3,026 Works

Entwicklung einer Simulationsmethodik zur schnellen Dimensionierung komplexer Materialflusssysteme

Svenja Bahnsen, Harald Köck, Johannes Hinckeldeyn & Jochen Kreutzfeldt
Simulation models play an important role in the planning and development in intralogistics. Especially the layout and dimensioning of order picking processes, warehouses and handling engineering is often based on static estimations and rules of thumb. This leads to inferior planning results, because dynamic effects, such as peaks of orders, and sequential process steps are often neglected. The most common solution at the moment are event discrete simulation models, which create a significant workload for...

Deep-Learning-Verfahren zur 3D-Objekterkennung in der Logistik

Marko Thiel, Johannes Hinckeldeyn & Jochen Kreutzfeldt
The reliable detection of objects in sensor data is a fundamental requirement for the autono-mization of logistic processes. Especially the recognition of objects in 3D sensor data is important for flexible autonomous applications. Deep learning represents the state of the art for object recognition in 2D image data. This article presents various current approaches to use deep learning for 3D object recognition. An essential feature of these approaches is the use of point clouds as...

Nanoporous-gold-polypyrrole hybrid materials for millimeter-sized free standing actuators

Benedikt Roschning & Jörg Weissmüller
Advanced Materials Interfaces published by Wiley-VCH GmbH This work studies the actuation of hybrid materials made from nanoporous gold, polypyrrole, and aqueous electrolyte. The deposition protocol affords a conformal polypyrrole coating on the entire internal interface of millimeter-sized nanoporous metal specimens made by dealloying. The hybrid material emerges when the remaining pore space is filled with perchloric acid. The metal serves as load-bearing and electronically conductive substrate, the polypyrrole as functional active component for actuation,...

Synthetic pathways and processes for effective production of 5-hydroxytryptophan and serotonin from glucose in Escherichia coli

José Aníbal Mora Villalobos & An-Ping Zeng
Tryptophan derivatives such as 5-hydroxytryptophan (5HTP) and serotonin are valuable molecules with pharmaceutical interest. 5HTP is presently mainly obtained by extraction from the plant Griffonia simplicifolia and serotonin is produced by chemical synthesis. A simple biotechnological method for the production of these compounds is desired.

The biobased economy and their tools and products: A short overview

Ina Körner

The composition of bioresources - Compounds, quantities, interactions, analytics

Ina Körner

Vibro-acoustic and nonlinear analysis of cadavric femoral bone impaction in cavity preparations

Sebastian Oberst, Johanna Bätz, Graeme Michael Campbell, Frank Lampe, Joseph C. S. Lai, Norbert Hoffmann & Michael Morlock
Owing to an ageing population, the impact of unhealthy lifestyle, or simply congenital or gender specific issues (dysplasia), degenerative bone and joint disease (osteoarthritis) at the hip pose an increasing problem in many countries. Osteoarthritis is painful and causes mobility restrictions; amelioration is often only achieved by replacing the complete hip joint in a total hip arthroplasty (THA). Despite significant orthopaedic progress related to THA, the success of the surgical process relies heavily on the...

3D printed nozzles on a silicon fluidic chip

Sven Bohne, Michael Heymann, Henry N. Chapman, Hoc Khiem Trieu & Saša Bajt
Serial femtosecond crystallography is a new method for protein structure determination utilizing intense and destructive X-ray pulses generated by free-electron lasers. The approach requires the means to deliver hydrated protein crystals to a focused X-ray beam and replenish them at the repetition rate of the pulses. A liquid-jet sample delivery system where a gas dynamic virtual nozzle is printed directly on a silicon-glass microfluidic chip using a 2-photon-polymerization 3D printing process is implemented. This allows...

Dealloying progress during nanoporous structure evolution analyzed by In situ resistometry

Eva-Maria Steyskal, Michael Seidl, Matthias Graf & Roland Würschum
The progress of dealloying, an electrochemical synthesis method capable of producing nanoporous structures with bulk outer dimensions, is studied by in situ resistometry. The resistance increases by three orders of magnitude while nanoporous gold or platinum is formed. Simultaneous monitoring of charge flow and electrical resistance increase proves to be an ideal combination for analyzing the etching progress, which in accordance with recent studies can be demonstrated to occur in two steps referred to as...

An external calibration system for DBF receiver arrays at Ka-band

Minh Nhat Pham
In der vorliegenden Arbeit wird ein Online-Kalibrierverfahren mit an-Bord Sonden für DBF Empfangssysteme entwickelt. Das sogenannte externe Konzept ist nicht nur für die Kalibrierung der Kanalschwankungen entwickelt aber auch für die Kalibrierung der Kanal-schwankungen und –Kopplung erweitert. Die Anwendbarkeit des Kalibrierkonzepts ist durch Experimente in Labor demonstriert.

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...

M02.010 Determination of settleable matter

Tanja Millfahrt & Alina Stahl
This method describes the determination of settleable matter by volume in water and waste water (see DIN 38409-9).

M03.005 Qualitative and quantitative determination of saponins by LC-MSTOF and LC-MS/MS

Alina Stahl & Heike Frerichs
Mit der vorliegenden Methode können die Ginsenoside Panaxatriol, Panaxadiol, Rb1, Rd, Rg3, Rh2, Compound K und F2, sowie die beiden Sojasaponine Aa und Bb in enzymatisch behandelten Soja- oder Ginsengextrakten quantitativ erfasst werden. Die quantitative Messung verschiedener Saponine (aktuell z.B. Rg1, Rb1, Panaxatriol und Panaxadiol) erfolgt mittels LC-MSMS (Sciex Qtrap 5500) mit einer Luna C18-Säule in positiver und negativer Polarität (gleichzeitig). Die Auswertung erfolgt über eine externe Kalibrierung mit Integration der Peakfläche. Sollen andere Saponin-Abbauprodukte...

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...

Experimental and analytical investigation of cemented tungsten carbide ultra-short pulse laser ablation

Juan Pablo Calderón Urbina, Christian Daniel & Claus Emmelmann
Ultra-short pulse laser processing of hard materials, such as cemented tungsten carbide, requires an accurate and agile experimental and analytical investigation to obtain adequate information and setting parameters to maximize ablation rate. Therefore, this study presents a systematic approach which, first, experimentally searches for the variables with the most significant influence on the objective using a design of experiments method; and second, analyzes by means of existing ablation theory the interaction of the material and...

Overall process analysis and optimisation for CO₂ capture from coal fired power plants based on phase change solvents forming two liquid phases

Ulrich Liebenthal, Diego D. D. Pinto, Juliana G. M.-S. Monteiro, Hallvard F. Svendsen & Alfons Kather
In this work the potential of a novel post-combustion CO₂ capture process is analysed with respect to the integrated overall process. As solvent a blend of two amines (DEEA/MAPA) which forms two liquid phases under CO₂ loading is used. The two phases have distinct physical characteristics. Only the heavy phase, rich in CO₂ loading, is led to the desorber. The novel solvent combination promises very low energy consumption compared to a 30 wt.-% MEA solution....

Biotechnological strategies for the recovery of valuable and critical raw materials from waste electrical and electronic equipment (WEEE) - A review

Arda Işıldar, Eric D. van Hullebusch, Markus Lenz, Gijs Du Laing, Alessandra Marra, Alessandra Cesaro, Sandeep Panda, Ata Akcil, Mehmet Ali Kücüker & Kerstin Kuchta
Critical raw materials (CRMs) are essential in the development of novel high-tech applications. They are essential in sustainable materials and green technologies, including renewable energy, emissionfree electric vehicles and energy-efficient lighting. However, the sustainable supply of CRMs is a major concern. Recycling end-of-life devices is an integral element of the CRMs supply policy of many countries. Waste electrical and electronic equipment (WEEE) is an important secondary source of CRMs. Currently, pyrometallurgical processes are used to...

Human-sized magnetic particle imaging for brain applications

Matthias Gräser, Florian Thieben, Patryk Szwargulski, Franziska Werner, Nadine Gdaniec, Marija Boberg, Florian Griese, Martin Möddel, Peter Ludewig, Dionys van de Ven, Oliver M. Weber, Oliver Woywode, Bernhard Gleich & Tobias Knopp
Determining the brain perfusion is an important task for diagnosis of vascular diseases such as occlusions and intracerebral haemorrhage. Even after successful diagnosis, there is a high risk of restenosis or rebleeding such that patients need intense attention in the days after treatment. Within this work, we present a diagnostic tomographic imager that allows access to brain perfusion quantitatively in short intervals. The device is based on the magnetic particle imaging technology and is designed...

Directional soliton and breather beams

Amin Chabchoub, Kento Mozumi, Norbert Hoffmann, Alexander V. Babanin, Alessandro Toffoli, James N. Steer, Ton S. van den Bremer, Nail N. Akhmediev, Miguel Onorato & Takuji Waseda
Solitons and breathers are nonlinear modes that exist in a wide range of physical systems. They are fundamental solutions of a number of nonlinear wave evolution equations, including the unidirectional nonlinear Schrödinger equation (NLSE). We report the observation of slanted solitons and breathers propagating at an angle with respect to the direction of propagation of the wave field. As the coherence is diagonal, the scale in the crest direction becomes finite; consequently, beam dynamics form....

Quantitative study of H protein lipoylation of the glycine cleavage system and a strategy to increase its activity by co-expression of LplA

Xinyi Zhang, Mei Li, Yingying Xu, Jie Ren & An-Ping Zeng
Glycine cleavage system (GCS) plays a key role in one-carbon (C1) metabolism related to the biosynthesis of a number of key intermediates with significance in both biomedicine and biotechnology. Despite extensive studies of the proteins (H, T, P and L) involved and the reaction mechanisms of this important enzyme complex little quantitative data are available. In this work, we have developed a simple HPLC method for direct analysis and quantification of the apo- and lipoylated...

High-rate nitrification of membrane-filtrated saline landfill leachate using fixed-bed biofilm reactors

Sreenivasan Ramaswami
Alleine durch Umkehrosmose (UO) kann hochammoniumhaltigen Deponiesickerwässer nicht ausreichend behandelt werden. Die mehrstufige Hochdruckmembrananlage (inklusiv UO und Nanofiltration (NF) Verfahren) für die Sickerwasseraufbereitung in Deponie Ihlenberg ergibt sich ein unzureichender Ammoniumrückhalt. In dieser Arbeit wurde die Nitrifikation in belüfteten Festbettreaktoren untersucht, um dieses Problem zu lösen. Mit dem NF-Permeat des UO-Retentats des Rohsickerwassers (mit 16 g/L Cl-, 45 mS/cm) wurden Nitrifikationseffizienzen über 97% bei Volumenbelastungsraten von ca. 1100 g NH4+-N/(m3∙d) bei 25°C erreicht. Basierend der...

Advancing the fabrication of YSZ-inverse photonic glasses for broadband omnidirectional reflector films

Jefferson Jean Do Rosário, Quynh Yen Häntsch, Robert M. Pasquarelli, Pavel N. Dyachenko, Eleonora Vriend, Alexander Petrov, Kaline P. Furlan, Manfred Eich & Gerold A. Schneider
A single-step and all-colloidal deposition method to fabricate yttrium-stabilized zirconia (YSZ)-inverse photonic glasses with 3 μm pores was developed. The process is based on electrostatic attraction and repulsion in suspension, controlled by surface charge of polystyrene (PS)microspheres and YSZ nanoparticles, used as pore templates and matrix material, respectively. The pH was used as a tool to change surface charges and particle-particle interactions. Photonic glass films with 3 μm pores yielded broadband omnidirectional reflection over the...

Compilation for real-time systems : an overview of the WCET-aware C compiler WCC

Dominic Paul Oehlert, Arno Luppold & Heiko Falk
Traditionell finden Design und zeitliche Analyse eines eingebetteten harten Echtzeitsystems getrennt voneinander statt. Dies führt zu einem komplexen Designfluss, der menschliche Interaktion benötigt. Weiter optimieren Standardcompiler in Bezug auf die durchschnittliche Performanz, so dass der Systemdesigner nicht bei der Optimierung hinsichtlich der schlimmstmöglichen Programmlaufzeit unterstützt wird. Der WCET-Aware C Compiler WCC verbessert diese Situation, indem Planbarkeitsanalysen eng in den Compilierungs- und Optimierungsprozess mit eingebuden werden. Weiter bietet der Compiler gezielte Möglichkeiten um echtzeitbewusst Optimierungen durchzuführen...

Co-cultivation of Lactobacillus zeae and Veillonella criceti for the production of propionic acid

David Dietz, Wael Sabra & An-Ping Zeng
In this work a defined co-culture of the lactic acid bacterium Lactobacillus zeae and the propionate producer Veillonella criceti has been studied in continuous stirred tank reactor (CSTR) and in a dialysis membrane reactor. It is the first time that this reactor type is used for a defined co-culture fermentation. This reactor allows high mixing rates and working with high cell densities, making it ideal for co-culture investigations. In CSTR experiments the co-culture showed over...

Development of a scalable method for the efficient simulation of flows using dynamic goal-oriented local grid-adaptation

Manuel Manzke
Zur effizienten Simulation von maritimen Strömungen wurde ein Verfahren zur lokalen dynamischen Gitter Adaption in ein paralleles Berechnungsverfahren, welches auf dem Druckkorrekturalgorithmus basiert und unstrukturierte Gitter nutzt, integriert. Es wurden verschiedene Verfeinerungs-Indikatoren implementiert, angefangen bei Strömungsmerkmal-basierten bis hin zu ziel-orientierten Fehler Abschätzungen, welche aus der adjungierten Lösung des primalen Strömungsproblems gewonnen werden. Die Effizienz der Simulation von freien Oberflächen Strömungen wurde durch ein explizites Verfahren zu Schärfung der Grenzfläche, welches auf existierende VoF Methoden angewendet...

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