Magnetization Dynamics of an Individual Single-Crystalline Fe-Filled Carbon Nanotube

The magnetization dynamics of individual Fe-filled multiwall carbon-nanotubes (FeCNT), grown by chemical vapor deposition, are investigated by microresonator ferromagnetic resonance (FMR) and Brillouin light scattering (BLS) microscopy and corroborated by micromagnetic simulations. Currently, only static magnetometry measurements are available. They suggest that the FeCNTs consist of a single-crystalline Fe nanowire throughout the length. The number and structure of the FMR lines and the abrupt decay of the spin-wave transport seen in BLS indicate, however, that the Fe filling is not a single straight piece along the length. Therefore, a stepwise cutting procedure is applied in order to investigate the evolution of the ferromagnetic resonance lines as a function of the nanowire length. The results show that the FeCNT is indeed not homogeneous along the full length but is built from 300 to 400 nm long single-crystalline segments. These segments consist of magnetically high quality Fe nanowires with almost the bulk values of Fe and with a similar small damping in relation to thin films, promoting FeCNTs as appealing candidates for spin-wave transport in magnonic applications. © 2019 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei

Extreme Ultraviolet (EUV) Sources for Lithography based on Synchrotron Radiation

The study presented here was initiated by a discussion to investigate the possibility of using synchrotron radiation as a source for the Next Generation Lithography (NGL) based on the EUV-concept (Extreme Ultra-Violet; here 13.5 nm or 11.3 nm radiation, respectively). The requirements are: 50 W, 2% bandwidth and minimal power outside this bandwidth. Three options were investigated. The first two deal with radiation from bending magnets and undulators. The results confirm the earlier work by Oxfords Instrument and others that these light-sources lack in-band power while emitting excessive out-of-band radiation. The third approach is a FEL (Free Electron Laser) driven by a 500 MeV linear accelerator with a superconducting mini-undulator as radiation emitting device. Such a device would produce in-band EUV-power in excess of 50 W with negligible out-of-band power.Comment: Submitted to Nuclear Instruments and Methods

Antiphase domains in Langmuir-Blodgett films

For bilayer stacks of non-centrosymmetrical molecules, formed by the Langmuir-Blodgett (LB) technique (Y deposition), 00l peaks for the bilayer period are usually observed in the X-ray specular reflectivity curve, in this study, we show that the introduction of stacking disorder at lower transfer ratios and the subsequent partial repair of defects by a parallel shift of oppositely oriented molecules into the vacancies may result in the formation of antiphase domains and in an increase in the average monolayer symmetry followed by quenching of the bilayer peaks. The X-ray reflectivity data, obtained for multilayers of penta-alkynes, are used to demonstrate this real structural effect, which is expected to be of general importance for X-ray and neutron reflectivity data reduction and for the structural modelling of multilayers

Models for the development of sustainable agriculture.

COMUNIICA (IICA) 1(3) p. 29-33Aborda el tema del desarrollo a partir del uso racional de los recursos. Inicia con la conceptualización del desarrollo sostenible, enuncia los requisitos e implicaciones para este tipo de desarrollo, comenta la importancia de los modelos de desarrollo sostenible y las ventanas de sostenibilidad, para finalizar con los esperable en este campo en el futuro

A comprehensive and consistent design-to-noise study of high-lift profiles and their noise reduction potential

The optimal design of future transport aircraft has to comply with further tightened environmental requirements. Therefore, the usage of mature design tools is mandatory that provide on the one hand side a prediction capability for the effect of even subtle design variations. On the other hand, predictions with short turnaround time of the order of 100 CPUh are necessary to enable a sufficient resolution of the design space at acceptable numerical effort. For aerodynamic analysis with Computational Fluid Dynamics (CFD), Reynolds Averaged Navier-Stokes Simulation (RANS) has matured as a state-of-the-art simulation tool in industry that provides the crucial short turnaround times and sufficient reliability of results. However, up to date no useful acoustic metric could be derived from the RANS flow variables that could be further utilized for aeroacoustics driven design (design-to-noise). Scale resolving simulation tools, on the other hand, require a simulation effort far beyond 100 CPUh and are of limited use if a large set of variants has to be studied. In some predecessor work Computational Aeroacoustics (CAA) simulation with vortex sound sources derived from RANS deduced synthetic turbulence has demonstrated a feasible way to model broadband noise spectra for problems such as trailing edge noise or high-lift slat noise. Successful simulations revealed that i) major noise source characteristics can be deduced from a space-time stochastic realization of synthetic turbulence and that ii) CAA turnaround times are comparable to that of RANS. Hence, the approach has some potential to bridge the current prediction gap by providing sufficiently efficient a meaningful acoustic metric from RANS turbulence data. In this work a 2-D design study has been carried out using 5 different high-lift profiles to demonstrate the applicability of the approach for design-to-noise applications. CAA and CFD simulations have been conducted using 3 different velocities (40m/s, 50m/s, and 61.5m/s). Acoustic results (narrow band spectra) and time averaged aerodynamic characteristics (cp-distribution) of the 2-D design study have been cross-compared for the F16 reference high-lift profile with a scale resolving approach. Good agreement for both data sets could be demonstrated. With the Very Long Chord Slat (VLCS) variant a geometry intended to lower the noise emissions of the F16 reference profile has been studied. Two novel Krüger flap designs have been evaluated concerning their noise reduction trends. Meaningful noise trends and clear noise reduction potentials could be identified. Conventional slat noise is found to scale with the fourth power of Mach number. For the F16 reference profile a gap/overlap slat setting variation study has been performed. The gap variation study revealed clearer noise reduction potential yielding about 3dB overall sound pressure level (OASPL) reduction towards the ground. The VLCS yields an OASPL noise reduction potential of up to 6dB towards the ground, as was found in previous experimental studies. The Krüger flap designs yield the clearest noise reduction potential. For the first considered Krüger design, OASPL noise reduction yields on average 6dB over the entire lower polar arc range. A second aerodynamically optimized Krüger design, however significantly loses part of the noise reduction potential, thus indicating the importance of an holistic approach towards high-lift design that incorporates besides aerodynamic also aeroacoustics characteristics