2,205 Works

Extraction and Fractionation of Natural Organic Compounds from Plant Materials with Supercritical Carbon Dioxide

Leandro Danielski
The aim of the present work was the measurement and modeling of multicomponent mixtures under supercritical conditions. The extraction and fractionation of natural organic components from rice bran and mandarin peel oils using supercritical carbon dioxide as solvent were investigated. Solid extractions and countercurrent experiments were performed from 7.5 to 40 MPa and from 35 to 70 °C. The results obtained have shown that supercritical technology can be chosen as an alternative process for the...

Development of a minimum stability criterion to prevent large amplitude roll motions in following seas

Florian Kluwe
The intact stability of ships, their ability to withstand external forces and loads without capsizing, to date is still evaluated on the basis of empirical and semi-empirical criteria. A number of accidents in the past years show that these existing criteria do not provide a sufficient safety level, especially with respect to certain ship types, like RoRo-vessels and large Container Ships. In particular, the dynamic behavior in longitudinal waves is not addressed by the existing...

Experimental investigation of the inertia and damping coefficients of a spheroid and surface ship in free heave

Georg Weinblum, S. Brooks & Paul Golovato
Experimental investigation of the inertia and damping coefficients of a spheroid and surface ship in free heave

Thinner and better: (Ultra-)low grammage bacterial cellulose nanopaper-reinforced polylactide composite laminates

Martin Hervy, Frederic Bock & Koon-Yang Lee
One of the rate-limiting steps in the large-scale production of cellulose nanopaper-reinforced polymer composites is the time consuming dewatering step to produce the reinforcing cellulose nanopapers. In this work, we show that the dewatering time of bacterial cellulose (BC)-in-water suspension can be reduced by reducing the grammage of BC nanopaper to be produced. The influence of BC nanopaper grammage on the tensile properties of BC nanopaper-reinforced polylactide (PLLA) composites is also investigated in this work....

Vergleich verschiedener linearer Algorithmen für Spline-Kurven

Axel Busch
Vergleich verschiedener linearer Algorithmen für Spline-Kurven Vergleich verschiedener linearer Algorithmen für Spline-Kurven: Die vorliegende Studienarbeit soll durch emen praktischen Vergleich die Brauchbarkeit verschiedener Spline-Algorithmen untersuchen. Alle hier behandelten Splines sind von nur einem Parameter abhängig, d.h. es sind Kurven, die aber teilweise auch frei im Raum liegen können. Als Maßstab für die Qualität eines Splines werden die folgenden Kriterien berücksichtigt: 1. Die entstehende Kurve soll möglichst glatt sein. 2. Der Rechenaufwand soll gering sein. 3....

Untersuchung über den Schiffsverkehr in der inneren Deutschen Bucht im Bereich der Wegeführungsenden

Kîng H. Kwik
Untersuchung über den Schiffsverkehr in der inneren Deutschen Bucht im Bereich der Wegeführungsenden

Active vibration control using the centrifugal forces of eccentrically rotating masses

Richard Bäumer
In this PhD thesis, active vibration control using eccentrically rotating masses is investigated. The basic layout of the so-called twin rotor damper (TRD) consists of two eccentric control masses rotating about two parallel axes. In a preferred mode of op-eration, the continuous rotation mode, both control masses rotate in opposite direction with a constant angular velocity. Under further operational constraints, the generated centrifugal forces superimpose to a harmonic control force in a single direction. The...

Extraction of oil and minor compounds from oil palm fruit with supercritical carbon dioxide

Phan-Tai Huan & Gerd Brunner
A significant quantity of tocochromanols and carotenoids remains in the residual from palm oil production by traditional screw pressing. Supercritical carbon dioxide extraction was used as alternative method with the purpose to recover better these valuable minor compounds. Total oil yield and co-extracted water were investigated in the course of extraction. Tocochromanols and carotenoids were evaluated, not only in the extraction oil, but also in the oil of residual fibre. Modelling of extraction process was...

Process development for production of aerogels with controlled morphology as potential drug carrier systems

Mohammad Alnaief
Aerogels are nanoporous materials with extremely low bulk density and high specific surface area. Usually they are produced following the sol-gel process followed by suitable solvent removal. In the past few years Aerogels have drawn an increasingly attention in different scientific and industrial applications. Because of their outstanding properties, they have been shown to be potential drug carrier systems. The aim of this work is to extend their potential in pharmaceutical applications by filling the...

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.

Bruchversuche an geschweißten Transportaugen für Schiffssektionen

Adolph Krohn
Bruchversuche an geschweißten Transportaugen für Schiffssektionen

ACRITH - High Accuracy Arithmetic Subroutine Library

Siegfried M. Rump
In the following the computer implementation of the new numerical methods presented in "Numerical results with verified accuracy" in this proceedings will be described. ...

Transport in nanoporous materials including MOFs : the applicability of Fick’s laws

Tobias Titze, Alexander Lauerer, Lars Heinke, Christian Chmelik, Nils E. R. Zimmermann, Frerich Keil, Douglas M. Ruthven & Jörg Kärger
Die Diffusion in nanoporösen Wirt-Gast-Systemen wird oft als viel zu kompliziert angesehen, als dass sie mit so “einfachen” Beziehungen wie dem ersten und zweiten Fickschen Gesetz vereinbar sein könnte. Wir zeigen nun, dass die mikroskopischen Diffusionsmesstechniken, vor allem die NMR-Spektroskopie mit gepulsten Feldgradienten (PFG) und die Mikrobildgebung mittels Interferenzmikroskopie (IFM) und IR-Mikroskopie (IRM), den direkten experimentellen Nachweis für die Anwendbarkeit der Fickschen Gesetze auf solche Systeme liefern. Dies gilt oft auch dann noch, wenn die...

Hybrid system calibration for multidimensional magnetic particle imaging

Anselm von Gladiß, Matthias Gräser, Patryk Szwargulski, Tobias Knopp & Thorsten M. Buzug
Magnetic particle imaging visualizes the spatial distribution of superparamagnetic nanoparticles. Because of its key features of excellent sensitivity, high temporal and spatial resolution and biocompatibility of the tracer material it can be used in multiple medical imaging applications. The common reconstruction technique for Lissajous-type trajectories uses a system matrix that has to be previously acquired in a time-consuming calibration scan, leading to long downtimes of the scanning device. In this work, the system matrix is...

Numerical investigation of compaction of deformable particles with bonded-particle model

Maksym Dosta, Clara Costa & Hazim Ali Al-Qureshi
In this contribution, a novel approach developed for the microscale modelling of particles which undergo large deformations is presented. The proposed method is based on the bonded-particle model (BPM) and multi-stage strategy to adjust material and model parameters. By the BPM, modelled objects are represented as agglomerates which consist of smaller ideally spherical particles and are connected with cylindrical solid bonds. Each bond is considered as a separate object and in each time step the...

Methoden zur Berechnung der Strömung um Körper in unbegrenzter idealer Flüssigkeit

Heinrich Söding
Methoden zur Berechnung der Strömung um Körper in unbegrenzter idealer Flüssigkeit

Impact of powdered activated carbon structural properties on removal of organic foulants in combined adsorption-ultrafiltration

Martin Schulz, Sönke Bünting & Mathias Ernst
The impact of structural properties of three commercial PACs as well as two mechanically ground PACs on their efficiency in NOM removal and fouling reduction in combined adsorption-ultrafiltration (PAC-UF) of northern German groundwater was investigated. All PACs showed highest adsorption affinity for medium molecular weight NOM fractions. The meso-pore surface area rather than the total surface area (B.E.T.) mainly governed the extent of NOM removal. However, adsorption of macromolecular NOM fractions, which were found to...

Lösender Angriff auf zementgebundene Baustoffe – Veränderungen der Porenstruktur und Folgen für Transport- und Korrosionsprozesse

Holle Kerstin Goedeke
Es wurden Korrosionsversuche an Zementmörteln mit stationären und instationären Randbedingungen durchgeführt. In weiteren Versuchen wurden die Veränderung der Porosität und Porenstruktur sowie die damit verbundenen Auswirkungen auf die Stofftransportprozesse betrachtet. Weiterhin wurden Simulationsberechnungen durchgeführt. Mit dem Ziel einer Verbesserung der Berechnung von Transportprozessen erfolgte eine Anwendung verschiedener Porenstrukturmodelle auf experimentell ermittelte Daten. Den Abschluss bildet die Vorstellung eines neuen Modellansatzes zur Beschreibung der Porenstrukturänderung infolge von Korrosionsprozessen.

Über die Ermittlung der schiffsähnlichen Umströmungskörper vorgegebener Quell-Senken-Verteilungen mit Hilfe elektronischer Rechenmaschinen

Klaus Eggers & Wolfgang Wetterling
Über die Ermittlung der schiffsähnlichen Umströmungskörper vorgegebener Quell-Senken-Verteilungen mit Hilfe elektronischer Rechenmaschinen

15. Seminar der LIBER Architecture Group

Inken Feldsien-Sudhaus
This year the National Library of Spain in Madrid hosted the 15th Seminar of the LIBER Architecture Group from 12th to 17th of April 2010. The innovative offer of tours and speeches as well as the possibility of program exchanges attracted interested participants from every corner of Europe. Of course, subjects such as renovation and extension of existing facilities abounded. This year to enhance more subjects of the day, several talks were directed towards the...

Reinigung schwermetallhaltiger Böden : ein Verfahrenskonzept

Simone Wömmel, Wolfgang Calmano & Kai Heining
Es wird eine neue Behandlungsmethode für schwermetallkontaminierte Böden vorgeschlagen, die aus mehreren Verfahrenschritten besteht. Zuerst wird eine Extraktion der Schwermetalle aus dem Boden mit schwachen organischen Säuren wie Essigsäure oder Citronensäure durchgeführt. Bei Bodenproben, die bis zu 149 g Blei/kg und bis zu 18 g Antimon/kg enthielten, wurden mit Essigsäure eine 83 %ige Abtrennung des Bleis und mit Citronensäure eine selektive 85 %ige Abtrennung des Antimons erreicht. Blei wird aus den hochkonzentrierten Eluaten in einer...

Dominant damping effects in friction brake noise, vibration and harshness : the relevance of joints

Merten Tiedemann, Sebastian Kruse & Norbert Hoffmann
The experimental analysis of a single component of a brake system and an assembly consisting of three components is used to clarify the relevance of joints in terms of damping and non-linearity in state-of-the-art brake systems. For this purpose a series of experimental modal analyses are conducted. A comparison of the results obtained from the single component and from the assembly strongly indicate that the joints which necessarily exist in an assembled structure have a...

Exchange of heavy metals between sediment components and water

Wolfgang Calmano, Wolfgang Ahlf & Ulrich Förstner
(...) The composition of interstitial waters in sediments is perhaps the most sensitive indicator of the types and the extent of reactions that take place between pollutant-loaded sediment particles and the aqueous phase that contacts them. The large surface area of fine-grained sediment in relation to the small volume of its trapped interstitial water ensures that minor reactions with the solid phases will be shown by major changes in the composition of the aqueous phase.

Große Pyramide - Der asymmetrische Kristall

Hans Jelitto
Der vorliegende Aufsatz befasst sich mit der geometrischen Form der Cheops-Pyramide in Gizeh. In der Ägyptologie wird der gemessene Böschungswinkel der Pyramide (51°50'40"), d. h. der Neigungswinkel der Seitenflächen, auf das Verhältnis 7/11 zurückgeführt. Daneben tauchen in der Literatur in diesem Zusammenhang seit über 100 Jahren regelmäßig die transzendente Zahl pi sowie die irrationale Zahl des goldenen Schnitts (phi) auf. Auf der anderen Seite wurde festgestellt, dass die vier Grundkanten der quadratischen Pyramide um bis...

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...

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