2,086 Works

Versuche zur Querkrafttragfähigkeit von Stahlbetonplatten unter auflagernahen Einzellasten : Versuchsbericht

Lukas Henze & Günter Axel Rombach
Test report on a series of tests on the shear capacity and load transfer of reinforced concrete slabs without shear reinforcement under concentrated block loads.

Sediment quality objectives and criteria development in Germany

Ulrich Förstner, Wolfgang Ahlf & Wolfgang Calmano
New objectives regarding the improvement of water quality as well as problems with the resuspension and land deposition of dredged materials require a standardized assessment of sediment quality. Numerical approaches are based on the accumulation, pore water concentrations, solid/liquid partition and elution properties of contaminants; these non-biological schemes can be extended and completed by additional biological criteria. Specific biological approaches have been combined with chemical surveys (for example Sediment Quality Triad). In Germany, numerical criteria...

Einfluss von Druckmittelspannungen auf die Betriebsfestigkeit von geschweißten Schiffskonstruktionen

Jörg Rörup
Einfluss von Druckmittelspannungen auf die Betriebsfestigkeit von geschweißten Schiffskonstruktionen

Facial animation using muscles to control the mimic articulation of phonemes

Anna Mempel
This master thesis describes an approach to facial animation using the muscle feature of Autodesk Maya. The skeletal, muscular and skin anatomy of the human head is abstracted from nature. The muscular structure is modelled to act as a highly reusable interface between any skull and skin model. The muscle actions are based on the Facial Action Coding System and are implemented using weights painted on the skin mesh. By combining several muscle actions it...

Modellversuche zur Steuerfähigkeit eines Schiffes im achterlichen Seegang

Peter Boese
Modellversuche zur Steuerfähigkeit eines Schiffes im achterlichen Seegang

Dead time optimization method for power converter

Christian Deselaers, U. Bergmann & Frank Gronwald
This paper introduces a method for dead time optimization in variable speed motor drive systems. The aim of this method is to reduce the conduction time of the freewheeling diode to a minimum without generation of cross conduction. This results in lower losses, improved EMC, and less overshooting of the phase voltage. The principle of the method is to detect beginning cross currents without adding additional components in the half bridge like resistors or inductances....

A continuum mechanical model for the description of solvent induced swelling in polymeric glasses: Thermomechanics coupled with diffusion

Jana Wilmers & Swantje Bargmann
The problem of interest is the numerical modelling of Case II diffusion in polymeric glasses. Case II diffusion is characterised by a strong coupling between diffusion and deformation and is highly temperature dependent. In this work, a general continuum mechanical framework describing a three-way coupling of thermomechanics and diffusion is adapted to the description of Case II diffusion. Numerical studies are carried out to examine the capability of the model and the nature of the...

M03.006 Content of free fat by Soxhlet extraction

Eike Romann, Andrea Simon & Alina Stahl
Der Fettgehalt einer Probe wird durch Soxhlet-Extraktion bestimmt. Dabei wird die homogenisierte Probe mit Petroleumbenzin (40-60°C) für 6 Stunden in einer Soxhlet-Apparatur gekocht, das Lösungsmittel wird anschließend abdestilliert und der Gehalt des Gesamtfettes wird gravimetrisch bestimmt. Der Anteil an eingeschlossenen Lipiden in einer Probe (z.B. Milchfett) wird mit dieser Methode nicht erfasst.

Steuerung der Reaktionsselektivität der biokatalytischen Fettsäureestersynthese

Sören Baum
Eine industrielle Herausforderung für die lösungsmittelfreie Synthese von hochreinem Mono oder –diacylglyceride (MAG´s & DAG´s) ist das dem Reaktionssystems innewohnende Phasenverhalten und die daraus resultierenden geringen Reaktionsselektivitäten. In der vorliegenden Dissertation konnte durch geringe Mengen des amphoteren Tensids Cocoamidpropyl Betain in einer lösungsmittelfreien Biokatalyse eine Steigerung der Selektivität hinzu MAG’s sowie die Löslichkeit von Glycerol in der unpolaren Reaktionsphase gezeigt werden und somit wurden gleiche MAG Gleichgewichtsanteile erreicht wie unter Einsatz des Lösungsmittels tert-Butanol. Eine...

M03.010 Determination of anions in aqueous samples by ion chromatography

Jörg Carstens, Eike Romann & Alina Stahl
Anions such as chloride, nitrate, phosphate, sulfate, fluoride, nitrite, bromide and sulfite in aqueous samples are determined through ion chromatography by using an anion exchange column and a carbonate eluent. Quantification is performed by comparison of peak areas in standards and samples.

M03.008 Determination of free carbohydrates and organic acids by ion exclusion HPLC-RI

Jörg Carstens & Alina Stahl
Aqueous samples are centrifuged and directly analysed by an HPLC system coupled to a refractive index detector to determine free carbohydrates such as cellobiose, glucose, xylose, arabinose and degradation products like HMF and furfural. Bound carbohydrates are extracted with acid hydrolysis (4% H2SO4) beforehand. Separation is performed with an ion exclusion HPLC phase column.

Towards sustainable development by creation of green social entrepreneur's communities

Ali Zahedi & Ralf Otterpohl
Entrepreneurship is a part of economy which is demanded in modern open economies. Structural changes in the society are needed for creation of entrepreneurship. The current situation shows a clash between the economic and the ecological system in global scale which will result in grave ecological catastrophes for the future. In this article, feasibility of shifting with a structural change in order to redefine links between economy, ecology and society through sustainability will be investigated....

M03.007 Determination of free carbohydrates by HPLC-RI

Jörg Carstens, Eike Romann & Alina Stahl
For the determination of free carbohydrates and their degradation products, such as cellobiose, glucose, xylose, arabinose, HMF and furfural, aqueous samples are centrifuged and analysed by an HPLC system coupled to a refractive index detector. Separation is performed with a Polymer-based HPLC phase column which combines steric exclusion, ligand exchange and partition effects.

Effect of cavity preparation and bone mineral density on bone-interface densification and bone-implant contact during press-fit implantation of hip stems

Johanna Bätz, Philipp Messer-Hannemann, Frank Lampe, Anke Klein, Klaus Püschel, Michael Morlock & Graeme Michael Campbell
Implant loosening and periprosthetic fracture are two major revision causes for uncemented hip stems. The chosen method of cavity preparation could play a key role for both failure mechanisms. The aim of this study was to determine the dependence of the broach type as well as patient bone mineral density (BMD) on densification and contact conditions at the bone-implant interface. Hip stems were implanted into cadaveric femora using compaction, blunt extraction or sharp extraction broaches...

Electrical stimulation of NIH-3T3 cells with platinum-PEDOT-electrodes integrated in a bioreactor

Grit Blume, Wiebke Müller-Wichards, Christiane Göpfert, Ralf Pörtner & Jörg Müller
The objective of this work involves the development and integration of electrodes for the electrical stimulation of cells within a bioreactor. Electrodes need to fit properties such as biocompatibility, large reversible charge transfer and high flexibility in view of their future application as implants on the tympanic membrane. Flexible thin-film platinum-poly(3,4-ethylene-dioxythiophene)-electrodes on a poly(ethylene terephthalate)-foil manufactured using microsystems technology were integrated into a bioreactor based on the design of a 24 well plate. The murine...

Interpolationsbasierte Reduzierte-Basis-Modellierung von Lösungskurven mit Umkehrpunkten

Hagen Eichel
Simulating physical processes often leads to large systems of parameter dependent nonlinear equations. To reduce the computational complexity reduced basis methods are used, that can be distinguished in local and global methods. Turning points with respect to the parameter are usually not permitted when using global methods. In this work a global interpolation based approach for problems with turning points is developed and its advantages and limits are demonstrated.

Development of hydrogen storage systems using Sodium alanate

Gustavo Adolfo Lozano Martinez
Hydrogen storage systems based on sodium alanate are studied, modelled, and optimised, on the basis of both experimental and theoretical approaches. The experimental hydrogen sorption behaviour (kinetics, heat transfer and cycling) of small cells up to kg-scale storage tanks is compared and analysed. In particular the effect of the size of the system, powder compaction, and addition of expanded graphite on the sorption behaviour is investigated and characterized. In order to implement simulations and further...

Implementing Global Masters into Parallel Condensation

Andreas Pelzer, Birgit Hofferek & Heinrich Voß
The dynamic analysis of structures leads to very large generalized eigenvalue problems. Their number of unknowns can be reduced to a manageable size by condensation methods which can be parallelized by combining it with substructuring. In this note we implement global masters into the parallel condensation process.

From open source in the digital to the physical world: a smooth transfer?

Nizar Abdelkafi, Thorsten Blecker & Christina Raasch
The purpose of this paper is to investigate the transferability of the open source principles of product development from the realm of software to the realm of physical products.

Damage stability and subdivision of semisubmersible rigs

Walter Abicht
Damage stability and subdivision of semisubmersible rigs

Ultra-high performance concrete (UHCP) precast segmental bridges

Jaewoo Shin
Brücken werden schon seit vielen Tausenden von Jahren errichtet. Es liegen somit schon viele Erfahrungen vor. Dennoch werden neue Bauverfahren benötigt, die eine schnellere Errichtung der Konstruktion ermöglichen, weitgehend ohne Beeinflussung des vorhandenen Verkehrs. Weiterhin werden Bauwerke gesucht, die die zunehmenden Verkehrs- und Umwelteinwirkungen aufnehmen können und neue Baustoffe, die die Dauerhaftigkeit verbessern und somit die Unterhaltskosten reduzieren. Extern vorgespannte Segmentfertigteilbrücken (PSB) sind eine Lösung für diese Anforderungen. Die großen Vorteile dieser Bauweise belegen die...

Rapid sample delivery for megahertz serial crystallography at X-ray FELs

Max Oliver Wiedorn, Salah Awel, Andrew J. Morgan, Kartik Ayyer, Yaroslav Gevorkov, Holger Fleckenstein, Nils Roth, Luigi Adriano, Richard Bean, Kenneth R. Beyerlein, Joe Chen, Jesse Coe, Francisco Cruz-Mazo, Tomas Ekeberg, Rita Graceffa, Michael Heymann, Daniel A. Horke, Juraj Knoška, Valerio Mariani, Reza Nazari, Dominik Oberthür, Amit K. Samanta, Raymond G. Sierra, Claudiu A. Stan, Oleksandr Yefanov … & Henry N. Chapman
Liquid microjets are a common means of delivering protein crystals to the focus of X-ray free-electron lasers (FELs) for serial femtosecond crystallography measurements. The high X-ray intensity in the focus initiates an explosion of the microjet and sample. With the advent of X-ray FELs with megahertz rates, the typical velocities of these jets must be increased significantly in order to replenish the damaged material in time for the subsequent measurement with the next X-ray pulse....

Recovery of differential equations from impulse response time series data for model identification and feature extraction

Merten Stender, Sebastian Oberst & Norbert Hoffmann
Time recordings of impulse-type oscillation responses are short and highly transient. These characteristics may complicate the usage of classical spectral signal processing techniques for (a) describing the dynamics and (b) deriving discriminative features from the data. However, common model identification and validation techniques mostly rely on steady-state recordings, characteristic spectral properties and non-transient behavior. In this work, a recent method, which allows reconstructing differential equations from time series data, is extended for higher degrees of...

Lubrication analyses of cam and flat-faced follower

Hazim U. Jamali, Amjad Al-Hamood, Oday Ibraheem Abdullah, Adolfo Senatore & Josef Schlattmann
The principal factors that affect the characteristics of contact problem between cam and follower vary enormously during the operating cycle of this mechanism. This includes radius of curvature, surface velocities and applied load. It has been found over the last decades that the mechanism operates under an extremely thin film of lubricant. Any practical improvement in the level of film thickness that separates the contacted surfaces represents an essential step towards a satisfactory design of...

Content management and knowledge management : two faces of ontology-based deep-level interpretation of text

Irma Sofia Espinosa Peraldi
In order to make content management systems able to exploit annotations about content semantics for the management of content, this work proposes an approach for text interpretation that is built on the principles of logic-based abduction. The approach is presented in the context of a framework that allows for a deep-level interpretation of text. The research contributions of this work encompass (1) a framework for the integration of shallow-processing techniques of text with logic-based techniques...

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