Vorhersage des Einflusses der magnetischen Suszeptibilität des Bodens auf die Funktionsweise von Metalldetektoren bei der Landminensuche – Fallbeispiel Angola

Zur Räumung der als Relikte bewaffneter Konflikte im Boden liegenden Landminen werden wegen geringer Kosten und leich-ter Anwendbarkeit vor allem Metalldetektoren eingesetzt. Tropische Böden bereiten dabei häufig Probleme, da ihre magnetische Suszeptibilität zu starken Einschränkungen wie z.B. Fehlalarmen führt. In einer Studie an 511 Proben von lateritischen Böden aus 15 tropischen Ländern konnten PREETZ et al. (2008) ein Klassifikationssystem entwickeln, das die magnetische Suszeptibilität nach dem Ausgangsgestein und dem Verwitterungsgrad des Bodens einzu-schätzen erlaubt. Um die in vielen Ländern vorliegenden Bodenkarten nutzen zu können, wurde nach einem Algorithmus gesucht, der die Zielgröße direkt zu Bodentypen nach dem FAO- oder WRB-System in Beziehung setzt. Als regionales Fallbeispiel diente Angola. Auf der Grundlage vorhandener Bodenkarten und der Definitionen diagnostischer Horizonte nach dem FAO-/WRB-System wurde ein zusätzliches Schema entwickelt, das die örtlich verbreiteten Ferralsols, Plinthosols, Acrisols und sonstigen Bodentypen nach dem prognostizierten Grad der magnetischen Suszeptibilität in 4 Klassen unterschiedlichen Einflusses auf die Funktionsweise von Metalldetektoren einteilt. Das Ergebnis besteht in landesweiten Karten, die die Medianwerte und die 90 %-Quantile der prognostizierten magnetischen Suszeptibilität darstellen und als Hilfsmittel bei der Planung der Landminensuche eingesetzt werden können

Schlussbericht ExpTurb: Design einer Experimentalturbine

Das DLR entwickelt die "Plattform Windenergie", wovon die Errichtung mehrerer Windenergieanlagen wesentlicher Bestandteil ist. Eine diese Anlagen ist die als modularer Versuchsträger konzipierte Experimentalturbine. Sie soll der Validierung von Methoden und Modellen sowie die Erprobung von Technologien dienen. Ziel des Projekts war die Entwicklung eines entsprechenden Anlagendesigns. Das Ergebnis sind Dokumente, Daten und numerische Modelle, die diese einzigartige Experimentalturbine beschreiben. Das Design der pitchgesteuerten Anlage mit 500 kW Nennleistung wurde durch ein erfahrenes Ingenieurbüro von einem bewährten kommerziellen Entwurf abgeleitet. Seine Besonderheit liegt in der konsequenten Entwicklung für die Erforschung des Rotors der Zukunft. Daher umfasst das Design ein eigens entwickeltes sehr schlankes Rotorblatt, das die Vergleichbarkeit mit der Aerodynamik aktueller Multi-MW-Anlangen herstellt, hohe Schnelllaufzahlen ermöglicht und eine wechselbare Blattspitze besitzt. Die Anlagengröße war ebenso ein Designkriterium wie der Zugang zu allen Baugruppen. Ein besonders dynamisches Pitchsystem und eine Lidar-Plattform auf dem Gondeldach sind weitere Merkmale. Die Experimentalturbine ist durch die Kombination dieser Eigenschaften ein besonderer Versuchsträger für Experimente zur Untersuchung der Aerodynamik, Aeroakustik, Aeroelastik, Regelung und Meteorologie von Windenergieanlagen

The Effect of Shock Control Bumps on the Transonic Flutter and Buffeting Characteristics of a Typical Wing Section

We investigate the effects of small-scale airfoil geometry modifications, in particular so-called shock control bumps (SCB), on the transonic flutter and buffeting behavior of a classical two-degree-of-freedom model employing linearized stability analysis. The unsteady aerodynamic forces are modelled by solving the discretized RANS equations with respect to small-perturbation mesh deformation input. Special emphasis is put on the coupling of fluid modes and structural modes. SCBs that are designed initially towards purely aerodynamic buffet suppression perform also well in the aeroelastic analysis with respect to fluid-mode flutter. Classical flutter and buffeting are found to be separated by an apparent wall of stability. It is further noted that SCBs can potentially serve to improve the classical flutter behavior in the transonic dip region

Wind turbine stability: Comparison of state-of-the-art aeroelastic simulation tools

As rotor diameters and blade flexibility are increasing, current and future generation wind turbines are more susceptible to aeroelastic instabilities. It is thus important to know the prediction capabilities of state-of-the-art simulation tools in regards of the onset of aeroelastic instability. This article presents results of a code-to-code comparison of five different simulation codes using a representative wind turbine model. It is shown that the models are in good agreement in terms of isolated structural dynamics and steady state aeroelastics. The more complex the test cases become, the more significant are the differences in the results. In the final step of comparison, the aeroelastic stability limit is determined through a run-away analysis. The instability onset is predicted at different wind speeds and the underlying mechanisms differ between the tools. A Campbell diagram is used to correlate the findings of time domain simulation tools with those of a linear analysis in the frequency domain

Controlled induction of human pancreatic progenitors produces functional beta‐like cells in vitro

Directed differentiation of human pluripotent stem cells into functional insulin‐producing beta‐like cells holds great promise for cell replacement therapy for patients suffering from diabetes. This approach also offers the unique opportunity to study otherwise inaccessible aspects of human beta cell development and function in vitro. Here, we show that current pancreatic progenitor differentiation protocols promote precocious endocrine commitment, ultimately resulting in the generation of non‐functional polyhormonal cells. Omission of commonly used BMP inhibitors during pancreatic specification prevents precocious endocrine formation while treatment with retinoic acid followed by combined EGF/KGF efficiently generates both PDX1+ and subsequent PDX1+/NKX6.1+ pancreatic progenitor populations, respectively. Precise temporal activation of endocrine differentiation in PDX1+/NKX6.1+ progenitors produces glucose‐responsive beta‐like cells in vitro that exhibit key features of bona fide human beta cells, remain functional after short‐term transplantation, and reduce blood glucose levels in diabetic mice. Thus, our simplified and scalable system accurately recapitulates key steps of human pancreas development and provides a fast and reproducible supply of functional human beta‐like cells.SynopsisFocusing on developmental mechanisms, the results of this study further accelerate successful differentiation of human ESCs into functional pancreatic beta cells.Exclusion of commonly used BMP inhibitors during human embryonic stem cell to pancreatic progenitor differentiation prevents precocious endocrine induction.Sequential exposure of foregut cells to retinoic acid followed by combined EGF/KGF treatment establishes highly pure PDX1+ and PDX1+/NKX6.1+ progenitor populations, respectively.Precise temporal induction of endocrine differentiation in PDX1+/NKX6.1+ progenitors, but not in PDX1+/NKX6.1− progenitors, results in the generation of functional beta‐like cells in vitro.Beta‐like cells exhibit key features of bona fide human beta cells, remain functional after short‐term transplantation, and reduce blood glucose levels in diabetic mice.Focusing on developmental mechanisms, the results of this study further accelerate successful differentiation of human ESCs into functional pancreatic beta cells.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/111932/1/embj201591058.reviewer_comments.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/111932/2/embj201591058.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/111932/3/embj201591058-sup-0001-FigsS1-S4.pd

Gust response: a validation experiment and preliminary numerical simulations

In this paper the experimental setup and first results for a gust generator experiment will be presented. The experiment was carried out in the transonic wind-tunnel facility in Goettingen (DNW-TWG). The first goal of the experiment was to answer the question, whether it is possible to induce an unsteady flow field with a rigid moving profile as a gust generator. Furthermore the main objective of the experiment was the understanding of the physical phenomena of an impacting gust on an elastic structure. For that purpose a new set-up has been constructed and built, which allows the investigation of two subsequent airfoil-models in the flow of the wind tunnel. The first airfoil is active and should produce a generic gust. The second model located downstream is passive and responds to the unsteady load changes induced by the moving active profile. For a first investigation, amplitudes and frequencies were varied as well as the vertical position of both airfoils relative to each other. The experiment was conducted to deliver a comprehensive data base for validating the DLR in-house fluid-structure-interaction software “PyCSM” which has been developed for aeroelastic simulations in time domain. In order to support the experiment in the preparation phase, fluid-structure-interaction simulations in time domain have been carried out. These simulations mainly show the response amplitudes expected for the passive wing. For that purpose the DLR TAU Code for the calculation of the steady and unsteady aerodynamic loads and a finite element shell model have been used

The aeroelastic impact of engine thrust and gyroscopics on aircraft flutter instabilities

Since more and more modern civil aircraft are equipped with UHBR-engines for reasons of fuel efficiency and environmental aspects, the need to tackle specific engine related dynamic problems has occurred. The request for UHBR-engines with high bypass ratio numbers and with their intrinsic advantages of economic fuel consumption and lower acoustic emission asks for enhanced vibration prediction capabilities. Beside the energetic benefits such engines add to the aircraft design their rotating large diameter fans can influence the dynamic behaviour of the complete elastic aircraft fuselage in a very unfavourable manner. Additional questions which arise with regard to structural dynamics and aeroelastic stability are treated in this work. Especially in the scenario when large rotating engine masses are to be combined with elastic wing structures the possible occurrence of specific structural vibration problems can be avoided by taking the gyroscopic effects into account. As another important engine related aspect the modelling and the impact of the engine thrust is highlighted by integrating the first order deformation induced terms into the dynamical simulation model. By introducing an increased coupling level between the degrees of freedom in the equation of motion (through additional off-diagonal terms) both eigenfrequencies and eigenmodes are affected. In the case of high engine participation in the structural deformation we can observe a lowering of the eigenfrequencies (in the test aeroplane up to 6[%]) and a loss in symmetry properties in the now strongly asymmetric eigenmodes. With the occurrence of flutter cases the critical speed had been experienced to shift about an amount of similar magnitude. Although in the presented cases the flutter speed moved to higher values, it was found indespensable to check every individual aircraft configuration with regard to the stability margin

STRUCTURAL DYNAMIC INFLUENCE OF AN UHBR ENGINE ON A COANDA-WING

Due to the need of higher efficiency and the reduction of CO2 and noise emission the bypass ratio of gas turbines tends to increase. This leads to higher rotational masses which arises the question of gyroscopic moments influencing the eigenbehavior of the aircraft and thus the system stability regarding structural depended phenomena, e.g. flutter. Therefore this paper presents a multibody model to determine the structural coupling between a Coanda wing and an ultra high bypass ratio gas turbine (BPR of 17). The results in form of the spectral analysis of an eigenvalue analysis enables the understanding of the coupling mechanisms and gyroscopic influences. By analyzing the time dependent behavior of the wing-engine system under consid- eration of a follower force, representing the thrust, deepens the understanding of the structural load at the wing root

Windkanal-Flatteruntersuchungen an einem endlichen, geraden 2d-Verdichtergitter in inkompressibler Strömung

Es werden Windkanal-Flatteruntersuchungen an einem ebenen, geraden 2d-Verdichtergitter beschrieben. Die Schaufeln des Gitters sind in speziellen Aufhängungen drehelastisch gelagert. Bei unterkritischen Geschwindigkeiten wird das Gitter über eine zwangsbewegte Schaufel erregt. Gemessene Frequenzgänge werden auf Eigenschwingungen hin analysiert. Mit Hilfe dieser Ergebnisse lässt sich der Flattermechanismus beschreiben. Zum Vergleich werden Flatterrechnungen für ein 2d-Ringgitter sowie ein endliches, gerades Gitter durchgeführt