354 Works

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....

Wie digital ist Informationskompetenz? : Materialien zu einem Workshop

Thomas Hapke
Workshop am 5. Februar 2016 auf dem Kunst- und Mediencampus Finkenau der Hochschule für Angewandte Wissenschaften Hamburg (Folien, Reader, Ergebnisse) im Rahmen der Move and Make – in/trans/formation durch Themen, Trends und Visionen - Fachtagung des Department Information der HAW Hamburg anlässlich 70 Jahre bibliothekarische Ausbildung für öffentliche und wissenschaftliche Bibliotheken in Hamburg und 45 Jahre Fachbereich Bibliothek und Information an der Hochschule für Angewandte Wissenschaften (http://intransformation.hamburg/).

Das Jubiläums-Stichwort „in/trans/formation“ zu 70 Jahren BibliothekarischeThomas...

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...

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.

Performance evaluation of a sensor concept for solving the direct kinematics problem of general planar 3-RPR parallel mechanisms by using solely the linear actuators’ orientations

Stefan Schulz
In this paper, we experimentally evaluate the performance of a sensor concept for solving the direct kinematics problem of a general planar 3-RPR parallel mechanism by using solely the linear actuators’ orientations. At first, we review classical methods for solving the direct kinematics problem of parallel mechanisms and discuss their disadvantages on the example of the general planar 3-RPR parallel mechanism, a planar parallel robot with two translational and one rotational degrees of freedom, where...

Recycling-oriented design in soft robotics

Anh Minh Nguyen & Arthur Seibel
Soft robotics is a novel approach in the field of robotics. Soft robots or soft actuators are typically polymer-based and are characterized by their flexibility and adaptability, which brings new far-reaching applications. Soft robotics is currently at the peak of its research. One circumstance that is also present in this age is constant climate change; there is a demand for sustainability. This goes hand in hand with the design of products that are suitable for...

Desiccant-assisted air conditioning system relying on solar and geothermal energy during summer and winter

Peter Niemann, Finn Richter, Arne Speerforck & Gerhard Schmitz
At Hamburg University of Technology the combination of an open cycle desiccant-assisted air conditioning system and a geothermal system is investigated in the framework of different research projects for several years. The objective of this study is to investigate the energy efficiency of the overall system and to evaluate the geothermal system during summer and winter mode, based on data measured for a temperate climate region. Monitoring results of the performance for dehumidification and remoistening...

Process and mechanical properties: Applicability of a scandium modified Al-alloy for laser additive manufacturing

K. Schmidtke, F. Palm, A. Hawkins & Claus Emmelmann
The applicability of an aluminium alloy containing scandium for laser additive manufacturing (LAM) is considered. Modified aluminium alloys with a scandium content beyond the eutectic point offer great potential to become a high prioritized aerospace material. Depending on other alloying elements like magnesium or zirconium, strongly required weight reduction, corrosion resistance and improved strength properties of metallic light weight alloys can be achieved. The development, production and testing of parts built up by a laser...

Facing the challenge of sustainable bioenergy production : could halophytes be part of the solution?

Ahmed Debez, Ikram Belghith, Jan Friesen, Carsten Montzka & Skander Elleuche
Due to steadily growing population and economic transitions in the more populous countries, renewable sources of energy are needed more than ever. Plant biomass as a raw source of bioenergy and biofuel products may meet the demand for sustainable energy; however, such plants typically compete with food crops, which should not be wasted for producing energy and chemicals. Second-generation or advanced biofuels that are based on renewable and non-edible biomass resources are processed to produce...

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...

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...

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...

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...

A biologically inspired framework for the intelligent control of mechatronic systems and its application to a micro diving agent

Wallace Moreira Bessa, Gerrit Brinkmann, Daniel-André Dücker, Edwin Kreuzer & Eugen Solowjow
Mechatronic systems are becoming an intrinsic part of our daily life, and the adopted control approach in turn plays an essential role in the emulation of the intelligent behavior. In this paper, a framework for the development of intelligent controllers is proposed. We highlight that robustness, prediction, adaptation, and learning, which may be considered the most fundamental traits of all intelligent biological systems, should be taken into account within the project of the control scheme....

Development of plasma-laser-hybrid welding process

Claus Emmelmann, Marc Kirchhoff & Nikolai Petri
In order to fulfill demands for quality and efficiency in the field of welding engineering, numerous works in research on the optimization of the welding processes are in progress. [1] Aims of this research are increasing the welding speed, stabilizing the welding processes, decreasing the reject rate and reducing the pre and post welding machining. This work relates to the development of a new plasma-laser hybrid welding method in order to increase the productivity of...

Reclaiming biologically pretreated greywater for reuse by photocatalytic oxidation: qualitative study on the removal of trace organics

Holger Gulyas, Carlos F. Liriano Jorge, Margrit Reich & Ralf Otterpohl
This study was carried out for gathering qualitative information about the potential of photocatalytic oxidation for the removal of trace organics (analysed by gas chromatography coupled to mass spectrometry, GC/MS) from biologically pretreated greywater to make it suitable for high quality reuse applications like groundwater recharge. Additionally, fractions of bulk organics (humic substances, building blocks, and low molecular weight organic acids) were quantified by liquid chromatography with organic carbon detection. Biologically pretreated greywater was subjected...

Multi-fixed-bed bioreactor system applied for bioprocess development of immobilized lactic acid bacteria

Rebecca Faschian, Sonakshi De & Ralf Pörtner
The multi-fixed-bed bioreactor “Multiferm” provides a downscaled system for the development of fixed-bed processes with immobilized microorganisms or cells. It consists of twelve single fixed-bed units that can be operated independently. Different bacterial strains, carriers used for immobilization, media or flow rates can be studied in one compact experimental set-up. Experiments can be run in parallel to allow for determination of experimental errors. In these studies several continuous cultivations were carried out with Lactobacillus delbrueckii...

Sex differences in the morphological failure patterns following hip resurfacing arthroplasty

Andrea Hinsch, Eik Vettorazzi, Michael Morlock, Wolfgang Rüther, Michael Amling & Jozef Zustin
Background: Metal-on-metal hybrid hip resurfacing arthroplasty (with a cementless acetabular component and a cemented femoral component) is offered as an alternative to traditional total hip arthroplasty for the young and active adult with advanced osteoarthritis. Although it has been suggested that women are less appropriate candidates for metal-on-metal arthroplasty, the mechanisms of prosthesis failure has not been fully explained. While specific failure patterns, particularly osteonecrosis and delayed type hypersensitivity reactions have been suggested to be...

Compiler-based code compression for hard real-time systems

Kateryna Muts, Arno Luppold & Heiko Falk
Real-Time Systems often come with additional requirements apart from being functionally correct and adhering to their timing constraints. Another common additional optimization goal is to meet code size requirements. Code compression techniques might be utilized to meet code size constraints in embedded systems. We show how to extend a compiler targeting hard real-time systems by an asymmetric compiler-based code compression/decompression, where the compression is performed at the compilation time and the decompression takes place at...

Systematic development of lightweight components for highly dynamic laser-remote-scanners using topology optimization

Claus Emmelmann, Marc Kirchhoff & Frank Beckmann
Lightweight design is an important issue within the product development process, especially if components are subjected to dynamical movements. This paper is a systematical approach for the development of weight optimized components for laser remote scanners using topology optimization. A topology optimization of a mirror mount is demonstrated, starting with the determination of mechanical boundary conditions of a complex laser remote scanner. Based on the optimization results, the process of designing a component suitable for...

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.

Post-processing of additively manufactured cutting edges by laser ablation

Sina Hallmann, Tim Wolny & Claus Emmelmann
In the packaging industry, cutting dies are used to process paper based material. The dies are mainly manufactured via steel strip principle, which consists of many manual steps and is difficult to automate. Laser material processing represents a promising approach to simplify manufacturing. This study realized additively manufactured cutting edges post-processed by laser ablation to achieve a defined final profile shape. First verification shows that laser ablation appears to be attractive for finishing of additively...

BEM and FEM results of displacements in a poroelastic column

Bettina Albers, Stavros A. Savidis, H. Ercan Tasan, Otto von Estorff & Malte Gehlken
The dynamical investigation of two-component poroelastic media is important for practical applications. Analytic solution methods are often not available since they are too complicated for the complex governing sets of equations. For this reason, often some existing numerical methods are used. In this work results obtained with the finite element method are opposed to those obtained by Schanz using the boundary element method. Not only the influence of the number of elements and time steps...

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