• CPES Testing with mosaik: Co-Simulation Planning, Execution and Analysis 

  Steinbrink, Cornelius; Blank-Babazadeh, Marita; El-Ama, André; Holly, Stefanie; Bengt, Lüers; Nebel-Wenner, Marvin; Ramírez Acosta, Rebeca P.; Raub, Thomas; Schwarz, Jan Sören; Stark, Sanja; Astrid, Nieße; Lehnhoff, Sebastian (Basel : MDPI, 2019)

  The complex nature of cyber-physical energy systems (CPES) makes systematic testing of new technologies for these setups challenging. Co-simulation has been identified as an efficient and flexible test approach that allows ...
• Exploring the Causes of Power-Converter Failure in Wind Turbines based on Comprehensive Field-Data and Damage Analysis 

  Fischer, Katharina; Pelka, Karoline; Puls, Sebastian; Poech, Max-Hermann; Mertens, Axel; Bartschat, Arne; Tegtmeier, Bernd; Broer, Christian; Wenske, Jan (Basel : MDPI, 2019)

  Power converters are among the most frequently failing components of wind turbines. Despite their massive economic impact, the actual causes and mechanisms underlying these failures have remained in the dark for many years. ...
• Frequency-domain modeling of harmonic interactions in pulse-width modulated voltage-source inverter drives 

  John, Malte (Hannover : Institutionelles Repositorium der Leibniz Universität Hannover, 2019)

  The method presented in this thesis allows for the calculation of the current and voltage spectra of a drive system for the steady state, while considering the influence of interactions between the system components. The ...
• Representation and contextualization for document understanding 

  Tran, Nam Khanh (Hannover : Institutionelles Repositorium der Leibniz Universität Hannover, 2019)

  Document understanding requires discovery of meaningful patterns in text, which in turn involves analyzing documents and extracting useful information for a certain purpose. There is a multitude of problems that need to ...
• Concepts and tools for the effective and efficient use of web archives 

  Holzmann, Helge (Hannover : Institutionelles Repositorium der Leibniz Universität Hannover, 2019)

  Web archives constitute valuable sources for researchers in various disciplines. However, their sheer size, the typically broad scope and their temporal dimension make them difficult to work with. We have identified three ...
• Fast pulsed operation of a small non-radioactive electron source with continuous emission current control 

  Cochems, Philipp; Kirk, Ansgar T.; Bunert, Erik; Runge, M.; Goncalves, P.; Zimmermann, Stefan (College Park, MA : American Institute of Physics (AIP), 2015)

  Non-radioactive electron sources are of great interest in any application requiring the emission of electrons at atmospheric pressure, as they offer better control over emission parameters than radioactive electron sources ...
• A compact high-resolution X-ray ion mobility spectrometer 

  Reinecke, Tobias; Kirk, Ansgar T.; Heptner, Andre; Niebuhr, D.; Böttger, S.; Zimmermann, Stefan (College Park, MA : American Institute of Physics (AIP), 2016)

  For the ionization of gaseous samples, most ion mobility spectrometers employ radioactive ionization sources, e.g., containing 63Ni or 3H. Besides legal restrictions, radioactive materials have the disadvantage of a constant ...
• Shutterless ion mobility spectrometer with fast pulsed electron source 

  Bunert, Erik; Heptner, Andre; Reinecke, T.; Kirk, Ansgar T.; Zimmermann, Stefan (College Park, MA : American Institute of Physics (AIP), 2017)

  Ion mobility spectrometers (IMS) are devices for fast and very sensitive trace gas analysis. The measuring principle is based on an initial ionization process of the target analyte. Most IMS employ radioactive electron ...
• A sensitive gas chromatography detector based on atmospheric pressure chemical ionization by a dielectric barrier discharge 

  Kirk, Ansgar T.; Last, Torben; Zimmermann, Stefan (Amsterdam : Elsevier, 2017)

  In this work, we present a novel concept for a gas chromatography detector utilizing an atmospheric pressure chemical ionization which is initialized by a dielectric barrier discharge. In general, such a detector can be ...
• Ion mobility spectrometer with orthogonal X-Ray source for increased sensitivity 

  Bunert, Erik; Reinecke, Tobias; Kirk, Ansgar T.; Bohnhorst, Alexander; Zimmermann, Stefan (Amsterdam : Elsevier, 2018)

  Ion mobility spectrometers (IMS) are compact devices for extremely sensitive detection of proton and electron affine volatile compounds down to low pptv concentrations within less than a second. The measuring principle ...
• A simple centripetal force model for explaining the focusing effect of ion funnels 

  Allers, Maria; Kirk, Ansgar T.; Zimmermann, Stefan (Amsterdam : Elsevier, 2018)

  The ion funnel is one of the key components for transferring ions from higher pressure into vacuum. While known for over twenty years and thoroughly analyzed by mathematical means and simulations, its working principle ...
• Pulsed electron source for atmospheric pressure chemical ionization in ion mobility spectrometry 

  Bunert, Erik; Heptner, Andre; Kirk, Ansgar T.; Käbein, Oliver; Zimmermann, Stefan; Kusch, Alexander; Wurz, Marc Christopher (Piscataway, NJ : IEEE, 2017)

  Ion mobility spectrometers (IMS) are measurement devices for fast and ultra-sensitive trace gas analysis. Most IMS employ radioactive electron sources, such as 3 H or 63 Ni, to provide free electrons with high kinetic ...
• Ionenmobilitätsspektrometrie 

  Kirk, Ansgar T.; Zimmermann, Stefan (Weinheim : Wiley, 2016)

  Ionenmobilitätsspektrometer sind extrem schnelle und sensitive Sensoren für Spurengase, welche diese anhand ihrer Bewegung durch ein Neutralgas unter dem Einfluss eines elektrischen Feldes identifizieren. In diesem Artikel ...
• In-circuit-measurement of parasitic elements in high gain high bandwidth low noise transimpedance amplifiers 

  Cochems, Philipp; Kirk, Ansgar T.; Zimmermann, Stefan (College Park, MA : American Institute of Physics (AIP), 2014)

  Parasitic elements play an important role in the development of every high performance circuit. In the case of high gain, high bandwidth transimpedance amplifiers, the most important parasitic elements are parasitic ...
• Bradbury-Nielsen vs. Field switching shutters for high resolution drift tube ion mobility spectrometers 

  Kirk, Ansgar T.; Zimmermann, Stefan (Berlin, Heidelberg : Springer, 2014)

  A key component in the design of every drift tube ion mobility spectrometer (IMS) is the ion shutter which controls the injection of ions into the drift tube. Especially, compact drift tube IMS require very short injection ...
• Pushing a compact 15 cm long ultra-high resolution drift tube ion mobility spectrometer with R = 250 to R = 425 using peak deconvolution 

  Kirk, Ansgar T.; Zimmermann, Stefan (Berlin, Heidelberg : Springer, 2015)

  Recently, we have published an analytical model describing the resolution and signal-to-noise-ratio of peaks present in an ion mobility spectrum acquired by a drift tube instrument. Based on this model, we designed a ...
• An analytical model for the optimum drift voltage of drift tube ion mobility spectrometers with respect to resolving power and detection limits 

  Kirk, Ansgar T.; Zimmermann, Stefan (Berlin, Heidelberg : Springer, 2015)

  One of the key experimental parameters of measurements using a drift tube ion mobility spectrometer is the drift voltage applied across its length, as it governs a multitude of processes during the ion drift. While the ...
• Transient simulation of moving ion clouds in time-of-flight ion mobility spectrometers operating with DC and AC fields 

  Allers, M.; Bohnhorst, A.; Kirk, Ansgar T.; Ungethüm, B.; Walte, A.; Zimmermann, S. (Berlin, Heidelberg : Springer, 2015)

  Ion mobility spectrometers can be divided by their principle of ion separation. For example, classical drift tube time-of-flight Ion Mobility Spectrometers (IMS) separate ions by the absolute value of their low field ion ...
• Simulation aided design of a low cost ion mobility spectrometer based on printed circuit boards 

  Bohnhorst, A.; Kirk, Ansgar T.; Zimmermann, S. (Berlin, Heidelberg : Springer, 2016)

  Miniaturized low-cost drift tubes with high analytical performance are a key component for the design of powerful and mass-deployable hand-held ion mobility spectrometers. Thus, a simple model that estimates the influence ...
• A universal relationship between optimum drift voltage and resolving power 

  Kirk, Ansgar T.; Bakes, Kai; Zimmermann, Stefan (Berlin, Heidelberg : Springer, 2017)

  The drift voltage is one of the key experimental parameters of any drift tube ion mobility spectrometer. In this work, we show that a universal relationship between optimum drift voltage and the resolving power reached at ...

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