498 Works

Fleet based schedule optimisation for product tanker considering shipʼs stability

Anisa Rizvanolli, Alexander Haupt, Peter Marvin Müller & Jorin Dornemann
Purpose: Scheduling a fleet of product tankers in a cost effective and robust way to satisfy orders is a complex task. A variety of constraints and preferences complicate this attempt. Manual solutions as common in tramp shipping are not sufficient to deliver optimal and robust schedules. Methodology: For this, we present a mixed integer linear programming formulation of the scheduling problem. Additionally intact stability calculations for each ship of the fleet are implemented in a...

Industrial tracking camera and product vision detection system

Wisam T. Abbood, Hiba K. Hussein & Oday Ibraheem Abdullah
Many industrial and commercial applications today are beginning to use autonomous systems to increase productivity and reduce costs for production and manpower. Most of these applications are only semi- autonomous, it still needs assistance from a human to start up or receive continual instructions. It can be improve the productivity using the image processing techniques based on the camera processing capabilities and more efficient vehicles. This research paper describes a vision tracking system platform and...

Computational micromechanics of matrix-inclusion composites

Konrad Schneider
This thesis is concerned with aspects of the computational retrievement of macroscopic material responses and investigations of the microscopic deformation behavior of random matrix-inclusion composites. To this end, the focus lies on the representative volume element (RVE) approach in the scope of finite element analyses and its applicability and integration into engineering practice. The artificial random generation of the microstructural geometry, in a periodic and non-periodic manner, is established by studying and enhancing existing methods...

Adaptive failure detection and correction in dynamic patient-networks

Martin Ringwelski, Andreas Timm-Giel & Volker Turau
Wireless sensors have been studied over recent years for different promising applications with high value for individuals and society. A good example are wireless sensor networks for patients allowing for better and more efficient monitoring of patients in hospitals or even early discharge form hospital and monitoring at home. These visions have hardly led research as reliability is and issue with wireless networks to be known error-prone. In life critical applications like health care this...

Effects of processing parameters on 3D structural ordering and optical properties of inverse opal photonic crystals produced by atomic layer deposition

Heloisa G. Campos, Kaline Pagnan Furlan, Daniel E. Garcia, Robert H. Blick, Robert Zierold, Manfred Eich, Dachamir Hotza & Rolf Janßen
Vertical convective self‐assembly has been extensively used for the preparation of direct photonic crystals, which can be later infiltrated with a more stable material, such as oxide ceramics, by atomic layer deposition. However, the relationship between the self‐assembly parameters of the direct photonic crystals and the optical properties of the inverse opal photonic crystals remains elusive. In this work, the effect of different experimental parameters on the 3D structure and the density of defects of...

Reasoning about non-functional properties using compiler intrinsic function annotations

Shashank Jadhav, Mikko Julian Roth, Heiko Falk, Chris Brown & Adam Barwell

Friction-induced vibrations during tightening of bolted joints : analytical and experimental results

Nicolaj Baramsky, Arthur Seibel & Josef Schlattmann
Bolted joints are one of the most used machine elements. Holding together structures of all sizes, the integrity rests on their shoulders. Thus, an accurate and reliable assembly of the joint is crucial. While it is the aim to not experience friction-induced vibrations at all, at some situations, it is unavoidable. These cases, however, have yet been out of the focus of control algorithms due to the volatile nature of the process. This contribution delivers...

Continuing education and personalization of design methods to improve their acceptance in practice : an explorative study

Selin Üreten, Gregor Beckmann, Eilika Schwenke, Dieter Krause & Shi Cao
One possibility to establish and foster efficient method transfer from academia to industry is via the heads of professional designers and design students. The transfer and use of design methods in a sustainable way is related to the methods' acceptance by the user which is accompanied by many challenges. Educational concepts and design method adaptions have been chosen as decisive control parameters among many others in order to understand and evaluate how these can influence...

Comparative study of the path integration method and the stochastic averaging method for nonlinear roll motion in random beam seas

Wei Chai, Leo Dostal, Arvid Naess & Bernt J. Leira
In this work, the path integration method and the energy-based stochastic averaging method are introduced in order to study the stochastic responses of ship roll motion in random beam seas. Based on the Markov property of the dynamical system, the path integration (PI) method provides approximate solution to the governing Fokker-Planck (FP) equation. On the other hand, the stochastic averaging method leads to a dimension reduction of the original system, but the essential behavior is...

Key parameters of measles virus production for oncolytic virotherapy

Katja Weiss, Denise Salzig, Michael D. Mühlebach, Klaus Cichutek, Ralf Pörtner & Peter Czermak
Attenuated measles virus has revealed selective tumor cell killing and is currently tested in clinical trials for the therapy of cancer patients. The amount of infectious particles per dose needed for oncolytic therapy can be more than a million times higher compared to vaccination. This requires highly effective production processes which guarantee the measles virus quantities needed for its use in cancer therapy. Referring to measles virus production itself, several factors are influencing process parameters...

Integral analysis of labor productivity

Thomas Czumanski & Hermann Lödding
Analyzing and improving the productivity of labor-intensive manufacturing and assembly operations remains a crucial task for industrial companies. Because of the heterogeneous causes for productivity losses, the analysis requires a comprehensive data acquisition and evaluation. With this paper we introduce a state-oriented approach providing the possibility to identify and prioritize the different impacts on labor productivity for subsequent process enhancements. With a case study, we show how to visualize and evaluate state data of an...

Determining the potential to Improve schedule compliance

Andreas Piontek & Hermann Lödding
High schedule compliance is very important but rarely achieved in make-to-order productions. Especially when orders are released too late (e. g. due to missing raw material) it is challenging to identify how many orders can still be produced in time. This paper shows how companies can identify their potential to increase schedule compliance by earliest operation due-date sequencing. The simple model shows that five parameters determine the potential to increase schedule compliance through sequencing: the...

Dead time optimization method for power converter

Christian Deselaers, U. Bergmann & Frank Gronwald
This paper introduces a method for dead time optimization in variable speed motor drive systems. The aim of this method is to reduce the conduction time of the freewheeling diode to a minimum without generation of cross conduction. This results in lower losses, improved EMC, and less overshooting of the phase voltage. The principle of the method is to detect beginning cross currents without adding additional components in the half bridge like resistors or inductances....

Preparation of biopolymer aerogels using green solvents

Raman Subrahmanyam, Pavel Gurikov, Imke Meissner & Irina Smirnova
Although the first reports on aerogels made by Kistler1 in the 1930s dealt with aerogels from both inorganic oxides (silica and others) and biopolymers (gelatin, agar, cellulose), only recently have biomasses been recognized as an abundant source of chemically diverse macromolecules for functional aerogel materials. Biopolymer aerogels (pectin, alginate, chitosan, cellulose, etc.) exhibit both specific inheritable functions of starting biopolymers and distinctive features of aerogels (80-99% porosity and specific surface up to 800 m2/g). This...

A thermomechanically consistent constitutive theory for modeling micro-void and/or micro-crack driven failure in metals at finite strains

Celal Soyarslan, Ismaíl Cem Türtük, Babur Deliktas & Swantje Bargmann
Within a continuum approximation, we present a thermomechanical finite strain plasticity model which incorporates the blended effects of micro-heterogeneities in the form of micro-cracks and micro-voids. The former accounts for cleavage-type of damage without any volume change whereas the latter is a consequence of plastic void growth. Limiting ourselves to isotropy, for cleavage damage a scalar damage variable d ϵ [0, 1] is incorporated. Its conjugate variable, the elastic energy release rate, and evolution law...

Influência da espessura do filme polimérico intermediário na resistência mecânica de juntas híbridas de alumínio 2024-T3 e CF-PPS produzidas por união pontual por fricção

Natália Manente André, Seyed Mohammad Goushegir, Jorge F. dos Santos, Leonardo Bresciani Canto & Sergio Amancio
Friction Spot Joining (FSpJ) is an innovative friction-based joining technique for metalpolymer hybrid structures. Friction spot joints of aluminum alloy 2024-T3 and carbon‑fiber reinforced poly(phenylene sulfide) composite laminate (CF-PPS) were produced with an additional PPS film interlayer. Two different film thicknesses were investigated in this study: 100 and 500 μm. Lap shear testing demonstrated that the joints produced with 100 μm film (2093 ± 180 N) were stronger than the joints with 500 μm (708...

A new cerebral vessel benchmark dataset (CAPUT) for validation of image-based aneurysm deformation estimation algorithms

Daniel Schetelig, Andreas M. J. Frölich, Tobias Knopp & René Werner
Hemodynamic properties and deformation of vessel structures are assumed to be correlated to the initiation, development, and rupture of cerebral aneurysms. Therefore, precise quantification of wall motion is essential. However, using standard-of-care imaging data, approaches for patient-specific estimation of pulsatile deformation are prone to uncertainties due to, e.g., contrast agent inflow-related intensity changes and small deformation compared to the image resolution. A ground truth dataset that allows evaluating and finetuning algorithms for deformation estimation is...

Accelerating the numerical computation of indirect lightning effects by means of vector fitting

Jürgen Anatzki & Frank Gronwald
In the context of numerical computation of indirect lightning effects it is customary to use volume-discretizing methods in time domain, such as the Finite Difference Time Domain (FDTD) method, the Finite Integration Technique (FIT), or the Transmission Line Matrix (TLM) method. If standard lightning electromagnetic pulses (LEMPs) of tenths of microseconds duration are used as excitations, these methods require long computation times, as implied by the Courant criterion. It is proposed to use shorter pulse...

Network acceptance test for maritime ethernet/IP-networks

René Steinrücken

GPU-accelerated LBM-VOF two-phase flow simulations with grid refinement

Martin Gehrke, Dennis Mierke, Christian F. Janßen & Thomas Rung
The contribution is devoted to a novel grid refinement technique for GPU-accelerated Lattice Boltzmann Method (LBM) dedicated to free surface flow simulations in marine applications. LBM implementations are mostly based on homogeneous isotropic Cartesian discretizations of the computational domain. Challenges occur when a refined spatial and temporal resolution is locally required. To efficiently address this demand, local grid refinement is often deployed to regions featuring small scale structures and effects to be resolved. Within the...

On the placement of on-body antennas for ultra wideband capsule endoscopy

Jan-Christoph Brumm & Gerhard Bauch
Ultra wideband communication is proposed as an alternative to increase the data rate for in-body to on-body communication compared with existing narrowband standards. However, up to now, it is unknown, which maximum data rates can be achieved in this environment. The channel capacity is a theoretic tool that allows quantifying this limit. In a frequency-dependent environment like the human body, it is necessary to know the frequency dependence of the communication channel to calculate the...

Dataset of ptychographic X-ray computed tomography of inverse opal photonic crystals produced by atomic layer deposition

Kaline P. Furlan, Emanuel Larsson, Ana Diaz, Mirko Holler, Tobias Krekeler, Martin Ritter, Alexander Yu. Petrov, Manfred Eich, Robert Blick, Gerold A. Schneider, Imke Greving, Robert Zierold & Rolf Janßen
This data article describes the detailed parameters for synthesizing mullite inverse opal photonic crystals via Atomic Layer Deposition (ALD), as well as the detailed image analysis routine used to interpret the data obtained by the measurement of such photonic crystals, before and after the heat treatment, via Ptychographic X-ray Computed Tomography (PXCT). The data presented in this article are related to the research article by Furlan and co-authors entitled "Photonic materials for high-temperature applications: Synthesis...

Strategische Ansätze der Bundesländer zur Digitalisierung in der Hochschulbildung

Christiane Arndt & Lisa Figura
In 16 Fallbeschreibungen werden öffentlich zugängliche strategische Dokumente auf Bundeslandebene dargestellt. Der inhaltliche Fokus liegt auf Digitalisierung in der Hochschulbildung.

Dynamic simulation of different transport options of renewable hydrogen to a refinery in a coupled energy system approach

Lisa Andresen, Carsten Bode & Gerhard Schmitz
Three alternative transport options for hydrogen generated from excess renewable power to a refinery of different scales are compared to the reference case by means of hydrogen production cost, overall efficiency, and CO2 emissions. The hydrogen is transported by a) the natural gas grid and reclaimed by the existing steam reformer, b) an own pipeline and c) hydrogen trailers. The analysis is applied to the city of Hamburg, Germany, for two scenarios of installed renewable...

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