464 Works

CRISPR/Cas9-facilitated engineering with growth-coupled and sensor-guided in vivo screening of enzyme variants for a more efficient chorismate pathway in E. coli

Minliang Chen, Lin Chen & An-Ping Zeng
Protein engineering plays an increasingly important role in developing new and optimizing existing metabolic pathways for biosynthesis. Conventional screening approach of libraries of gene and enzyme variants is often done using a host strain under conditions not relevant to the cultivation or intracellular conditions of the later production strain. This does not necessarily result in the identification of the best enzyme variant for in vivo use in the production strain. In this work, we propose...

The influence of clamping pressure on joint formation and mechanical performance of Ti6Al4V/CF-PEEK friction-riveted joints

Natascha Zocoller Borba, Jorge F. dos Santos & Sergio T. Amancio-Filho
This work aims at investigating the influence of pre-set clamping pressure on the joint formation and mechanical strength of overlapping direct-friction-riveted joints. A pneumatic fixture device was developed for this work, with clamping pressure varying from 0.2 MPa to 0.6 MPa. A case study on overlapping joints using Ti6Al4V rivets and woven carbon fiber-reinforced polyether-ether-ketone (CF-PEEK) parts were produced. Digital image correlation and microscopy revealed the expected compressive behavior of the clamping system and the...

A review of the application of machine learning and data mining approaches in continuum materials mechanics

Frederic E. Bock, Roland C. Aydin, Christian J. Cyron, Norbert Huber, Surya R. Kalidindi & Benjamin Klusemann
Machine learning tools represent key enablers for empowering material scientists and engineers to accelerate the development of novel materials, processes and techniques. One of the aims of using such approaches in the field of materials science is to achieve high-throughput identification and quantification of essential features along the process-structure-property-performance chain. In this contribution, machine learning and statistical learning approaches are reviewed in terms of their successful application to specific problems in the field of continuum...

The dynamic behaviour of a non-stationary elevator compensating rope system under harmonic and stochastic excitations

Stefan Kaczmarczyk, Radoslaw Marek Iwankiewicz & Yoshiaki Terumichi
Moving slender elastic elements such as ropes, cables and belts are pivotal components of vertical transportation systems such as traction elevators. Their lengths vary within the host building structure during the elevator operation which results in the change of the mass and stiffness characteristics of the system. The structure of modern high-rise buildings is flexible and when subjected to loads due to strong winds and earthquakes it vibrates at low frequencies. The inertial load induced...

Development of a synthetic synovial fluid for tribological testing

Emely Lea Bortel, Baptiste Charbonnier & Roman Heuberger
Wear tests of joint prostheses are usually performed using bovine calf serum. The results from different laboratories are hardly ever comparable as, for example, the protein concentration and the protein composition of the serum-based test liquids vary. In addition, the viscosity of these test liquids is similar to that of water and does not match the more viscous synovial fluid. The present work was aimed at developing a synthetic synovial fluid as an alternative to...

Fail-safe optimization of beam structures

Julian Kajo Lüdeker & Benedikt Kriegesmann
In the current work, a fail-safe optimization of beam structures is carried out. This approach may provide an insight into the robustness of lattice structures. The use of beam elements allows a commonly used engineering approach for obtaining a fail-safe design to be applied. This consists of removing one beam element at a time and optimizing the remaining structure. At the end of the process, the maximum beam radii are used for the final design....

Social Influence, status, and entrepreneurial entry: evidence from the comic book industry

Michael Engel
Diese Dissertation untersucht wie sich die Struktur sozialer Netzwerke auf den unternehmerischen Eintritt auswirkt. Sie analysiert die Effekte von sozialem Einfluss und Status auf die Entscheidung von Personen, ein neues, selbst erstelltes Angebot auf den Markt zu bringen. Bisherige Arbeiten haben diese Effekte zwar nachgewiesen, konnten die zugrundeliegenden Mechanismen aber noch nicht aufdecken. Ausgehend von der Netzwerktheorie leiten wir Hypothesen zu proximitätsbasierten Ansteckungs- und statusbasierten Konvergenzmechanismen ab und testen sie im Kontext der Comic-Industrie mit...

An example of visually supported design of modular product families

Nicolas Gebhardt, Tammo Bahns & Dieter Krause
© 2014 Published by Elsevier B.V. To offer individualized products at globally marketable prices, the Integrated PKT-Approach for Developing Modular Product Families aims to generate high external product variety based on a low internal process and component variety. Specific visualizations are an important factor in the success of this approach. In this paper the Module Interface Graph (MIG) developed at the Institute for Product Development and Mechanical Engineering Design (PKT) is used to show how...

A discussion on present theories of rubber friction, with particular reference to different possible choices of arbitrary roughness cutoff parameters

Andrea Genovese, Flavio Farroni, Antonio Papangelo & Michele Ciavarella
Since the early study by Grosch in 1963 it has been known that rubber friction shows generally two maxima with respect to speed - the first one attributed to adhesion, and another at higher velocities attributed to viscoelastic losses. The theory of Klüppel and Heinrich and that of Persson suggests that viscoelastic losses crucially depend on the “multiscale” aspect of roughness and in particular on truncation at fine scales. In this study, we comment a...

Analysis of refrigerant pipe pressure drop of a CO₂ air conditioning unit for vehicles

Christoph Subei & Gerhard Schmitz
This study investigates the pressure drop in refrigerant pipes of a CO₂ automotive air conditioning unit. A test rig to measure the pressure drop of arbitrarily shaped pipes is presented. As boundary conditions at the inlet of the test section, mass flow, pressure and enthalpy of the refrigerant are independently adjustable to values that cover the whole operating range of a CO₂ automotive air conditioning system for cars in the premium segment. Numerical analysis using...

Digital transformation in maritime and city logistics : smart solutions for logistics

This volume contains research contributions by an international group of authors addressing innovative and technology-based approaches for logistics and sustainability. They present simulation studies, systems and models for optimizations and digitalized solutions with a focus on maritime as well port and city logistics. This volume, edited by Carlos Jahn, Wolfgang Kersten, and Christian Ringle, provides valuable insights into digital transformation in logistics with regard to: Maritime and Port Logistics, City Logistics, Sustainability and Business Analytics.

Breaking through the bottlenecks using artificial intelligence

Julia Feldt, Henning Kontny & Axel Wagenitz
Purpose: Performance of Supply Chain is highly dependent on weak spots, so-called bottlenecks. This research paper presents the findings from the analysis of operation processes of a mid-sized producing company and the digital solution for opening up the bottlenecks in order to achieve effectiveness by cutting down the order lead time. Methodology: The study is employing several rounds of simulation based on processes and data from a manufacturing company. Findings: Simulation results demonstrate that by...

Sharing information across company borders in industry 4.0

Kai-Ingo Voigt, Julian Müller, Johannes Veile & Marie-Christin Schmidt
Purpose: Industry 4.0's potentials can only unfold exhaustively if information is shared across company boarders and along supply chains. Exchanging information, however, implies several challenges for companies. This holds especially true if it is transmitted automatically and digitally, as promoted by the concept of Industry 4.0. In response to these challenges, this paper analyzes how information sharing changes in Industry 4.0 contexts. Methodology: Expert interviews with 17 representatives from supply chain management departments of German...

Machine learning in demand planning : cross-industry overview

Nikolas Ulrich Moroff & Saskia Sardesai
Purpose: This paper aims to give an overview about the current state of research in the field of machine learning methods in demand planning. A cross-industry analysis for current machine learning approaches within the field of demand planning provides a decision-making support for the manufacturing industry. Methodology: Based on a literature research, the applied machine learning methods in the field of demand planning are identified. The literature research focuses on machine learning applications across industries...

Automatic identification system (AIS) data based ship-supply forecasting

Sandra Lechtenberg, Diego de Siqueira Braga & Bernd Hellingrath
Purpose: The bulk cargo shipping industry is characterized by high cost pressure. Chartering vessels at low prices is important to increase the margin of transporting cargo. This paper proposes a three-step, AI-based methodology to support this by forecasting the number of available ships in a region at a certain time. Methodology: Resulting from discussions with experts, this work proposes a threestep process to forecast ship numbers. It implements, compares and evaluates different AI approaches for...

Cyber-attack impact estimation for a port

Sandra König, Stefan Rass & Stefan Schauer
Purpose: We investigate consequences of a cyber-attack on a port through a simulation model. Motivated by the impact of NotPetya on the container company A.P. Møller-Maersk and the entire supply chain we propose a method to estimate the consequences. Such estimation is a first step towards the identification of protection measures. Methodology: We represent a port as a network of interdependent cyber and physical assets. The operational state of each component is measured on a...

Digitalized and autonomous transport – challenges and chances

Sascha Stradner & Uwe Brunner
Purpose: European Logistics is characterized by a matured infrastructure. Nevertheless, industry has to catch up in terms of digitalized and autonomous transport. The awareness-rising of industrial companies in this area is still limited. Therefore, the paper includes a research in order to find out the reasons for hesitations of manufacturing industry. Methodology: For this purpose, an overview of digitalized and autonomous transport based on a literature research is given and reflected at the beginning. The...

Business analytics on ais data: potentials, limitations and perspectives

Tina Scheidweiler & Carlos Jahn
Purpose: As maritime digitalization progresses, great opportunities for maritime transport arise: The introduction of the AIS opened up a number of possibilities and perspectives for increasing efficiency, automation and cost reduction using business analytics and machine learning in the supply chain and maritime sector. Methodology: Various analysis and forecast techniques of machine learning as well as interactive visualizations are presented for the automated analysis of ship movement patterns, risk assessments of encounter situations of two...

Experimental investigation of a downwind coned wind turbine rotor under yawed conditions: preliminary results

Christian Schulz, Klaus Wieczorek, Stefan Netzband & Moustafa Abdel-Maksoud
The growing number of Floating Offshore Wind Turbine (FOWT) concepts that utilize a single point mooring and therefore rely on the self-alignment capabilities of the wind turbine (e.g. SCD nezzy or SelfAligner by CRUSE Offshore) demands an extension of the simulation methods used for their development. A crucial issue for these concepts is the accurate prediction of forces and moments, which contribute to the self-alignment. In contrast to the well-studied behaviour of torque and thrust,...

On the fatigue behaviour and modelling of fatigue life for laser-welded Ti-6Al-4V

Fedor Fomin
Das Ziel der vorliegenden Arbeit ist die experimentelle und theoretische Untersuchung des Ermüdungsverhaltens der laserstrahlgeschweißten Titan-Legierung Ti-6Al-4V im Bereich von hohen Lastzyklen. Die werkstoffmechanischen Vorgänge der Rissinitiierung in der Schweißnaht und Einfluss von Schweißfehlern auf die Ermüdungseigenschaften wurden ausführlich erforscht. Verschiedene Arten von Behandlungsverfahren nach dem Schweißen mit dem Ziel, die Lebensdauer der geschweißten Strukturen zu erhöhen, wurden analysiert. Abschließend wurde ein bruchmechanisches Berechnungsmodell entwickelt, welche die Abschätzung der Dauerfestigkeit von Schweißverbindungen und deren Streuung...

Zero stress aging of glass and carbon fibers in water and oil : strength reduction explained by dissolution kinetics

Andreas T. Echtermeyer, Andrey E. Krauklis, Abedin I. Gagani & Erik Sæter
Understanding the strength degradation of glass and carbon fibers due to exposure to liquids over time is important for structural applications. A model has been developed for glass fibers that links the strength reduction in water to the increase of the Griffith flaw size of the fibers. The speed of the increase is determined by regular chemical dissolution kinetics of glass in water. Crack growth and strength reduction can be predicted for several water temperatures...

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...

Sustainable decision making under uncertainty: A case study in dredged material management

Alexander Scheffler, Thomas Roth & Wolfgang Ahlf
Background: The port of Lübeck is one of Germany's most important harbours for goods traffic to and from the Baltic Sea Region. Sedimentation from the River Trave requires regularly maintenance dredging as well as capital dredging operations in order to maintain the operational capability of the port. A range of solutions for sustainable dredged material handling exist and an assessment of these options often proves to be challenging for decision makers. Multi-criteria decision analysis (MCDA)...

Microstructure evolution and stress corrosion cracking behavior in short-term thermomechanically processed Al-Cu-Li alloys

Jannik Entringer
Der stetig wachsende Zugang in den Weltraum hinterlässt menschliche Spuren in erdnahen Umlaufbahnen. Weltraumschrott stellt heute ein erhebliches Risiko für aktive Missionen dar. Die Reduzierung des Weltraumschrotts ist die einzige Möglichkeit den Weltraumzugang nachhaltig zu erhalten. Eine Strategie zur Vermeidung zukünftigen Weltraummülls besteht darin, ausgediente Raumfahrzeuge zum kontrollierten Verglühen in die Atmosphäre zu manövrieren. Diese Strategie wird ab der frühen Entwurfsphase für neue Raumfahrzeuge verfolgt und wird sich auf Materialentscheidungen auswirken. Titan, welches derzeit als...

Constant depth scoring of fibre reinforced plastic structures to prevent delamination

Tobias Geis, Christian Klingelhöller & Wolfgang Hintze
Scoring of the outer layers of a workpiece with small engagement (ae) using circular saws is a well known method to avoid unwanted delamination of these layers, such as coatings of wooden particle boards. In edge milling fibre reinforced plastics (FRP), delamination also occurs in the top or bottom layer of the component and requires time intensive rework or scrapping of material. A combined process of scoring and milling is presented in this paper as...

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  • 2019
    464

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    464