Plasmageactiveerde CO2-neutrale brandstofproductie

In een samenwerking van de Technische Universiteit Eindhoven (faculteit Technische Natuurkunde) en het FOM-instituut DIFFER (Dutch Institute for Fundamental Energy Research) zoeken we naar productieprocessen om CO2 om te zetten naar een brandstof. Aan de basis van het productieproces staat een gasontlading. De energie die nodig is om het resulterende plasma te laten branden zal in de toekomst afkomstig zijn van duurzame energiebronnen. Een succesvolle methode zal leiden tot verminderde CO2-emissies en opslag van duurzaam opgewekte energie

Retrieval of temperature and water vapor profiles from radio occultation refractivity and bending angle measurements using an Optimal Estimation approach: a simulation study

International audienceThe Optimal Estimation Method is used to retrieve temperature and water vapor profiles from simulated radio occultation measurements in order to assess how different retrieval schemes may affect the assimilation of this data. High resolution ECMWF global fields are used by a state-of-the-art radio occultation simulator to provide quasi-realistic bending angle and refractivity profiles. Both types of profiles are used in the retrieval process to assess their advantages and disadvantages. The impact of the GPS measurement is expressed as an improvement over the a priori knowledge (taken from a 24h old analysis). Large improvements are found for temperature in the upper troposphere and lower stratosphere. Only very small improvements are found in the lower troposphere, where water vapor is present. Water vapor improvements are only significant between about 1 km to 7 km. No pronounced difference is found between retrievals based upon bending angles or refractivity. Results are compared to idealized retrievals, where the atmosphere is spherically symmetric and instrument noise is not included. Comparing idealized to quasi-realistic calculations shows that the main impact of a ray tracing algorithm can be expected for low latitude water vapor, where the horizontal variability is high. We also address the effect of altitude correlations in the temperature and water vapor. Overall, we find that water vapor and temperature retrievals using bending angle profiles are more CPU intensive than refractivity profiles, but that they do not provide significantly better results

Implementation of ROSA radio occultation data handling into EUMETSAT and GRAS SAF processing

Within this contribution, outcomes from a GRAS - SAF Visiting Scientist activity focused on the analysis of ROSA data quality for their use in operational weather forecasting will be described and main results will be shown. The ROSA Radio Occultation instrument has been developed by Thales-Alenia-Space, Italy and was funded by the Italian Space Agency (ASI). Such instrument is actually flying on-board three opportunity missions: the Indian OCEANSAT-2, the Argentinean SAC-D and the Indian-French MEGATROPIQUES. Focus of this Visiting Scientist activity has primarily been the analysis of ROSA data from OCEANSAT-2.This activity was divided into two parts. In the first one, performed at EUMETSAT, ROSA data processing was implemented into the EUMETSAT YAROS processor. The required updates into such processing package were implemented in order to make it able to properly manage also ROSA raw observations. It has to be noted that this processor is the baseline for the operational next generation EUMETSAT Radio Occultation ground segment: any changes performed in the framework of YAROS can easily be transferred to the operational ground segment. The YAROS - EUMETSAT processor was then updated and adapted to work with the ROSA raw data, tracking frequencies and instrument database. Adaptation to open loop data, navigation bits acquisition and potentially ionospheric measurement will be performed in the next future. NetCDF-4 YAROS output files are phases, amplitudes, bending angles over impact parameter, along with all other required data. Robust bias and standard deviation of bending angles to ECMWF collocated data were the statistical indicators generated to evaluate the quality of the ROSA observations. The second part of the activity was the adaptation of the GRAS-SAF ROPP (Radio Occultation Processing Package) processor for ROSA data processing. This second part was performed at Danish Meteorological Institute and has been focused on bending angles, refractivity and higher level product generation and validation against ECMWF and co-located occultation profiles. For the first time, one month of ROSA data have been deeply analyzed by a state-of-the-art Radio Occultation processing software and results will be described in the framework of this contributio

Retrieval of temperature and water vapor profiles from radio occultation refractivity and bending angle measurements using an Optimal Estimation approach: a simulation study

The Optimal Estimation Method is used to retrieve temperature and water vapor profiles from simulated radio occultation measurements in order to assess how different retrieval schemes may affect the assimilation of this data. High resolution ECMWF global fields are used by a state-of-the-art radio occultation simulator to provide quasi-realistic bending angle and refractivity profiles. Both types of profiles are used in the retrieval process to assess their advantages and disadvantages. The impact of the GPS measurement is expressed as an improvement over the a priori knowledge (taken from a 24h old analysis). Large improvements are found for temperature in the upper troposphere and lower stratosphere. Only very small improvements are found in the lower troposphere, where water vapor is present. Water vapor improvements are only significant between about 1 km to 7 km. No pronounced difference is found between retrievals based upon bending angles or refractivity. Results are compared to idealized retrievals, where the atmosphere is spherically symmetric and instrument noise is not included. Comparing idealized to quasi-realistic calculations shows that the main impact of a ray tracing algorithm can be expected for low latitude water vapor, where the horizontal variability is high. We also address the effect of altitude correlations in the temperature and water vapor. Overall, we find that water vapor and temperature retrievals using bending angle profiles are more CPU intensive than refractivity profiles, but that they do not provide significantly better results

Controlling the nitric and nitrous oxide production of an atmospheric pressure plasma jet-/title-

International audienceAtmospheric pressure plasma jets are non-thermal plasmas and have the ability to create reactive species. These features make it a very attractive tool for biomedi-cal applications. In this work, we studied NO and N 2 O production, which are two species having biomedical properties. NO plays a role in the vascularization and in ulcer treatment, while N 2 O is used as anesthetic and analgesic gas. In this study, the plasma source is similar to the COST Reference Microplasma Jet (–APPJ). Helium is used as feed gas with small admixtures of molecular nitrogen and oxygen of below 1%. The absolute densities of NO and N 2 O were measured in the effluent of an atmospheric pressure RF plasma jet by means of ex-situ quantum-cascade laser absorption spectroscopy via a multi-pass cell in Herriot configuration. We will show that the species' production is dependent on several parameters such as power, flow and oxygen and nitrogen admixture. The NO and N 2 O densities are strongly dependent on the N 2-O 2 ratio. Changing this ratio allows for choosing between a NO-rich or a N 2 O-rich regime [1]. [1] Douat et al, PSST, 25 (2016) 02502

Die Verbildlichung von Klangstrukturen im Kontext der Entwicklung von Werkzeugen für die Medienproduktion

Audio ist einer der wichtigsten Aspekte bei mediengestützten Produktionen. Allerdings sind die Oberflächen zur Suche, Erstellung und Manipulation von Audio häufig getrieben durch die zugrundeliegenden technischen Parameter. Diese Parameter beschreiben in der Regel weder deren Bedeutung für den Sound noch welche Qualitäten im Sound zum Ausdruck kommen. Dadurch bieten solche Oberflächen selten eine intuitive, noch expressive Handhabe, da zuerst ein Übersetzungsprozess von der künstlerischen Idee hin zu den technischen Parametern erfolgen muss. Um die Oberflächen nahbarer und nachvollziehbar zu gestalten, wird daher die Verbildlichung der Strukturen von Sound auf verschiedenen Ebenen betrachtet. Insbesondere wie visuelle Momente zur Interaktion mit Audio genutzt werden können, wird herausgestellt. Auf diese Weise wird die grafische Erweiterung von technischer spektraler Editierung als Beispiel für die direkte Signalverarbeitung diskutiert. Auch werden metaphorische Visualisierungen für Audioeffekte thematisiert. Zudem wird das mentale Modell von Audio analysiert, welches hier assoziativ durch Skizzen als abstrakte visuelle Repräsentationen erhoben wird. Daher wurden Studien zur Erhebung und Bewertung von Skizzen durchgeführt, die je einen Sound abbilden. Aus den resultierenden Skizzenassoziationen ist ein Vorgehen zur Ableitung einer Klassifikation des skizzenbasierten mentalen Modells entstanden. Diese Klassifikation ist ein möglicher Ausgangspunkt für die Entwicklung von Werkzeugen und bietet ein Bewusstsein der Ausdrucksmöglichkeiten beim Einsatz grafischer Assoziationen bis hin zu Affordanzen im Design von Datensätzen für maschinelles Lernen. Denn es wurden auch statistische Zusammenhänge der Kenntnisse der zeichnenden Personen und den verwendeten Skizzenklassen untersucht. Dadurch kann die Art der Abbildung in Bezug zur gewünschten Zielgruppe gewählt werden.Audio is one of the most important aspects of media-based productions. However, the interfaces for searching, creating, and manipulating audio are often driven by the underlying technical parameters. These parameters usually do not describe their meanings for the sound, nor what qualities are expressed in the sound. As a result, such surfaces rarely offer an intuitive, nor expressive way of interacting, since a translation process from the artistic idea to the technical parameters must take place first. In order to make the interfaces more approachable and comprehensible, the visualization of the structures of sound is therefore considered on different levels. In particular, how visualizations can be used to interact with audio will be highlighted. In this way, the graphical extension of technical spectral editing is discussed as an example of direct signal processing. Also, metaphorical visualizations for audio effects are addressed. In addition, the mental model of audio is analyzed, which is here elicited associatively through sketches as abstract visual representations. Therefore, studies were conducted to collect and evaluate sketches, each depicting one sound. From the resulting sketch associations, a procedure for deriving a classification of the sketch-based mental model has been developed. This classification is a possible starting point for tool development and provides an awareness of the expressive possibilities when using graphical associations up to affordances in the design of datasets for machine learning. In fact, statistical correlations of the knowledge of the people drawing and the classes of sketches used were also investigated. This allows to choose the type of illustration in relation to the desired target group

A Transfer Function Method to Calculate the Outcome of Radiation Measurements of a Buck Converter

Radiation measurements are performed in fully or semi-anechoic chambers or GTEM cells and are usually costly and time-consuming. In addition, most manufacturers of electronic devices do not have the capability to perform such measurements quickly by themselves. The transfer function approach aims at simplifying this problem: once the characteristics of the measurement setup are captured in a transfer function, the conducted characterization of the device under test (DUT) is sufficient to calculate the results of a radiation measurement. This is justified by the assumption that the radiation is mainly generated by the currents on the supply cables and the DUT is small compared to the smallest wavelength considered. Additionally, the DUT should behave linearly. In previous work [2] it was shown that a characterization of the DUT as a Norton equivalent source together with the scattering parameters of the measurement setup are sufficient to calculate the voltage at the received antenna in an anechoic chamber. In this work, the method is applied to a buck converter for both a GTEM cell and a fully-anechoic chamber setup