374 Works

Development of cube texture in coarse grained copper

M. Sindel, G. D. Köhlhoff, K. Lücke & B. J. Duggan
Cube oriented deformed material has been detected in the rolling texture measured on edge sectionsof heavily rolled coarse grained copper. The level of intensity is low, and seems to be independent ofrolling reduction over the range 93–98%. Recrystallization textures show an increasing strength ofCube with rolling reduction. The evidence is consistent with the idea that Cube nuclei are created bya mechanism similar to that proposed by Dillamore and Katoh, and the strength of the recrystallizedCube...

From the World Brain to the first transatlantic information dialogue : activities in information and documentation in Germany in the first half of the 20th Century

Thomas Hapke
It is not enough to found libraries. It is necessary, by means of lectures and bibliographic. lists, to instruct those eager for knowledge in the best methods of utilizing their treasures. And this is by no means so easy as it sounds!

A three-component model of the control error in manual tracking of continuous random signals

Hans Gerisch, Gerhard Staude, Werner Wolf & Gerhard Bauch
The performance of human operators acting within closed-loop control systems is investigated in a classic tracking task. The dependence of the control error (tracking error) on the parameters display gain, k(display), and input signal frequency bandwidth, f(g), which alter task difficulty and presumably the control delay, is studied with the aim of functionally specifying it via a model.

Weblog campaigning in the German Bundestag election 2005

Steffen Albrecht, Maren Lübcke & Rasco Hartig-Perschke
Election campaigns are catalysts for new forms of political communication. They are a field of experimentation for new techniques and technologies to reach target groups and influence voters. This article explores how weblogs were used in the 2005 Bundestag election campaign in Germany, examining their effect on the mediatized political field. It is based on an empirical analysis of 317 campaign weblogs.

Influence of cooling on curing temperature distribution during cementing of modular cobalt-chromium and monoblock polyethylene acetabular cups

Stephan Rothstock, Mahnaz Saadatmand, Matthias Vollmer, Andreas Paech, Christian Jürgens, Roman Nassutt & Michael Morlock
Total hip replacements for older patients are usually cemented to ensure high postoperative primary stability. Curing temperatures vary with implant material and cement thickness (30°C to 70°C), whereas limits for the initiation of thermal bone damage are reported at 45°C to 55°C. Thus, optimizing surgical treatment and the implant material are possible approaches to lower the temperature. The aim of this study was to investigate the influence of water cooling on the temperature magnitude at...

Biomechanical, morphological, and histological analysis of early failures in hip resurfacing arthroplasty

Michael Morlock, Nicholas Bishop, Wolfgang Rüther, Günter Delling & Michael Hahn
The present revival of hip resurfacing arthroplasty may be related to an increase in early failures owing to the challenging technique of the procedure. Fifty-five retrieved implants were analysed with respect to wear, cement mantle and cement penetration, fracture and head morphology, as well as standard histology. Femoral neck fractures occurred in median after 102 days. The time to failure was shorter for older women. Major deviations from the suggested cement mantle thickness and cement...

The cultural economy of cities : a comparative study of the audiovisual sector in Hamburg and Lisbon

Eduardo Brito-Henriques & Joachim Thiel
This article examines the role that big cities play in an ongoing change towards a ‘global cultural economy’. Starting from Allen Scott’s argument that a handful of urban flagships may benefit from this shift, it looks for an alternative approach to the territorial dimension of the ‘culture–economy nexus’ based on a more complex understanding of urban culture. A broad theoretical discussion of Scott’s ideas, as well as on the key concepts of culture, economy and...

Development of an in situ extraction process of fatty acids from microalgae cultures

Philipp Glembin
In this work micellar extraction was investigated in order to develop an alternative process for the in situ extraction of hydrophobic substances from microalgae cultures. The main requirements for an in situ extraction process such as biocompatibility, phase separation behavior and partitioning of the hydrophobic target substance between micellar- and aqueous phases were studied for a number of surfactants. The cloud point temperatures (CPT) as well as the biocompatibility of the nonionic surfactants with the...

Structural and differential analysis for program comprehension of executables

Arne Wichmann
Wir führen eine strukturelle Analyse (StA), die Schlüsselstellen für das Programmverständnis von ausführbaren Programmen identifiziert, und eine differenzielle Analyse (DiA), die Ähnlichkeiten zwischen solchen ausführbaren Programmen identifiziert, ein. Unsere StA basiert auf einer neuen Abstraktion von Kontrollflussinformationen auf Statementebene zu einer Repräsentation mit einer graphischen Ansicht, die eine intuitive Identifizierung von mitgelieferten Mustern ermöglicht. Unsere DiA basiert auf Sequenzalignments und benötigt nur die Position und Größe der Funktionen. Wir validieren die StA manuell mit einer...

Biomechanical evaluation of 3 stabilization methods on acromioclavicular joint dislocations

Jakob V. Nüchtern, Kay Sellenschloh, Nick Bishop, Sabrina Jauch, Daniel Briem, Michael Hoffmann, Wolfgang Lehmann, Klaus Pueschel, Michael Morlock, Johannes M. Rueger & Lars G. Großterlinden
Traumatic acromioclavicular (AC) joint dislocations can be addressed with several surgical stabilization techniques. The aim of this in vitro study was to evaluate biomechanical features of the native joint compared with 3 different stabilization methods: locking hook plate (HP), TightRope (TR), and bone anchor system (AS).

Assembly force and taper angle difference influence the relative motion at the stem-neck interface of bi-modular hip prostheses

Henning Haschke, Sabrina Y. Jauch-Matt, Kay Sellenschloh, Gerd Huber & Michael Morlock
Bi-modular hip arthroplasty prostheses allow adaptation to the individual patient anatomy and the combination of different materials but introduce an additional interface, which was related lately to current clinical issues. Relative motion at the additional taper interface might increase the overall risk of fretting, corrosion, metallic debris and early failure. The aim of this study was to investigate whether the assembly force influences the relative motion and seating behaviour at the stem-neck interface of a...

Modelling of ballistic impact over a ceramic-metal protection system

Leandro Neckel, Dachamir Hotza, Daniel Stainer, Rolf Janßen & Hazim Ali Al-Qureshi
The behavior of ceramic-metal protection against a projectile impact is modeled. The model takes into account the mass and velocity for each stage of the phenomenon. A former model was modified considering more realistic parameters such as geometries and deformation profile. To analyze the model, simulations on different parameters have been run. The impact results of different ballistic projectiles were simulated, and the movement was plotted. In addition, a deterministic simulation on the mechanical properties...

A statistical study of scattering in periodic and random helix layers

Christian Meiners & Arne F. Jacob
This paper aims at providing information on scattering in layers composed of periodic and non-periodic arrangements of small metal helices. Metal helices exhibit a pronounced resonance and are thus very effective scatterers.

On the effects of the external surface on the equilibrium transport in zeolite crystals

Nils E. R. Zimmermann, Berend Smit & Frerich Keil
With the aid of molecular simulation techniques (molecular dynamics [MD], Grand-Canonical Monte Carlo [GCMC], and reactive flux correlation function [RFCF]), the influence of the external surface on the equilibrium permeation of methane and ethane into and out of an AFI-type zeolite crystal has been studied. In particular, “extended dynamically corrected transition state theory”, that has been proven to describe the transport of tracers in periodic crystals correctly, has been applied to surface problems. The results...

Influence of drayage patterns on truck appointment systems

Ann-Kathrin Lange, Kristof Ole Kühl, Anne Kathrina Schwientek & Carlos Jahn
Truck appointment systems (TAS) are a well-recognized method to smooth the peaks in truck arrivals at seaport container terminals and thereby reduce operation costs for the terminals and waiting times for trucking companies. This study analyzes the influence of different drayage patterns on the success of a TAS at seaport container terminals by means of a discrete event simulation model. These drayage patterns vary in the percentages of transports between container terminals and container terminals...

Clinical and wear analyses of 9 large metal-on-metal total hip prostheses

Maarten C. Koper, Nina M. C. Mathijssen, Florian Witt, Michael Morlock & Stephan B. W. Vehmeijer
Metal-on-Metal (MoM) total hip arthroplasties (THA) are associated with pseudotumor formation and high revision rates. This prospective study analysed the clinical and wear analyses of 9 large Metal-on-Metal (MoM) total hip arthroplasties (THA) to understand the underlying mechanisms of failure. The MoM bearings were revised for multiple reasons; the main reason was pseudotumor formation.

Membrane-type acoustic metamaterials for aircraft noise shields

Felix Langfeldt
In der Arbeit werden akustische Membran-Metamaterialien auf ihre Anwendbarkeit zur effizienten Reduktion von tieffrequenten Tönen untersucht. Es werden analytische Modelle zur Berechnung der Schalldämmung von Schallschutzmaßnahmen mit Membran-Metamaterialien entwickelt. Diese Modelle werden verwendet, um ein Schallschutzschild für einen Flugzeugrumpf zu entwerfen. Die experimentelle Charakterisierung des Schallschutzschildmodells erfolgt unter realitätsähnlichen Einbau- und Anregungsbedingungen an einer Flugzeugrumpfteststruktur.

What pathways lead to frugal innovation? : Some insights on modes & routines of frugal, technical inventions based on an analysis of patent data in German auto components industry

Rajnish Tiwari & Stephan Bergmann
Frugal innovations, i.e. affordable products and services with appropriately good quality, are getting increasingly important for securing long-term competitiveness in both, the developing world and in industry nations. Nevertheless, ensuring actual implementation of technology-driven frugal inventions remains an under-researched area. This study investigates modes and routines employed by techno-entrepreneurs from industry nations when innovating frugally. The study is based on the patent data of seven auto component sector firms from Germany with a documented history...

Electro-conductive composite gold-polyethersulfone-ultrafiltration-membrane : characterization of membrane and natural organic matter (NOM) filtration performance at different in-stiu applied surface potentials

Tomi Mantel, Paul Benne, Stanislav Parsin & Mathias Ernst
Next to the pore size distribution, surface charge is considered to be one main factor in the separation performance of ultrafiltration (UF) membranes. By applying an external surface potential onto an electro-conductive UF membrane, electrostatic induced rejection was investigated. This study introduces in a first part a relatively simple but yet not reported technology of membrane modification with direct current sputter deposition of ultrathin (15 nm) highly conductive gold layers. In a second part, characterization...

An analytical model for wireless mesh networks with collision-free TDMA and finite queues

Florian Kauer & Volker Turau
Wireless mesh networks are a promising technology for connecting sensors and actuators with high flexibility and low investment costs. In industrial applications, however, reliability is essential. Therefore, two time-slotted medium access methods, DSME and TSCH, were added to the IEEE 802.15.4 standard. They allow collision-free communication in multi-hop networks and provide channel hopping for mitigating external interferences. The slot schedule used in these networks is of high importance for the network performance. This paper supports...

Analysis of the influence of imaging-related uncertainties on cerebral aneurysm deformation quantification using a no-deformation physical flow phantom

Daniel Schetelig, Jan Sedlacik, Jens Fiehler, Andreas M. J. Frölich, Tobias Knopp, Thilo Sothmann, Jonathan Waschkewitz & René Werner
Cardiac-cycle related pulsatile aneurysm motion and deformation is assumed to provide valuable information for assessing cerebral aneurysm rupture risk. Accordingly, numerous studies addressed quantification of cerebral aneurysm wall motion and deformation. Most of them utilized in vivo imaging data, but image-based aneurysm deformation quantification is subject to pronounced uncertainties: unknown ground-truth deformation; image resolution in the order of the expected deformation; direct interplay between contrast agent inflow and image intensity. To analyze the impact of...

Hierarchical aerographite 3D flexible networks hybridized by InP micro/nanostructures for strain sensor applications

Irina Plesco, Julian Strobel, Fabian Schütt, Cameliu Constantin Himcinschi, Nabiha Ben Sedrine, Teresa Monteiro, Maria Rosário Correia, Leonid Gorceac, Boris Cinic, Veaceslav Ursaki, Janik Marx, Bodo Fiedler, Yogendra Kumar Mishra, Lorenz Kienle, Rainer Adelung & Ion Tiginyanu
In the present work, we report on development of three-dimensional flexible architectures consisting of an extremely porous three-dimensional Aerographite (AG) backbone decorated by InP micro/nanocrystallites grown by a single step hydride vapor phase epitaxy process. The systematic investigation of the hybrid materials by scanning electron microscopy demonstrates a rather uniform spatial distribution of InP crystallites without agglomeration on the surface of Aerographite microtubular structures. X-ray diffraction, transmission electron microscopy and Raman scattering analysis demonstrate that...

Extension of multi-commodity closed-loop supply chain network design by aggregate production planning

Leena Steinke & Kathrin Fischer
In this work the influence of production and capacity planning on decisions regarding facility location, distribution quantities and component remanufacturing (and vice versa) in a closed-loop supply chain network (CLSCN) with multiple make-to-order products is studied. A mathematical model, the facility location, capacity and aggregate production planning with remanufacturing (FLCAPPR) model, for designing the CLSCN, for planning capacities at the facilities and for structuring the production and distribution system of the network cost-optimally, is formulated....

Restarting iterative projection methods for Hermitian nonlinear eigenvalue problems with minmax property

Marta Betcke & Heinrich Voß
In this work we present a new restart technique for iterative projection methods for nonlinear eigenvalue problems admitting minmax characterization of their eigenvalues. Our technique makes use of the minmax induced local enumeration of the eigenvalues in the inner iteration. In contrast to global numbering which requires including all the previously computed eigenvectors in the search subspace, the proposed local numbering only requires a presence of one eigenvector in the search subspace. This effectively eliminates...

The road to a digitalized supply chain management: smart and digital solutions for supply chain management

Wolfgang Kersten, Thorsten Blecker & Christian M. Ringle
This volume contains research contributions by an international group of authors addressing innovative and technology-based approaches for logistics and supply chains. They present business models and investment options for enhanced strategic decision making as well as recent approaches for supply chain analytics and risk management. This volume, edited by Wolfgang Kersten, Thorsten Blecker and Christian Ringle, provides valuable insights into the digitalization of Supply Chain Management and Logistics with regard to: Innovation and Technology Management,...

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