TY  - JOUR
A1  - Leingartner, Max
A1  - Maurer, Johannes
A1  - Ferrein, Alexander
A1  - Steinbauer, Gerald
T1  - Evaluation of Sensors and Mapping Approaches for Disasters in Tunnels
JF  - Journal of Field Robotics
N2  - Ground or aerial robots equipped with advanced sensing technologies, such as three-dimensional laser scanners and advanced mapping algorithms, are deemed useful as a supporting technology for first responders. A great deal of excellent research in the field exists, but practical applications at real disaster sites are scarce. Many projects concentrate on equipping robots with advanced capabilities, such as autonomous exploration or object manipulation. In spite of this, realistic application areas for such robots are limited to teleoperated reconnaissance or search. In this paper, we investigate how well state-of-the-art and off-the-shelf components and algorithms are suited for reconnaissance in current disaster-relief scenarios. The basic idea is to make use of some of the most common sensors and deploy some widely used algorithms in a disaster situation, and to evaluate how well the components work for these scenarios. We acquired the sensor data from two field experiments, one from a disaster-relief operation in a motorway tunnel, and one from a mapping experiment in a partly closed down motorway tunnel. Based on these data, which we make publicly available, we evaluate state-of-the-art and off-the-shelf mapping approaches. In our analysis, we integrate opinions and replies from first responders as well as from some algorithm developers on the usefulness of the data and the limitations of the deployed approaches, respectively. We discuss the lessons we learned during the two missions. These lessons are interesting for the community working in similar areas of urban search and rescue, particularly reconnaissance and search.
Y1  - 2016
U6  - https://doi.org/10.1002/rob.21611
SN  - 1556-4967
VL  - 33
IS  - 8
SP  - 1037
EP  - 1057
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Haag, S.
A1  - Zontar, D.
A1  - Schleupen, Josef
A1  - Müller, T.
A1  - Brecher, C.
T1  - Chain of refined perception in self-optimizing assembly of micro-optical systems
JF  - Journal of sensors and sensor systems
N2  - Today, the assembly of laser systems requires a large share of manual operations due to its complexity regarding the optimal alignment of optics. Although the feasibility of automated alignment of laser optics has been shown in research labs, the development effort for the automation of assembly does not meet economic requirements – especially for low-volume laser production. This paper presents a model-based and sensor-integrated assembly execution approach for flexible assembly cells consisting of a macro-positioner covering a large workspace and a compact micromanipulator with camera attached to the positioner. In order to make full use of available models from computer-aided design (CAD) and optical simulation, sensor systems at different levels of accuracy are used for matching perceived information with model data. This approach is named "chain of refined perception", and it allows for automated planning of complex assembly tasks along all major phases of assembly such as collision-free path planning, part feeding, and active and passive alignment. The focus of the paper is put on the in-process image-based metrology and information extraction used for identifying and calibrating local coordinate systems as well as the exploitation of that information for a part feeding process for micro-optics. Results will be presented regarding the processes of automated calibration of the robot camera as well as the local coordinate systems of part feeding area and robot base.
Y1  - 2014
U6  - https://doi.org/10.5194/jsss-3-87-2014
SN  - 2194-878X
VL  - 3
IS  - 1
SP  - 87
EP  - 95
PB  - Copernicus Publ.
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Ferrein, Alexander
A1  - Schiffer, Stefan
A1  - Booysen, T.
A1  - Stopforth, R.
T1  - Why it is harder to run RoboCup in South Africa: Experiences from German South African collaborations
JF  - International Journal of Advanced Robotic Systems
N2  - Robots are widely used as a vehicle to spark interest in science and technology in learners. A number of initiatives focus on this issue, for instance, the Roberta Initiative, the FIRST Lego League, the World Robot Olympiad and RoboCup Junior. Robotic competitions are valuable not only for school learners but also for university students, as the RoboCup initiative shows. Besides technical skills, the students get some project exposure and experience what it means to finish their tasks on time. But qualifying students for future high-tech areas should not only be for students from developed countries. In this article, we present our experiences with research and education in robotics within the RoboCup initiative, in Germany and South Africa; we report on our experiences with trying to get the RoboCup initiative in South Africa going. RoboCup has a huge support base of academic institutions in Germany; this is not the case in South Africa. We present our ‘north–south’ collaboration initiatives in RoboCup between Germany and South Africa and discuss some of the reasons why we think it is harder to run RoboCup in South Africa.
Y1  - 2016
U6  - https://doi.org/10.1177/1729881416662789
SN  - 1729-8806
VL  - 13
IS  - 5
SP  - 1
EP  - 13
ER  - 
TY  - JOUR
A1  - Rietsch, Stefan H. G.
A1  - Brunheim, Sascha
A1  - Orzada, Stephan
A1  - Voelker, Maximilian N.
A1  - Maderwald, Stefan
A1  - Bitz, Andreas
A1  - Gratz, Marcel
A1  - Ladd, Mark E.
A1  - Quick, Harald H.
T1  - Development and evaluation of a 16-channel receive-only RF coil to improve 7T ultra-high field body MRI with focus on the spine
JF  - Magnetic Resonance in Medicine
Y1  - 2019
U6  - https://doi.org/10.1002/mrm.27731
SN  - 1522-2594
IS  - Early view
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Limpert, Nicolas
A1  - Wiesen, Patrick
A1  - Ferrein, Alexander
A1  - Kallweit, Stephan
A1  - Schiffer, Stefan
T1  - The ROSIN Project and its Outreach to South Africa
JF  - R&D Journal
Y1  - 2019
VL  - 35
SP  - 1
EP  - 6
ER  - 
TY  - JOUR
A1  - Fagan, Andrew J.
A1  - Bitz, Andreas
A1  - Björkman-Burtscher, Isabella M.
A1  - Collins, Christopher M.
A1  - Kimbrell, Vera
A1  - Raaijmakers, Alexander J. E.
T1  - 7T MR Safety
JF  - Journal of Magnetic Resonance Imaging (JMRI)
Y1  - 2021
U6  - https://doi.org/10.1002/jmri.27319
SN  - 1522-2586
VL  - 53
IS  - 2
SP  - 333
EP  - 346
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Serror, Martin
A1  - Hack, Sacha
A1  - Henze, Martin
A1  - Schuba, Marko
A1  - Wehrle, Klaus
T1  - Challenges and Opportunities in Securing the Industrial Internet of Things
JF  - IEEE Transactions on Industrial Informatics
Y1  - 2021
U6  - https://doi.org/10.1109/TII.2020.3023507
SN  - 1941-0050
VL  - 17
IS  - 5
SP  - 2985
EP  - 2996
PB  - IEEE
CY  - New York
ER  - 
TY  - JOUR
A1  - Fiedler, Thomas M.
A1  - Ladd, Mark E.
A1  - Clemens, Markus
A1  - Bitz, Andreas
T1  - Safety of subjects during radiofrequency exposure in ultra-high-field magnetic resonance imaging
JF  - IEEE Letters on Electromagnetic Compatibility Practice and Applications
N2  - Magnetic resonance imaging (MRI) is one of the most important medical imaging techniques. Since the introduction of MRI in the mid-1980s, there has been a continuous trend toward higher static magnetic fields to obtain i.a. a higher signal-to-noise ratio. The step toward ultra-high-field (UHF) MRI at 7 Tesla and higher, however, creates several challenges regarding the homogeneity of the spin excitation RF transmit field and the RF exposure of the subject. In UHF MRI systems, the wavelength of the RF field is in the range of the diameter of the human body, which can result in inhomogeneous spin excitation and local SAR hotspots. To optimize the homogeneity in a region of interest, UHF MRI systems use parallel transmit systems with multiple transmit antennas and time-dependent modulation of the RF signal in the individual transmit channels. Furthermore, SAR increases with increasing field strength, while the SAR limits remain unchanged. Two different approaches to generate the RF transmit field in UHF systems using antenna arrays close and remote to the body are investigated in this letter. Achievable imaging performance is evaluated compared to typical clinical RF transmit systems at lower field strength. The evaluation has been performed under consideration of RF exposure based on local SAR and tissue temperature. Furthermore, results for thermal dose as an alternative RF exposure metric are presented.
Y1  - 2020
SN  - 2637-6423
U6  - https://doi.org/10.1109/LEMCPA.2020.3029747
VL  - 2
IS  - 3
SP  - 1
EP  - 8
PB  - IEEE
CY  - New York, NY
ER  - 
TY  - JOUR
A1  - Hüning, Felix
A1  - Backes, Andreas
T1  - Direct observation of large Barkhausen jump in thin Vicalloy wires
JF  - IEEE Magnetics Letters
Y1  - 2020
SN  - 1949-307X
U6  - https://doi.org/10.1109/LMAG.2020.3046411
VL  - 11
IS  - Art. 2506504
SP  - 1
EP  - 4
PB  - IEEE
CY  - New York, NY
ER  - 
TY  - JOUR
A1  - Harzheim, Thomas
A1  - Mühmel, Marc
A1  - Heuermann, Holger
T1  - A SFCW harmonic radar system for maritime search and rescue using passive and active tags
JF  - International Journal of Microwave and Wireless Technologies
N2  - This paper introduces a new maritime search and rescue system based on S-band illumination harmonic radar (HR). Passive and active tags have been developed and tested while attached to life jackets and a small boat. In this demonstration test carried out on the Baltic Sea, the system was able to detect and range the active tags up to a distance of 5800 m using an illumination signal transmit-power of 100 W. Special attention is given to the development, performance, and conceptual differences between passive and active tags used in the system. Guidelines for achieving a high HR dynamic range, including a system components description, are given and a comparison with other HR systems is performed. System integration with a commercial maritime X-band navigation radar is shown to demonstrate a solution for rapid search and rescue response and quick localization.
KW  - Radar
KW  - microwave measurements
KW  - harmonic radar
KW  - harmonic radar tags
KW  - nonlinear VNA measurements
Y1  - 2021
U6  - https://doi.org/10.1017/S1759078721000520
VL  - 13
IS  - Special Issue 7
SP  - 691
EP  - 707
PB  - Cambridge University Press
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Reinhardt, T.
A1  - Bitz, Andreas
A1  - El Ouardi, A.
A1  - Streckert, J.
A1  - Sommer, A.
A1  - Lerchl, A.
A1  - Hansen, V.
T1  - Exposure set-ups for in vivo experiments using radial waveguides
JF  - Radiation Protection Dosimetry
Y1  - 2007
U6  - https://doi.org/10.1093/rpd/ncm370
SN  - 1742-3406
VL  - 124
IS  - 1
SP  - 21
EP  - 26
ER  - 
TY  - JOUR
A1  - Sommer, Angela M.
A1  - Bitz, Andreas
A1  - Streckert, Joachim
A1  - Hansen, Volkert W.
A1  - Lerchl, Alexander
T1  - Lymphoma development in mice chronically exposed to UMTS-modulated radiofrequency electromagnetic fields
JF  - Radiation Research
Y1  - 2007
U6  - https://doi.org/10.1667/RR0857.1
SN  - 1938-5404
VL  - 168
IS  - 1
SP  - 72
EP  - 80
ER  - 
TY  - JOUR
A1  - Sukhotina, Irina
A1  - Streckert, Joachim R.
A1  - Bitz, Andreas
A1  - Hansen, Volkert W.
A1  - Lerchl, Alexander
T1  - 1800 MHz electromagnetic field effects on melatonin release from isolated pineal glands
JF  - Journal of Pineal Research
Y1  - 2006
U6  - https://doi.org/10.1111/j.1600-079X.2005.00284.x
SN  - 1600-079X
VL  - 40
IS  - 1
SP  - 86
EP  - 91
ER  - 
TY  - JOUR
A1  - Franke, Helmut
A1  - Streckert, Joachim
A1  - Bitz, Andreas
A1  - Goeke, Johannes
A1  - Hansen, Volkert
A1  - Ringelstein, E. Bernd
A1  - Nattkämper, Heiner
A1  - Galle, Hans-Joachim
A1  - Stögbauer, Florian
T1  - Effects of Universal Mobile Telecommunications System (UMTS) electromagnetic fields on the blood-brain barrier in vitro
JF  - Radiation Research
Y1  - 2005
U6  - https://doi.org/10.1667/RR3424.1
SN  - 1938-5404
VL  - 164
IS  - 3
SP  - 258
EP  - 269
ER  - 
TY  - JOUR
A1  - Wissen, M.
A1  - Bogdanski, N.
A1  - Scheer, H.-C.
A1  - Bitz, Andreas
A1  - Ahrens, G.
A1  - Gruetzner, G.
T1  - Implication of the light polarisation for UV curing of pre-patterned resists
JF  - Microelectronic Engineering
Y1  - 2005
U6  - https://doi.org/10.1016/j.mee.2004.12.099
SN  - 0167-9317
VL  - 78-79
SP  - 659
EP  - 664
ER  - 
TY  - JOUR
A1  - Ndoumbè Mbonjo Mbonjo, H.
A1  - Streckert, J.
A1  - Bitz, Andreas
A1  - Hansen, V.
A1  - Glasmachers, A.
A1  - Gencol, S.
A1  - Rozic, D.
T1  - Generic UMTS test signal for RF bioelectromagnetic studies
JF  - Bioelectromagnetics
Y1  - 2004
U6  - https://doi.org/10.1002/bem.20007
SN  - 1521-186X
VL  - 25
IS  - 6
SP  - 415
EP  - 425
ER  - 
TY  - JOUR
A1  - Sommer, Angela M.
A1  - Streckert, Joachim
A1  - Bitz, Andreas
A1  - Hansen, Volkert W.
A1  - Lerchl, Alexander
T1  - No effects of GSM-modulated 900 MHz electromagnetic fields on survival rate and spontaneous development of lymphoma in female AKR/J mice
JF  - BMC Cancer
Y1  - 2004
U6  - https://doi.org/10.1186/1471-2407-4-77
VL  - 77
IS  - 4
ER  - 
TY  - JOUR
A1  - Hansen, Volkert W.
A1  - Bitz, Andreas
A1  - Streckert, Joachim R.
T1  - RF Exposure of Biological Systems in Radial Waveguides
JF  - IEEE Transactions on Electromagnetic Compatibility
Y1  - 1999
U6  - https://doi.org/10.1109/15.809852
SN  - 1558-187X
VL  - 41
IS  - 4
SP  - 487
EP  - 493
ER  - 
TY  - JOUR
A1  - Orzada, Stephan
A1  - Solbach, Klaus
A1  - Gratz, Marcel
A1  - Brunheim, Sascha
A1  - Fiedler, Thomas M.
A1  - Johst, Sören
A1  - Bitz, Andreas
A1  - Shooshtary, Samaneh
A1  - Abuelhaija, Asjraf
A1  - Voelker, Maximilian N.
A1  - Rietsch, Stefan H. G.
A1  - Kraff, Oliver
A1  - Maderwald, Stefan
A1  - Flöser, Martina
A1  - Oehmingen, Mark
A1  - Quick, Harald H.
A1  - Ladd, Mark E.
T1  - A 32-channel parallel transmit system add-on for 7T MRI
JF  - Plos one
Y1  - 2019
U6  - https://doi.org/10.1371/journal.pone.0222452
ER  - 
TY  - JOUR
A1  - Köhler, Klemens
T1  - A conflict theory perspective of IT attacks – consequences for IT security education
N2  - Cyberspace is "the environment formed by physical and non-physical components to store, modify, and exchange data using computer networks" (NATO CCDCOE). Beyond that, it is an environment where people interact. IT attacks are hostile, non-cooperative interactions that can be described with conflict theory. Applying conflict theory to IT security leads to different objectives for end-user education, requiring different formats like agency-based competence developing games.
Y1  - 2020
IS  - Preprint
ER  - 
TY  - JOUR
A1  - Köhler, Klemens
A1  - Röpke, René
A1  - Wolf, Martin
T1  - Through a mirror darkly – On the obscurity of teaching goals in game-based learning in IT security
JF  - ISAGA 2019: Simulation Gaming Through Times and Disciplines
N2  - Teachers and instructors use very specific language communicating teaching goals. The most widely used frameworks of common reference are the Bloom’s Taxonomy and the Revised Bloom’s Taxonomy. The latter provides distinction of 209 different teaching goals which are connected to methods. In Competence Developing Games (CDGs - serious games to convey knowledge) and in IT security education, a two- or three level typology exists, reducing possible learning outcomes to awareness, training, and education. This study explores whether this much simpler framework succeeds in achieving the same range of learning outcomes. Method wise a keyword analysis was conducted. The results were threefold: 1. The words used to describe teaching goals in CDGs on IT security education do not reflect the whole range of learning outcomes. 2. The word choice is nevertheless different from common language, indicating an intentional use of language. 3. IT security CDGs use different sets of terms to describe learning outcomes, depending on whether they are awareness, training, or education games. The interpretation of the findings is that the reduction to just three types of CDGs reduces the capacity to communicate and think about learning outcomes and consequently reduces the outcomes that are intentionally achieved.
KW  - IT security education
KW  - Competence Developing Games
KW  - Game-based learning
KW  - Keyword analysis
KW  - Bloom’s Taxonomy
Y1  - 2021
U6  - https://doi.org/10.1007/978-3-030-72132-9_6
N1  - ISAGA 2019 - International Simulation and Gaming Association Conference. 26-30 August 2019. Warsaw, Poland.

Part of the Lecture Notes in Computer Science book series (LNCS, volume 11988)
SP  - 61
EP  - 73
PB  - Springer
CY  - Cham
ER  - 
TY  - JOUR
A1  - Leise, Philipp
A1  - Eßer, Arved
A1  - Eichenlaub, Tobias
A1  - Schleiffer, Jean-Eric
A1  - Altherr, Lena
A1  - Rinderknecht, Stephan
A1  - Pelz, Peter F.
T1  - Sustainable system design of electric powertrains - comparison of optimization methods
JF  - Engineering Optimization
N2  - The transition within transportation towards battery electric vehicles can lead to a more sustainable future. To account for the development goal ‘climate action’ stated by the United Nations, it is mandatory, within the conceptual design phase, to derive energy-efficient system designs. One barrier is the uncertainty of the driving behaviour within the usage phase. This uncertainty is often addressed by using a stochastic synthesis process to derive representative driving cycles and by using cycle-based optimization. To deal with this uncertainty, a new approach based on a stochastic optimization program is presented. This leads to an optimization model that is solved with an exact solver. It is compared to a system design approach based on driving cycles and a genetic algorithm solver. Both approaches are applied to find efficient electric powertrains with fixed-speed and multi-speed transmissions. Hence, the similarities, differences and respective advantages of each optimization procedure are discussed.
KW  - Powertrain
KW  - stochastic optimization
KW  - global optimization
KW  - genetic algorithm
Y1  - 2021
U6  - https://doi.org/10.1080/0305215X.2021.1928660
SN  - 0305-215X
PB  - Taylor & Francis
CY  - London
ER  - 
TY  - JOUR
A1  - Altherr, Lena
A1  - Ederer, Thorsten
A1  - Lorenz, Ulf
A1  - Pelz, Peter F.
A1  - Pöttgen, Philipp
ED  - Lübbecke, Marco
ED  - Koster, Arie
ED  - Letmathe, Peter
ED  - Madlener, Reihard
ED  - Peis, Britta
ED  - Walther, Grit
T1  - Experimental validation of an enhanced system synthesis approach
JF  - Operations Research Proceedings 2014
N2  - Planning the layout and operation of a technical system is a common task
for an engineer. Typically, the workflow is divided into consecutive stages: First,
the engineer designs the layout of the system, with the help of his experience or of
heuristic methods. Secondly, he finds a control strategy which is often optimized
by simulation. This usually results in a good operating of an unquestioned sys-
tem topology. In contrast, we apply Operations Research (OR) methods to find a
cost-optimal solution for both stages simultaneously via mixed integer program-
ming (MILP). Technical Operations Research (TOR) allows one to find a provable
global optimal solution within the model formulation. However, the modeling error
due to the abstraction of physical reality remains unknown. We address this ubiq-
uitous problem of OR methods by comparing our computational results with mea-
surements in a test rig. For a practical test case we compute a topology and control
strategy via MILP and verify that the objectives are met up to a deviation of 8.7%.
Y1  - 2014
SN  - 978-3-319-28695-2
U6  - https://doi.org/10.1007/978-3-319-28697-6_1
PB  - Springer
CY  - Basel
ER  - 
TY  - JOUR
A1  - Sun, Hui
A1  - Altherr, Lena
A1  - Pei, Ji
A1  - Pelz, Peter F.
A1  - Yuan, Shouqi
T1  - Optimal booster station design and operation under uncertain load
JF  - Applied Mechanics and Materials
N2  - Given industrial applications, the costs for the operation and maintenance of a pump system typically far exceed its purchase price. For finding an optimal pump configuration which minimizes not only investment, but life-cycle costs, methods like Technical Operations Research which is based on Mixed-Integer Programming can be applied. However, during the planning phase, the designer is often faced with uncertain input data, e.g. future load demands can only be estimated. In this work, we deal with this uncertainty by developing a chance-constrained two-stage (CCTS) stochastic program. The design and operation of a booster station working under uncertain load demand are optimized to minimize total cost including purchase price, operation cost incurred by energy consumption and penalty cost resulting from water shortage. We find optimized system layouts using a sample average approximation (SAA) algorithm, and analyze the results for different risk levels of water shortage. By adjusting the risk level, the costs and performance range of the system can be balanced, and thus the
system’s resilience can be engineered
KW  - Stochastic Programming
KW  - Chance Constraint
KW  - Engineering Application
KW  - Pump System
KW  - Water Distribution
Y1  - 2018
U6  - https://doi.org/10.4028/www.scientific.net/AMM.885.102
SN  - 1662-7482
VL  - 885
SP  - 102
EP  - 115
PB  - Trans Tech Publications
CY  - Bäch
ER  - 
TY  - JOUR
A1  - Altherr, Lena
A1  - Brötz, Nicolas
A1  - Dietrich, Ingo
A1  - Gally, Tristan
A1  - Geßner, Felix
A1  - Kloberdanz, Hermann
A1  - Leise, Philipp
A1  - Pelz, Peter Franz
A1  - Schlemmer, Pia
A1  - Schmitt, Andreas
T1  - Resilience in mechanical engineering - a concept for controlling uncertainty during design, production and usage phase of load-carrying structures
JF  - Applied Mechanics and Materials
N2  - Resilience as a concept has found its way into different disciplines to describe the ability of an individual or system to withstand and adapt to changes in its environment. In this paper, we provide an overview of the concept in different communities and extend it to the area of mechanical engineering. Furthermore, we present metrics to measure resilience in technical systems and illustrate them by applying them to load-carrying structures. By giving application examples from the Collaborative Research Centre (CRC) 805, we show how the concept of resilience can be used to control uncertainty during different stages of product life.
Y1  - 2018
SN  - 1662-7482
U6  - https://doi.org/10.4028/www.scientific.net/AMM.885.187
VL  - 885
SP  - 187
EP  - 198
PB  - Trans Tech Publications
CY  - Bäch
ER  - 
TY  - JOUR
A1  - Rausch, Lea
A1  - Friesen, John
A1  - Altherr, Lena
A1  - Meck, Marvin
A1  - Pelz, Peter F.
T1  - A holistic concept to design optimal water supply infrastructures for informal settlements using remote sensing data
JF  - Remote Sensing
N2  - Ensuring access to water and sanitation for all is Goal No. 6 of the 17 UN Sustainability Development Goals to transform our world. As one step towards this goal, we present an approach that leverages remote sensing data to plan optimal water supply networks for informal urban settlements. The concept focuses on slums within large urban areas, which are often characterized by a lack of an appropriate water supply. We apply methods of mathematical optimization aiming to find a network describing the optimal supply infrastructure. Hereby, we choose between different decentral and central approaches combining supply by motorized vehicles with supply by pipe systems. For the purposes of illustration, we apply the approach to two small slum clusters in Dhaka and Dar es Salaam. We show our optimization results, which represent the lowest cost water supply systems possible. Additionally, we compare the optimal solutions of the two clusters (also for varying input parameters, such as population densities and slum size development over time) and describe how the result of the optimization depends on the entered remote sensing data.
KW  - water supply design
KW  - mathematical optimization
KW  - slum classification
KW  - remote sensing
Y1  - 2018
SN  - 2072-4292
U6  - https://doi.org/10.3390/rs10020216
VL  - 10
IS  - 2
SP  - 1
EP  - 23
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Altherr, Lena
A1  - Joggerst, Laura
A1  - Leise, Philipp
A1  - Pfetsch, Marc E.
A1  - Schmitt, Andreas
A1  - Wendt, Janine
T1  - On obligations in the development process of resilient systems with algorithmic design methods
JF  - Applied Mechanics and Materials
N2  - Advanced computational methods are needed both for the design of large systems and to compute high accuracy solutions. Such methods are efficient in computation, but the validation of results is very complex, and highly skilled auditors are needed to verify them. We investigate legal questions concerning obligations in the development phase, especially for technical systems developed using advanced methods. In particular, we consider methods of resilient and robust optimization. With these techniques, high performance solutions can be found, despite a high variety of input parameters. However, given the novelty of these methods, it is uncertain whether legal obligations are being met. The aim of this paper is to discuss if and how the choice of a specific computational method affects the developer’s product liability. The review of legal obligations in this paper is based on German law and focuses on the requirements that must be met during the design and development process.
KW  - legal obligations
KW  - product liability
KW  - design of technical systems
KW  - optimization
KW  - resilience
Y1  - 2018
SN  - 1662-7482
U6  - https://doi.org/10.4028/www.scientific.net/AMM.885.240
VL  - 885
IS  - 885
SP  - 240
EP  - 252
PB  - Trans Tech Publications
CY  - Bäch
ER  - 
TY  - JOUR
A1  - Pöttgen, Philipp
A1  - Ederer, Thorsten
A1  - Altherr, Lena
A1  - Lorenz, Ulf
A1  - Pelz, Peter F.
T1  - Examination and optimization of a heating circuit for energy-efficient buildings
JF  - Energy Technology
N2  - The conference center darmstadtium in Darmstadt is a prominent example of energy efficient buildings. Its heating system consists of different source and consumer circuits connected by a Zortström reservoir. Our goal was to reduce the energy costs of the system as much as possible. Therefore, we analyzed its supply circuits. The first step towards optimization is a complete examination of the system: 1) Compilation of an object list for the system, 2) collection of the characteristic curves of the components, and 3) measurement of the load profiles of the heat and volume-flow demand. Instead of modifying the system manually and testing the solution by simulation, the second step was the creation of a global optimization program. The objective was to minimize the total energy costs for one year. We compare two different topologies and show opportunities for significant savings.
KW  - energy transfer
KW  - heating system
KW  - programming
KW  - system optimization
KW  - technical operations research
Y1  - 2015
SN  - 2194-4296
U6  - https://doi.org/10.1002/ente.201500252
VL  - 4
IS  - 1
SP  - 136
EP  - 144
PB  - WILEY-VCH Verlag
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Altherr, Lena
A1  - Ederer, Thorsten
A1  - Pöttgen, Philipp
A1  - Lorenz, Ulf
A1  - Pelz, Peter F.
ED  - Pelz, Peter F.
ED  - Groche, Peter
T1  - Multicriterial optimization of technical systems considering multiple load and availability scenarios
JF  - Applied Mechanics and Materials
N2  - Cheap does not imply cost-effective -- this is rule number one of zeitgeisty system design. The initial investment accounts only for a small portion of the lifecycle costs of a technical system. In fluid systems, about ninety percent of the total costs are caused by other factors like power consumption and maintenance. With modern optimization methods, it is already possible to plan an optimal technical system considering multiple objectives. In this paper, we focus on an often neglected contribution to the lifecycle costs: downtime costs due to spontaneous failures. Consequently, availability becomes an issue.
KW  - sustainability
KW  - availability
KW  - energy efficiency
KW  - mixed-integer linear programming
KW  - system synthesis
Y1  - 2015
SN  - 1660-9336
U6  - https://doi.org/10.4028/www.scientific.net/AMM.807.247
VL  - 807
SP  - 247
EP  - 256
ER  - 
TY  - JOUR
A1  - Czarnecki, Christian
A1  - Spiliopoulou, Myra
T1  - A holistic framework for the implementation of a next generation network
JF  - International Journal of Business Information Systems
N2  - As the potential of a next generation network (NGN) is recognised, telecommunication companies consider switching to it. Although the implementation of an NGN seems to be merely a modification of the network infrastructure, it may trigger or require changes in the whole company, because it builds upon the separation between service and transport, a flexible bundling of services to products and the streamlining of the IT infrastructure. We propose a holistic framework, structured into the layers ‘strategy’, ‘processes’ and ‘information systems’ and incorporate into each layer all concepts necessary for the implementation of an NGN, as well as the alignment of these concepts. As a first proof-of-concept for our framework we have performed a case study on the introduction of NGN in a large telecommunication company; we show that our framework captures all topics that are affected by an NGN implementation.
KW  - next generation network
KW  - telecommunication
KW  - NGN
KW  - IP-based networks
KW  - product bundling
Y1  - 2012
U6  - https://doi.org/10.1504/IJBIS.2012.046291
SN  - 1746-0972
VL  - 9
IS  - 4
SP  - 385
EP  - 401
PB  - Inderscience Enterprises
CY  - Olney, Bucks
ER  - 
TY  - JOUR
A1  - Czarnecki, Christian
A1  - Winkelmann, Axel
A1  - Spiliopoulou, Myra
T1  - Services in electronic telecommunication markets: a framework for planning the virtualization of processes
JF  - Electronic Markets
N2  - The potential of electronic markets in enabling innovative product bundles through flexible and sustainable partnerships is not yet fully exploited in the telecommunication industry. One reason is that bundling requires seamless de-assembling and re-assembling of business processes, whilst processes in telecommunication companies are often product-dependent and hard to virtualize. We propose a framework for the planning of the virtualization of processes, intended to assist the decision maker in prioritizing the processes to be virtualized: (a) we transfer the virtualization pre-requisites stated by the Process Virtualization Theory in the context of customer-oriented processes in the telecommunication industry and assess their importance in this context, (b) we derive IT-oriented requirements for the removal of virtualization barriers and highlight their demand on changes at different levels of the organization. We present a first evaluation of our approach in a case study and report on lessons learned and further steps to be performed.
KW  - Telecommunication
KW  - Services
KW  - Process virtualization
KW  - Product bundling
KW  - Transformation
Y1  - 2010
U6  - https://doi.org/10.1007/s12525-010-0045-8
SN  - 1422-8890
VL  - 20
IS  - 3-4
SP  - 197
EP  - 207
PB  - Springer
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Schopp, Christoph
A1  - Doll, Timo
A1  - Gräser, Ulrich
A1  - Harzheim, Thomas
A1  - Heuermann, Holger
A1  - Kling, Rainer
A1  - Marso, Michael
T1  - Capacitively Coupled High-Pressure Lamp Using Coaxial Line Networks
JF  - IEEE Transactions on Microwave Theory and Techniques
N2  - This paper describes the development of a capacitively coupled high-pressure lamp with input power between 20 and 43 W at 2.45 GHz, using a coaxial line network. Compared with other electrodeless lamp systems, no cavity has to be used and a reduction in the input power is achieved. Therefore, this lamp is an alternative to the halogen incandescent lamp for domestic lighting. To serve the demands of domestic lighting, the filling of the lamp is optimized over all other resulting requirements, such as high efficacy at low induced powers and fast startups. A workflow to develop RF-driven plasma applications is presented, which makes use of the hot S-parameter technique. Descriptions of the fitting process inside a circuit and FEM simulator are given. Results of the combined ignition and operation network from simulations and measurements are compared. An initial prototype is built and measurements of the lamp's lighting properties are presented along with an investigation of the efficacy optimizations using large signal amplitude modulation. With this lamp, an efficacy of 135 lmW -1 is achieved.
Y1  - 2016
U6  - https://doi.org/10.1109/TMTT.2016.2600326
SN  - 0018-9480
VL  - 64
IS  - 10
SP  - 3363
EP  - 3368
PB  - IEEE
CY  - New York, NY
ER  - 
TY  - JOUR
A1  - Schiffer, Stefan
A1  - Ferrein, Alexander
T1  - Decision-Theoretic Planning with Fuzzy Notions in GOLOG
JF  - International Journal of Uncertainty, Fuzziness and Knowledge-Based Systems
N2  - In this paper we present an extension of the action language Golog that allows for using fuzzy notions in non-deterministic argument choices and the reward function in decision-theoretic planning. Often, in decision-theoretic planning, it is cumbersome to specify the set of values to pick from in the non-deterministic-choice-of-argument statement. Also, even for domain experts, it is not always easy to specify a reward function. Instead of providing a finite domain for values in the non-deterministic-choice-of-argument statement in Golog, we now allow for stating the argument domain by simply providing a formula over linguistic terms and fuzzy uents. In Golog’s forward-search DT planning algorithm, these formulas are evaluated in order to find the agent’s optimal policy. We illustrate this in the Diner Domain where the agent needs to calculate the optimal serving order.
Y1  - 2016
U6  - https://doi.org/10.1142/S0218488516400134
SN  - 1793-6411
VL  - 24
IS  - Issue Suppl. 2
SP  - 123
EP  - 143
PB  - World Scientific
CY  - Singapur
ER  - 
TY  - JOUR
A1  - Rietsch, Stefan H. G.
A1  - Pfaffenrot, Viktor
A1  - Bitz, Andreas
A1  - Orzada, Stephan
A1  - Brunheim, Sascha
A1  - Lazik-Palm, Andrea
A1  - Theysohn, Jens M.
A1  - Ladd, Mark E.
A1  - Quick, Harald H.
A1  - Kraff, Oliver
T1  - An 8-channel transceiver 7-channel receive RF coil setup for high SNR ultrahigh-field MRI of the shoulder at 7T
JF  - Medical Physics
Y1  - 2017
U6  - https://doi.org/10.1002/mp.12612
SN  - 0094-2405
IS  - Article in press
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Ferrein, Alexander
A1  - Steinbauer, Gerald
T1  - The Interplay of Aldebaran and RoboCup
JF  - KI - Künstliche Intelligenz
Y1  - 2016
U6  - https://doi.org/10.1007/s13218-016-0440-1
SN  - 1610-1987
VL  - 30
IS  - 3-4
SP  - 325
EP  - 326
PB  - Springer
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Steinbauer, Gerald
A1  - Ferrein, Alexander
T1  - 20 Years of RoboCup
JF  - KI - Künstliche Intelligenz
Y1  - 2016
U6  - https://doi.org/10.1007/s13218-016-0442-z
SN  - 1610-1987
VL  - 30
IS  - 3-4
SP  - 221
EP  - 224
PB  - Springer
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Ferrein, Alexander
A1  - Steinbauer, Gerald
T1  - Looking back on 20 Years of RoboCup
JF  - KI - Künstliche Intelligenz
Y1  - 2016
U6  - https://doi.org/10.1007/s13218-016-0443-y
SN  - 1610-1987
VL  - 30
IS  - 3-4
SP  - 321
EP  - 323
PB  - Springer
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Orzada, Stephan
A1  - Bitz, Andreas
A1  - Johst, Sören
A1  - Gratz, Marcel
A1  - Völker, Maximilian N.
A1  - Kraff, Oliver
A1  - Abuelhaija, Ashraf
A1  - Fiedler, Thomas M.
A1  - Solbach, Klaus
A1  - Quick, Harald H.
A1  - Ladd, Mark E.
T1  - Analysis of an integrated 8-Channel Tx/Rx body array for use as a body coil in 7-Tesla MRI
JF  - Frontiers in Physics
Y1  - 2017
U6  - https://doi.org/10.3389/fphy.2017.00017
SN  - 2296-424X
N1  - Article number 17
VL  - 5
IS  - Jun
ER  - 
TY  - JOUR
A1  - Hofmann, Till
A1  - Limpert, Nicolas
A1  - Mataré, Victor
A1  - Schönitz, Sebastian
A1  - Niemueller, Tim
A1  - Ferrein, Alexander
A1  - Lakemeyer, Gerhard
T1  - The Carologistics RoboCup Logistics Team 2018
N2  - The Carologistics team participates in the RoboCup Logistics League for the seventh year. The RCLL requires precise vision,
manipulation and path planning, as well as complex high-level decision
making and multi-robot coordination. We outline our approach with an
emphasis on recent modifications to those components.
The team members in 2018 are David Bosen, Christoph Gollok, Mostafa
Gomaa, Daniel Habering, Till Hofmann, Nicolas Limpert, Sebastian Schönitz,
Morian Sonnet, Carsten Stoffels, and Tarik Viehmann.
This paper is based on the last year’s team description.
Y1  - 2018
ER  - 
TY  - JOUR
A1  - Schmidt, Katharina
A1  - Forkmann, Katarina
A1  - Schultz, Heidrun
A1  - Gratz, Marcel
A1  - Bitz, Andreas
A1  - Wiech, Katja
A1  - Bingel, Ulrike
T1  - Enhanced Neural Reinstatement for Evoked Facial Pain Compared With Evoked Hand Pain
JF  - The  Journal of Pain
Y1  - 2019
U6  - https://doi.org/10.1016/j.jpain.2019.03.003
SN  - 1526-5900
IS  - In Press, Corrected Proof
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - König, Johannes Alexander
A1  - Wolf, Martin
T1  - GHOST: An Evaluated Competence Developing Game for Cybersecurity Awareness Training
JF  - International Journal on Advances in Security
N2  - To train end users how to interact with digital systems is indispensable to ensure a strong computer security. 'Competence Developing Game'-based approaches are particularly suitable for this purpose because of their motivation-and simulation-aspects. In this paper the Competence Developing Game 'GHOST' for cybersecurity awareness trainings and its underlying patterns are described. Accordingly, requirements for an 'Competence Developing Game' based training are discussed. Based on these requirements it is shown how a game can fulfill these requirements. A supplementary game interaction design and a corresponding evaluation study is shown. The combination of training requirements and interaction design is used to create a 'Competence Developing Game'-based training concept. A part of these concept is implemented into a playable prototype that serves around one hour of play respectively training time. This prototype is used to perform an evaluation of the game and training aspects of the awareness training. Thereby, the quality of the game aspect and the effectiveness of the training aspect are shown.
Y1  - 2018
SN  - 1942-2636
VL  - 11
IS  - 3 & 4
SP  - 274
EP  - 287
PB  - IARIA Journals
ER  - 
TY  - JOUR
A1  - Schopp, Christoph
A1  - Britun, Nikolay
A1  - Vorac, Jan
A1  - Synek, Petr
A1  - Snyders, Rony
A1  - Heuermann, Holger
T1  - Thermal and Optical Study on the Frequency Dependence of an Atmospheric Microwave Argon Plasma Jet
JF  - IEEE Transactions on Plasma Science
Y1  - 2019
SN  - 1939-9375
VL  - 47
IS  - 7
SP  - 3176
EP  - 3181
PB  - IEEE
CY  - New York
ER  - 
TY  - JOUR
A1  - Noureddine, Yacine
A1  - Kraff, Oliver
A1  - Ladd, Mark E.
A1  - Wrede, Karsten
A1  - Chen, Bixia
A1  - Quick, Harald H.
A1  - Schaefers, Georg
A1  - Bitz, Andreas
T1  - Radiofrequency induced heating around aneurysm clips using a generic birdcage head coil at 7 Tesla under consideration of the minimum distance to decouple multiple aneurysm clips
JF  - Magnetic Resonance in Medicine
Y1  - 2019
U6  - https://doi.org/10.1002/mrm.27835
SN  - 1522-2594
IS  - Early view
SP  - 1
EP  - 17
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Claer, Mario
A1  - Ferrein, Alexander
A1  - Schiffer, Stefan
T1  - Calibration of a Rotating or Revolving Platform with a LiDAR Sensor
JF  - Applied Sciences
Y1  - 2019
U6  - https://doi.org/10.3390/app9112238
SN  - 2076-3417
VL  - Volume 9
IS  - issue 11, 2238
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Orzada, Stephan
A1  - Fiedler, Thomas M.
A1  - Bitz, Andreas
A1  - Ladd, Mark E.
A1  - Quick, Harald H.
T1  - Local SAR compression with overestimation control to reduce maximum relative SAR overestimation and improve multi-channel RF array performance
JF  - Magnetic Resonance Materials in Physics, Biology and Medicine
N2  - Objective
In local SAR compression algorithms, the overestimation is generally not linearly dependent on actual local SAR. This can lead to large relative overestimation at low actual SAR values, unnecessarily constraining transmit array performance.

Method
Two strategies are proposed to reduce maximum relative overestimation for a given number of VOPs. The first strategy uses an overestimation matrix that roughly approximates actual local SAR; the second strategy uses a small set of pre-calculated VOPs as the overestimation term for the compression.

Result
Comparison with a previous method shows that for a given maximum relative overestimation the number of VOPs can be reduced by around 20% at the cost of a higher absolute overestimation at high actual local SAR values.

Conclusion
The proposed strategies outperform a previously published strategy and can improve the SAR compression where maximum relative overestimation constrains the performance of parallel transmission.
Y1  - 2020
SN  - 1352-8661
U6  - https://doi.org/10.1007/s10334-020-00890-0
IS  - 34 (2021)
SP  - 153
EP  - 164
PB  - Springer
CY  - Heidelberg
ER  - 
TY  - JOUR
A1  - Müller, Tim M.
A1  - Leise, Philipp
A1  - Lorenz, Imke-Sophie
A1  - Altherr, Lena
A1  - Pelz, Peter F.
T1  - Optimization and validation of pumping system design and operation for water supply in high-rise buildings
JF  - Optimization and Engineering
N2  - The application of mathematical optimization methods for water supply system design and operation provides the capacity to increase the energy efficiency and to lower the investment costs considerably. We present a system approach for the optimal design and operation of pumping systems in real-world high-rise buildings that is based on the usage of mixed-integer nonlinear and mixed-integer linear modeling approaches. In addition, we consider different booster station topologies, i.e. parallel and series-parallel central booster stations as well as decentral booster stations. To confirm the validity of the underlying optimization models with real-world system behavior, we additionally present validation results based on experiments conducted on a modularly constructed pumping test rig. Within the models we consider layout and control decisions for different load scenarios, leading to a Deterministic Equivalent of a two-stage stochastic optimization program. We use a piecewise linearization as well as a piecewise relaxation of the pumps’ characteristics to derive mixed-integer linear models. Besides the solution with off-the-shelf solvers, we present a problem specific exact solving algorithm to improve the computation time. Focusing on the efficient exploration of the solution space, we divide the problem into smaller subproblems, which partly can be cut off in the solution process. Furthermore, we discuss the performance and applicability of the solution approaches for real buildings and analyze the technical aspects of the solutions from an engineer’s point of view, keeping in mind the economically important trade-off between investment and operation costs.
KW  - Technical Operations Research
KW  - MINLP
KW  - MILP
KW  - Experimental validation
KW  - Pumping systems
Y1  - 2020
U6  - https://doi.org/10.1007/s11081-020-09553-4
SN  - 1573-2924
VL  - 2021
IS  - 22
SP  - 643
EP  - 686
PB  - Springer
ER  - 
TY  - JOUR
A1  - Altherr, Lena
A1  - Leise, Philipp
A1  - Pfetsch, Marc E.
A1  - Schmitt, Andreas
T1  - Algorithmic design and resilience assessment of energy efficient high-rise water supply systems
JF  - Applied Mechanics and Materials
N2  - High-rise water supply systems provide water flow and suitable pressure in all levels of tall buildings. To design such state-of-the-art systems, the consideration of energy efficiency and the anticipation of component failures are mandatory. In this paper, we use Mixed-Integer Nonlinear Programming to compute an optimal placement of pipes and pumps, as well as an optimal control strategy.Moreover, we consider the resilience of the system to pump failures. A resilient system is able to fulfill a predefined minimum functionality even though components fail or are restricted in their normal usage. We present models to measure and optimize the resilience. To demonstrate our approach, we design and analyze an optimal resilient decentralized water supply system inspired by a real-life hotel building.
KW  - MINLP
KW  - Buffering Capacity
KW  - Uncertainty
KW  - Water Supply Networks
KW  - Booster Stations
Y1  - 2018
U6  - https://doi.org/10.4028/www.scientific.net/AMM.885.211
SN  - 1662-7482
VL  - 885
SP  - 211
EP  - 223
PB  - Trans Tech Publications
CY  - Bäch
ER  - 
TY  - JOUR
A1  - Ferrein, Alexander
A1  - Steinbauer, Gerald
T1  - 20 Years of RoboCup -  A Subjective Retrospection
JF  - KI - Künstliche Intelligenz
N2  - This summer, RoboCup competitions were held for the 20th time in Leipzig, Germany. It was the second time that RoboCup took place in Germany, 10 years after the 2006 RoboCup in Bremen. In this article, we give an overview on the latest developments of RoboCup and what happened in the different leagues over the last decade. With its 20th edition, RoboCup clearly is a success story and a role model for robotics competitions. From our personal view point, we acknowledge this by giving a retrospection about what makes RoboCup such a success.
Y1  - 2016
U6  - https://doi.org/10.1007/s13218-016-0449-5
SN  - 1610-1987
VL  - 30
IS  - 3
SP  - 225
EP  - 232
PB  - Springer
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Orzada, Stephan
A1  - Johst, Sören
A1  - Maderwald, Stefan
A1  - Bitz, Andreas
A1  - Solbach, Klaus
A1  - Ladd, Mark E.
T1  - Mitigation of B1(+) inhomogeneity on single-channel transmit systems with TIAMO
JF  - Magnetic Resonance in Medicine
Y1  - 2013
U6  - https://doi.org/10.1002/mrm.24453
SN  - 1522-2594
VL  - 70
IS  - 1
SP  - 290
EP  - 294
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Orzada, S.
A1  - Maderwald, S.
A1  - Poser, B. A.
A1  - Johst, S.
A1  - Kannengiesser, S.
A1  - Ladd, M. E.
A1  - Bitz, Andreas
T1  - Time-interleaved acquisition of modes: an analysis of SAR and image contrast implications
JF  - Magnetic Resonance in Medicine
N2  - s the magnetic field strength and therefore the operational frequency in MRI are increased, the radiofrequency wavelength approaches the size of the human head/body, resulting in wave effects which cause signal decreases and dropouts. Especially, whole-body imaging at 7 T and higher is therefore challenging. Recently, an acquisition scheme called time-interleaved acquisition of modes has been proposed to tackle the inhomogeneity problems in high-field MRI. The basic premise is to excite two (or more) different Burn:x-wiley:07403194:media:MRM23081:tex2gif-stack-1 modes using static radiofrequency shimming in an interleaved acquisition, where the complementary radiofrequency patterns of the two modes can be exploited to improve overall signal homogeneity. In this work, the impact of time-interleaved acquisition of mode on image contrast as well as on time-averaged specific absorption rate is addressed in detail. Time-interleaved acquisition of mode is superior in Burn:x-wiley:07403194:media:MRM23081:tex2gif-stack-2 homogeneity compared with conventional radiofrequency shimming while being highly specific absorption rate efficient. Time-interleaved acquisition of modes can enable almost homogeneous high-field imaging throughout the entire field of view in PD, T2, and T2*-weighted imaging and, if a specified homogeneity criterion is met, in T1-weighted imaging as well.
Y1  - 2012
U6  - https://doi.org/10.1002/mrm.23081
SN  - 1522-2594
VL  - 67
IS  - 4
SP  - 1033
EP  - 1041
PB  - Wiley-Liss
CY  - New York
ER  -