464 Works

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...

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...

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...

Network acceptance test for maritime ethernet/IP-networks

René Steinrücken

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...

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.

Draft genome sequence of type strain Clostridium pasteurianum DSM 525 (ATCC 6013) : a promising producer of chemicals and fuels

Sugima Rappert, Lifu Song, Wael Sabra, Wei Wang & An-Ping Zeng
Clostridium pasteurianum, an anaerobic bacterium able to utilize atmospheric free nitrogen for biosynthesis, has recently been proven to be a promising producer of chemicals and fuels, such as 1,3-propanediol and n-butanol. Here, we report the high-quality draft genome sequence of DSM 525, a type strain of C. pasteurianum.

Integration of oxygen-containing exhaust gas into the air separation unit of an oxyfuel power plant

Jens Dickmeis & Alfons Kather
The Oxyfuel process is one possible solution to lower the high specific CO2 emissions of coal-fired power plants. The flue gas generated by this process has a high CO2 content, due to the missing nitrogen. However the dried flue gas still contains approximately 15 vol% (dry) impurities (NOx, SOx, O2, N2 and Ar). To further increase the CO2 purity the flue gas needs to be treated in a gas processing unit (GPU). Additional downstream gas...

Evaluation of fixed-bed cultures with immobilized Lactococcus Lactis ssp. Lactis on different scales

Rebecca Faschian, Ilyas Eren, Steven Minden & Ralf Pörtner
Fixed-bed processes, where cells are immobilized within macroporous carriers, are a promising alternative to processes with suspended cells. A scale-up concept is presented in order to evaluate the performance as part of process design of fixed-bed processes. Therefore, Lactococcus lactis cultivation in chemostat and batch mode was compared to fixed bed cultures on three different scales, the smallest being the downscaled Multiferm with 10 mL fixed bed units, the second a 100 mL fixed-bed reactor...

Autonomous vehicles and autonomous driving in freight transport

Heike Flämig
The degree of vehicle automation is continuously rising in all modes of transport both on public traffic infrastructure and in-house transport within company grounds, in order to improve the productivity, reliability, and flexibility of transport.

On the process-related rivet microstructural evolution, material flow and mechanical properties of Ti-6Al-4V/GFRP friction-riveted joints

Natascha Zocoller Borba, Conrado R. M. Afonso, Lucian A. Blaga, Jorge F. dos Santos, Leonardo Bresciani Canto & Sergio Amancio
In the current work, process-related thermo-mechanical changes in the rivet microstructure, joint local and global mechanical properties, and their correlation with the rivet plastic deformation regime were investigated for Ti-6Al-4V (rivet) and glass-fiber-reinforced polyester (GF-P) friction-riveted joints of a single polymeric base plate. Joints displaying similar quasi-static mechanical performance to conventional bolted joints were selected for detailed characterization. The mechanical performance was assessed on lap shear specimens, whereby the friction-riveted joints were connected with AA2198...

Label-free photonic biosensors fabricated with low-loss hydrogenated amorphous silicon resonators

Timo Lipka, Lennart Wahn, Hoc Khiem Trieu, Lutz Hilterhaus & Jörg Müller
The precise detection of chemicals and biomolecules is of great interest in the areas of biotechnology and medical diagnostics. Thus, there is a need for highly sensitive, small area, andlow-cost sensors. We fabricated and optically characterized hydrogenated amorphous silicon photonic resonators for label-free lab-on-chip biosensors. The sensing was performed with small-footprint microdisk and microring resonators that detect a refractive-index change via the evanescent electric field. Homogeneous sensing with NaCl and surface-sensing experiments with immobilized bovine...

Energetic evaluation of different flow sheet modifications of post-combustion CO₂ capture plant at coal and natural gas fired power plant for a generic improved solvent

Sören Ehlers, Volker Roeder, Alfons Kather, Prachi Singh & John Davison
The post-combustion capture (PCC) technology is a promising possibility to reduce CO₂ emissions of fossil fuel fired power plants. One of the main concerns for the PCC is the loss in electric power output. A reduction in efficiency penalty for solvent based PCC can be achieved by improving the solvent properties as well as by improving the process design. There are many different process flow sheet modifications with an improvement in process design reported in...

Hybrid instrumentation in lumbar spinal fusion : a biomechanical evaluation of three different Instrumentation techniques

Peter Obid, Reza Danyali, Rebecca Kueny, Gerd Huber, Michael Reichl, Alexander Richter, Thomas Niemeyer, Michael Morlock, Klaus Püschel & Hüseyin Übeyli
Study Design Ex vivo human cadaveric study. Objective The development or progression of adjacent segment disease (ASD) after spine stabilization and fusion is a major problem in spine surgery. Apart from optimal balancing of the sagittal profile, dynamic instrumentation is often suggested to prevent or impede ASD. Hybrid instrumentation is used to gain stabilization while allowing motion to avoid hypermobility in the adjacent segment. In this biomechanical study, the effects of two different hybrid instrumentations...

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...

Thermodynamic assessment of the fixed-bed downdraft gasification process of fallen leaves pelletized with glycerol as binder

William A. González, Felix Zimmermann & Juan Fernando Pérez
In this work, the effect of airflow rate and glycerol content of pelletized fallen leaves (FL) on a fixed bed gasification process is studied. FLs were collected in the main campus of the University of Antioquia (Medellin, Colombia). Levels of airflow rate tested were 0.075, 0.150, and 0.225 kg/s/m2; and the glycerol content of pellets evaluated were 0 and 5%wt. When the airflow rate increased, flame front velocity increased up to 51.3%. This behavior was...

Registration Year

  • 2019

Resource Types

  • Text