Functional aromatic polyamides

We describe herein the state of the art following the last 8 years of research into aromatic polyamides, wholly aromatic polyamides or aramids. These polymers belong to the family of high performance materials because of their exceptional thermal and mechanical behavior. Commercially, they have been transformed into fibers mainly for production of advanced composites, paper, and cut and fire protective garments. Huge research efforts have been carried out to take advantage of the mentioned characteristics in advanced fields related to transport applications, optically active materials, electroactive materials, smart materials, or materials with even better mechanical and thermal behavior.FEDER and both the Spanish Ministerio de Economía, Industria y Competitividad (MAT2014-54137-R) and the Consejería de Educación—Junta de Castilla y León (BU061U16

The semicircular flow of the data economy

This paper revisits the traditional ‘circular flow’ of the macroeconomy (Samuelson, 1948) and reworks it to capture the use of big data and artificial intelligence in the economy. The characterisation builds on the multifaceted role of data to conceptualise markets and differentiate them depending on whether data is an output, a means of payment, or an input in knowledge extraction processes. After this, the main differences between the circular flow economy and the data economy are described, identifying the new flows and agents and the circular flow assumptions that do not seem to be as relevant to the workings of the data economy. The result is a ‘semicircular’ flow diagram: unprocessed data flow from individuals, families, and firms to data holders. Only data processed in the form of digital services flows back to families and firms. The new model is used to explore the potential for market failures. Knowledge extraction to generate digital services occurs within a ‘black box’ that displays natural monopoly characteristics. Data holders operate simultaneously in the markets for data generation and knowledge extraction. They generate the amount of knowledge that maximises their profit. This creates data underutilisation and asymmetries between data holders and other agents in the economy such as anti-trust authorities, central banks, scientific communities, consumers, and firms. Public intervention should facilitate additional generation of knowledge by developing additional merit and non-rival uses of data in such a way that knowledge generation maximises the social gain from digitalisation. The semicircular model can incorporate data leakages and knowledge injections activated by data taxation. Data taxes should be paid with data respecting existing legislation, privacy concerns, and preserve the incentives of the data holder to innovate in competitive data generation markets. A centralised data authority, as initially proposed by Martens (2016) and more recently by Scott Morton et al. (2019), would be responsible for knowledge generation and aim to achieve better regulation, standards, and transparency, and maximise common good. Our conclusions are in line with an extensive user-centric approach to data portability (De Hert et al., 2018). This paper contributes to the digital economy discussion by developing a simple theoretical motivation for increased access to data for the public good, which will stimulate further theoretical and empirical exercises and lead to policy actions.JRC.I.1-Monitoring, Indicators & Impact Evaluatio

18F-FDG-PET Imaging Patterns in Autoimmune Encephalitis: Impact of Image Analysis on the Results

Brain positron emission tomography imaging with 18Fluorine-fluorodeoxyglucose (FDG-PET) has demonstrated utility in suspected autoimmune encephalitis. Visual and/or assisted image reading is not well established to evaluate hypometabolism/hypermetabolism. We retrospectively evaluated patients with autoimmune encephalitis between 2003 and 2018. Patients underwent EEG, brain magnetic resonance imaging (MRI), cerebrospinal fluid (CSF) sampling and autoantibodies testing. Individual FDG-PET images were evaluated by standard visual reading and assisted by voxel-based analyses, compared to a normal database. For the latter, three different methods were performed: two based on statistical surface projections (Siemens syngo.via Database Comparison, and 3D-SSP Neurostat) and one based on statistical parametric mapping (SPM12). Hypometabolic and hypermetabolic findings were grouped to identify specific patterns. We found six cases with definite diagnosis of autoimmune encephalitis. Two cases had anti-LGI1, one had anti-NMDA-R and two anti-CASPR2 antibodies, and one was seronegative. 18F-FDG-PET metabolic abnormalities were present in all cases, regardless of the method of analysis. Medial–temporal and extra-limbic hypermetabolism were more clearly depicted by voxel-based analyses. We found autoantibody-specific patterns in line with the literature. Statistical surface projection (SSP) methods (Neurostat and syngo.via Database Comparison) were more sensitive and localized larger hypermetabolic areas. As it may lead to comparable and accurate results, visual analysis of FDG-PET studies for the diagnosis of autoimmune encephalitis benefits from voxel-based analysis, beyond the approach based on MRI, CSF sample and EEG

Understanding and optimizing microstrip patch antenna cross polarization radiation on element level for demanding phased array antennas in weather radar applications

The antenna cross polarization suppression (CPS) is of significant importance for the accurate calculation of polarimetric weather radar moments. State-of-the-art reflector antennas fulfill these requirements, but phased array antennas are changing their CPS during the main beam shift, off-broadside direction. Since the cross polarization (x-pol) of the array pattern is affected by the x-pol element factor, the single antenna element should be designed for maximum CPS, not only at broadside, but also for the complete angular electronic scan (e-scan) range of the phased array antenna main beam positions. Different methods for reducing the x-pol radiation from microstrip patch antenna elements, available from literature sources, are discussed and summarized. The potential x-pol sources from probe fed microstrip patch antennas are investigated. Due to the lack of literature references, circular and square shaped X-Band radiators are compared in their x-pol performance and the microstrip patch antenna size variation was analyzed for improved x-pol pattern. Furthermore, the most promising technique for the reduction of x-pol radiation, namely "differential feeding with two RF signals 180° out of phase", is compared to single fed patch antennas and thoroughly investigated for phased array applications with simulation results from CST MICROWAVE STUDIO (CST MWS). A new explanation for the excellent port isolation of dual linear polarized and differential fed patch antennas is given graphically. The antenna radiation pattern from single fed and differential fed microstrip patch antennas are analyzed and the shapes of the x-pol patterns are discussed with the well-known cavity model. Moreover, two new visual based electromagnetic approaches for the explanation of the x-pol generation will be given: the field line approach and the surface current distribution approach provide new insight in understanding the generation of x-pol component in microstrip patch antenna radiation patterns

Design and development of phased-array antennas for dual-polarized weather radar applications

Phased array weather radar antennas with beam steering capabilities are suitable alternatives to weather radars with mechanically scanning reflector antennas. Dual-polarized phased-array weather radar antennas, however, demand careful assessment of the x-polar characteristics. The low x-pol radiation of polarimetric weather radar antennas is of significant importance for the proper classification and qualitative estimation of hydrometeors in illuminate volumes. Unfortunately, array antennas display changing x-pol contributions during the electronical beam steering process. Typically, the x-pol radiation will be substantially increased in the co-polar main beam direction but also in other angular directions. Consequently, it is a vital challenge to design arrays with low x-pol contribution during beam steering. In this dissertation a new phased-array weather radar concept is developed. The phased array system configuration can be used to substitute state-of-the-art weather radars with reflector antennas. Furthermore, a dense network of these phased-array radars can be used to substitute a network of high power weather radars, which are used nowadays. The research focus of this work is the development of a dual-polarized microstrip patch antenna with phased-array capability and very high polarization purity. In this regard, new graphical techniques are developed to investigate the causes and the reduction of the x-pol radiation of isolated (stand-alone) microstrip patch antennas. To further reduce the x-pol contribution of antennas, optimization methods have been investigated, evaluated and developed. For the first time in literature, differential-feed antenna arrays are compared to excitation optimized single-feed antenna arrays in their x-pol contribution in the boresight direction and during beam steering. In particular, two dual-polarized 4x8 antenna arrays have been developed and simulated by CST MWS, produced as multilayer PCB and verified at the compact antenna test range at RWTH Aachen. The results show that the x-pol contributions of arrays are significantly reduced for differentially-feed antenna arrays, even when beam steering is performed. During the azimuth scan of 120_ a record setting x-pol suppression of -45 dB and -36 dB could be measured for the horizontal and vertical polarization channels, respectively.Wetterradarsysteme mit phasengesteuerten Antennen stellen eine echte Alternative zu Wetterradarsystemen mit mechanisch drehenden Reflektorantennen dar. Dual-polarisierte phasengesteuerte Antennen müssen jedoch sehr genau in ihrem Kreuzpolarisationsverhalten verifiziert werden, um für den Wetterradarbereich von Nutzen zu sein. Die Unterdrückung der kreuzpolaren Anteile von Radarantennen ist von fundamentaler Bedeutung, um Hydrometeore mit Hilfe von polarimetrischen Wetterradarsystemen klassifizieren und qualitativ bestimmen zu können. Die hohe Anforderung an Polarisationsreinheit ist mit aktuell erhältlichen Arraydesigns nur schwierig zu realisieren, da sich die Kreuzpolarisationsunterdrückung während des elektronischen Schwenks der Hauptkeule signifikant verschlechtert. Diese Dissertation stellt ein Wetterradar Systemkonzept mit phasengesteuerter Gruppenantenne vor, welches die aktuell genutzten Wetterradare mit Reflektorantennen ablösen könnte. Der Fokus der Arbeit wurde auf die Entwicklung einer Dual-polarimetrischen, polarisationsreinen und phasengesteuerten Mikrostreifenleiterantennen gelegt. Hierbei wurden neue grafische Verfahren entwickelt, die es ermöglichen, die Generierung der kreuzpolaren Anteile von isolierten Patchantennen (Einzelpatche) zu erklären und zu minimieren. Um die kreuzpolaren Anteile weiter herabzusetzen wurden Optimierungsverfahren für Arrayantennen erforscht, bewertet und neu entwickelt. Zum ersten Mal wurden differentiell gespeiste mit einzeln gespeisten Antennenarrays in ihrem Kreuzpolarisationsverhalten während des elektronischen Schwenks der Hauptkeule verglichen. Zwei Dual- polarimetrische 4x8 Antennenarrays (differentiell gespeist und mit optimierter Phasenansteuerung) wurden zu diesem Zweck mittels CST MWS entworfen, simuliert, als Multilagenplatine gefertigt und an der Antennentestanlage der RWTH Aachen vermessen. Die Resultate zeigen, dass die Kreuzpolarisationsanteile bei differentiell gespeisten Mikrostreifenleiterantennen in Gruppenkonfiguration, selbst beim elektronischen Schwenk der Hauptkeule, signifikant minimiert werden konnten. Für einen azimutalen Scanbereich von 120_ konnte eine exzellente Kreuzpolarisationsunterdrückung zwischen -45 dB und -36 dB messtechnisch für den horizontalen und vertikalen Polarisationskanal nachgewiesen werden

Design and development of phased-array antennas for dual-polarized weather radar applications

Phased array weather radar antennas with beam steering capabilities are suitable alternatives to weather radars with mechanically scanning reflector antennas. Dual-polarized phased-array weather radar antennas, however, demand careful assessment of the x-polar characteristics. The low x-pol radiation of polarimetric weather radar antennas is of significant importance for the proper classification and qualitative estimation of hydrometeors in illuminate volumes. Unfortunately, array antennas display changing x-pol contributions during the electronical beam steering process. Typically, the x-pol radiation will be substantially increased in the co-polar main beam direction but also in other angular directions. Consequently, it is a vital challenge to design arrays with low x-pol contribution during beam steering. In this dissertation a new phased-array weather radar concept is developed. The phased array system configuration can be used to substitute state-of-the-art weather radars with reflector antennas. Furthermore, a dense network of these phased-array radars can be used to substitute a network of high power weather radars, which are used nowadays. The research focus of this work is the development of a dual-polarized microstrip patch antenna with phased-array capability and very high polarization purity. In this regard, new graphical techniques are developed to investigate the causes and the reduction of the x-pol radiation of isolated (stand-alone) microstrip patch antennas. To further reduce the x-pol contribution of antennas, optimization methods have been investigated, evaluated and developed. For the first time in literature, differential-feed antenna arrays are compared to excitation optimized single-feed antenna arrays in their x-pol contribution in the boresight direction and during beam steering. In particular, two dual-polarized 4x8 antenna arrays have been developed and simulated by CST MWS, produced as multilayer PCB and verified at the compact antenna test range at RWTH Aachen. The results show that the x-pol contributions of arrays are significantly reduced for differentially-feed antenna arrays, even when beam steering is performed. During the azimuth scan of 120_ a record setting x-pol suppression of -45 dB and -36 dB could be measured for the horizontal and vertical polarization channels, respectively.Wetterradarsysteme mit phasengesteuerten Antennen stellen eine echte Alternative zu Wetterradarsystemen mit mechanisch drehenden Reflektorantennen dar. Dual-polarisierte phasengesteuerte Antennen müssen jedoch sehr genau in ihrem Kreuzpolarisationsverhalten verifiziert werden, um für den Wetterradarbereich von Nutzen zu sein. Die Unterdrückung der kreuzpolaren Anteile von Radarantennen ist von fundamentaler Bedeutung, um Hydrometeore mit Hilfe von polarimetrischen Wetterradarsystemen klassifizieren und qualitativ bestimmen zu können. Die hohe Anforderung an Polarisationsreinheit ist mit aktuell erhältlichen Arraydesigns nur schwierig zu realisieren, da sich die Kreuzpolarisationsunterdrückung während des elektronischen Schwenks der Hauptkeule signifikant verschlechtert. Diese Dissertation stellt ein Wetterradar Systemkonzept mit phasengesteuerter Gruppenantenne vor, welches die aktuell genutzten Wetterradare mit Reflektorantennen ablösen könnte. Der Fokus der Arbeit wurde auf die Entwicklung einer Dual-polarimetrischen, polarisationsreinen und phasengesteuerten Mikrostreifenleiterantennen gelegt. Hierbei wurden neue grafische Verfahren entwickelt, die es ermöglichen, die Generierung der kreuzpolaren Anteile von isolierten Patchantennen (Einzelpatche) zu erklären und zu minimieren. Um die kreuzpolaren Anteile weiter herabzusetzen wurden Optimierungsverfahren für Arrayantennen erforscht, bewertet und neu entwickelt. Zum ersten Mal wurden differentiell gespeiste mit einzeln gespeisten Antennenarrays in ihrem Kreuzpolarisationsverhalten während des elektronischen Schwenks der Hauptkeule verglichen. Zwei Dual- polarimetrische 4x8 Antennenarrays (differentiell gespeist und mit optimierter Phasenansteuerung) wurden zu diesem Zweck mittels CST MWS entworfen, simuliert, als Multilagenplatine gefertigt und an der Antennentestanlage der RWTH Aachen vermessen. Die Resultate zeigen, dass die Kreuzpolarisationsanteile bei differentiell gespeisten Mikrostreifenleiterantennen in Gruppenkonfiguration, selbst beim elektronischen Schwenk der Hauptkeule, signifikant minimiert werden konnten. Für einen azimutalen Scanbereich von 120_ konnte eine exzellente Kreuzpolarisationsunterdrückung zwischen -45 dB und -36 dB messtechnisch für den horizontalen und vertikalen Polarisationskanal nachgewiesen werden

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