencies of 92 % were achieved. The work encloses both mathematical backgrounds of pulsed resonant circuits and practical implementation of low-inductive power stages.

Influence of Emitter Surface Roughness and Emission Inhomogeneity on Efficiency and Stability of High Power Fusion Gyrotrons

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Book Series: Karlsruher Forschungsberichte aus dem Institut für Hochleistungsimpuls- und Mikrowellentechnik ISSN: 21922764 ISBN: 9783731505785 Year: Volume: 9 Pages: XV, 197 p. DOI: 10.5445/KSP/1000058566 Language: ENGLISH
Publisher: KIT Scientific Publishing
Subject: Technology (General)
Added to DOAB on : 2019-07-30 20:01:59
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The increasing demand for powerful, reliable, and efficient gyrotron oscillators for Electron Cyclotron Resonance Heating (ECRH) in fusion plasma experiments requires a close look at the various factors in gyrotrons that determine gyrotron performance. In this frame, the influence of emitter surface roughness, emission inhomogeneity, and secondary electron generation on gyrotron operation is presented, with focus on Low Frequency Oscillations (LFOs) and Electron Beam Halo (EBH) generation.

At the doors of lexical access: The importance of the first 250 milliseconds in reading

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889192601 Year: Pages: 112 DOI: 10.3389/978-2-88919-260-1 Language: English
Publisher: Frontiers Media SA
Subject: Psychology --- Science (General)
Added to DOAB on : 2015-12-03 13:02:24
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Correct word identification and processing is a prerequisite for accurate reading, and decades of psycholinguistic and neuroscientific research have shown that the magical moments of visual word recognition are short-lived and markedly fast. The time window in which a given letter string passes from being a mere sequence of printed curves and strokes to acquiring the word status takes around one third of a second. In a few hundred milliseconds, a skilled reader recognizes an isolated word and carries out a number of underlying processes, such as the encoding of letter position and letter identity, and lexico-semantic information retrieval. However, the precise manner (and order) in which these processes occur (or co-occur) is a matter of contention subject to empirical research. There's no agreement regarding the precise timing of some of the essential processes that guide visual word processing, such as precise letter identification, letter position assignment or sub-word unit processing (bigrams, trigrams, syllables, morphemes), among others. Which is the sequence of processes that lead to lexical access? How do these and other processes interact with each other during the early moments of word processing? Do these processes occur in a serial fashion or do they take place in parallel? Are these processes subject to mutual interaction principles? Is feedback allowed for within the earliest stages of word identification? And ultimately, when does the reader's brain effectively identify a given word? A vast number of questions remain open, and this Research Topic will cover some of them, giving the readership the opportunity to understand how the scientific community faces the problem of modeling the early stages of word identification according to the latest neuroscientific findings.

Zustandsbestimmung von externen Spanngliedern und Schrägseilen mit Frequenzanalysen

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Book Series: Karlsruher Reihe Massivbau, Baustofftechnologie, Materialprüfung / Institut für Massivbau und Baustofftechnologie ; Materialprüfungs- und Forschungsanstalt Karlsruhe ISSN: 1869912X ISBN: 9783731507727 Year: Volume: 83 Pages: X, 286 p. DOI: 10.5445/KSP/1000081010 Language: GERMAN
Publisher: KIT Scientific Publishing
Subject: General and Civil Engineering
Added to DOAB on : 2019-07-28 18:37:01
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In this work, the measurement system ResoCable®, consisting of hardware and software, was developed with the implementation and evaluation of the frequency measurements of external tendons and cables. Numerous measurements at external tendons and cables were conducted. Among them, the behavior of strands and deflection points was investigated with FE calculations.

Aktive Frequenzvervielfacher zur Signalerzeugung im Millimeter- und Submillimeterwellen Frequenzbereich

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Book Series: Karlsruher Forschungsberichte aus dem Institut für Hochfrequenztechnik und Elektronik ISSN: 18684696 ISBN: 9783731503545 Year: Volume: 79 Pages: XIII, 158 p. DOI: 10.5445/KSP/1000046156 Language: GERMAN
Publisher: KIT Scientific Publishing
Subject: Technology (General)
Added to DOAB on : 2019-07-30 20:01:57
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In this work a new transistor topology for frequency multiplication is developed, achieving relative bandwidths of complex and balanced structures with only four transistors. It enables the highest bandwidth in active multiplication beyond 110 GHz. Cascading techniques are shown enabling a cascaded frequency multiplier by eight with a frequency range of 220 to 320 GHz. For the first time an active frequency multiplier by six reaches output frequencies up to 670 GHz.

Evolution von Relationen in temporalen partiten Themen-Graphen

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ISBN: 9783731503408 Year: Pages: II, 136 p. DOI: 10.5445/KSP/1000045521 Language: GERMAN
Publisher: KIT Scientific Publishing
Subject: Business and Management
Added to DOAB on : 2019-07-30 20:02:00
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In this work a model is engineered to depict topic relationships as graphs between detected topics of different time windows. By varying and shifting the time span of consideration the relationships between topics can be mapped with a variable complexity including the topic frequencies. Topic life cycles as well as changes in thematic relationships and their evolution become perceptible. Topics found can be matched in structure as well as their temporal progression to existing events.

Feasibility and Operational Limits for a 236 GHz Hollow-Cavity Gyrotron for DEMO

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Book Series: Karlsruher Forschungsberichte aus dem Institut für Hochleistungsimpuls- und Mikrowellentechnik ISSN: 21922764 ISBN: 9783731507178 Year: Volume: 12 Pages: XIV, 241 p. DOI: 10.5445/KSP/1000073581 Language: ENGLISH
Publisher: KIT Scientific Publishing
Subject: Technology (General)
Added to DOAB on : 2019-07-30 20:02:01
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The DEMOnstration fusion power plant (DEMO) will be the first fusion reactor, which is intended to generate net electrical power. For successful operation of DEMO, high-power gyrotrons with operating frequencies up to 240 GHz are required for plasma heating and stabilization. In this work, a systematic feasibility study and tolerance analysis are performed for the conventional-type hollow-cavity DEMO gyrotrons. The various approaches are also suggested to identify its operational limits.

Terabit-Rate Transmission Using Optical Frequency Comb Sources

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Book Series: Karlsruhe Series in Photonics and Communications / Karlsruhe Institute of Technology, Institute of Photonics and Quantum Electronics (IPQ) ISSN: 18651100 ISBN: 9783731506409 Year: Volume: 20 Pages: XIV, 176 p. DOI: 10.5445/KSP/1000066936 Language: ENGLISH
Publisher: KIT Scientific Publishing
Subject: Technology (General)
Added to DOAB on : 2019-07-30 20:02:01
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Energy-efficient Tbit/s optical interconnects are key elements for future communication systems. Three novel optical frequency comb sources are investigated, which have the potential of being integrated in chip-scale Tbit/s transmitters. Such frequency combs provide a large number of carriers. The equidistance of the comb lines helps to minimize spectral guard bands. For each type of comb source, coherent data transmission experiments show the potential for Tbit/s data transmission rates.

Personalized Multi-Scale Modeling of the Atria: Heterogeneities, Fiber Architecture, Hemodialysis and Ablation Therapy

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Book Series: Karlsruhe transactions on biomedical engineering / Ed.: Karlsruhe Institute of Technology / Institute of Biomedical Engineering ISSN: 18645933 ISBN: 9783866449480 Year: Volume: 19 Pages: XVI, 297 p. DOI: 10.5445/KSP/1000031226 Language: ENGLISH
Publisher: KIT Scientific Publishing
Subject: Technology (General)
Added to DOAB on : 2019-07-30 20:02:02
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This book targets three fields of computational multi-scale cardiac modeling. First, advanced models of the cellular atrial electrophysiology and fiber orientation are introduced. Second, novel methods to create patient-specific models of the atria are described. Third, applications of personalized models in basic research and clinical practice are presented. The results mark an important step towards the patient-specific model-based atrial fibrillation diagnosis, understanding and treatment.

SAR Prediction and SAR Management for Parallel Transmit MRI

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Book Series: Karlsruhe transactions on biomedical engineering / Ed.: Karlsruhe Institute of Technology / Institute of Biomedical Engineering ISSN: 18645933 ISBN: 9783866448001 Year: Volume: 16 Pages: VIII, 124 p. DOI: 10.5445/KSP/1000025607 Language: ENGLISH
Publisher: KIT Scientific Publishing
Subject: Technology (General)
Added to DOAB on : 2019-07-30 20:02:02
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Parallel transmission enables control of the RF field in high-field Magnetic Resonance Imaging (MRI). However, the approach has also caused concerns about the specific absorption rate (SAR) in the patient body. The present work provides new concepts for SAR prediction. A novel approach for generating human body models is proposed, based on a water-fat separated MRI pre-scan. Furthermore, this work explores various approaches for SAR reduction.

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