2,228 Works

Exakte Fehlerschranken für Eigenwerte und Eigenvektoren

Siegfried M. Rump
Wie (...) bereits deutlich gemacht, können auf Rechenanlagen durch Rundungsfehler große Ungenauigkeiten entstehen. Dies kann sich insbesondere schwerwiegend auswirken, wenn die Ergebnisse nicht als falsch erkannt werden und mit ihnen weiter gerechnet wird. (...) In der vorliegenden Arbeit werden Algorithmen vorgestellt, die bewiesene Fehlerschranken für Eigenwert/Eigenvektorpaare berechnen. Da die erhaltenen Ergebnisse bewiesenermaßen richtig sind, entfällt der bis jetzt notwendige Mehraufwand des Benutzers für Kontrollen im Algorithmus und am Ergebnis, durch die letzlich doch keine Sicherheit...

Assessment of power consumption of helicopter flight control systems without swashplate

Tom Neuheuser & Udo B. Carl
Nowadays helicopter flight control in the most common configurations is realized by collective and cyclic variation of the angle of attack of each rotor blade. The collective blade control pitches the rotor blades to equal angles of attack around their longitudinal axis, changing the rotor thrust at constant rotor speed. Yaw and roll control is realized via cyclic blade motion by changing the angle of attack of every rotor blade locally and periodically during one...

Schiffe geringsten Widerstandes

Georg Weinblum, Dieter Wustrau & Gerrit Vossers
Schiffe geringsten Widerstandes

Entwicklungstrends bei Basissystemen und ihre Wechselwirkungen zum Flugzeugentwurf : 2. Symposium Flugzeug-Systemtechnik, Workshop DGLR-Fachausschuß S2.1 "Starrflügelsysteme"

Dieter Scholz & Deutsche Gesellschaft Für Luft- Und Raumfahrt-Lilienthal-Oberth E.V. (DGLR)
Workshop am Technologiezentrum Hamburg-Finkenwerder, 15./16. September 1997, Tagungsband / Fachausschuß S2.1 Starrflügelsysteme, Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V. (DGLR) / 2. Symposium Flugzeug-Systemtechnik. Inhalt: Teil A: Aspekte des Gesamtflugzeugs, Teil B: Systeme und Flugzeug-Nutzung, Teil C: Systeme und Flugzeugauslegung, Teil D: Systemrepräsentanz in Flugsimulatoren

Algorithms for verified inclusions: theory and practice

Siegfried M. Rump
In the following basic principles of algorithms computing guaranteed bounds are developed from a theoretical and a practical point of view. Some fundamental theoretical facts are repeated where, for more detailed information, the reader is referred to the literature (...) Furthermore practical aspects are discussed, especially how the process of computing a guaranteed result really works performed by means of checking assumptions of mathematical theorems. This checking process is performed automatically. The various steps from...

PLOTRS Ein Plot Programm für ROSTE

Chen Far Hung
PLOTRS Ein Plot Programm für ROSTE

Wasserbauliche Systemanalyse zur Bewertung der Auswirkungen des Klimawandels für tidebeeinflusste Nebengewässer der Elbe

Edgar Nehlsen
Die vorliegende Arbeit behandelt drei wesentliche wasserbauliche Fragestellungen an den Nebenflüssen der Unterelbe. Diese beziehen sich auf i) den Hochwasserschutz, ii) die Morphodynamik und die morphologische Entwicklung sowie iii) die Auswirkungen des Klimawandels auf das Abflussgeschehen sowie die Morphodynamik in den tidebeeinflussten Unterläufen.

SO2 emissions from Popocatépetl volcano : emission rates and plume imaging using optical remote sensing techniques

Michel Grutter, Roberto Basaldud, Claudia Rivera, Roland Harig, W. Junkerman, Ernesto Caetano & Hugo Delgado Granados
Sulfur diOxide emissions from the Popocatépetl volcano in central Mexico were measured during the MILAGRO field campaign in March 2006. A stationary scanning DOAS (Differential Optical Absorption Spectrometer) was used to monitor the SO2 emissions from the volcano and the results were compared with traverses done with a COSPEC from the ground and a DOAS instrument on board an ultra-light aircraft. Daytime evolutions as well as day-today variation of the SO2 emissions are reported. A...

A model-order reduction technique for low rank rational perturbations of linear eigenproblems

Heinrich Voß & Frank Blömeling
Large and sparse rational eigenproblems where the rational term is of low rank k arise in vibrations of fluid–solid structures and of plates with elastically attached loads. Exploiting model order reduction techniques, namely the Pad´e approximation via block Lanczos method, problems of this type can be reduced to k–dimensional rational eigenproblems which can be solved efficiently by safeguarded iteration.

Fluid-structure interaction of flexible lifting bodies with multi-body dynamics of order-reduced models and the actuator-line method

Sönke Neumann
Die Entwicklung von innovativen Quellen erneuerbarer Energie stellt neue Anforderungen an Simulationswerkzeuge. In dieser Dissertation werden modellbasierte Methoden zur Abbildung einer Fluid-Struktur-Interaktion am Beispiel einer Vertikalachsenturbine entwickelt. Die Kinematik einer Turbine wird durch einen Mehrkörperansatz mit flexiblen Körpern simuliert. Die Dynamik der flexiblen Körper ist durch ordnungsreduzierte Modelle repräsentiert. Die Fluiddynamik wird über Reynolds-gemittelte Navier-Stokes-Gleichungen in Verbindung mit einer Aktuatorlinienmethode abgebildet. Diese benutzt ein reduziertes Modell eines Tragfügels, der durch externe Kräfte in den Momentengleichungen...

Technologiegestützte Angebotserstellung für den Umbau komplexer Investitionsgüter

Fedor Titov
This thesis develops a modular tender preparation process for retrofit projects of complex investetment goods like ships, buildings or industrial plants in three steps: data preparation, solution finding and outcome provision. Several methods and adapted technological tools support this process and reduce the effort for the tender preparation. They allow furthermore to integrate the customer in the deci-sion process and thus to increase his acceptance of the solution.

Investigating the thermodynamic performances of TO-based metamaterial tunable cells with an entropy generation approach

Guoqiang Xu, Haochun Zhang, Xiu Zhang & Yan Jin
Active control of heat flux can be realized with transformation optics (TO) thermal metamaterials. Recently, a new class of metamaterial tunable cells has been proposed, aiming to significantly reduce the difficulty of fabrication and to flexibly switch functions by employing several cells assembled on related positions following the TO design. However, owing to the integration and rotation of materials in tunable cells, they might lead to extra thermal losses as compared with the previous continuum...

Sediment criteria development : contributions from environmental geochemistry to water quality management

Ulrich Förstner, Wolfgang Ahlf, Wolfgang Calmano & Michael Kersten
The role of sediments as carriers and potential sources of contaminants is reviewed. A program of sediment studies will normally consist of a series of objectives of increasing complexity, each drawing part of its information from the preceding data base. The study of dated sediment cores has proven particulary useful as it provides a historical record of the various influences on the aquatic system by indicating both the natural background levels and the man-induced accumulation...

Entwicklung einer Suchfunktion mit Information-Retrieval-Schnittstelle für den Dokumentenserver OPUS unter besonderer Berücksichtigung von Entwurfsmustern

Oliver Marahrens
In der vorliegenden Abschlussarbeit wurde eine Suchfunktion für den Dokumentenserver TUBdok, der von der Universitätsbibliothek an der Technischen Universität Hamburg-Harburg betrieben wird, entwickelt. Für die Suche wurde eine in das Dokumentenserver-System eingepasste Oberfläche entwickelt. Außerdem steht eine per URL ansteuerbare Information-Retrieval-Schnittstelle zur Verfügung, die das layout-unabhängige XML-Format OpenSearch zurückgibt. Die Suchfunktion basiert auf Apache Lucene und wurde über eine im Zend-Framework vorhandene Implementierung in den PHP-basierten Dokumentenserver integriert. Auch das Indizierungssystem, mit dem die Inhalte...

TUHH Spektrum Oktober 2005

Präsident Der Technischen Universität Hamburg-Harburg
Carbon Nanotubes, Nanotechnologie in Werkstoffen, Extremozyme als Biokatalysatoren, Neue Prüftechnologie zur Erkennung gefälschter Münzen, Logistik, Abenteuer Studium

Implementation of earthworm-assisted constructed wetlands to treat wastewater and possibility of using alternative plants in constructed wetlands

Nathasith Chiarawatchai
The aim of this research was to add the earthworms into the constructed wetlands, both in Germany and Thailand, in order to investigate whether they could improve the treatment performances. For Germany, earthworm-assisted constructed wetlands exhibited better treatment efficiency than conventional vertical subsurface-flow constructed wetlands and the unplanted constructed wetlands with earthworms. For Thailand, the production of sludge on the surface of wetlands was reduced by 40% with earthworms. Apart from that, alternative plants with...

Modeling of aerated upflowed fixed bed reactors for the nitrification

Joachim Behrendt
A mathematical model for the nitrification in an aerated fixed bed reactor has been developed. This model is based on material balances in the bulk liquid, gas phase and in the biofilm area. The fixed bed is divided into a number of cells according to the reduced remixing behaviour. A fixed bed cell consists of 4 compartments: the support, the gas phase, the bulk liquid phase and the stagnant volume containing the biofilm. In the...

Fracture toughness of porous materials – Experimental methods and data

Hans Jelitto & Gerold A. Schneider
We provide numerical experimental data and detailed information about the sample preparation and the experimental methods, used by different research groups for measuring the fracture toughness of porous materials. These data are supplemental information to the publication “A Geometric Model for the Fracture Toughness of Porous Materials,” [1], which is based on experimental data of ceramic and polymer materials. For the sake of completeness, we provide here also data from fracturing metallic foams. The corresponding...

Clinical and wear analyses of 9 large metal-on-metal total hip prostheses

Maarten C. Koper, Nina M. C. Mathijssen, Florian Witt, Michael Morlock & Stephan B. W. Vehmeijer
Metal-on-Metal (MoM) total hip arthroplasties (THA) are associated with pseudotumor formation and high revision rates. This prospective study analysed the clinical and wear analyses of 9 large Metal-on-Metal (MoM) total hip arthroplasties (THA) to understand the underlying mechanisms of failure. The MoM bearings were revised for multiple reasons; the main reason was pseudotumor formation.

Robust sampled-data control of hydraulic flight control actuators

Markus Gustav Kliffken
In todays flight-by-wire systems the primary flight control surfaces of modern commercial and transport aircraft are driven by electro hydraulic linear actuators. Changing flight conditions as well as nonlinear actuator dynamics may be interpreted as parameter uncertainties of the linear actuator model. This demands a robust design for the controller. Here the parameter space design is used for the direct sampled-data controller synthesis. Therefore, a static output controller is choosen, the model discretized by approximation...

Omnidirectional photonic band gap in polymer photonic crystal slabs

Jan Hendrik Wülbern, Markus Schmidt, Manfred Eich, Uwe Hübner, Richard Boucher, Frank Marlow & Willi Volksen
In this letter, we report on the experimental observation of a complete in-plane photonic band gap for transverse-electric-like polarized modes in a polymer photonic crystal slab with a triangular array of holes. We performed transmission measurements on two-dimensional photonic crystal slabs in both principal directions of the triangular lattice. For a propagation distance of 40 lattice constants, the transmission was effectively suppressed regardless of propagation direction below −15 dB over a bandwidth of 65  nm. The...

Reconstruction of governing equations from vibration measurements for geometrically nonlinear systems

Marco Didonna, Merten Stender, Antonio Papangelo, Filipe Fontanela, Michele Ciavarella & Norbert Hoffmann
Data-driven system identification procedures have recently enabled the reconstruction of governing differential equations from vibration signal recordings. In this contribution, the sparse identification of nonlinear dynamics is applied to structural dynamics of a geometrically nonlinear system. First, the methodology is validated against the forced Duffing oscillator to evaluate its robustness against noise and limited data. Then, differential equations governing the dynamics of two weakly coupled cantilever beams with base excitation are reconstructed from experimental data....

Agrochemical plastic packaging waste decontamination for recycling: pilot tests in Italy

Caterina Picuno, Zoe Godosi, Kerstin Kuchta & Pietro Picuno
Agriculture, one of the main economic pillars in Europe, plays a growing important role towards the environmental sustainability of the extra-urban land, in which the agricultural activities may proactively contribute to control and regulate the whole ecological conditions. Modern agriculture currently needs big quantities of agrochemicals, which are necessary for the growth and protection of crops and animals. These agrochemicals are commercially distributed to consumers in many types of containers. The most widely used packaging...

Ultimate strength of ship plating - A proof of capacity under combined in-plane loads

Richard C. Hayward
Die Arbeit beschäftigt sich mit der Notwendigkeit eines Nachweises der Plattenkapazität unter kombinierten Belastungen in der Plattenebene. Umfangreiche numerische Studien unter Nutzung der Finite-Elemente-Methode sind durchgeführt worden. Alle für den Schiffbau relevanten Lastkombinationen und Plattenkonfigurationen wurden hierbei berücksichtigt. Die Studien werden verwendet, um die Versagensmechanik der Platten zu untersuchen und bestehende Nachweise der Plattenkapazität zu bewerten. Um sowohl qualitative als auch quantitative Akzeptanzkriterien zu erfüllen, wird ein neuer Nachweis der Plattenkapazität unter kombinierten Belastungen in...

Smart logistics of organic waste collection in cities

Lorena Bearzotti, Javier Maturana & Maria Isabel Vega
Waste management is a growing problem all around the world with implications to society, environment, health and economy. In this context, the waste is considered as the last step in the consuming process. However, a smart waste management is possible by the generation of value from the garbage and the optimization of collection routes, landfills location and the determination of the transport fleet. This article addresses the problem of value generation from organic waste in...

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