Bird strike by artificial and real birds on aircraft leading edges

Aircraft wing and stabiliser leading edges need to be analysed against bird strike. Incident statistics reveal that these components are set out to this type of impact which leads to damage. Hence, airworthiness certification asks for safety measures. This approach is similar to other aircraft or helicopter [1] components which are prone to bird strike. Here are discussed horizontal and vertical stabiliser designs to improve the integrity after bird strike. The designs were developed for hybrid laminar flow control (HLFC) i. e. incorporate a suction technology to improve laminarity at the leading edge. At detail scale, particular a splitter or deflector design with a tailored skin single duct (TSSD) with a variable porosity was shown. Two horizontal stabiliser demonstrators with microperforated titanium skins were highlighted as these were applied for the first back-to-back testing of artificial bird versus real bird at a full-scale level. The identical structures were impacted each under identical boundary conditions by the different bird types resulting in comparable deformation and damage pattern. The latest DLRRAB (DLR reinforced artificial bird) artificial bird in ellipsoidal shape and a duck with a weight of 3.6 kg (8 lbs) for both was applied. The advantages of artificial birds and the particular challenges of testing with real birds were compared on the basis of load measurements and impact on hemispherical leading edges of aluminium. A possible path from real over biofidelic to artificial birds for representative and test-to-test repeatable testing together with numerical simulation was sketched. The approach with artificial bird models may offer an alternative method to animal experiments

Impact Studies with Reduced Size Aircraft Stabiliser Demonstrators Including Hybrid Laminar Flow Control Technology

Impact with large-scale projectiles like birds needs analyses at full-scale. The reason is that the impact behaviour can yet not be scaled from small-size demonstrators. The impact studies presented here aim to analyse hybrid laminar flow control (HLFC) structures for stabilizer or wing leading edges. To mature HLFC technology, impact requirements need to be incorporated during the design phase and have to be fulfilled during the certification process. Therefore, simulation methodologies play an important role to integrate impact designs in an early design stage. Within a project where HLFC is applied on the horizontal stabiliser, several design and manufacturing tests are conducted. A reduced-size demonstrator with a short span width but a full cross-section was selected for manufacturing and design purposes. The reduced-size demonstrator has been selected as a mean for impact studies based on earlier simulation and experimental studies. A symmetric vertical stabiliser design of similar size was used to build up a simulation model of an asymmetric horizontal stabiliser design. In several steps, this demonstrator was already verified experimentally by a soft body impact. It was proven that both the design and the design methodology including the demonstrator size was applicable. During the design process of the current horizontal stabiliser HLFC design, structural and manufacturing details were analysed with respect to consequences on the impact behaviour. The structural analyses with respect to impact were performed with explicit finite element and particle flow simulation tools. It is envisaged to subject this demonstrator also to impact testing in order to gather important validation data for the used impact simulation tools. The boundary conditions of the two approaches are similar. However, the HLFC principle is designed different. The current design of the asymmetric demonstrator for a horizontal stabiliser leading edge incorporating a chambered HLFC approach was simulated under soft body impact. It proves sufficient resistance against impact loading. At a later stage, it will be impact tested for validation purposes, too

Drohnenschlag auf Hubschrauberscheiben

Zunehmend werden Drohnen in der Nähe von Hubschraubern gesichtet. Darüber hinaus stellt für Hubschrauber im Einsatz auch die absichtlich herbeigeführte Kollision mit einer Drohne eine mögliche Gefahr dar. Ziel der Forschung ist es, die Gefährdung von Insassen durch Drohnenschlag auf die Cockpitverglasung im Vergleich zum Vogelschlag zu bewerten. Dazu werden durch geeignete Tests überprüfte Computermodelle sowohl der Struktur als auch der Drohne und des Vogels eingesetzt. Increasingly there are drone sightings close to helicopters. An accidental or deliberate collision of drones and rotorcrafts is a possible hazard to safe operation. Objective of the research is to determine the threat of drone strike on the cockpit glazing in comparison to bird strike. Computer models of the helicopter structure as well as the drone and bird impactors are applied here. Suitable tests are carried out to validate this numerical approach

The WaveDAQ integrated Trigger and Data Acquisition System for the MEG II experiment

The WaveDAQ is a newly-designed digitization Trigger and Data AcQuisition system (TDAQ) allowing Multi-gigasample waveform recording on a large amount of channels (up to 16384) by using the DRS4 analog switched capacitor array as downconverting ASIC. A high bandwidth, programmable input stage has been coupled with a bias generator to allow SiPM operation without need of any other external apparatus. The trigger generation is tightly coupled within the system to limit the required depth of the analog memory, allowing faster digitization speeds. This system has been designed for the MEG experiment upgrade but also proved to be highly scalable and already found other applications.Comment: This manuscript is for conference record of the 21st IEEE Real Time conference onl

Development of the photomultiplier tube readout system for the first Large-Sized Telescope of the Cherenkov Telescope Array

The Cherenkov Telescope Array (CTA) is the next generation ground-based very high energy gamma-ray observatory. The Large-Sized Telescope (LST) of CTA targets 20 GeV -- 1 TeV gamma rays and has 1855 photomultiplier tubes (PMTs) installed in the focal plane camera. With the 23 m mirror dish, the night sky background (NSB) rate amounts to several hundreds MHz per pixel. In order to record clean images of gamma-ray showers with minimal NSB contamination, a fast sampling of the signal waveform is required so that the signal integration time can be as short as the Cherenkov light flash duration (a few ns). We have developed a readout board which samples waveforms of seven PMTs per board at a GHz rate. Since a GHz FADC has a high power consumption, leading to large heat dissipation, we adopted the analog memory ASIC "DRS4". The sampler has 1024 capacitors per channel and can sample the waveform at a GHz rate. Four channels of a chip are cascaded to obtain deeper sampling depth with 4096 capacitors. After a trigger is generated in a mezzanine on the board, the waveform stored in the capacitor array is subsequently digitized with a low speed (33 MHz) ADC and transferred via the FPGA-based Gigabit Ethernet to a data acquisition system. Both a low power consumption (2.64 W per channel) and high speed sampling with a bandwidth of $>$300 MHz have been achieved. In addition, in order to increase the dynamic range of the readout we adopted a two gain system achieving from 0.2 up to 2000 photoelectrons in total. We finalized the board design for the first LST and proceeded to mass production. Performance of produced boards are being checked with a series of quality control (QC) tests. We report the readout board specifications and QC results.Comment: In Proceedings of the 34th International Cosmic Ray Conference (ICRC2015), The Hague, The Netherlands. All CTA contributions at arXiv:1508.0589

From Flavour to SUSY Flavour Models

If supersymmetry (SUSY) will be discovered, successful models of flavour not only have to provide an explanation of the flavour structure of the Standard Model fermions, but also of the flavour structure of their scalar superpartners. We discuss aspects of such "SUSY flavour" models, towards predicting both flavour structures, in the context of supergravity (SUGRA). We point out the importance of carefully taking into account SUSY-specific effects, such as 1-loop SUSY threshold corrections and canonical normalization, when fitting the model to the data for fermion masses and mixings. This entangles the flavour model with the SUSY parameters and leads to interesting predictions for the sparticle spectrum. We demonstrate these effects by analyzing an example class of flavour models in the framework of an SU(5) Grand Unified Theory with a family symmetry with real triplet representations. For flavour violation through the SUSY soft breaking terms, the class of models realizes a scheme we refer to as "Trilinear Dominance", where flavour violation effects are dominantly induced by the trilinear terms.Comment: 44 pages, 10 figures, version published in Nuclear Physics

The Changing Landscape for Stroke\ua0Prevention in AF: Findings From the GLORIA-AF Registry Phase 2

Background GLORIA-AF (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients with Atrial Fibrillation) is a prospective, global registry program describing antithrombotic treatment patterns in patients with newly diagnosed nonvalvular atrial fibrillation at risk of stroke. Phase 2 began when dabigatran, the first non\u2013vitamin K antagonist oral anticoagulant (NOAC), became available. Objectives This study sought to describe phase 2 baseline data and compare these with the pre-NOAC era collected during phase 1. Methods During phase 2, 15,641 consenting patients were enrolled (November 2011 to December 2014); 15,092 were eligible. This pre-specified cross-sectional analysis describes eligible patients\u2019 baseline characteristics. Atrial fibrillation disease characteristics, medical outcomes, and concomitant diseases and medications were collected. Data were analyzed using descriptive statistics. Results Of the total patients, 45.5% were female; median age was 71 (interquartile range: 64, 78) years. Patients were from Europe (47.1%), North America (22.5%), Asia (20.3%), Latin America (6.0%), and the Middle East/Africa (4.0%). Most had high stroke risk (CHA2DS2-VASc [Congestive heart failure, Hypertension, Age  6575 years, Diabetes mellitus, previous Stroke, Vascular disease, Age 65 to 74 years, Sex category] score  652; 86.1%); 13.9% had moderate risk (CHA2DS2-VASc = 1). Overall, 79.9% received oral anticoagulants, of whom 47.6% received NOAC and 32.3% vitamin K antagonists (VKA); 12.1% received antiplatelet agents; 7.8% received no antithrombotic treatment. For comparison, the proportion of phase 1 patients (of N = 1,063 all eligible) prescribed VKA was 32.8%, acetylsalicylic acid 41.7%, and no therapy 20.2%. In Europe in phase 2, treatment with NOAC was more common than VKA (52.3% and 37.8%, respectively); 6.0% of patients received antiplatelet treatment; and 3.8% received no antithrombotic treatment. In North America, 52.1%, 26.2%, and 14.0% of patients received NOAC, VKA, and antiplatelet drugs, respectively; 7.5% received no antithrombotic treatment. NOAC use was less common in Asia (27.7%), where 27.5% of patients received VKA, 25.0% antiplatelet drugs, and 19.8% no antithrombotic treatment. Conclusions The baseline data from GLORIA-AF phase 2 demonstrate that in newly diagnosed nonvalvular atrial fibrillation patients, NOAC have been highly adopted into practice, becoming more frequently prescribed than VKA in Europe and North America. Worldwide, however, a large proportion of patients remain undertreated, particularly in Asia and North America. (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients With Atrial Fibrillation [GLORIA-AF]; NCT01468701

Versuche zur Kalibrierung der Dehnstange einer Impact-Kraftmessvorrichtung

Innerhalb dieses Berichts wird die Kalibrierung der Dehnstange, die das zentrale Element zur Datengenerierung der Impact-Kraftmessvorrichtung ist, dokumentiert. Mit dieser Vorrichtung sollen die Kräfte während eines Aufpralls, möglicherweise auch die kinetische Energie eines Projektils bzw. die absorbierte Energie einer Struktur abgeleitet werden