@inproceedings{SchmidtsKraftWinkensetal.2021, author = {Schmidts, Oliver and Kraft, Bodo and Winkens, Marvin and Z{\"u}ndorf, Albert}, title = {Catalog integration of heterogeneous and volatile product data}, series = {DATA 2020: Data Management Technologies and Applications}, booktitle = {DATA 2020: Data Management Technologies and Applications}, publisher = {Springer}, address = {Cham}, isbn = {978-3-030-83013-7}, doi = {10.1007/978-3-030-83014-4_7}, pages = {134 -- 153}, year = {2021}, abstract = {The integration of frequently changing, volatile product data from different manufacturers into a single catalog is a significant challenge for small and medium-sized e-commerce companies. They rely on timely integrating product data to present them aggregated in an online shop without knowing format specifications, concept understanding of manufacturers, and data quality. Furthermore, format, concepts, and data quality may change at any time. Consequently, integrating product catalogs into a single standardized catalog is often a laborious manual task. Current strategies to streamline or automate catalog integration use techniques based on machine learning, word vectorization, or semantic similarity. However, most approaches struggle with low-quality or real-world data. We propose Attribute Label Ranking (ALR) as a recommendation engine to simplify the integration process of previously unknown, proprietary tabular format into a standardized catalog for practitioners. We evaluate ALR by focusing on the impact of different neural network architectures, language features, and semantic similarity. Additionally, we consider metrics for industrial application and present the impact of ALR in production and its limitations.}, language = {en} } @inproceedings{MeckMuellerAltherretal.2020, author = {Meck, Marvin M. and M{\"u}ller, Tim M. and Altherr, Lena and Pelz, Peter F.}, title = {Improving an industrial cooling system using MINLP, considering capital and operating costs}, series = {Operations Research Proceedings 2019}, booktitle = {Operations Research Proceedings 2019}, publisher = {Springer}, address = {Cham}, isbn = {978-3-030-48438-5 (Print)}, doi = {10.1007/978-3-030-48439-2_61}, pages = {505 -- 512}, year = {2020}, abstract = {The chemical industry is one of the most important industrial sectors in Germany in terms of manufacturing revenue. While thermodynamic boundary conditions often restrict the scope for reducing the energy consumption of core processes, secondary processes such as cooling offer scope for energy optimisation. In this contribution, we therefore model and optimise an existing cooling system. The technical boundary conditions of the model are provided by the operators, the German chemical company BASF SE. In order to systematically evaluate different degrees of freedom in topology and operation, we formulate and solve a Mixed-Integer Nonlinear Program (MINLP), and compare our optimisation results with the existing system.}, language = {en} } @article{MuellerLeiseLorenzetal.2020, author = {M{\"u}ller, Tim M. and Leise, Philipp and Lorenz, Imke-Sophie and Altherr, Lena and Pelz, Peter F.}, title = {Optimization and validation of pumping system design and operation for water supply in high-rise buildings}, series = {Optimization and Engineering}, volume = {2021}, journal = {Optimization and Engineering}, number = {22}, publisher = {Springer}, issn = {1573-2924}, doi = {10.1007/s11081-020-09553-4}, pages = {643 -- 686}, year = {2020}, abstract = {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.}, language = {en} } @inproceedings{MuellerAltherrLeiseetal.2020, author = {M{\"u}ller, Tim M. and Altherr, Lena and Leise, Philipp and Pelz, Peter F.}, title = {Optimization of pumping systems for buildings: Experimental validation of different degrees of model detail on a modular test rig}, series = {Operations Research Proceedings 2019}, booktitle = {Operations Research Proceedings 2019}, publisher = {Springer}, address = {Cham}, isbn = {978-3-030-48438-5}, doi = {10.1007/978-3-030-48439-2_58}, pages = {481 -- 488}, year = {2020}, abstract = {Successful optimization requires an appropriate model of the system under consideration. When selecting a suitable level of detail, one has to consider solution quality as well as the computational and implementation effort. In this paper, we present a MINLP for a pumping system for the drinking water supply of high-rise buildings. We investigate the influence of the granularity of the underlying physical models on the solution quality. Therefore, we model the system with a varying level of detail regarding the friction losses, and conduct an experimental validation of our model on a modular test rig. Furthermore, we investigate the computational effort and show that it can be reduced by the integration of domain-specific knowledge.}, language = {en} } @article{AltherrLeisePfetschetal.2018, author = {Altherr, Lena and Leise, Philipp and Pfetsch, Marc E. and Schmitt, Andreas}, title = {Algorithmic design and resilience assessment of energy efficient high-rise water supply systems}, series = {Applied Mechanics and Materials}, volume = {885}, journal = {Applied Mechanics and Materials}, publisher = {Trans Tech Publications}, address = {B{\"a}ch}, issn = {1662-7482}, doi = {10.4028/www.scientific.net/AMM.885.211}, pages = {211 -- 223}, year = {2018}, abstract = {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.}, language = {en} } @article{ZabirovSchleserBucherer2021, author = {Zabirov, Alexander and Schleser, Markus and Bucherer, Sebastian}, title = {F{\"u}ge- und Dichtkonzept f{\"u}r einen Leichtbauverbrennungsmotor}, series = {adh{\"a}sion KLEBEN \& DICHTEN}, volume = {65}, journal = {adh{\"a}sion KLEBEN \& DICHTEN}, number = {11}, publisher = {Springer Nature}, address = {Cham}, issn = {2192-8681}, doi = {10.1007/s35145-021-0531-5}, pages = {12 -- 19}, year = {2021}, language = {de} } @incollection{PfetschAbeleAltherretal.2021, author = {Pfetsch, Marc E. and Abele, Eberhard and Altherr, Lena and B{\"o}lling, Christian and Br{\"o}tz, Nicolas and Dietrich, Ingo and Gally, Tristan and Geßner, Felix and Groche, Peter and Hoppe, Florian and Kirchner, Eckhard and Kloberdanz, Hermann and Knoll, Maximilian and Kolvenbach, Philip and Kuttich-Meinlschmidt, Anja and Leise, Philipp and Lorenz, Ulf and Matei, Alexander and Molitor, Dirk A. and Niessen, Pia and Pelz, Peter F. and Rexer, Manuel and Schmitt, Andreas and Schmitt, Johann M. and Schulte, Fiona and Ulbrich, Stefan and Weigold, Matthias}, title = {Strategies for mastering uncertainty}, series = {Mastering uncertainty in mechanical engineering}, booktitle = {Mastering uncertainty in mechanical engineering}, publisher = {Springer}, address = {Cham}, isbn = {978-3-030-78353-2}, doi = {10.1007/978-3-030-78354-9_6}, pages = {365 -- 456}, year = {2021}, abstract = {This chapter describes three general strategies to master uncertainty in technical systems: robustness, flexibility and resilience. It builds on the previous chapters about methods to analyse and identify uncertainty and may rely on the availability of technologies for particular systems, such as active components. Robustness aims for the design of technical systems that are insensitive to anticipated uncertainties. Flexibility increases the ability of a system to work under different situations. Resilience extends this characteristic by requiring a given minimal functional performance, even after disturbances or failure of system components, and it may incorporate recovery. The three strategies are described and discussed in turn. Moreover, they are demonstrated on specific technical systems.}, language = {en} } @article{Olbertz2021, author = {Olbertz, Klaus}, title = {Wichtige arbeitsrechtliche Entwicklungen im Jahr 2020 : Der Jahresr{\"u}ckblick auf alles Wissenswerte im Arbeitsrecht des vergangenen Jahres}, series = {NWB - Steuer- und Wirtschaftsrecht}, journal = {NWB - Steuer- und Wirtschaftsrecht}, number = {10}, issn = {0028-3460}, pages = {703 -- 715}, year = {2021}, abstract = {Im Anschluss an die arbeitsrechtlichen Jahres{\"u}bersichten der vergangenen Jahre (NWB 5/2019 S. 266; NWB 8/2020 S. 557) gibt der nachfolgende Beitrag einen {\"U}berblick {\"u}ber relevante Entwicklungen im Arbeitsrecht des Jahres 2020. Der erste Teil besch{\"a}ftigt sich hierbei mit gesetzlichen {\"A}nderungen. Neben Regelungen, die auf die COVID-19-Pandemie zur{\"u}ckgef{\"u}hrt werden k{\"o}nnen, hat der Gesetzgeber auch andere Vorhaben umgesetzt. So wurde u. a. das Arbeitnehmerentsenderecht reformiert. F{\"u}r Diskussionen sorgt(e) zudem das Gesetzesvorhaben zur Regelung mobiler Arbeit. Im zweiten Teil werden f{\"u}r die Praxis wichtige h{\"o}chstrichterliche Gerichtsentscheidungen zum Arbeitsrecht erl{\"a}utert, alphabetisch sortiert von A (wie Antidiskriminierungsrecht) bis U (wie Urlaub).}, language = {de} } @article{Olbertz2021, author = {Olbertz, Klaus}, title = {Die Flexibilisierung von Arbeitszeit durch den Abruf von Arbeit : M{\"o}glichkeiten und Grenzen arbeitsvertraglicher Gestaltung zur Vermeidung von „Leerlaufzeiten"}, series = {NWB - Steuer- und Wirtschaftsrecht}, journal = {NWB - Steuer- und Wirtschaftsrecht}, number = {15}, issn = {0028-3460}, pages = {1055 -- 1063}, year = {2021}, abstract = {Die Arbeitswelt ist im Umbruch. Der Bedarf an flexiblen Arbeitszeitmodellen nimmt stetig zu, wobei die Corona-Pandemie dieses Bed{\"u}rfnis nochmals versch{\"a}rft hat. Gerade auch in kleineren und mittleren Unternehmen w{\"a}chst die Notwendigkeit, den Einsatz der Besch{\"a}ftigten m{\"o}glichst bedarfsgerecht zu steuern, also bei guter Auftragslage mehr Arbeitszeit abzurufen und bei ausbleibenden Auftr{\"a}gen die Arbeitszeit zu reduzieren und somit bezahlte „Leerlaufzeiten" zu vermeiden. Der Gesetzgeber stellt den Arbeitgebern hierf{\"u}r das Instrument der sog. Abrufarbeit ( \S 12 Teilzeit- und Befristungsgesetz - TzBfG ) zur Verf{\"u}gung. In dem nachfolgenden Beitrag werden M{\"o}glichkeiten und Grenzen der Abrufarbeit skizziert und konkrete arbeitsvertragliche Gestaltungsm{\"o}glichkeiten aufgezeigt.}, language = {de} } @article{Olbertz2021, author = {Olbertz, Klaus}, title = {Vertragsgestaltungen bei der Besch{\"a}ftigung von Rentnern in Unternehmen : (Befristete) Besch{\"a}ftigungsverh{\"a}ltnisse als sinnvolles Instrument zum Schließen von Personall{\"u}cken}, series = {NWB - Steuer- und Wirtschaftsrecht}, journal = {NWB - Steuer- und Wirtschaftsrecht}, number = {25}, issn = {0028-3460}, pages = {1810 -- 1817}, year = {2021}, language = {de} } @misc{Olbertz2019, author = {Olbertz, Klaus}, title = {Sozialversicherungspflicht eines Minderheitsgesellschafter-Gesch{\"a}ftsf{\"u}hrers einer Familiengesellschaft}, series = {Gesellschafts- und Wirtschaftsrecht : GWR}, journal = {Gesellschafts- und Wirtschaftsrecht : GWR}, number = {3}, issn = {1868-1816}, pages = {48 -- 48}, year = {2019}, language = {de} } @misc{Olbertz2019, author = {Olbertz, Klaus}, title = {Kein Anspruch des Arbeitnehmers auf Verzugspauschale bei Lohnverzug des Arbeitgebers}, series = {Gesellschafts- und Wirtschaftsrecht : GWR}, journal = {Gesellschafts- und Wirtschaftsrecht : GWR}, number = {4}, issn = {1868-1816}, pages = {75 -- 75}, year = {2019}, language = {de} } @misc{Olbertz2019, author = {Olbertz, Klaus}, title = {Kirchenmitgliedschaft als Einstellungskriterium}, series = {Gesellschafts- und Wirtschaftsrecht : GWR}, journal = {Gesellschafts- und Wirtschaftsrecht : GWR}, number = {6}, issn = {1868-1816}, pages = {111 -- 111}, year = {2019}, language = {de} } @misc{Olbertz2019, author = {Olbertz, Klaus}, title = {Zuordnung von befristet versetzten Arbeitnehmern zu einem {\"u}bergehenden Betriebsteil}, series = {Gesellschafts- und Wirtschaftsrecht : GWR}, journal = {Gesellschafts- und Wirtschaftsrecht : GWR}, number = {7}, issn = {1868-1816}, pages = {132 -- 132}, year = {2019}, language = {de} } @misc{Olbertz2019, author = {Olbertz, Klaus}, title = {Keine sachgrundlose Befristung bei acht Jahre zur{\"u}ckliegender Vorbesch{\"a}ftigung}, series = {Gesellschafts- und Wirtschaftsrecht : GWR}, journal = {Gesellschafts- und Wirtschaftsrecht : GWR}, number = {11}, issn = {1868-1816}, pages = {201 -- 201}, year = {2019}, language = {de} } @misc{Olbertz2019, author = {Olbertz, Klaus}, title = {Vorlagebeschluss - Kopftuchverbot erneut vor dem EuGH}, series = {Gesellschafts- und Wirtschaftsrecht : GWR}, journal = {Gesellschafts- und Wirtschaftsrecht : GWR}, number = {11}, issn = {1868-1816}, pages = {203 -- 203}, year = {2019}, language = {de} } @article{BraunChengDoweyetal.2021, author = {Braun, Sebastian and Cheng, Chi-Tsun and Dowey, Steve and Wollert, J{\"o}rg}, title = {Performance evaluation of skill-based order-assignment in production environments with multi-agent systems}, series = {IEEE Journal of Emerging and Selected Topics in Industrial Electronics}, journal = {IEEE Journal of Emerging and Selected Topics in Industrial Electronics}, number = {Early Access}, publisher = {IEEE}, address = {New York}, issn = {2687-9735}, doi = {10.1109/JESTIE.2021.3108524}, year = {2021}, abstract = {The fourth industrial revolution introduces disruptive technologies to production environments. One of these technologies are multi-agent systems (MASs), where agents virtualize machines. However, the agent's actual performances in production environments can hardly be estimated as most research has been focusing on isolated projects and specific scenarios. We address this gap by implementing a highly connected and configurable reference model with quantifiable key performance indicators (KPIs) for production scheduling and routing in single-piece workflows. Furthermore, we propose an algorithm to optimize the search of extrema in highly connected distributed systems. The benefits, limits, and drawbacks of MASs and their performances are evaluated extensively by event-based simulations against the introduced model, which acts as a benchmark. Even though the performance of the proposed MAS is, on average, slightly lower than the reference system, the increased flexibility allows it to find new solutions and deliver improved factory-planning outcomes. Our MAS shows an emerging behavior by using flexible production techniques to correct errors and compensate for bottlenecks. This increased flexibility offers substantial improvement potential. The general model in this paper allows the transfer of the results to estimate real systems or other models.}, language = {en} } @article{JahnkeRousselHombachetal.2016, author = {Jahnke, Siegfried and Roussel, Johanna and Hombach, Thomas and Kochs, Johannes and Fischbach, Andreas and Huber, Gregor and Scharr, Hanno}, title = {phenoSeeder - A robot system for automated handling and phenotyping of individual seeds}, series = {Plant physiology}, volume = {172}, journal = {Plant physiology}, number = {3}, publisher = {Oxford University Press}, address = {Oxford}, issn = {0032-0889}, doi = {10.1104/pp.16.01122}, pages = {1358 -- 1370}, year = {2016}, abstract = {The enormous diversity of seed traits is an intriguing feature and critical for the overwhelming success of higher plants. In particular, seed mass is generally regarded to be key for seedling development but is mostly approximated by using scanning methods delivering only two-dimensional data, often termed seed size. However, three-dimensional traits, such as the volume or mass of single seeds, are very rarely determined in routine measurements. Here, we introduce a device named phenoSeeder, which enables the handling and phenotyping of individual seeds of very different sizes. The system consists of a pick-and-place robot and a modular setup of sensors that can be versatilely extended. Basic biometric traits detected for individual seeds are two-dimensional data from projections, three-dimensional data from volumetric measures, and mass, from which seed density is also calculated. Each seed is tracked by an identifier and, after phenotyping, can be planted, sorted, or individually stored for further evaluation or processing (e.g. in routine seed-to-plant tracking pipelines). By investigating seeds of Arabidopsis (Arabidopsis thaliana), rapeseed (Brassica napus), and barley (Hordeum vulgare), we observed that, even for apparently round-shaped seeds of rapeseed, correlations between the projected area and the mass of seeds were much weaker than between volume and mass. This indicates that simple projections may not deliver good proxies for seed mass. Although throughput is limited, we expect that automated seed phenotyping on a single-seed basis can contribute valuable information for applications in a wide range of wild or crop species, including seed classification, seed sorting, and assessment of seed quality.}, language = {en} } @article{Wrede2016, author = {Wrede, Oliver}, title = {Continuity in travel information}, series = {Information Design Journal}, volume = {22}, journal = {Information Design Journal}, number = {2}, publisher = {John Benjamins}, address = {Amsterdam}, issn = {0142-5471}, doi = {10.1075/idj.22.2.09wre}, pages = {172 -- 178}, year = {2016}, abstract = {This article discusses the contrast between the information transportation companies provide to travellers and that of their brand messaging. Companies' brand messaging often portrays the service they provide as pleasant, stress free and perfect. Customers and users of the service, on the other hand, often describe their experience of the service as a negative one. This article suggests that the brand value would be greater if transportation companies paid more attention to the users' experience when designing their information systems, particularly in worst case scenarios.}, language = {en} } @article{NeuJanserKhatibietal.2017, author = {Neu, Eugen and Janser, Frank and Khatibi, Akbar A. and Orifici, Adrian C.}, title = {Fully Automated Operational Modal Analysis using multi-stage clustering}, series = {Mechanical Systems and Signal Processing}, volume = {Vol. 84, Part A}, journal = {Mechanical Systems and Signal Processing}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0888-3270}, doi = {10.1016/j.ymssp.2016.07.031}, pages = {308 -- 323}, year = {2017}, language = {en} } @article{RegerDoeringKuhnhenne2016, author = {Reger, V. and D{\"o}ring, Bernd and Kuhnhenne, M.}, title = {Passive und aktive Maßnahmen zur Fl{\"a}chenk{\"u}hlung im Stahl(leicht)bau}, series = {Bauingenieur}, volume = {91}, journal = {Bauingenieur}, number = {Jul/Aug}, publisher = {VDI Fachmedien}, address = {D{\"u}sseldorf}, issn = {0005-6650}, doi = {10.37544/0005-6650-2016-07-08-63}, pages = {309 -- 316}, year = {2016}, abstract = {Mit steigenden D{\"a}mmstandards und h{\"o}heren Komfortanforderungen der Nutzer ger{\"a}t die Problematik der sommerlichen {\"U}berhitzung zunehmend in den Fokus. Um die {\"U}berhitzung m{\"o}glichst gering zu halten, sind Maßnahmen und L{\"o}sungen zu entwickeln, die den potenziellen K{\"u}hlbedarf eines Geb{\"a}udes vermeiden sowie reduzieren. Im Rahmen des europ{\"a}ischen Forschungsprojektes BATIMASS wurden Techniken untersucht, die die sommerliche Raumtemperatur ohne zus{\"a}tzliche K{\"u}hlung (passiv) oder aber mit energieeffizienter wasserbasierter Fl{\"a}chenk{\"u}hlung (aktiv) reduzieren und die besonders f{\"u}r Geb{\"a}ude in Stahl(leicht)bauweise geeignet sind. Daf{\"u}r wurde die Methodik der thermisch {\"a}quivalenten Decke weiterentwickelt, um das thermische Verhalten von Profilblechdecken in Geb{\"a}uden f{\"u}r beide L{\"o}sungsans{\"a}tze analysieren zu k{\"o}nnen. Dar{\"u}ber hinaus wurde der Einsatz von Phasenwechselmaterial (PCM) zur Steigerung der Speicherf{\"a}higkeit von leichten Decken mit besonders geringer thermischer Masse in Simulationen sowie im Labor untersucht und bewertet.}, language = {de} } @inproceedings{KesslerBalcGebhardtetal.2017, author = {Kessler, Julia and Balc, Nicolae and Gebhardt, Andreas and Abbas, Karim}, title = {Basic research on lattice structures focused on the reliance of the cross sectional area and additional coatings}, series = {The 4th International Conference on Computing and Solutions in Manufacturing Engineering 2016 - CoSME'16}, booktitle = {The 4th International Conference on Computing and Solutions in Manufacturing Engineering 2016 - CoSME'16}, edition = {Vol. 94}, doi = {10.1051/matecconf/20179403008}, pages = {7 S.}, year = {2017}, language = {en} } @misc{Schreiber2016, author = {Schreiber, Marc}, title = {Mit Maximum-Entropie das Parsing nat{\"u}rlicher Sprache erlernen}, publisher = {FH Aachen}, address = {Aachen}, pages = {23 Seiten}, year = {2016}, abstract = {F{\"u}r die Verarbeitung von nat{\"u}rlicher Sprache ist ein wichtiger Zwischenschritt das Parsing, bei dem f{\"u}r S{\"a}tze der nat{\"u}rlichen Sprache Ableitungsb{\"a}ume bestimmt werden. Dieses Verfahren ist vergleichbar zum Parsen formaler Sprachen, wie z. B. das Parsen eines Quelltextes. Die Parsing-Methoden der formalen Sprachen, z. B. Bottom-up-Parser, k{\"o}nnen nicht auf das Parsen der nat{\"u}rlichen Sprache {\"u}bertragen werden, da keine Formalisierung der nat{\"u}rlichen Sprachen existiert [3, 12, 23, 30]. In den ersten Programmen, die nat{\"u}rliche Sprache verarbeiten [32, 41], wurde versucht die nat{\"u}rliche Sprache mit festen Regelmengen zu verarbeiten. Dieser Ansatz stieß jedoch schnell an seine Grenzen, da die Regelmenge nicht vollst{\"a}ndig sowie nicht minimal ist und wegen der ben{\"o}tigten Menge an Regeln schwer zu verwalten ist. Die Korpuslinguistik [22] bot die M{\"o}glichkeit, die Regelmenge durch Supervised-Machine-Learning-Verfahren [2] abzul{\"o}sen. Teil der Korpuslinguistik ist es, große Textkorpora zu erstellen und diese mit sprachlichen Strukturen zu annotieren. Zu diesen Strukturen geh{\"o}ren sowohl die Wortarten als auch die Ableitungsb{\"a}ume der S{\"a}tze. Vorteil dieser Methodik ist es, dass repr{\"a}sentative Daten zur Verf{\"u}gung stehen. Diese Daten werden genutzt, um mit Supervised-Machine-Learning-Verfahren die Gesetzm{\"a}ßigkeiten der nat{\"u}rliche Sprachen zu erlernen. Das Maximum-Entropie-Verfahren ist ein Supervised-Machine-Learning-Verfahren, das genutzt wird, um nat{\"u}rliche Sprache zu erlernen. Ratnaparkhi [25] nutzt Maximum-Entropie, um Ableitungsb{\"a}ume f{\"u}r S{\"a}tze der nat{\"u}rlichen Sprache zu erlernen. Dieses Verfahren macht es m{\"o}glich, die nat{\"u}rliche Sprache (abgebildet als Σ∗) trotz einer fehlenden formalen Grammatik zu parsen.}, language = {de} } @article{Wollert2016, author = {Wollert, J{\"o}rg}, title = {OS-Funktionalit{\"a}t ohne OS f{\"u}r das IoT}, series = {Design \& Elektronik}, journal = {Design \& Elektronik}, number = {11}, publisher = {WEKA-Fachmedien}, address = {M{\"u}nchen}, issn = {0933-8667}, pages = {85 -- 90}, year = {2016}, abstract = {Low-end-Embedded-Plattformen stellen eine hohe Anforderung an die Entscheidungsf{\"a}higkeit des Entwicklers: Zum n{\"a}chstgr{\"o}ßeren Prozessor greifen und ein Betriebssystem benutzen oder doch besser auf das Betriebssystem verzichten? Die Frage l{\"a}sst sich einfach beantworten: Einen Nanokernel verwenden und das Embedded-System mit einem minimalen Footprint realisieren. Adam Dunkels Protothreads sind eine ausgesprochen effiziente Art, Mikrocontroller gut strukturiert zu programmieren und gleichzeitig auf Overhead zu verzichten. So k{\"o}nnen auch mit kleinen 8-bit-Prozessoren anspruchsvolle Aufgaben in einem Thread-Modell bearbeitet werden. Man muss also nicht immer das Rad neu erfinden oder gleich auf Linux-basierte Systeme zur{\"u}ckgreifen.}, language = {de} } @book{LauthKowalczyk2015, author = {Lauth, Jakob and Kowalczyk, J{\"u}rgen}, title = {Thermodynamik : eine Einf{\"u}hrung}, publisher = {Springer Spektrum}, address = {Berlin}, isbn = {978-3-662-46228-7}, doi = {10.1007/978-3-662-46229-4}, pages = {XVIII, 380 S.: Ill., graph. Darst.}, year = {2015}, language = {de} } @incollection{Lind2016, author = {Lind, Thorsten Patric}, title = {Wirkungen der Er{\"o}ffnung des Insolvenzverfahrens : \S\S 129, 132, 133, 144, 145}, series = {Bankenkommentar zum Insolvenzrecht. - 3. Auflage}, booktitle = {Bankenkommentar zum Insolvenzrecht. - 3. Auflage}, publisher = {Finanz Colloquium}, address = {Heidelberg}, isbn = {978-3-95725-016-2}, pages = {1277 -- 1767}, year = {2016}, language = {de} } @article{FunkeKeinzKustereretal.2016, author = {Funke, Harald and Keinz, Jan and Kusterer, Karsten and Ayed, Anis Haj and Kazari, Masahide and Kitajima, Junichi and Horikawa, Atsushi and Okada, Kunio}, title = {Experimental and Numerical Study on Optimizing the Dry Low NOₓ Micromix Hydrogen Combustion Principle for Industrial Gas Turbine Applications}, series = {Journal of Thermal Science and Engineering Applications}, volume = {9}, journal = {Journal of Thermal Science and Engineering Applications}, number = {2}, publisher = {ASME}, address = {New York, NY}, issn = {1948-5093}, doi = {10.1115/1.4034849}, pages = {021001 -- 021001-10}, year = {2016}, abstract = {Combined with the use of renewable energy sources for its production, hydrogen represents a possible alternative gas turbine fuel for future low-emission power generation. Due to the difference in the physical properties of hydrogen compared to other fuels such as natural gas, well-established gas turbine combustion systems cannot be directly applied to dry low NOₓ (DLN) hydrogen combustion. The DLN micromix combustion of hydrogen has been under development for many years, since it has the promise to significantly reduce NOₓ emissions. This combustion principle for air-breathing engines is based on crossflow mixing of air and gaseous hydrogen. Air and hydrogen react in multiple miniaturized diffusion-type flames with an inherent safety against flashback and with low NOₓ emissions due to a very short residence time of the reactants in the flame region. The paper presents an advanced DLN micromix hydrogen application. The experimental and numerical study shows a combustor configuration with a significantly reduced number of enlarged fuel injectors with high-thermal power output at constant energy density. Larger fuel injectors reduce manufacturing costs, are more robust and less sensitive to fuel contamination and blockage in industrial environments. The experimental and numerical results confirm the successful application of high-energy injectors, while the DLN micromix characteristics of the design point, under part-load conditions, and under off-design operation are maintained. Atmospheric test rig data on NOₓ emissions, optical flame-structure, and combustor material temperatures are compared to numerical simulations and show good agreement. The impact of the applied scaling and design laws on the miniaturized micromix flamelets is particularly investigated numerically for the resulting flow field, the flame-structure, and NOₓ formation.}, language = {en} } @article{AyedKustererFunkeetal.2016, author = {Ayed, Anis Haj and Kusterer, Karsten and Funke, Harald and Keinz, Jan}, title = {CFD Based Improvement of the DLN Hydrogen Micromix Combustion Technology at Increased Energy Densities}, series = {American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS)}, volume = {26}, journal = {American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS)}, number = {3}, publisher = {GSSRR}, issn = {2313-4402}, pages = {290 -- 303}, year = {2016}, abstract = {Combined with the use of renewable energy sources for its production, Hydrogen represents a possible alternative gas turbine fuel within future low emission power generation. Due to the large difference in the physical properties of Hydrogen compared to other fuels such as natural gas, well established gas turbine combustion systems cannot be directly applied for Dry Low NOx (DLN) Hydrogen combustion. Thus, the development of DLN combustion technologies is an essential and challenging task for the future of Hydrogen fuelled gas turbines. The DLN Micromix combustion principle for hydrogen fuel has been developed to significantly reduce NOx-emissions. This combustion principle is based on cross-flow mixing of air and gaseous hydrogen which reacts in multiple miniaturized diffusion-type flames. The major advantages of this combustion principle are the inherent safety against flash-back and the low NOx-emissions due to a very short residence time of reactants in the flame region of the micro-flames. The Micromix Combustion technology has been already proven experimentally and numerically for pure Hydrogen fuel operation at different energy density levels. The aim of the present study is to analyze the influence of different geometry parameter variations on the flame structure and the NOx emission and to identify the most relevant design parameters, aiming to provide a physical understanding of the Micromix flame sensitivity to the burner design and identify further optimization potential of this innovative combustion technology while increasing its energy density and making it mature enough for real gas turbine application. The study reveals great optimization potential of the Micromix Combustion technology with respect to the DLN characteristics and gives insight into the impact of geometry modifications on flame structure and NOx emission. This allows to further increase the energy density of the Micromix burners and to integrate this technology in industrial gas turbines.}, language = {en} } @article{Thomas2016, author = {Thomas, Axel}, title = {Genussrechte als Instrument der Unternehmensfinanzierung von kommunalen Wohnungs- baugesellschaften}, series = {VM Verwaltung und Management}, volume = {22}, journal = {VM Verwaltung und Management}, number = {6}, publisher = {Nomos}, address = {Baden-Baden}, issn = {0947-9856}, doi = {10.5771/0947-9856-2016-6-322}, pages = {322 -- 327}, year = {2016}, abstract = {Die kommunalen Wohnungsbaugesellschaften und ihr Gesch{\"a}ftszweck bzw. Versorgungsauftrag erfahren aus gesamtgesellschaftlichen Gr{\"u}nden aktuell einen erheblichen Bedeutungszuwachs. Der kommunale Wohnungsbau soll und muss intensiviert werden, da z.B. zunehmend Wohnungsbindungen auslaufen. Bezahlbare Neubauten fehlen speziell Familien, Senioren, Studenten und Fl{\"u}chtlingen. Um das Investitionsvolumen zu bew{\"a}ltigen, bedarf es nicht nur der F{\"o}rderkredite, sondern auch der Zuf{\"u}hrung „frischen Kapitals". Der Beitrag stellt dar, dass Genussrechte ein interessantes und oft unbekanntes Finanzierungsinstrument f{\"u}r kommunale Wohnungsbaugesellschaften mit passgenauen Ausgestaltungsm{\"o}glichkeiten sind. Mit Hilfe von Genussrechten k{\"o}nnen die notwendigen Neubau-Investitionen solide mit Quasi-Eigenkapital unterlegt werden und den sozialen Wohnungsbau wiederbeleben. Genussrechte als Hybridkapital lassen sich mangels gesetzlicher Eingrenzung exakt und individuell ebenso an die Bed{\"u}rfnisse der kommunalen Wohnungsbaugesellschaft anpassen wie an die der Gesellschafter und des jeweiligen Neubauvorhabens.}, language = {de} } @book{Tuennemann2016, author = {T{\"u}nnemann, Thomas}, title = {Formine : Neo Style : Workshop 2016}, editor = {T{\"u}nnemann, Thomas}, address = {Aachen}, isbn = {978-3-9811003-7-2}, publisher = {Fachhochschule Aachen}, pages = {83 S.}, year = {2016}, abstract = {Leitung und Konzeption: Thomas T{\"u}nnemann, Professor f{\"u}r Gestalten, FB Architektur, FH Aachen: Mit Beitr{\"a}gen von Miriam Azzab, Larissa Rohr, Janna Steinhart, Felix Reymann, Kevin Osterkamp, Mark Kieckhefer, Pia Bienert, Sarah Schuhmann, Hermann Stuzmann, Silvana Hecklinger, Thorsten, K{\"o}llen, Jesse Dilworth, Silke Wanders, Tomas T{\"u}nnemann und Jan Waschinzki}, language = {de} } @incollection{Lind2017, author = {Lind, Thorsten Patric}, title = {Er{\"o}ffnung des Insolvenzverfahrens. Erfaßtes Verm{\"o}gen und Verfahrensbeteiligte. Insolvenzverwalter, Organe der Gl{\"a}ubiger : \S\S 56-62, 66-72, 74-79}, series = {Insolvenzrecht : Kommentar / hrsg. von Martin Ahrens; Markus Gehrlein; Andreas Ringstmeier . - 3. Auflage}, booktitle = {Insolvenzrecht : Kommentar / hrsg. von Martin Ahrens; Markus Gehrlein; Andreas Ringstmeier . - 3. Auflage}, publisher = {Luchterhand}, address = {K{\"o}ln}, isbn = {978-3-472-08669-7}, pages = {690 - 752; 776 - 797; 802 - 818}, year = {2017}, language = {de} } @article{OrzadaJohstMaderwaldetal.2013, author = {Orzada, Stephan and Johst, S{\"o}ren and Maderwald, Stefan and Bitz, Andreas and Solbach, Klaus and Ladd, Mark E.}, title = {Mitigation of B1(+) inhomogeneity on single-channel transmit systems with TIAMO}, series = {Magnetic Resonance in Medicine}, volume = {70}, journal = {Magnetic Resonance in Medicine}, number = {1}, publisher = {Wiley}, address = {Weinheim}, issn = {1522-2594}, doi = {10.1002/mrm.24453}, pages = {290 -- 294}, year = {2013}, language = {en} } @article{OrzadaMaderwaldPoseretal.2012, author = {Orzada, S. and Maderwald, S. and Poser, B. A. and Johst, S. and Kannengiesser, S. and Ladd, M. E. and Bitz, Andreas}, title = {Time-interleaved acquisition of modes: an analysis of SAR and image contrast implications}, series = {Magnetic Resonance in Medicine}, volume = {67}, journal = {Magnetic Resonance in Medicine}, number = {4}, publisher = {Wiley-Liss}, address = {New York}, issn = {1522-2594}, doi = {10.1002/mrm.23081}, pages = {1033 -- 1041}, year = {2012}, abstract = {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.}, language = {en} } @article{KobusBitzUdenetal.2012, author = {Kobus, Thiele and Bitz, Andreas and Uden, Mark J. van and Lagemaat, Miram W. and Rothgang, Eva and Orzada, Stephan and Heerschap, Arend and Scheenen, Tom W. J.}, title = {In vivo 31P MR spectroscopic imaging of the human prostate at 7 T: safety and feasibility}, series = {Magnetic Resonance in Medicine}, volume = {68}, journal = {Magnetic Resonance in Medicine}, number = {6}, publisher = {Wiley-Liss}, address = {New York}, issn = {1522-2594}, doi = {10.1002/mrm.24175}, pages = {1683 -- 1695}, year = {2012}, abstract = {31P MR spectroscopic imaging of the human prostate provides information about phosphorylated metabolites that could be used for prostate cancer characterization. The sensitivity of a magnetic field strength of 7 T might enable 3D 31P MR spectroscopic imaging with relevant spatial resolution in a clinically acceptable measurement time. To this end, a 31P endorectal coil was developed and combined with an eight-channel 1H body-array coil to relate metabolic information to anatomical location. An extensive safety validation was performed to evaluate the specific absorption rate, the radiofrequency field distribution, and the temperature distribution of both coils. This validation consisted of detailed Finite Integration Technique simulations, confirmed by MR thermometry and Burn:x-wiley:07403194:media:MRM24175:tex2gif-stack-1 measurements in a phantom and in vivo temperature measurements. The safety studies demonstrated that the presence of the 31P endorectal coil had no influence on the specific absorption rate levels and temperature distribution of the external eight-channel 1H array coil. To stay within a 10 g averaged local specific absorption rate of 10 W/kg, a maximum time-averaged input power of 33 W for the 1H array coil was allowed. For transmitting with the 31P endorectal coil, our safety limit of less than 1°C temperature increase in vivo during a 15-min MR spectroscopic imaging experiment was reached at a time-averaged input power of 1.9 W. With this power setting, a second in vivo measurement was performed on a healthy volunteer. Using adiabatic excitation, 3D 31P MR spectroscopic imaging produced spectra from the entire prostate in 18 min with a spatial resolution of 4 cm3. The spectral resolution enabled the separate detection of phosphocholine, phosphoethanolamine, inorganic phosphate, and other metabolites that could play an important role in the characterization of prostate cancer.}, language = {en} } @article{OrzadaMaderwaldPoseretal.2010, author = {Orzada, Stephan and Maderwald, Stefan and Poser, Benedikt Andreas and Bitz, Andreas and Quick, Harald H. and Ladd, Mark E.}, title = {RF excitation using time interleaved acquisition of modes (TIAMO) to address B1 inhomogeneity in high-field MRI}, series = {Magnetic Resonance in Medicine}, volume = {64}, journal = {Magnetic Resonance in Medicine}, number = {2}, publisher = {Wiley-Liss}, address = {New York}, issn = {1522-2594}, doi = {10.1002/mrm.22527}, pages = {327 -- 333}, year = {2010}, abstract = {As the field strength and, therefore, the operational frequency in MRI is increased, the wavelength approaches the size of the human head/body, resulting in wave effects, which cause signal decreases and dropouts. Several multichannel approaches have been proposed to try to tackle these problems, including RF shimming, where each element in an array is driven by its own amplifier and modulated with a certain (constant) amplitude and phase relative to the other elements, and Transmit SENSE, where spatially tailored RF pulses are used. In this article, a relatively inexpensive and easy to use imaging scheme for 7 Tesla imaging is proposed to mitigate signal voids due to B1 field inhomogeneity. Two time-interleaved images are acquired using a different excitation mode for each. By forming virtual receive elements, both images are reconstructed together using GRAPPA to achieve a more homogeneous image, with only small SNR and SAR penalty in head and body imaging at 7 Tesla.}, language = {en} } @article{UmutluBitzMaderwaldetal.2013, author = {Umutlu, Lale and Bitz, Andreas and Maderwald, Stefan and Orzada, Stephan and Kinner, Sonja and Kraff, Oliver and Brote, Irina and Ladd, Susanne C. and Schroeder, Tobias and Forsting, Michael}, title = {Contrast-enhanced ultra-high-field liver MRI: a feasibility trial}, series = {European Journal of Radiology}, volume = {82}, journal = {European Journal of Radiology}, number = {5}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0720-048X}, doi = {10.1016/j.ejrad.2011.07.004}, pages = {760 -- 767}, year = {2013}, language = {en} } @article{YazdanbakhshSolbachBitz2012, author = {Yazdanbakhsh, Pedram and Solbach, Klaus and Bitz, Andreas}, title = {Variable power combiner for RF mode shimming in 7-T MR imaging}, series = {IEEE Transaction on Biomedical Engineering}, volume = {59}, journal = {IEEE Transaction on Biomedical Engineering}, number = {9}, publisher = {IEEE}, address = {New York}, issn = {1558-2531}, doi = {10.1109/TBME.2012.2205926}, pages = {2549 -- 2557}, year = {2012}, abstract = {This contribution discusses the utilization of RF power in an MRI system with RF mode shimming which enables the superposition of circularly polarized modes of a transmit RF coil array driven by a Butler matrix. Since the required power for the individual modes can vary widely, mode-shimming can result in a significant underutilization of the total available RF power. A variable power combiner (VPC) is proposed to improve the power utilization: it can be realized as a reconfiguration of the MRI transmit system by the inclusion of one additional matrix network which receives the power from all transmit amplifiers at its input ports and provides any desired (combined) power distribution at its output ports by controlling the phase and amplitude of the amplifiers' input signals. The power distribution at the output ports of the VPC is then fed into the "mode" ports of the coil array Butler matrix in order to superimpose the spatial modes at the highest achievable power utilization. The VPC configuration is compared to the standard configuration of the transmit chain of our MRI system with 8 transmit channels and 16 coils. In realistic scenarios, improved power utilization was achieved from 17\% to 60\% and from 14\% to 55\% for an elliptical phantom and a region of interest in the abdomen, respectively, and an increase of the power utilization of 1 dB for a region of interest in the upper leg. In general, it is found that the VPC allows significant improvement in power utilization when the shimming solution demands only a few modes to be energized, while the technique can yield loss in power utilization in cases with many modes required at high power level.}, language = {en} } @article{ProchnowGebingLadageetal.2011, author = {Prochnow, Nora and Gebing, Tina and Ladage, Kerstin and Krause-Finkeldey, Dorothee and Ourdi, Abessamad El and Bitz, Andreas and Streckert, Joachim and Hansen, Volkert and Dermietzel, Rolf}, title = {Electromagnetic field effect or simply stress? Effects of UMTS exposure on hippocampal longterm plasticity in the context of procedure related hormone release}, series = {PLoS one}, volume = {6}, journal = {PLoS one}, number = {5}, publisher = {PLOS}, address = {San Francisco}, doi = {10.1371/journal.pone.0019437}, pages = {e19437}, year = {2011}, abstract = {Harmful effects of electromagnetic fields (EMF) on cognitive and behavioural features of humans and rodents have been controversially discussed and raised persistent concern about adverse effects of EMF on general brain functions. In the present study we applied radio-frequency (RF) signals of the Universal Mobile Telecommunications System (UMTS) to full brain exposed male Wistar rats in order to elaborate putative influences on stress hormone release (corticosteron; CORT and adrenocorticotropic hormone; ACTH) and on hippocampal derived synaptic long-term plasticity (LTP) and depression (LTD) as electrophysiological hallmarks for memory storage and memory consolidation. Exposure was computer controlled providing blind conditions. Nominal brain-averaged specific absorption rates (SAR) as a measure of applied mass-related dissipated RF power were 0, 2, and 10 W/kg over a period of 120 min. Comparison of cage exposed animals revealed, regardless of EMF exposure, significantly increased CORT and ACTH levels which corresponded with generally decreased field potential slopes and amplitudes in hippocampal LTP and LTD. Animals following SAR exposure of 2 W/kg (averaged over the whole brain of 2.3 g tissue mass) did not differ from the sham-exposed group in LTP and LTD experiments. In contrast, a significant reduction in LTP and LTD was observed at the high power rate of SAR (10 W/kg). The results demonstrate that a rate of 2 W/kg displays no adverse impact on LTP and LTD, while 10 W/kg leads to significant effects on the electrophysiological parameters, which can be clearly distinguished from the stress derived background. Our findings suggest that UMTS exposure with SAR in the range of 2 W/kg is not harmful to critical markers for memory storage and memory consolidation, however, an influence of UMTS at high energy absorption rates (10 W/kg) cannot be excluded.}, language = {en} } @article{OrzadaBitzSchaeferetal.2011, author = {Orzada, Stephan and Bitz, Andreas and Sch{\"a}fer, Lena C. and Ladd, Susanne C. and Ladd, Mark E. and Maderwald, Stefan}, title = {Open design eight-channel transmit/receive coil for high-resolution and real-time ankle imaging at 7 T}, series = {Medical Physics}, volume = {38}, journal = {Medical Physics}, number = {3}, publisher = {Wiley}, address = {Hoboken}, issn = {2473-4209}, doi = {10.1118/1.3553399}, pages = {1162 -- 1167}, year = {2011}, abstract = {Purpose: At 1.5 T, real-time MRI of joint movement has been shown to be feasible. However, 7 T, provides higher SNR and thus an improved potential for parallel imaging acceleration. The purpose of this work was to build an open, U-shaped eight-channel transmit/receive microstrip coil for 7 T MRI to enable high-resolution and real-time imaging of the moving ankle joint. Methods: A U-shaped eight-channel transmit/receive array for the human ankle was built.urn:x-wiley:00942405:mp3399:equation:mp3399-math-0001-parameters and urn:x-wiley:00942405:mp3399:equation:mp3399-math-0002-factor were measured. SAR calculations of different ankle postures were performed to ensure patient safety. Inhomogeneities in the transmit field consequent to the open design were compensated for by the use of static RF shimming. High-resolution and real-time imaging was performed in human volunteers. Results: The presented array showed good performance with regard to patient comfort and image quality. High acceleration factors of up to 4 are feasible without visible acceleration artifacts. Reasonable image homogeneity was achieved with RF shimming. Conclusions: Open, noncylindrical designs for transmit/receive coils are practical at 7 T and real-time imaging of the moving joint is feasible with the presented coil design.}, language = {en} } @article{KraffBitzDammannetal.2010, author = {Kraff, Oliver and Bitz, Andreas and Dammann, Philipp and Ladd, Susanne C. and Ladd, Mark E. and Quick, Harald H.}, title = {An eight-channel transmit/receive multipurpose coil for musculoskeletal MR imaging at 7 T}, series = {Medical Physics}, volume = {37}, journal = {Medical Physics}, number = {12}, publisher = {Wiley}, address = {Hoboken, NJ}, issn = {2473-4209}, doi = {10.1118/1.3517176}, pages = {6368 -- 6376}, year = {2010}, abstract = {Purpose: MRI plays a leading diagnostic role in assessing the musculoskeletal (MSK) system and is well established for most questions at clinically used field strengths (up to 3 T). However, there are still limitations in imaging early stages of cartilage degeneration, very fine tendons and ligaments, or in locating nerve lesions, for example. 7 T MRI of the knee has already received increasing attention in the current published literature, but there is a strong need to develop new radiofrequency (RF) coils to assess more regions of the MSK system. In this work, an eight-channel transmit/receive RF array was built as a multipurpose coil for imaging some of the thus far neglected regions. An extensive coil characterization protocol and first in vivo results of the human wrist, shoulder, elbow, knee, and ankle imaged at 7 T will be presented. Methods: Eight surface loop coils with a dimension ofurn:x-wiley:00942405:media:mp7176:mp7176-math-0001 were machined from FR4 circuit board material. To facilitate easy positioning, two coil clusters, each with four loop elements, were combined to one RF transmit/receive array. An overlapped and shifted arrangement of the coil elements was chosen to reduce the mutual inductance between neighboring coils. A phantom made of body-simulating liquid was used for tuning and matching on the bench. Afterward, the S-parameters were verified on a human wrist, elbow, and shoulder. For safety validation, a detailed compliance test was performed including full wave simulations of the RF field distribution and the corresponding specific absorption rate (SAR) for all joints. In vivo images of four volunteers were assessed with gradient echo and spin echo sequences modified to obtain optimal image contrast, full anatomic coverage, and the highest spatial resolution within a reasonable acquisition time. The performance of the RF coil was additionally evaluated by in vivo B1 mapping. Results: A comparison of B1 per unit power, flip angle distribution, and anatomic images showed a fairly homogeneous excitation for the smaller joints (elbow, wrist, and ankle), while for the larger joints, the shoulder and especially the knee, B1 inhomogeneities and limited penetration depth were more pronounced. However, the greater part of the shoulder joint could be imaged.In vivo images rendered very fine anatomic details such as fascicles of the median nerve and the branching of the nerve bundles. High-resolution images of cartilage, labrum, and tendons could be acquired. Additionally, turbo spin echo (TSE) and inversion recovery sequences performed very well. Conclusions: This study demonstrates that the concept of two four-channel transmit/receive RF arrays can be used as a multipurpose coil for high-resolutionin vivo MR imaging of the musculoskeletal system at 7 T. Not only gradient echo but also typical clinical and SAR-intensive sequences such as STIR and TSE performed well. Imaging of small structures and peripheral nerves could in particular benefit from this technique.}, language = {en} } @article{OrzadaLaddBitz2016, author = {Orzada, Stephan and Ladd, Mark E. and Bitz, Andreas}, title = {A method to approximate maximum local SAR in multichannel transmit MR systems without transmit phase information}, series = {Magnetic Resonance in Medicine}, volume = {78}, journal = {Magnetic Resonance in Medicine}, number = {2}, publisher = {International Society for Magnetic Resonance in Medicine}, issn = {1522-2594}, doi = {10.1002/mrm.26398}, pages = {805 -- 811}, year = {2016}, abstract = {Purpose To calculate local specific absorption rate (SAR) correctly, both the amplitude and phase of the signal in each transmit channel have to be known. In this work, we propose a method to derive a conservative upper bound for the local SAR, with a reasonable safety margin without knowledge of the transmit phases of the channels. Methods The proposed method uses virtual observation points (VOPs). Correction factors are calculated for each set of VOPs that prevent underestimation of local SAR when the VOPs are applied with the correct amplitudes but fixed phases. Results The proposed method proved to be superior to the worst-case calculation based on the maximum eigenvalue of the VOPs. The mean overestimation for six coil setups could be reduced, whereas no underestimation of the maximum local SAR occurred. In the best investigated case, the overestimation could be reduced from a factor of 3.3 to a factor of 1.7. Conclusion The upper bound for the local SAR calculated with the proposed method allows a fast estimation of the local SAR based on power measurements in the transmit channels and facilitates SAR monitoring in systems that do not have the capability to monitor transmit phases}, language = {en} } @article{ChenSchoembergKraffetal.2016, author = {Chen, Bixia and Schoemberg, Tobias and Kraff, Oliver and Dammann, Philipp and Bitz, Andreas and Schlamann, Marc and Quick, Harald H. and Ladd, Mark E. and Sure, Ulrich and Wrede, Karsten H.}, title = {Cranial fixation plates in cerebral magnetic resonance imaging: a 3 and 7 Tesla in vivo image quality study}, series = {Magnetic Resonance Materials in Physics, Biology and Medicine}, volume = {29}, journal = {Magnetic Resonance Materials in Physics, Biology and Medicine}, number = {3}, publisher = {Springer}, address = {Berlin}, issn = {1352-8661}, doi = {10.1007/s10334-016-0548-1}, pages = {389 -- 398}, year = {2016}, abstract = {Objective This study assesses and quantifies impairment of postoperative magnetic resonance imaging (MRI) at 7 Tesla (T) after implantation of titanium cranial fixation plates (CFPs) for neurosurgical bone flap fixation. Materials and methods The study group comprised five patients who were intra-individually examined with 3 and 7 T MRI preoperatively and postoperatively (within 72 h/3 months) after implantation of CFPs. Acquired sequences included T₁-weighted magnetization-prepared rapid-acquisition gradient-echo (MPRAGE), T₂-weighted turbo-spin-echo (TSE) imaging, and susceptibility-weighted imaging (SWI). Two experienced neurosurgeons and a neuroradiologist rated image quality and the presence of artifacts in consensus reading. Results Minor artifacts occurred around the CFPs in MPRAGE and T2 TSE at both field strengths, with no significant differences between 3 and 7 T. In SWI, artifacts were accentuated in the early postoperative scans at both field strengths due to intracranial air and hemorrhagic remnants. After resorption, the brain tissue directly adjacent to skull bone could still be assessed. Image quality after 3 months was equal to the preoperative examinations at 3 and 7 T. Conclusion Image quality after CFP implantation was not significantly impaired in 7 T MRI, and artifacts were comparable to those in 3 T MRI.}, language = {en} } @article{SchmidtForkmannSinkeetal.2016, author = {Schmidt, K. and Forkmann, K. and Sinke, C. and Gratz, M. and Bitz, Andreas and Bingel, U.}, title = {The differential effect of trigeminal vs. peripheral pain stimulation on visual processing and memory encoding is influenced by pain-related fear}, series = {NeuroImage}, volume = {134}, journal = {NeuroImage}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1053-8119}, doi = {10.1016/j.neuroimage.2016.03.026}, pages = {386 -- 395}, year = {2016}, abstract = {Compared to peripheral pain, trigeminal pain elicits higher levels of fear, which is assumed to enhance the interruptive effects of pain on concomitant cognitive processes. In this fMRI study we examined the behavioral and neural effects of trigeminal (forehead) and peripheral (hand) pain on visual processing and memory encoding. Cerebral activity was measured in 23 healthy subjects performing a visual categorization task that was immediately followed by a surprise recognition task. During the categorization task subjects received concomitant noxious electrical stimulation on the forehead or hand. Our data show that fear ratings were significantly higher for trigeminal pain. Categorization and recognition performance did not differ between pictures that were presented with trigeminal and peripheral pain. However, object categorization in the presence of trigeminal pain was associated with stronger activity in task-relevant visual areas (lateral occipital complex, LOC), memory encoding areas (hippocampus and parahippocampus) and areas implicated in emotional processing (amygdala) compared to peripheral pain. Further, individual differences in neural activation between the trigeminal and the peripheral condition were positively related to differences in fear ratings between both conditions. Functional connectivity between amygdala and LOC was increased during trigeminal compared to peripheral painful stimulation. Fear-driven compensatory resource activation seems to be enhanced for trigeminal stimuli, presumably due to their exceptional biological relevance.}, language = {en} } @article{BankOrzadaSmitsetal.2015, author = {Bank, Bart L. van de and Orzada, Stephan and Smits, Frits and Lagemaat, Miriam W. and Rodgers, Christopher T. and Bitz, Andreas and Scheenen, Tom W. J.}, title = {Optimized (31) P MRS in the human brain at 7 T with a dedicated RF coil setup}, series = {NMR in Biomedicine}, volume = {28}, journal = {NMR in Biomedicine}, number = {11}, publisher = {Wiley}, address = {Weinheim}, issn = {1099-1492}, doi = {10.1002/nbm.3422}, pages = {1570 -- 1578}, year = {2015}, language = {en} } @techreport{SansomLawsonTuchoetal.2016, author = {Sansom, M. and Lawson, R.M. and Tucho, R. and Kendrick, C. and Ogden, R. and Resalati, S. and Garay, R. and D{\"o}ring, Bernd and Reger, V. and Gilbert, J. and Heikkinen, J. and Hemmila, K.}, title = {Building in active thermal mass into steel structures (BATIMASS) - EUR 28166EN}, publisher = {Publications Office of the European Union}, address = {Luxembourg}, organization = {European Commission}, isbn = {978-92-79-63176-4}, issn = {1831-9424}, doi = {10.2777/25999}, pages = {147 Seiten}, year = {2016}, abstract = {The main objective of the BATIMASS project was to address how the energy balance in relatively lightweight steel buildings can be improved by building in 'active thermal mass' (ATM) into the building fabric. This was achieved through concept design, dynamic thermal modelling and testing of a number of potentially viable systems and concepts. A significant programme of thermal simulation modelling was undertaken utilising the thermally equivalent slab (TES) concept to model the passive thermal capacity effect of profiled, composite metal floor decks. It is apparent from the modelling results that thermal mass is a highly complex phenomenon which is highly dependent upon building type, occupancy patterns, climate and many other aspects of the building design and servicing strategy. The ATM systems developed, both conceptually and for prototype testing, focussed on water-cooled composite slabs, the Cofradal floor system and the phase change material (PCM) Energain. In addition to laboratory testing of prototypes, whole building monitoring was undertaken at the Kubik building in Spain and the RWTH test building in Germany. Advanced thermal modelling was also undertaken to estimate the likely benefits of the ATM concept designs developed and for comparison with the test results. In addition to thermal testing, structural tests were conducted on composite floor specimens incorporating embedded water pipes. This Final Report presents the results of the activities carried out under this RFCS contract RFSR CT 2012 00033. The work carried out is reported in six major sections corresponding to the technical Work Packages of the project. Only summaries of the work carried out are provided in this report; all work undertaken is fully reported in the formal project deliverables.}, language = {en} } @article{NoureddineBitzLaddetal.2015, author = {Noureddine, Yacine and Bitz, Andreas and Ladd, Mark E. and Th{\"u}rling, Markus and Ladd, Susanne C. and Schaefers, Gregor and Kraff, Oliver}, title = {Experience with magnetic resonance imaging of human subjects with passive implants and tattoos at 7 T: a retrospective study}, series = {Magnetic Resonance Materials in Physics, Biology and Medicine}, volume = {28}, journal = {Magnetic Resonance Materials in Physics, Biology and Medicine}, number = {6}, publisher = {Springer}, address = {Berlin}, issn = {1352-8661}, doi = {10.1007/s10334-015-0499-y}, pages = {577 -- 590}, year = {2015}, language = {en} } @article{LagemaatBreukelsVosetal.2016, author = {Lagemaat, Miriam W. and Breukels, Vincent and Vos, Eline K. and B., Adam and Uden, Mark J. van and Orzada, Stephan and Bitz, Andreas and Maas, Marnix C. and Scheenen, Tom W. J.}, title = {¹H MR spectroscopic imaging of the prostate at 7T using spectral-spatial pulses}, series = {Magnetic Resonance in Medicine}, volume = {75}, journal = {Magnetic Resonance in Medicine}, number = {3}, publisher = {International Society for Magnetic Resonance in Medicine}, issn = {1522-2594}, doi = {10.1002/mrm.25569}, pages = {933 -- 945}, year = {2016}, abstract = {Purpose To assess the feasibility of prostate ¹H MR spectroscopic imaging (MRSI) using low-power spectral-spatial (SPSP) pulses at 7T, exploiting accurate spectral selection and spatial selectivity simultaneously. Methods A double spin-echo sequence was equipped with SPSP refocusing pulses with a spectral selectivity of 1 ppm. Three-dimensional prostate ¹H-MRSI at 7T was performed with the SPSP-MRSI sequence using an 8-channel transmit array coil and an endorectal receive coil in three patients with prostate cancer and in one healthy subject. No additional water or lipid suppression pulses were used. Results Prostate ¹H-MRSI could be obtained well within specific absorption rate (SAR) limits in a clinically feasible time (10 min). Next to the common citrate signals, the prostate spectra exhibited high spermine signals concealing creatine and sometimes also choline. Residual lipid signals were observed at the edges of the prostate because of limitations in spectral and spatial selectivity. Conclusion It is possible to perform prostate ¹H-MRSI at 7T with a SPSP-MRSI sequence while using separate transmit and receive coils. This low-SAR MRSI concept provides the opportunity to increase spatial resolution of MRSI within reasonable scan times.}, language = {en} } @article{VosLagemaatBarentszetal.2014, author = {Vos, E. K. and Lagemaat, M. W. and Barentsz, J. O. and F{\"u}tterer, J. J. and Zamecnik, P. and Roozen, H. and Orzada, S. and Bitz, Andreas and Maas, M. C. and Scheenen, T. W. J.}, title = {Image quality and cancer visibility of T2-weighted Magnetic Resonance Imaging of the prostate at 7 Tesla}, series = {European Radiology}, volume = {24}, journal = {European Radiology}, number = {8}, publisher = {Springer}, address = {Cham}, issn = {1432-1084}, doi = {10.1007/s00330-014-3234-6}, pages = {1950 -- 1958}, year = {2014}, abstract = {Objectives To assess the image quality of T2-weighted (T2w) magnetic resonance imaging of the prostate and the visibility of prostate cancer at 7 Tesla (T). Materials \& methods Seventeen prostate cancer patients underwent T2w imaging at 7T with only an external transmit/receive array coil. Three radiologists independently scored images for image quality, visibility of anatomical structures, and presence of artefacts. Krippendorff's alpha and weighted kappa statistics were used to assess inter-observer agreement. Visibility of prostate cancer lesions was assessed by directly linking the T2w images to the confirmed location of prostate cancer on histopathology. Results T2w imaging at 7T was achievable with 'satisfactory' (3/5) to 'good' (4/5) quality. Visibility of anatomical structures was predominantly scored as 'satisfactory' (3/5) and 'good' (4/5). If artefacts were present, they were mostly motion artefacts and, to a lesser extent, aliasing artefacts and noise. Krippendorff's analysis revealed an α = 0.44 between three readers for the overall image quality scores. Clinically significant cancer lesions in both peripheral zone and transition zone were visible at 7T. Conclusion T2w imaging with satisfactory to good quality can be routinely acquired, and cancer lesions were visible in patients with prostate cancer at 7T using only an external transmit/receive body array coil.}, language = {en} } @article{LagemaatMaasVosetal.2015, author = {Lagemaat, Miriam W. and Maas, Marnix C. and Vos, Eline K. and Bitz, Andreas and Orzada, Stephan and Weiland, Elisabeth and Uden, Mark J. van and Kobus, Thiele and Heerschap, Arend and Scheenen, Tom W. J.}, title = {(31) P MR spectroscopic imaging of the human prostate at 7 T: T1 relaxation times, Nuclear Overhauser Effect, and spectral characterization}, series = {Magnetic Resonance in Medicine}, volume = {73}, journal = {Magnetic Resonance in Medicine}, number = {3}, publisher = {Wiley}, address = {Weinheim}, issn = {1522-2594}, doi = {10.1002/mrm.25209}, pages = {909 -- 920}, year = {2015}, language = {en} } @article{TheysohnKraffEilersetal.2014, author = {Theysohn, Jens M. and Kraff, Oliver and Eilers, Kristina and Andrade, Dorian and Gerwig, Marcus and Timmann, Dagmar and Schmitt, Franz and Ladd, Mark E. and Ladd, Susanne C. and Bitz, Andreas}, title = {Vestibular effects of a 7 Tesla MRI examination compared to 1.5 T and 0 T in healthy volunteers}, series = {PLoS one}, volume = {9}, journal = {PLoS one}, number = {3}, publisher = {PLOS}, address = {San Francisco}, issn = {1932-6203}, doi = {10.1371/journal.pone.0092104}, pages = {e92104}, year = {2014}, abstract = {Ultra-high-field MRI (7 Tesla (T) and above) elicits more temporary side-effects compared to 1.5 T and 3 T, e.g. dizziness or "postural instability" even after exiting the scanner. The current study aims to assess quantitatively vestibular performance before and after exposure to different MRI scenarios at 7 T, 1.5 T and 0 T. Sway path and body axis rotation (Unterberger's stepping test) were quantitatively recorded in a total of 46 volunteers before, 2 minutes after, and 15 minutes after different exposure scenarios: 7 T head MRI (n = 27), 7 T no RF (n = 22), 7 T only B₀ (n = 20), 7 T in \& out B₀ (n = 20), 1.5 T no RF (n = 20), 0 T (n = 15). All exposure scenarios lasted 30 minutes except for brief one minute exposure in 7 T in \& out B₀. Both measures were documented utilizing a 3D ultrasound system. During sway path evaluation, the experiment was repeated with eyes both open and closed. Sway paths for all long-lasting 7 T scenarios (normal, no RF, only B₀) with eyes closed were significantly prolonged 2 minutes after exiting the scanner, normalizing after 15 minutes. Brief exposure to 7 T B₀ or 30 minutes exposure to 1.5 T or 0 T did not show significant changes. End positions after Unterberger's stepping test were significantly changed counter-clockwise after all 7 T scenarios, including the brief in \& out B₀ exposure. Shorter exposure resulted in a smaller alteration angle. In contrast to sway path, reversal of changes in body axis rotation was incomplete after 15 minutes. 1.5 T caused no rotational changes. The results show that exposure to the 7 Tesla static magnetic field causes only a temporary dysfunction or "over-compensation" of the vestibular system not measurable at 1.5 or 0 Tesla. Radiofrequency fields, gradient switching, and orthostatic dysregulation do not seem to play a role.}, language = {en} }