464 Works

Prototype for a permissioned blockchain in aircraft MRO

Jakob Schyga, Johannes Hinckeldeyn & Jochen Kreutzfeldt
Purpose: The paper aims to show strengths, weaknesses and challenges in the application of Blockchain technology for aircraft maintenance, repair and overhaul (MRO). The analysis is based on a prototype of a permissioned Blockchain for the maintenance documentation of aircraft and their components. Methodology: A prototyping approach is used to gain a deeper understanding of the underlying problems and proposed solutions of applying Blockchain technology to aircraft MRO. The open source platform ‘Hyperledger Fabric‘ and...

On the origin of the anomalous compliance of dealloying-derived nanoporous gold

Dinh Bao Nam Ngo, Benedikt Roschning, Karsten Albe, Jörg Weissmüller & Jürgen Markmann
The origin of the anomalously compliant behavior of nanoporous gold is studied by comparing the elasticity obtained from molecular dynamics (MD) and finite element method (FEM) simulations. Both models yield a compliance, which is much higher than the predictions of the Gibson-Ashby scaling relation for metal foams and thus confirm the influence of other microstructural features besides the porosity. The linear elastic FEM simulation also yields a substantially stiffer response than the MD simulation, which...

Design of self-regulating planning model

Maria Paula Espitia Rincon, David Alejandro Sanabria Martínez, Kevin Alberto Abril Juzga & Andrés Felipe Santos Hernández
Purpose: This research aims to develop a dynamic and self-regulated application that considers demand forecasts, based on linear regression as a basic algorithm for machine learning. Methodology: This research uses aggregate planning and machine learning along with inventory policies through the solver excel tool to make optimal decisions at the distribution center to reduce costs and guarantee the level of service. Findings: The findings after this study pertain to planning supply tactics in real-time, self-regulation...

Optimization of maintenance operations for offshore wind farms

Jasper Steendijk & Wouter Beelaerts van Blokland
Purpose: The paper provides insights regarding the optimal maintenance strategies for offshore wind farms. The maintenance strategies distinct from each other with location of the operation base and manner of logistics regarding the vessels. Methodology: The methodology for modelling the transport for maintenance operations for offshore wind farms is done with a discrete event simulation with data regarding offshore maintenance operations provided from a large-scale research. Findings: The paper conclude with the optimal maintenance strategy...

Modelling of spare parts storage strategies for offshore wind

Moritz Jäger-Roschko, Jürgen Weigell & Carlos Jahn
Purpose: The production costs of offshore wind energy are currently very high compared to other means of energy production. During the operational phase of an offshore wind park 17% of the operational costs are logistics cost. To reduce the costs, innovative strategies have to be implemented, like improved spare part strategies. Methodology: In this paper, an agent-based model for the Operation and Maintenance (O&M) supply chain of offshore wind farms is developed analyzing if the...

Modeling autonomously controlled automobile terminal processes

Michael Görges & Michael Freitag
Purpose: Automobile terminals play an essential role in automotive supply chains. Due to short planning cycles and volatile planning information, the yard assignment determines terminals performance. Existing planning approaches are not able to cope with these dynamics. This contribution proposes a novel bio-analogue autonomous control method to face these dynamics, its effects and to improve the terminals performance. Methodology: Causes of internal and external terminals dynamics will be discussed and an autonomous control method will...

Optimization and simulation for sustainable supply chain design

Lucas Schreiber
Purpose: This paper provides an overview of analytical optimization models and simulation-based approaches coping with upcoming challenges concerning the growing requirements within the field of sustainable supply chain design. It aims to combine the two highlighted solution methods in order to propose a holistic approach for decision-making support in this area. Methodology: Initially, a literature review on current application solutions for sustainable supply chain design is given. The regarded and analyzed approaches will be clustered...

Bewertung einer Windparkausbaustrategie unter Verwendung eines analytischen Verlustmodells

Dirk Gelder
Ein analytisches Windverlustmodell wird implementiert um die Zusammensetzung und Verteilung von Windparks in drei Windzonen auf energetischen Ertrag zu untersuchen.

Preparative recovery of bioactive molecules from conditioned medium of CHO-K1 cell culture

Alan Eduardo Castillo Salvador
Diese Arbeit untersucht die biologische Aktivität von konditioniertem Medium und dessen Einfluss auf Wachstum, Tod und metabolische Kinetik von CHO-K1 Zellkulturen. Eine Membranadsorptionschromatographie-Methode wurde für die präparative Gewinnung der bioaktiven Moleküle entwickelt, die für einige der beschriebenen Effekte verantwortlich sind. Dies führte zur Isolierung von zwei Fraktionen, die nach der Supplementierung zur exponentiell wachsenden Zellen, biologische Aktivität zeigten. Die Ergebnisse dieser Arbeit weisen auf das Zusammenspiel zweier gegensätzlicher Signalmoleküle bei der Batch-Kultivierung von CHO-K1-Zellkulturen und...

Nonreciprocal nanophotonic structures

Dirk Jalas
Diese Arbeit präsentiert neue Konzepte für die Integration von nicht-reziproken optischen Komponenten. Es werden ein Isolator, ein Zirkulator, ein magneto-optischer Schalter sowie ein Faraday Rotator vorgestellt.

Porous gold with a nested-network architecture and ultrafine structure

Zhen Qi, Ulla Vainio, Andreas Kornowski, Martin Ritter, Horst Weller, Hai-Jun Jin & Jörg Weissmüller
© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. A preparation strategy is developed for monolithic samples of nanoporous gold with a hierarchical structure comprising two nested networks of solid "ligaments" on distinctly different structural length scales. The electrochemical dealloying protocol achieves a large retention of less noble element in a first corrosion step, thereby allowing an extra corrosion step which forms a separate structural hierarchy level. The beneficial impact of adding Pt to the...

Ein Bewertungsansatz zur Analyse von Zustandsmanagementsystemen in Verkehrsflugzeugen unter Berücksichtigung neuer Instandhaltungskonzepte

Nico Hölzel
Diese Forschungsarbeit beschäftigt sich mit der Technologiebewertung von Zustandsmanagementsystemen und zustandsorientierten/prädiktiven Instandhaltungs-konzepten für zukünftige Verkehrsflugzeuge. Dazu wird ein Modell zur Diskret-Ereignis-Simulation des Flugzeugbetriebs, der Ausfall- und Instandhaltungsereignisse und der Wirkung von Diagnose- und Prognosetechnologien im Flugzeuglebenszyklus unter Einbindung eines Optimierungsansatzes für die dynamische Instandhaltungsplanung entwickelt. Für die Bewertung des ökonomischen Nutzens aus Betreibersicht kommt eine Kosten-Nutzen-Analyse auf Basis der Discounted Cash-Flow Methode zum Einsatz. In einem Anwendungsfall wird das operationelle und wirtschaftliche Potenzial von Zustands-managementsystemen...

Tutorien zur Informatik

Dion Timmermann & Christian H. Kautz
Die Tutorien zur Informatik sind als ergänzende Lehrmaterialien konzipiert, die traditionelle Vorlesungen, Schulunterricht und klassische Lehrbücher komplementieren. Die Tutorien betonen vor allem das Verständnis der grundlegenden Konzepte der Informatik und Programmierung sowie deren Zusammenhänge. Durch u. a. das Treffen von Vorhersagen und das Ableiten sich daraus ergebender Konsequenzen, sollen Lernende ihr bisheriges Wissen überprüfen und Wiedersprüche ihres Verständnisses erkennen. Wie auch die Tutorien zur Physik und die Tutorien zur Elektrotechnik, basieren diese Materialien so weit...

The plastic yield and flow behavior in metallic glasses

Prakash Thamburaja, Benjamin Klusemann, Sara Adibi & Swantje Bargmann
Metallic glasses have vast potential applications as components in microelectronics- and nanoelectronics-type devices. The design of such components through computer simulations requires the input of a faithful set of continuum-based constitutive equations. However, one long-standing controversial issue in modeling the plastic behavior of metallic glasses at the continuum level is the use of the most appropriate plastic yield criterion and flow rule. Guided by a series of molecular dynamics simulations conducted at low-homologous temperatures under...

Changes in the microbial communities during co-composting of digestates

Ingrid H. Franke-Whittle, Alberto Confalonieri, Heribert Insam, Mirko Schlegelmilch & Ina Körner
Anaerobic digestion is a waste treatment method which is of increasing interest worldwide. At the end of the process, a digestate remains, which can gain added value by being composted. A study was conducted in order to investigate microbial community dynamics during the composting process of a mixture of anaerobic digestate (derived from the anaerobic digestion of municipal food waste), green wastes and a screened compost (green waste/kitchen waste compost), using the COMPOCHIP microarray. The...

Long-term decoding of movement force and direction with a wireless myoelectric implant

Pierre Morel, Enrico Ferrea, Bahareh Taghizadeh-Sarshouri, Josep Marcel Cardona Audí, Roman Ruff, Klaus-Peter Hoffmann, Sören Lewis, Michael Russold, Hans Dietl, Lait Abu Saleh, Dietmar Schröder, Wolfgang Krautschneider, Thomas Meiners & Alexander Gail
Objective. The ease of use and number of degrees of freedom of current myoelectric hand prostheses is limited by the information content and reliability of the surface electromyography (sEMG) signals used to control them. For example, cross-talk limits the capacity to pick up signals from small or deep muscles, such as the forearm muscles for distal arm amputations, or sites of targeted muscle reinnervation (TMR) for proximal amputations. Here we test if signals recorded from...

Adsorption of rare earth elements using bio-based sorbents

Arina Kosheleva, Iryna Atamaniuk, Natalia Politaeva & Kerstin Kuchta
Rare earth elements (REEs) have recently received significant attention due to their irreplaceable industrial application for the number of crucial advanced technologies in production of permanent magnets, batteries, luminescence lamps, lasers and other electronic and electrical goods. These technologies have been strongly affecting present consumption of REEs as well as looking for alternative sources, that would guarantee their sufficient supply for the future demand. This study investigates one of the possible and widely employed techniques...

Time-delay estimation for compound point-processes using hidden Markov models

Jens Wohlers, Alfred Mertins & Norbert Fliege
A new time-delay estimation algorithm for compound point-processes is presented. Compound point-processes, a generalization of temporal point-processes, describe processes with discrete events, where each occurrence time is associated with certain features. It is shown that, although the events are not observable, the time delays from events at one location to the same events at a second location can be estimated using hidden Markov models based on the associated features. We demonstrate the performance of this...

Early estimation of work contents for planning the one-of-a-kind production by the example of shipbuilding

Jan Niklas Sikorra, Axel Friedewald & Hermann Lödding
A transparent, reliable early estimation of work contents is crucial for capacity planning in shipyards. Yet most of the shipyards rely on practical experience of specialized production planners, for the early capacity estimation, which are prone to errors, as a bill of material is not available in the early stages of production planning in the one-of-a-kind production. This is due to a yet unfinished construction of the ship. This paper will discuss a method for...

Quantification of the contact area at the head-stem taper interface of modular hip prostheses

Florian Witt, Julian Gührs, Michael Morlock & Nicholas Bishop
Corrosion of modular taper junctions of hip implants may be associated with clinical failure. Taper design parameters, as well as the intraoperatively applied assembly forces, have been proposed to affect corrosion. Fretting corrosion is related to relative interface shear motion and fluid ingress, which may vary with contact force and area. It was hypothesised in this study that assembly forces modify the extent and distribution of the surface contact area at the taper interface between...

Sea surface wind measurement by airborne weather radar scanning in a wide-size sector

Alexey Nekrasov, Alena Khachaturian, Vladimir Veremyev & Mikhail Bogachev
We suggest a conceptual approach for measuring the near-surface wind vector over water using the airborne weather radar, in addition to its standard meteorological and navigation applications. The airborne weather radar operates in the ground-mapping mode in the range of high to medium incidence angles as a scatterometer. Using the aircraft rectilinear flight over the water surface, measuring the geometry and the geophysical model function, we show that the wind vector can be successfully recovered...

Damage modeling of small-scale experiments on dental enamel with hierarchical microstructure

Ingo Scheider, Tao Xiao, Ezgi D. Yilmaz, Gerold A. Schneider, Norbert Huber & Swantje Bargmann
Dental enamel is a highly anisotropic and heterogeneous material, which exhibits an optimal reliability with respect to the various loads occurring over years. In this work, enamel's microstructure of parallel aligned rods of mineral fibers is modeled and mechanical properties are evaluated in terms of strength and toughness with the help of a multiscale modeling method. The established model is validated by comparing it with the stress-strain curves identified by microcantilever beam experiments extracted from...

Jahresbericht des Präsidiums 2018

Hendrik Brinksma &
Jahresbericht des Präsidiums der TU Hamburg 2018

Rural bioresource management today - The agricultural residue sector

Ina Körner &

Flue gas concentrations and efficiencies of a coal-fired Oxyfuel power plant with circulating fluidised bed combustion

Matthias Weng, Claas Georg Günther & Alfons Kather
In contrast to an Oxyfuel process with pulverised coal (PC) firing, possible advantages of a circulating fluidised bed combustion (CFBC) are the in-furnace sulphur dioxide removal - no additional sulphur dioxide removal downstream the steam generator might be necessary - And the feasibility for concepts with a reduced flue gas recirculation. In [1] design conditions for the overall process of an Oxyfuel CFBC with highest flue gas recirculation up to 75 % are compared to...

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  • 2019
    464

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