NEWSKY - A concept for NEtWorking the SKY for civil aeronautical communications

In this paper, an overview of the NEWSKY project is given. This project is funded by the European Commission within the 6th framework program and will start in January 2007. The NEWSKY project is a feasibility study to clarify if it is possible to establish a heterogeneous network for aeronautical communications which is capable to integrate different communications systems as well as different applications into a single global aeronautical network. The envisaged applications comprise not only air-traffic control and management but also airline and passenger communications

Aeronautical Communications - An Important Enabler for Risk Mitigation

This presentation is a tutorial on aeronautical communications and intends to give an overview of both the current state-of-the-art and the initiated/planned developments in communications for Air-Traffic Management (ATM). Communication is an important enabler for future ATM strategies as defined within SESAR (Europe) or NextGen (US). Therefore, several activities for improving the state-of-the-art in aeronautical communications are currently in progress with the goal to increase connectivity between ground and aircraft as well as among aircraft themselves. Future aeronautical communication systems also play an important role with respect to future applications as considered for risk mitigation. For example, the implementation of an aviation meteorological information system for timely provision of meteorological data to flight crews is only possible if powerful data link communication systems and/or aeronautical communication networks are available

Influence of aerosols, clouds, and sunglint on polarization spectra of Earthshine

Ground-based observations of the Earthshine, i.e., the light scattered by Earth to the Moon, and then reflected back to Earth, simulate space observations of our planet and represent a powerful benchmark for the studies of Earth-like planets. Earthshine spectra are strongly linearly polarized, owing to scattering by molecules and small particles in the atmosphere of the Earth and surface reflection, and may allow us to measure global atmospheric and surface properties of planet Earth. Aims. We aim to interpret already published spectropolarimetric observations of the Earthshine by comparing them with new radiative transfer model simulations including a fully realistic three-dimensional (3D) surface-atmosphere model for planet Earth. We used the highly advanced Monte Carlo radiative transfer model MYSTIC to simulate polarized radiative transfer in the atmosphere of the Earth without approximations regarding the geometry, taking into account the polarization from surface reflection and multiple scattering by molecules, aerosol particles, cloud droplets, and ice crystals. We have shown that Earth spectropolarimetry is highly sensitive to all these input parameters, and we have presented simulations of a fully realistic Earth atmosphere-surface model including 3D cloud fields and two-dimensional (2D) surface property maps. Our modeling results show that scattering in high ice water clouds and reflection from the ocean surface are crucial to explain the continuum polarization at longer wavelengths as has been reported in Earthshine observations taken at the Very Large Telescope in 2011 (3.8 % and 6.6 % at 800 nm, depending on which part of Earth was visible from the Moon at the time of the observations). We found that the relatively high degree of polarization of 6.6 % can be attributed to light reflected by the ocean surface in the sunglint region

Development of anFPGA-based Data Reduction System for the Belle II DEPFET Pixel Detector

The innermost two layers of the Belle II detector at the KEKB collider in Tsukuba, Japan will be covered by highly granular DEPFET pixel sensors. The large number of pixels lead to a maximum data rate of 256 Gbps, which has to be significantly reduced by the Data Acquisition System. For data reduction, the hit information of the silicon-strip vertex detector surrounding the pixel detector is used to define so-called Regions of Interest (ROI) in the pixel detector. Only hit information of the pixels located inside these ROIs are saved. The ROIs for the pixel detector are computed by reconstructing track segments from strip data and extrapolation to the pixel detector. The goal is to achieve a reduction factor of up to 10 with this ROI selection. All the necessary processing stages, the receiving, decoding and multiplexing of SVD data on 48 optical fibers, the track reconstruction and the definition of the ROIs, will be performed by the DATCON system, developed in the scope of this thesis. The planned hardware design is based on a distributed set of Advanced Mezzanine Cards (AMC), each equipped with a Field Programmable Gate Array (FPGA) and four optical transceivers. An algorithm is developed based on a Hough Transformation, a commonly used pattern recognition method in image processing to identify the track segments in the strip detector and calculation of the track parameters. Using simulations, the performance of the developed algorithms are evaluated. For use in the DATCON system the Hough track reconstruction is implemented on FPGAs. Several tests of the modules required to create the ROIs are performed in a simulation environment and tested on the AMC hardware. After a line of successful tests, the DATCON prototype was used in two test beam campaigns to verify the concept and practice the integration with the other detector systems. The developed track reconstruction algorithm shows a high reconstruction efficiency down to low track momenta. A higher data reduction than originally intended was achieved within the limits of the available processing time. The FPGA track reconstruction algorithm is found to be even three times faster than demanded by the trigger rate of the experiment. The used concepts and developed algorithms are not specifically designed for the Belle II vertex detector only, but can be used in different experiments. It was successfully tested on the low-level trigger for Belle II, using drift chamber information and showed a comparably good track reconstruction performance

Mechatronische Osteosyntheseplatte

Ziel dieses Projektes ist die Entwicklung eines miniaturisierten vollimplantierbaren Gerätes zur Verlängerung von Kiefer- und Schädelknochen, basierend auf den Erkenntnissen von Plattenosteosynthese-Verfahren. Dieses Gerät, im folgenden Mechatronische Osteosyntheseplatte (kurz MO) oder Distraktor genannt, ist ein kleiner Teleskopaktuator, der eine Kraft von mindestens 30 N erzeugt, die zur Verlängerung eines Knochens benötigt wird. Der Antrieb erfolgt durch Formgedächtnisdrähte aus einer Nickel-Titan-Legierung, die im Inneren des Gerätes gespannt sind. Diese Drähte werden über eine drahtlose niederfrequente Energieeinkopplung mit Strom versorgt. Über einen Ratschenmechanismus wird die Kraft auf eine teleskopartig ausfahrende Platte übertragen. Der Distraktor wird direkt auf den Knochen mit kommerziell erhältlichen Titan-Knochenschrauben aufgeschraubt. Die Neuerung bei dieser Entwicklung ist u.a. der Antrieb durch Drähte aus Formgedächtnislegierung, sowie die vollständige Implantierbarkeit des Gerätes. Formgedächtnislegierungen können in kaltem Zustand mit geringem Kraftaufwand verformt werden. Werden sie anschließend erhitzt, so „erinnert“ sich die Legierung an ihre ursprüngliche Form und nimmt den vorherigen unverformten Zustand wieder ein. Ziel dieser Neuentwicklung ist, durch das vollständige Verschließen des operierten Bereichs die Infektionsgefahr zu minimieren, das Risiko für den Patienten zu senken und den Behandlungskonfort zu erhöhen. Durch die minimierte Narbenbildung wird das kosmetische Ergebnis ebenfalls verbessert. Desweiteren soll die Erfassung von Messwerten für Weg und Kraft integriert werden, um so dem betreuenden Arzt Auskunft über den Fortschritt des Verlängerungsprozess und die Heilung zu geben. Eingesetzt wird die Osteosynthese durch Knochenverlängerung in der plastischen Chirurgie bei Missbildungen, Fehlstellungen oder Unfällen

Frequency offset estimation for IFDMA uplink systems

This paper proposes two frequency offset estimation algorithms for the uplink of an Interleaved Frequency-Division Multiple-Access (IFDMA) system. One algorithm performs estimation in the frequency domain and the other in the time domain. Both algorithms are based on the maximum likelihood estimation (MLE) principle and use knowledge about pilot symbols. IFDMA utilizes a block-interleaved frequency allocation scheme to exploit the frequency diversity of the channel. In the presence of frequency offsets between users, multiple-access interference (MAI) appears, which has a negative impact on existing frequency offset estimation algorithms. The proposed algorithms are robust, since a special construction of pilot symbols allows to exclude a large amount of MAI in the presence of frequency offsets between users. As a result, the proposed time domain frequency estimation algorithm outperforms the frequency domain algorithm and all other known schemes

Acoustic effects of the coolant mass flow of an electric machine of a hybrid drive train

In this application paper, the influence of the coolant mantle on the acoustic radiation behaviour of a hybrid drive train is investigated. This was done on an electric machine on an acoustic component test bench. The coolant mass flow around the electric machine stator was varied and then completely drained. The electrical machine remained mechanically unchanged; any variations were made to the feed pumps on the test bench side. Triaxial acceleration sensors are glued to the machine housing and reviewed as evaluation criteria. For the evaluation, the square mean value of all three spatial directions of the glued acceleration sensors was calculated. The evaluation shows that there is no significant acoustic difference between an active stator cooling jacket and a stationary stator cooling jacket. If the stator cooling jacket is pumped out empty so that air remains in it, there is a strong reduction in surface acceleration. The observations are confirmed by analytical literature values. The results presented serve as a basis for further work and developments

Characterization and Application of Hard X-Ray Betatron Radiation Generated by Relativistic Electrons from a Laser-Wakefield Accelerator

The necessity for compact table-top x-ray sources with higher brightness, shorter wavelength and shorter pulse duration has led to the development of complementary sources based on laser-plasma accelerators, in contrast to conventional accelerators. Relativistic interaction of short-pulse lasers with underdense plasmas results in acceleration of electrons and in consequence in the emission of spatially coherent radiation, which is known in the literature as betatron radiation. In this article we report on our recent results in the rapidly developing field of secondary x-ray radiation generated by high-energy electron pulses. The betatron radiation is characterized with a novel setup allowing to measure the energy, the spatial energy distribution in the far-field of the beam and the source size in a single laser shot. Furthermore, the polarization state is measured for each laser shot. In this way the emitted betatron x-rays can be used as a non-invasive diagnostic tool to retrieve very subtle information of the electron dynamics within the plasma wave. Parallel to the experimental work, 3D particle-in-cell simulations were performed, proved to be in good agreement with the experimental results.Comment: 38 pages, 19 figures, submitted to the Journal of Plasma Physic