TY - JOUR A1 - Bitz, Andreas A1 - Zhou, Yi A1 - El Quardi, Abdessamad A1 - Streckert, Joachim T1 - Occupational Exposure at Mobile Communication Base Station Antenna Sites JF - Frequenz Y1 - 2009 U6 - https://doi.org/10.1515/FREQ.2009.63.7-8.123 SN - 2191-6349 VL - 63 IS - 7-8 SP - 123 EP - 128 ER - TY - JOUR A1 - Kraff, Oliver A1 - Bitz, Andreas A1 - Kruszona, Stefan A1 - Orzada, Stephan A1 - Schaefer, Lena C. A1 - Theysohn, Jens M. A1 - Maderwald, Stefan A1 - Ladd, Mark E. A1 - Quick, Harald H. T1 - An eight-channel phased array RF coil for spine MR imaging at 7 T JF - Investigative Radiology Y1 - 2009 U6 - https://doi.org/10.1097/RLI.0b013e3181b24ab7 SN - 1536-0210 VL - 44 IS - 11 SP - 734 EP - 740 PB - Lippincott Williams & Wilkins ER - TY - JOUR A1 - Klomp, D. W. J. A1 - Bitz, Andreas A1 - Heerschap, A. A1 - Scheenen, T. W. J. T1 - Proton spectroscopic imaging of the human prostate at 7 T JF - NMR in Biomedicine Y1 - 2009 U6 - https://doi.org/10.1002/nbm.1360 SN - 1099-1492 VL - 22 IS - 5 SP - 495 EP - 501 ER - TY - JOUR A1 - Heuermann, Holger A1 - Ibrahim, Irfan T1 - Improvements in the flicker noise reduction technique for osillator designs / Ibrahim, Irfan ; Heuermann, Holger JF - European Microwave Conference, 2009 : EuMC 2009 ; Sept. 29, 2009 - Oct. 1, 2009, Rome, Italy ; part of European Microwave Week (EuMW) / sponsored by EuMA, European Microwave Association ... Endorsed by IEEE Y1 - 2009 SN - 978-1-4244-4748-0 N1 - EuMC 2009 SP - 1215 EP - 1218 PB - IEEE CY - Piscataway, NJ ER - TY - JOUR A1 - Ferrein, Alexander A1 - Schiffer, Stefan A1 - Lakemeyer, Gerhard T1 - Embedding fuzzy controllers in golog / Ferrein, Alexander ; Schiffer, Stefan ; Lakemeyer, Gerhard JF - IEEE International Conference on Fuzzy Systems, 2009. FUZZ-IEEE 2009 Y1 - 2009 SN - 978-1-4244-3596-8 SP - 894 EP - 899 PB - IEEE CY - New York ER - TY - JOUR A1 - Heuermann, Holger A1 - Sadeghfam, Arash T1 - Enhanced system architecture for rugged wide band data transmission / Sadeghfam, A. ; Heuermann, H. JF - European Radar Conference, 2009 : EuRAD 2009 ; Sept. 30 - Oct. 2 2009, Rome, Italy ; part of the European Microwave Week (EuMW) / sponsored by EuMA, European Microwave Association Y1 - 2009 SN - 978-2-87487-014-9 N1 - Proceedings of the 6th European Radar Conference SP - 347 EP - 350 PB - IEEE CY - Piscataway, NJ ER - TY - JOUR A1 - Heinrichs, Uwe A1 - Utting, Jane F. A1 - Frauenrath, Tobias A1 - Hezel, Fabian A1 - Krombach, Gabriele A. A1 - Hodenius, Michael A. J. A1 - Kozerke, Sebastian A1 - Niendorf, Thoralf T1 - Myocardial T2 mapping free of distortion using susceptibility-weighted fast spin-echo imaging: A feasibility study at 1.5 T and 3.0 T JF - Magnetic Resonance in Medicine N2 - This study demonstrates the feasibility of applying free-breathing, cardiac-gated, susceptibility-weighted fast spin-echo imaging together with black blood preparation and navigator-gated respiratory motion compensation for anatomically accurate T₂ mapping of the heart. First, T₂ maps are presented for oil phantoms without and with respiratory motion emulation (T₂ = (22.1 ± 1.7) ms at 1.5 T and T₂ = (22.65 ± 0.89) ms at 3.0 T). T₂ relaxometry of a ferrofluid revealed relaxivities of R2 = (477.9 ± 17) mM⁻¹s⁻¹ and R2 = (449.6 ± 13) mM⁻¹s⁻¹ for UFLARE and multiecho gradient-echo imaging at 1.5 T. For inferoseptal myocardial regions mean T₂ values of 29.9 ± 6.6 ms (1.5 T) and 22.3 ± 4.8 ms (3.0 T) were estimated. For posterior myocardial areas close to the vena cava T₂-values of 24.0 ± 6.4 ms (1.5 T) and 15.4 ± 1.8 ms (3.0 T) were observed. The merits and limitations of the proposed approach are discussed and its implications for cardiac and vascular T₂-mapping are considered. Y1 - 2009 U6 - https://doi.org/10.1002/mrm.22054 SN - 1522-2594 VL - 62 IS - 3 SP - 822 EP - 828 PB - Wiley-Liss CY - New York ER - TY - JOUR A1 - Ferrein, Alexander A1 - Jacobs, Stefan A1 - Schiffer, Stefan A1 - Beck, Daniel T1 - Robust Collision Avoidance in Unknown Domestic Environments / Jacobs, Stefan ; Ferrein, Alexander ; Schiffer, Stefan ; Beck, Daniel ; Lakemeyer, Gerhard JF - ROBOCUP 2009: ROBOT SOCCER WORLD CUP XIII Y1 - 2009 N1 - Lecture Notes in Computer Science ; 5949 SP - 116 EP - 127 PB - Springer CY - Berlin ER - TY - JOUR A1 - Ferrein, Alexander A1 - Beck, Daniel A1 - Lakemeyer, Gerhard T1 - Landmark-Based Representations for Navigating Holonomic Soccer Robots / Beck, Daniel ; Ferrein, Alexander ; Lakemeyer, Gerhard JF - RoboCup 2008 : robot soccer world cup XII / Luca Iocchi ... (eds.) Y1 - 2009 SN - 978-3-642-02921-9 N1 - Lecture Notes in Computer Science ; 5399 SP - 25 EP - 36 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Heuermann, Holger A1 - Thalayasingam, K. T1 - Novel vector non-linear measurement system for intermodulation measurements / Thalayasingam, K.; Heuermann, H. JF - European Microwave Conference, 2009 : EuMC 2009 ; Sept. 29, 2009 - Oct. 1, 2009, Rome, Italy ; part of European Microwave Week (EuMW) / sponsored by EuMA, European Microwave Association ... Endorsed by IEEE Y1 - 2009 SN - 978-1-4244-4748-0 N1 - European Microwave Conference ; (39 : ; 2009.09.29-10.01 : ; Rome) SP - 926 EP - 929 PB - IEEE CY - Piscataway, NJ ER - TY - JOUR A1 - Köllensperger, P. A1 - Bragard, Michael A1 - Plum, T. A1 - De Doncker, R. W. T1 - The dual GCT : new high-power device using optimized GCT technology JF - IEEE transactions on industry applications Y1 - 2009 U6 - https://doi.org/10.1109/TIA.2009.2027364 SN - 0093-9994 VL - 45 IS - 5 SP - 1754 EP - 1762 ER - TY - CHAP A1 - Ferrein, Alexander A1 - Potgieter, Anet A1 - Steinbauer, Gerald T1 - Self-aware robots - What do we need from learning, deliberation, and reactive control? T2 - HYCAS 2009 : International Workshop on Hybrid Control of Autonomous Systems : Integrating Learning, Deliberation and Reactive Control : Pasadena, Calif., 13 July 2009 Y1 - 2009 SP - 1 EP - 5 PB - AAAI Pr. ER - TY - BOOK A1 - Ferrein, Alexander A1 - Pauli, J. A1 - Siebel, N. T. A1 - Steinbauer, Gerald T1 - Hybrid control for autonomous systems : [... 1st Workshop on Hybrid Control of Autonomous Systems - Integrating Learning, Deliberation and Reactive Control with the 21st International Joint Conference on Artificial Intelligence (IJCAI-09), held in Pasadena, CA, in July 2009] / ed. by Alexander Ferrein ... Y1 - 2009 ER - TY - JOUR A1 - Kob, Malte A1 - Frauenrath, Tobias T1 - A system for parallel measurement of glottis opening and larynx position JF - Biomedical Signal Processing and Control N2 - The simultaneous assessment of glottal dynamics and larynx position can be beneficial for the diagnosis of disordered voice or speech production and swallowing. Up to now, methods either concentrate on assessment of the glottis opening using optical, acoustical or electrical (electroglottography, EGG) methods, or on visualisation of the larynx position using ultrasound, computer tomography or magnetic resonance imaging techniques. The method presented here makes use of a time-multiplex measurement approach of space-resolved transfer impedances through the larynx. The fast sequence of measurements allows a quasi simultaneous assessment of both larynx position and EGG signal using up to 32 transmit–receive signal paths. The system assesses the dynamic opening status of the glottis as well as the vertical and back/forward motion of the larynx. Two electrode-arrays are used for the measurement of the electrical transfer impedance through the neck in different directions. From the acquired data the global and individual conductivity is calculated as well as a 2D point spatial representation of the minimum impedance. The position information is shown together with classical EGG signals allowing a synchronous visual assessment of glottal area and larynx position. A first application to singing voice analysis is presented that indicate a high potential of the method for use as a non-invasive tool in the diagnosis of voice, speech, and swallowing disorders. KW - EGG KW - Transfer impedance KW - Tomography KW - Larynx position KW - Voice assessment Y1 - 2009 U6 - https://doi.org/10.1016/j.bspc.2009.03.004 SN - 1746-8108 VL - 4 IS - 3 SP - 221 EP - 228 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Hillgärtner, Michael T1 - Normative Regulations JF - ECPE Cluster Seminar EMC in Hybrid and Electric Vehicles : 18 May 2010, Fraunhofer Institute Erlangen Y1 - 2010 N1 - Seminar EMC in Hybrid and Electric Vehicles <2010, Erlangen> PB - European Center for Power Electronics CY - Nürnberg ER - TY - CHAP A1 - Schnell, Michael A1 - Franzen, Nico A1 - Gligorevic, Snjezana T1 - L-DACS1 laboratory demonstrator development and compatibility measurement set-up T2 - IEEE/AIAA 29th Digital Avionics Systems Conference (DASC) : 3 - 7 Oct. 2010, Salt Lake City, Utah Y1 - 2010 SN - 9781424466160 ; 9781424466184 SP - 3E3-1 EP - 3E3-11 ER - TY - CHAP A1 - Walter, Michael A1 - Gligorevic, Snjezana A1 - Detert, Thorben A1 - Schnell, Michael T1 - UHF/VHF air-to-air propagation measurements T2 - Proceedings of the Fourth European Conference on Antennas and Propagation (EuCAP) : 12 - 16 April 2010, Barcelona, Spain Y1 - 2010 SN - 978-1-4244-6431-9 ; 978-84-7653-472-4 SP - 1 EP - 5 ER - TY - CHAP A1 - Gligorevic, Snjezana A1 - Pulini, Paola T1 - Simplified airport surface channel model based on the WSSUS assumption T2 - 2010 Integrated Communications, Navigation and Surveillance Conference (ICNS 2010) : Herndon, Virginia, USA, 11 - 13 May 2010 Y1 - 2010 SN - 978-1-4244-7457-8 SN - 2155-4943 SP - F2-1 EP - F2-11 ER - TY - JOUR A1 - Rens, Gavin A1 - Varzinczak, Ivan A1 - Meyer, Thomas A1 - Ferrein, Alexander T1 - A Logic for Reasoning about Actions and Explicit Observations JF - AI 2010: Advances in Artificial Intelligence 23rd Australasian Joint Conference, Adelaide, Australia, December 7-10, 2010. Proceedings Y1 - 2010 SN - 978-3-642-17431-5 N1 - Lecture Notes in Computer Science ; 6464 SP - 395 EP - 404 PB - Springer CY - Berlin ER - TY - JOUR A1 - Ferrein, Alexander A1 - Niemüller, Tim A1 - Steinbauer, Gerald T1 - Team Zadeat 2010 : application for participation Y1 - 2010 ER - TY - CHAP A1 - Bitz, Andreas A1 - Kraff, O. A1 - Orzada, S. A1 - Maderwald, S. A1 - Brote, I. A1 - Ladd, M. T1 - Experimental and Numerical Assessment of RF Safety of Transmit Coils at 7 Tesla T2 - ISMRM workshop on MR safety 2010 : RF heating of the human in MRI : workshop series. The Washington County Historic Courthouse, Stillwater, Minnesota, USA, 15 - 17 October 2010 Y1 - 2010 SN - 978-1-62276-088-6 SP - 195 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 - Orzada, Stephan A1 - Maderwald, Stefan A1 - Poser, Benedikt Andreas A1 - Bitz, Andreas A1 - Quick, Harald H. A1 - Ladd, Mark E. T1 - RF excitation using time interleaved acquisition of modes (TIAMO) to address B1 inhomogeneity in high-field MRI JF - Magnetic Resonance in Medicine N2 - 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. Y1 - 2010 U6 - https://doi.org/10.1002/mrm.22527 SN - 1522-2594 VL - 64 IS - 2 SP - 327 EP - 333 PB - Wiley-Liss CY - New York ER - TY - JOUR A1 - Kraff, Oliver A1 - Bitz, Andreas A1 - Dammann, Philipp A1 - Ladd, Susanne C. A1 - Ladd, Mark E. A1 - Quick, Harald H. T1 - An eight-channel transmit/receive multipurpose coil for musculoskeletal MR imaging at 7 T JF - Medical Physics N2 - 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. Y1 - 2010 U6 - https://doi.org/10.1118/1.3517176 SN - 2473-4209 VL - 37 IS - 12 SP - 6368 EP - 6376 PB - Wiley CY - Hoboken, NJ ER - TY - JOUR A1 - Schlamann, Marc A1 - Voigt, Melanie A. A1 - Maderwald, Stefan A1 - Bitz, Andreas A1 - Kraff, Oliver A1 - Ladd, Susanne C. A1 - Ladd, Mark E. A1 - Forsting, Michael A1 - Wilhelm, Hans T1 - Exposure to high-field MRI does not affect cognitive function JF - Journal of Magnetic Resonance Imaging N2 - Purpose To assess potential cognitive deficits under the influence of static magnetic fields at various field strengths some studies already exist. These studies were not focused on attention as the most vulnerable cognitive function. Additionally, mostly no magnetic resonance imaging (MRI) sequences were performed. Materials and Methods In all, 25 right-handed men were enrolled in this study. All subjects underwent one MRI examination of 63 minutes at 1.5 T and one at 7 T within an interval of 10 to 30 days. The order of the examinations was randomized. Subjects were referred to six standardized neuropsychological tests strictly focused on attention immediately before and after each MRI examination. Differences in neuropsychological variables between the timepoints before and after each MRI examination were assessed and P-values were calculated Results Only six subtests revealed significant differences between pre- and post-MRI. In these tests the subjects achieved better results in post-MRI testing than in pre-MRI testing (P = 0.013–0.032). The other tests revealed no significant results. Conclusion The improvement in post-MRI testing is only explicable as a result of learning effects. MRI examinations, even in ultrahigh-field scanners, do not seem to have any persisting influence on the attention networks of human cognition immediately after exposure. Y1 - 2010 U6 - https://doi.org/10.1002/jmri.22065 SN - 1522-2586 VL - 31 IS - 5 SP - 1061 EP - 1066 PB - Wiley-Liss CY - New York ER - TY - JOUR A1 - Schlamann, Marc A1 - Yoon, Min-Suk A1 - Maderwald, Stefan A1 - Pietrzyk, Thomas A1 - Bitz, Andreas A1 - Gerwig, Marcus A1 - Forsting, Michael A1 - Ladd, Susanne C. A1 - Ladd, Mark E. A1 - Kastrup, Oliver T1 - Short term effects of magnetic resonance imaging on excitability of the motor cortex at 1.5T and 7T JF - Academic Radiology N2 - Rationale and Objectives The increasing spread of high-field and ultra-high-field magnetic resonance imaging (MRI) scanners has encouraged new discussion of the safety aspects of MRI. Few studies have been published on possible cognitive effects of MRI examinations. The aim of this study was to examine whether changes are measurable after MRI examinations at 1.5 and 7 T by means of transcranial magnetic stimulation (TMS). Materials and Methods TMS was performed in 12 healthy, right-handed male volunteers. First the individual motor threshold was specified, and then the cortical silent period (SP) was measured. Subsequently, the volunteers were exposed to the 1.5-T MRI scanner for 63 minutes using standard sequences. The MRI examination was immediately followed by another TMS session. Fifteen minutes later, TMS was repeated. Four weeks later, the complete setting was repeated using a 7-T scanner. Control conditions included lying in the 1.5-T scanner for 63 minutes without scanning and lying in a separate room for 63 minutes. TMS was performed in the same way in each case. For statistical analysis, Wilcoxon's rank test was performed. Results Immediately after MRI exposure, the SP was highly significantly prolonged in all 12 subjects at 1.5 and 7 T. The motor threshold was significantly increased. Fifteen minutes after the examination, the measured value tended toward normal again. Control conditions revealed no significant differences. Conclusion MRI examinations lead to a transient and highly significant alteration in cortical excitability. This effect does not seem to depend on the strength of the static magnetic field. Y1 - 2010 U6 - https://doi.org/10.1016/j.acra.2009.10.004 SN - 1076-6332 VL - 17 IS - 3 SP - 277 EP - 281 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Ferrein, Alexander T1 - golog.lua: Towards a Non-Prolog Implementation of Golog for Embedded Systems Y1 - 2010 SP - 20 EP - 28 ER - TY - JOUR A1 - Ferrein, Alexander T1 - golog.lua: Towards a Non-Prolog Implementation of Golog for Embedded Systems JF - Cognitive Robotics / Lakemeyer, Gerhard (ed.) Y1 - 2010 N1 - Dagstuhl Seminar Proceedings ; 10081 SP - 1 EP - 15 ER - TY - JOUR A1 - Niemüller, Tim A1 - Ferrein, Alexander A1 - Lakemeyer, Gerhard T1 - A Lua-based Behavior Engine for Controlling the Humanoid Robot Nao JF - RoboCup 2009: Robot Soccer World Cup XIII Y1 - 2010 N1 - Lecture Notes in Computer Science ; 5949 SP - 240 EP - 251 ER - TY - JOUR A1 - Ferrein, Alexander A1 - Siebel, Nils T. A1 - Steinbauer, Gerald T1 - Hybrid control for autonomous systems — Integrating learning, deliberation and reactive control JF - Robotics and Autonomous Systems Y1 - 2010 SN - 0921-8890 VL - 58 IS - 9 SP - 1037 EP - 1038 ER - TY - JOUR A1 - von Knobelsdorf-Brenkenhoff, Florian A1 - Frauenrath, Tobias A1 - Prothmann, Marcel A1 - Dieringer, Matthias A. A1 - Hezel, Fabian A1 - Renz, Wolfgang A1 - Kretschel, Kerstin A1 - Niendorf, Thoralf A1 - Schulz-Menger, Jeanette T1 - Cardiac chamber quantification using magnetic resonance imaging at 7 Tesla—a pilot study N2 - Objectives Interest in cardiovascular magnetic resonance (CMR) at 7 T is motivated by the expected increase in spatial and temporal resolution, but the method is technically challenging. We examined the feasibility of cardiac chamber quantification at 7 T. Methods A stack of short axes covering the left ventricle was obtained in nine healthy male volunteers. At 1.5 T, steady-state free precession (SSFP) and fast gradient echo (FGRE) cine imaging with 7 mm slice thickness (STH) were used. At 7 T, FGRE with 7 mm and 4 mm STH were applied. End-diastolic volume, end-systolic volume, ejection fraction and mass were calculated. Results All 7 T examinations provided excellent blood/myocardium contrast for all slice directions. No significant difference was found regarding ejection fraction and cardiac volumes between SSFP at 1.5 T and FGRE at 7 T, while volumes obtained from FGRE at 1.5 T were underestimated. Cardiac mass derived from FGRE at 1.5 and 7 T was larger than obtained from SSFP at 1.5 T. Agreement of volumes and mass between SSFP at 1.5 T and FGRE improved for FGRE at 7 T when combined with an STH reduction to 4 mm. Conclusions This pilot study demonstrates that cardiac chamber quantification at 7 T using FGRE is feasible and agrees closely with SSFP at 1.5 T. Y1 - 2010 U6 - https://doi.org/10.1007/s00330-010-1888-2 SN - 0938-7994 VL - 20 SP - 2844 EP - 2852 PB - Springer CY - Berlin, Heidelberg ER - TY - JOUR A1 - Frauenrath, Tobias A1 - Hezel, Fabian A1 - Renz, Wolfgang A1 - de Geyer d'Orth, Thibaut A1 - Dieringer, Matthias A1 - von Knobelsdorf-Brenkenhoff, Florian A1 - Prothmann, Marcel A1 - Schulz-Menger, Jeanette A1 - Niendorf, Thoralf T1 - Acoustic cardiac triggering: a practical solution for synchronization and gating of cardiovascular magnetic resonance at 7 Tesla JF - Journal of Cardiovascular Magnetic Resonance N2 - Background To demonstrate the applicability of acoustic cardiac triggering (ACT) for imaging of the heart at ultrahigh magnetic fields (7.0 T) by comparing phonocardiogram, conventional vector electrocardiogram (ECG) and traditional pulse oximetry (POX) triggered 2D CINE acquisitions together with (i) a qualitative image quality analysis, (ii) an assessment of the left ventricular function parameter and (iii) an examination of trigger reliability and trigger detection variance derived from the signal waveforms. Results ECG was susceptible to severe distortions at 7.0 T. POX and ACT provided waveforms free of interferences from electromagnetic fields or from magneto-hydrodynamic effects. Frequent R-wave mis-registration occurred in ECG-triggered acquisitions with a failure rate of up to 30% resulting in cardiac motion induced artifacts. ACT and POX triggering produced images free of cardiac motion artefacts. ECG showed a severe jitter in the R-wave detection. POX also showed a trigger jitter of approximately Δt = 72 ms which is equivalent to two cardiac phases. ACT showed a jitter of approximately Δt = 5 ms only. ECG waveforms revealed a standard deviation for the cardiac trigger offset larger than that observed for ACT or POX waveforms. Image quality assessment showed that ACT substantially improved image quality as compared to ECG (image quality score at end-diastole: ECG = 1.7 ± 0.5, ACT = 2.4 ± 0.5, p = 0.04) while the comparison between ECG vs. POX gated acquisitions showed no significant differences in image quality (image quality score: ECG = 1.7 ± 0.5, POX = 2.0 ± 0.5, p = 0.34). Conclusions The applicability of acoustic triggering for cardiac CINE imaging at 7.0 T was demonstrated. ACT's trigger reliability and fidelity are superior to that of ECG and POX. ACT promises to be beneficial for cardiovascular magnetic resonance at ultra-high field strengths including 7.0 T. KW - Interval Time Series KW - Image Quality Score KW - Image Quality Assessment KW - Sound Pressure Level KW - Cardiovascular Magnetic Resonance Y1 - 2010 U6 - https://doi.org/10.1186/1532-429X-12-67 SN - 1532-429X VL - 12 IS - 1 PB - Elsevier CY - Amsterdam ER - TY - CHAP A1 - Penne, Jochen A1 - Profittlich, Martin A1 - Ringbeck, Thorsten A1 - Buxbaum, Bernd ED - D, Nicola D'Apuzzo T1 - Touchless detailed 3D scan of human hand anatomy using time-of-flight cameras T2 - Proceedings of the International Conference on 3D Body Scanning Technologies : Lugano, Switzerland, 19-20 October 2010 Y1 - 2010 SN - 978-3-033-02714-5 SP - 361 EP - 369 PB - Hometrica Consulting CY - Zürich ER - TY - CHAP A1 - Bragard, Michael A1 - Soltau, N. A1 - De Doncker, R. W. A1 - Schmiegel, A. T1 - Design and implementation of a 5 kW photovoltaic system with li-ion battery and additional DC-DC converter T2 - 2010 IEEE Energy Conversion Congress and Exposition (ECCE 2010) : Atlanta, Georgia, USA, 12 - 16 September 2010 / [sponsored by the IEEE Power Electronics and Industry Applications Societies] Y1 - 2010 SN - 978-1-4244-5286-6 (Print) SN - 978-1-4244-5287-3 (Online) U6 - https://doi.org/10.1109/ECCE.2010.5618220 SP - 2944 EP - 2949 PB - IEEE CY - Piscataway, NJ ER - TY - CHAP A1 - Bragard, Michael A1 - Conrad, M. A1 - De Doncker, R. W. T1 - The integrated emitter turn-off thyristor (IETO) : an innovative thyristor based high power semiconductor device using MOS assisted turn-off T2 - 2010 IEEE Energy Conversion Congress and Exposition (ECCE 2010) : Atlanta, Georgia, USA, 12 - 16 September 2010 / [sponsored by the IEEE Power Electronics and Industry Applications Societies] Y1 - 2010 SN - 978-1-4244-5286-6 (Print) SN - 978-1-4244-5287-3 (Online) U6 - https://doi.org/10.1109/ECCE.2010.5618410 SP - 4551 EP - 4557 PB - IEEE CY - Piscataway, NJ ER - TY - JOUR A1 - Niemüller, Tim A1 - Ferrein, Alexander A1 - Beck, Daniel A1 - Lakemeyer, Gerhard T1 - Design Principles of the Component-Based Robot Software Framework Fawkes JF - Simulation, Modeling, and Programming for Autonomous Robots Y1 - 2010 N1 - Lecture Notes in Computer Science ; 6472 ; Second International Conference, SIMPAR 2010, Darmstadt, Germany, November 15-18, 2010. Proceedings SP - 300 EP - 311 ER - TY - JOUR A1 - Ferrein, Alexander A1 - Steinbauer, Gerald T1 - On the Way to High-Level Programming for Resource-Limited Embedded Systems with Golog JF - Simulation, Modeling, and Programming for Autonomous Robots Y1 - 2010 N1 - Lecture Notes in Computer Science ; 6472 ; Second International Conference, SIMPAR 2010, Darmstadt, Germany, November 15-18, 2010. Proceedings SP - 229 EP - 240 ER - TY - JOUR A1 - Ferrein, Alexander T1 - Robot controllers for highly dynamic environments with real-time constraints JF - Künstliche Intelligenz : KI. 24 (2010), H. 2 Y1 - 2010 SN - 1610-1987 SP - 175 EP - 178 ER - TY - JOUR A1 - Schiffer, Stefan A1 - Ferrein, Alexander A1 - Lakemeyer, Gerhard T1 - Proceedings of the Fourth International Conference on Intelligent Robotics and Applications (ICIRA 2011) JF - Proceedings of the Fourth International Conference on Intelligent Robotics and Applications (ICIRA 2011) Y1 - 2010 SP - 1 EP - 10 ER - TY - JOUR A1 - Bragard, Michael A1 - Soltau, N. A1 - Thomas, S. A1 - De Doncker, R. W. T1 - The balance of renewable sources and user demands in grids : power electronics for modular battery energy storage systems JF - IEEE transactions on power electronics N2 - The continuously growing amount of renewable sources starts compromising the stability of electrical grids. Contradictory to fossil fuel power plants, energy production of wind and photovoltaic (PV) energy is fluctuating. Although predictions have significantly improved, an outage of multi-MW offshore wind farms poses a challenging problem. One solution could be the integration of storage systems in the grid. After a short overview, this paper focuses on two exemplary battery storage systems, including the required power electronics. The grid integration, as well as the optimal usage of volatile energy reserves, is presented for a 5- kW PV system for home application, as well as for a 100- MW medium-voltage system, intended for wind farm usage. The efficiency and cost of topologies are investigated as a key parameter for large-scale integration of renewable power at medium- and low-voltage. Y1 - 2010 U6 - https://doi.org/10.1109/TPEL.2010.2085455 SN - 0885-8993 VL - 25 IS - 12 SP - 3049 EP - 3056 PB - IEEE CY - New York ER - TY - JOUR A1 - Schubert, Nicole A1 - Scholl, Ingrid T1 - Comparing GPU-based multi-volume ray casting techniques JF - Computer Science - Research and Development Y1 - 2011 SN - 1865-2042 VL - 26 IS - 12 SP - 39 EP - 50 PB - Springer CY - Berlin ER - TY - JOUR A1 - Scholl, Ingrid A1 - Aach, Til A1 - Deserno, Thomas M. A1 - Kuhlen, Torsten T1 - Challenges of medical image processing JF - Computer Science - Research and Development Y1 - 2011 SN - 1865-2042 VL - 26 IS - 1-2 SP - 5 EP - 13 PB - Springer CY - Berlin ER - TY - JOUR A1 - Deserno, Thomas M. A1 - Aach, Til A1 - Amunts, Katrin A1 - Hillen, Walter A1 - Kuhlen, Torsten A1 - Scholl, Ingrid T1 - Advances in medical image processing : A special Issue on the Workshop in Aachen, Germany, March 2010 JF - Computer Science - Research and Development. 26 (2011), H. 1-2 Y1 - 2011 SN - 1865-2042 SP - 1 EP - 3 PB - springer CY - Berlin ER - TY - JOUR A1 - Hamm, Laurits A1 - Hartung, Frank T1 - High Quality Visual Communication based on IMS JF - Mobilkommunikation : Technologien und Anwendungen ; Vorträge der 16. ITG-Fachtagung vom 18. bis 19. Mai 2011 in Osnabrück / Veranst.: Informationstechnische Gesellschaft im VDE (ITG) ... Tagungsleitung: Ralf Tönjes. Programmkomitee/Hrsg.: Peter Roer Y1 - 2011 SN - 978-3-8007-3352-1 N1 - ITG-Fachbericht ; 230 ; Fachtagung Mobilkommunikation <16, 2011, Osnabrück> SP - 80 EP - 85 PB - VDE-Verl. CY - Berlin ER - TY - JOUR A1 - Hartung, Frank A1 - Kesici, Sinan A1 - Catrein, Daniel T1 - DRM protected Dynamic Adaptive HTTP Streaming JF - Proceedings of the 2011 ACM Multimedia Systems Conference [Elektronische Ressource] : February 23 - 25, 2011, San Jose, CA, USA / sponsored by: ACM SIGMM Y1 - 2011 SN - 9781450305181 N1 - ACM Multimedia Systems Conference ; (2 : ; 2011.02.23-25 : ; San Jose, Calif.) SP - 277 EP - 282 PB - ACM CY - New York, NY ER - TY - JOUR A1 - Maus, Stefan A1 - Höfken, Hans-Wilhelm A1 - Schuba, Marko T1 - Forensic Analysis of Geodata in Android Smartphones Y1 - 2011 N1 - Cyberforensics 2011, Glasgow SP - 1 EP - 11 ER - TY - JOUR A1 - Schaefer, Thomas A1 - Höfken, Hans-Wilhelm A1 - Schuba, Marko T1 - Windows Phone 7 from a Digital Forensics’ Perspective Y1 - 2011 N1 - ICDF2C <3, 2011, Dublin> PB - Springer CY - Berlin ER - TY - JOUR A1 - Engels, Elmar A1 - Krauskopf, S. T1 - Innovation in Motion-Logic programming - a versatile interface JF - Proceedings to the 12th International Workshop on Research and Education in Mechatronics, REM 2011, Kocaeli, Turkey, 15.09.-16.09.2011 Y1 - 2011 SN - 978-975-8047-96-3 PB - - ER - TY - CHAP A1 - Usai, Pierpaolo A1 - Corucci, Alessandro A1 - Gligorevic, Snjezana A1 - Monorchio, Agostino T1 - Estimation of airport surface propagation channel: ray tracing model and measurements T2 - Proceedings of the 5th European Conference on Antennas and Propagation (EUCAP) : 11 - 15 April 2011, Rome, Italy Y1 - 2011 SN - 978-1-4577-0250-1 SP - 1634 EP - 1638 ER - TY - CHAP A1 - Schneckenburger, N. A1 - Franzen, N. A1 - Gligorevic, Snjezana A1 - Schnell, M. T1 - L-band compatibility of LDACS1 T2 - IEEE/AIAA 30th Digital Avionics Systems Conference (DASC) : 16 - 20 Oct. 2011, Seattle, Wash. Y1 - 2011 SN - 978-1-61284-797-9 SN - 2155-7195 SP - 4C3-1 EP - 4C3-11 ER - TY - CHAP A1 - Gligorevic, Snjezana A1 - Schneckenburger, N. A1 - Franzen, N. A1 - Schnell, Michael A1 - Müller, S. A1 - Günzel, H. T1 - L-Band compatibility of LDACS1 T2 - 3rd CEAS Air and Space Conference, 24 - 28 October 2011, Venezia, Italy Y1 - 2011 SP - 1 EP - 8 ER - TY - CHAP A1 - Gligorevic, Snjezana A1 - Epple, Ulrich A1 - Schnell, Michael T1 - The LDACS1 physical layer design T2 - Future aeronautical communications Y1 - 2011 SN - 978-953-307-625-6 SP - 317 EP - 332 PB - Intech CY - London ER - TY - JOUR A1 - Ferrein, Alexander A1 - Marais, Stephen A1 - Potgieter, Anet A1 - Steinbauer, Gerald T1 - RoboCup Junior: A vehicle for S&T education in Africa? Y1 - 2011 SN - 978-1-61284-992-8 N1 - AFRICON, 2011 SP - 1 EP - 6 PB - IEEE CY - New York ER - TY - CHAP A1 - Schiffer, Stefan A1 - Ferrein, Alexander A1 - Lakemeyer, Gerhard T1 - Fuzzy representations and control for domestic service robots in Golog T2 - Intelligent robotics and applications : 4th International conference, ICIRA 2011, Aachen, Germany, December 6-8, 2011, proceedings, part I. (Lecture notes in computer science ; 7102) Y1 - 2011 SN - 978-3-642-25486-4 SP - 241 EP - 250 ER - TY - JOUR A1 - Ferrein, Alexander A1 - Rens, Gavin A1 - Meyer, Thomas A1 - Lakemeyer, Gerhard T1 - A Logic for Specifying Partially Observable Stochastic Domains / Rens, Gavin ; Meyer, Thomas ; Ferrein, Alexander ; Lakemeyer, Gerhard JF - Proceedings of the Ninth International Workshop pn non-Monotonic Reasoning, Action and Change (NRAC`11) Y1 - 2011 N1 - Technical Report RMIT-TR-11-02 SP - 15 EP - 22 ER - TY - CHAP A1 - Czarnecki, Christian A1 - Winkelmann, Axel A1 - Spiliopoulou, Myra ED - Pokorny, Jaroslav ED - Repa, Vaclav ED - Richta, Karel ED - Wojtkowski, Wita ED - Linger, Henry ED - Barry, Chris ED - Lang, Michael T1 - Making business systems in the telecommunication industry more customer-oriented T2 - Information Systems Development : Business Systems and Services: Modeling and Development N2 - Market changes have forced telecommunication companies to transform their business. Increased competition, short innovation cycles, changed usage patterns, increased customer expectations and cost reduction are the main drivers. Our objective is to analyze to what extend transformation projects have improved the orientation towards the end-customers. Therefore, we selected 38 real-life case studies that are dealing with customer orientation. Our analysis is based on a telecommunication-specific framework that aligns strategy, business processes and information systems. The result of our analysis shows the following: transformation projects that aim to improve the customer orientation are combined with clear goals on costs and revenue of the enterprise. These projects are usually directly linked to the customer touch points, but also to the development and provisioning of products. Furthermore, the analysis shows that customer orientation is not the sole trigger for transformation. There is no one-fits-all solution; rather, improved customer orientation needs aligned changes of business processes as well as information systems related to different parts of the company. KW - Business Process KW - Customer Orientation KW - Enterprise Architecture KW - Transformation Project KW - Telecommunication Industry Y1 - 2011 SN - 978-1-4419-9645-9 (Print) SN - 978-1-4419-9790-6 (Online) U6 - https://doi.org/10.1007/978-1-4419-9790-6_14 N1 - 19th International Conference on Information Systems Development held in Prague, Czech Republic, August 25 - 27, 2010. SP - 169 EP - 180 PB - Springer CY - New York ER - TY - JOUR A1 - Prochnow, Nora A1 - Gebing, Tina A1 - Ladage, Kerstin A1 - Krause-Finkeldey, Dorothee A1 - Ourdi, Abessamad El A1 - Bitz, Andreas A1 - Streckert, Joachim A1 - Hansen, Volkert A1 - Dermietzel, Rolf T1 - Electromagnetic field effect or simply stress? Effects of UMTS exposure on hippocampal longterm plasticity in the context of procedure related hormone release JF - PLoS one N2 - 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. Y1 - 2011 U6 - https://doi.org/10.1371/journal.pone.0019437 VL - 6 IS - 5 PB - PLOS CY - San Francisco ER - TY - JOUR A1 - Orzada, Stephan A1 - Bitz, Andreas A1 - Schäfer, Lena C. A1 - Ladd, Susanne C. A1 - Ladd, Mark E. A1 - Maderwald, Stefan T1 - Open design eight-channel transmit/receive coil for high-resolution and real-time ankle imaging at 7 T JF - Medical Physics N2 - 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. Y1 - 2011 U6 - https://doi.org/10.1118/1.3553399 SN - 2473-4209 VL - 38 IS - 3 SP - 1162 EP - 1167 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Kraff, Oliver A1 - Bitz, Andreas A1 - Breyer, Tobias A1 - Kruszona, Stefan A1 - Maderwald, Stefan A1 - Brote, Irina A1 - Gizewski, Elke R. A1 - Ladd, Mark E. A1 - Quick, Harald H. T1 - A transmit/receive radiofrequency array for imaging the carotid arteries at 7 Tesla: coil design and first in vivo results JF - Investigative Radiology N2 - Objective: To develop a transmit/receive radiofrequency (RF) array for magnetic resonance imaging (MRI) of the carotid arteries at 7 T. The prototype is characterized in numerical simulations and bench measurements, and the feasibility of plaque imaging at 7 T is demonstrated in first in vivo images. Materials and Methods: The RF phased array coil consists of 8 surface loop coils. To allow imaging of both sides of the neck, the RF array is divided into 2 coil clusters, each with 4 overlapping loop elements. For safety validation, numerical computations of the RF field distribution and the corresponding specific absorption rate were performed on the basis of a heterogeneous human body model. To validate the coil model, maps of the transmit B1+ field were compared between simulation and measurement. In vivo images of a healthy volunteer and a patient (ulcerating plaque and a 50% stenosis of the right internal carotid artery) were acquired using a 3-dimensional FLASH sequence with a high isotropic spatial resolution of 0.54 mm as well as using pulse-triggered proton density (PD)/T2-weighted turbo spin echo sequences. Results: Measurements of the S-parameters yielded a reflection and isolation of the coil elements of better than −18 and −13 dB, respectively. Measurements of the g-factor indicated good image quality for parallel imaging acceleration factors up to 2.4. A similar distribution and a very good match of the absolute values were found between the measured and simulated B1+ transmit RF field for the validation of the coil model. In vivo images revealed good signal excitation of both sides of the neck and a high vessel-to-background image contrast for the noncontrast-enhanced 3-dimensional FLASH sequence. Imaging at 7 T could depict the extent of stenosis, and revealed the disruption and ulcer of the plaque. Conclusions: This study demonstrates that 2 four-channel transmit/receive RF arrays for each side of the neck is a suitable concept for in vivo MRI of the carotid arteries at 7 Tesla. Further studies are needed to explore and exploit the full potential of 7 T high-field MRI for carotid atherosclerotic plaque imaging. Y1 - 2011 U6 - https://doi.org/10.1097/RLI.0b013e318206cee4 SN - 1536-0210 VL - 46 IS - 4 SP - 246 EP - 254 PB - Wolters Kluwer CY - Köln ER - TY - JOUR A1 - El Quardi, A. A1 - Streckert, J. A1 - Bitz, Andreas A1 - Münkner, S. A1 - Engel, J. A1 - Hansen, V. T1 - New fin-line devices for radiofrequency exposure of small biological samples in vitro allowing whole-cell patch clamp recordings JF - Bioelectromagnetics N2 - The development and analysis of three waveguides for the exposure of small biological in vitro samples to mobile communication signals at 900 MHz (GSM, Global System for Mobile Communications), 1.8 GHz (GSM), and 2 GHz (UMTS, Universal Mobile Telecommunications System) is presented. The waveguides were based on a fin-line concept and the chamber containing the samples bathed in extracellular solution was placed onto two fins with a slot in between, where the exposure field concentrates. Measures were taken to allow for patch clamp recordings during radiofrequency (RF) exposure. The necessary power for the achievement of the maximum desired specific absorption rate (SAR) of 20 W/kg (average over the mass of the solution) was approximately Pin = 50 mW, Pin = 19 mW, and Pin = 18 mW for the 900 MHz, 1800 MHz, and 2 GHz devices, respectively. At 20 W/kg, a slight RF-induced temperature elevation in the solution of no more than 0.3 °C was detected, while no thermal offsets due to the electromagnetic exposure could be detected at the lower SAR settings (2, 0.2, and 0.02 W/kg). A deviation of 10% from the intended solution volume yielded a calculated SAR deviation of 8% from the desired value. A maximum ±10% variation in the local SAR could occur when the position of the patch clamp electrode was altered within the area where the cells to be investigated were located. Y1 - 2011 U6 - https://doi.org/10.1002/bem.20621 SN - 1521-186X VL - 32 IS - 2 SP - 102 EP - 112 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Umutlu, Lale A1 - Orzada, Stephan A1 - Kinner, Sonja A1 - Maderwald, Stefan A1 - Bronte, Irina A1 - Bitz, Andreas A1 - Kraff, Oliver A1 - Ladd, Susanne C. A1 - Antoch, Gerald A1 - Ladd, Mark E. A1 - Quick, Harald H. A1 - Lauenstein, Thomas C. T1 - Renal imaging at 7 Tesla: preliminary results JF - European Radiology N2 - Objective To investigate the feasibility of 7T MR imaging of the kidneys utilising a custom-built 8-channel transmit/receive radiofrequency body coil. Methods In vivo unenhanced MR was performed in 8 healthy volunteers on a 7T whole-body MR system. After B0 shimming the following sequences were obtained: 1) 2D and 3D spoiled gradient-echo sequences (FLASH, VIBE), 2) T1-weighted 2D in and opposed phase 3) True-FISP imaging and 4) a T2-weighted turbo spin echo (TSE) sequence. Visual evaluation of the overall image quality was performed by two radiologists. Results Renal MRI at 7T was feasible in all eight subjects. Best image quality was found using T1-weighted gradient echo MRI, providing high anatomical details and excellent conspicuity of the non-enhanced vasculature. With successful shimming, B1 signal voids could be effectively reduced and/or shifted out of the region of interest in most sequence types. However, T2-weighted TSE imaging remained challenging and strongly impaired because of signal heterogeneities in three volunteers. Conclusion The results demonstrate the feasibility and diagnostic potential of dedicated 7T renal imaging. Further optimisation of imaging sequences and dedicated RF coil concepts are expected to improve the acquisition quality and ultimately provide high clinical diagnostic value. Y1 - 2011 SN - 1432-1084 VL - 21 IS - 4 SP - 841 EP - 849 PB - Springer CY - Berlin ER - TY - JOUR A1 - Booysen, Tracy A1 - Rieger, Michael A1 - Ferrein, Alexander T1 - Towards inexpensive robots for science & technology teaching and education in Africa Y1 - 2011 SN - 978-1-61284-992-8 N1 - AFRICON, 2011 SP - 1 EP - 6 PB - IEEE CY - New York ER - TY - JOUR A1 - Gspandl, Stephan A1 - Pill, Ingo A1 - Reip, Michael A1 - Steinbauer, Gerald A1 - Ferrein, Alexander T1 - Belief Management for High-Level Robot Programs JF - Proceedings of the Twenty-Second International Joint Conference on Artificial Intelligence [electronic resource] : Barcelona, Catalonia, Spain, 16 - 22 July 2011 / sponsored by International Joint Conferences on Artificial Intelligence (IJCAI) and the Association for the Advancement of Artificial Intelligence (AAAI). Ed. by Toby Walsh Y1 - 2011 N1 - International Joint Conference on Artificial Intelligence ; (22 : ; 2011.07.16-22 : ; Barcelona, Spain) ; IJCAI ; (22 : ; 2011.07.16-22 : ; Barcelona, Spain) SP - 900 EP - 905 ER - TY - JOUR A1 - Schiffer, Stefan A1 - Ferrein, Alexander A1 - Lakemeyer, Gerhard T1 - Reasoning with Qualitative Positional Information for Domestic Domains in the Situation Calculus JF - Journal of Intelligent & Robotic Systems Y1 - 2011 SN - 0921-0296 VL - 63 IS - 2 SP - 273 EP - 300 PB - Springer CY - Berlin ER - TY - CHAP A1 - Bragard, Michael A1 - Ronge, C. A1 - De Doncker, R. W. T1 - Sandwich design of high-power thyristor based devices with integrated MOSFET structure T2 - Proceedings of the 2011 - 14th - European Conference on Power Electronics and Applications (EPE 2011) : Aug. 30, 2011 - Sept. 1, 2011, Birmingham, United Kingdom Y1 - 2011 SN - 978-1-61284-167-0 (Print) SN - 978-90-75815-15-3 (Online) PB - IEEE CY - Piscataway, NJ ER - TY - CHAP A1 - Bragard, Michael A1 - Gottschlich, J. A1 - De Doncker, R. W. T1 - Design and realization of a credit card size driver stage for high power thyristor based devices with integrated MOS structure T2 - 2011 IEEE 8th International Conference on Power Electronics and ECCE Asia (ICPE & ECCE 2011) : Jeju, South Korea, 30 May 2011 - 3 June 2011 / [co-sponsored by the Korean Institute of Power Electronics ...] Y1 - 2011 SN - 978-1-61284-958-4 (Print) SN - 978-1-61284-956-0 (Online) U6 - https://doi.org/10.1109/ICPE.2011.5944661 SP - 1182 EP - 1189 PB - IEEE CY - Piscataway, NJ ER - TY - JOUR A1 - Martin, Conrad A1 - Frauenrath, Tobias A1 - Özerdem, Celal A1 - Renz, Wolfgang A1 - Niendorf, Thoralf T1 - Development and evaluation of a small and mobile Magneto Alert Sensor (MALSE) to support safety requirements for magnetic resonance imaging JF - European Radiology N2 - Objective The purpose of this study is to (i) design a small and mobile Magnetic field ALert SEnsor (MALSE), (ii) to carefully evaluate its sensors to their consistency of activation/deactivation and sensitivity to magnetic fields, and (iii) to demonstrate the applicability of MALSE in 1.5 T, 3.0 T and 7.0 T MR fringe field environments. Methods MALSE comprises a set of reed sensors, which activate in response to their exposure to a magnetic field. The activation/deactivation of reed sensors was examined by moving them in/out of the fringe field generated by 7TMR. Results The consistency with which individual reed sensors would activate at the same field strength was found to be 100% for the setup used. All of the reed switches investigated required a substantial drop in ambient magnetic field strength before they deactivated. Conclusions MALSE is a simple concept for alerting MRI staff to a ferromagnetic object being brought into fringe magnetic fields which exceeds MALSEs activation magnetic field. MALSE can easily be attached to ferromagnetic objects within the vicinity of a scanner, thus creating a barrier for hazardous situations induced by ferromagnetic parts which should not enter the vicinity of an MR-system to occur. KW - MRI KW - MR safety KW - Magneto alert sensor KW - High field MRI KW - Uktrahigh field MRI Y1 - 2011 U6 - https://doi.org/10.1007/s00330-011-2153-z SN - 1432-1084 VL - 21 SP - 2187 EP - 2192 PB - Springer CY - Berlin, Heidelberg ER - TY - JOUR A1 - Dieringer, Matthias A. A1 - Renz, Wolfgang A1 - Lindel, Tomasz D. A1 - Seifert, Frank A1 - Frauenrath, Tobias A1 - von Knobelsdorf-Brenkenhoff, Florian A1 - Waiczies, Helmar A1 - Hoffmann, Werner A1 - Rieger, Jan A1 - Pfeiffer, Harald A1 - Ittermann, Bernd A1 - Schulz-Menger, Jeanette A1 - Niendorf, Thoralf T1 - Design and application of a four-channel transmit/receive surface coil for functional cardiac imaging at 7T JF - Journal of Magnetic Resonance Imaging N2 - Purpose To design and evaluate a four-channel cardiac transceiver coil array for functional cardiac imaging at 7T. Materials and Methods A four-element cardiac transceiver surface coil array was developed with two rectangular loops mounted on an anterior former and two rectangular loops on a posterior former. specific absorption rate (SAR) simulations were performed and a Burn:x-wiley:10531807:media:JMRI22451:tex2gif-stack-1 calibration method was applied prior to obtain 2D FLASH CINE (mSENSE, R = 2) images from nine healthy volunteers with a spatial resolution of up to 1 × 1 × 2.5 mm3. Results Tuning and matching was found to be better than 10 dB for all subjects. The decoupling (S21) was measured to be >18 dB between neighboring loops, >20 dB for opposite loops, and >30 dB for other loop combinations. SAR values were well within the limits provided by the IEC. Imaging provided clinically acceptable signal homogeneity with an excellent blood-myocardium contrast applying the Burn:x-wiley:10531807:media:JMRI22451:tex2gif-stack-2 calibration approach. Conclusion A four-channel cardiac transceiver coil array for 7T was built, allowing for cardiac imaging with clinically acceptable signal homogeneity and an excellent blood-myocardium contrast. Minor anatomic structures, such as pericardium, mitral, and tricuspid valves and their apparatus, as well as trabeculae, were accurately delineated. Y1 - 2011 U6 - https://doi.org/10.1002/jmri.22451 SN - 1522-2586 VL - 33 IS - 3 SP - 736 EP - 741 PB - Wiley-Liss CY - New York ER - TY - CHAP A1 - Damm, Sebastian A1 - Ritz, Thomas A1 - Strauch, Jakob T1 - Adaption of archetype patterns for mobile cloud-based business apps T2 - 2011 IEEE International Conference on Pervasive Computing and Communications workshops (PerCom workshops 2011) : Seattle, Washington, USA, 21 - 25 March 2011 Y1 - 2011 SN - 978-1-61284-938-6 (Print) SN - 978-1-61284-936-2 (E-Book) U6 - https://doi.org/10.1109/PERCOMW.2011.5766849 SP - 100 EP - 105 PB - IEEE Service Center CY - Piscataway, NJ ER - TY - JOUR A1 - Niemüller, Tim A1 - Ferrein, Alexander A1 - Eckel, Gerhard A1 - Pirro, David A1 - Podbregar, Patrick A1 - Kellner, Tobias A1 - Rath, Christoph A1 - Steinbauer, Gerald T1 - Providing Ground-truth Data for the Nao Robot Platform JF - RoboCup 2010: Robot Soccer World Cup XIV Y1 - 2011 SN - 978-3-642-20217-9 N1 - Lecture Notes in Computer Science ; 6556 SP - 133 EP - 144 PB - Springer CY - Berlin ER - TY - JOUR A1 - Bragard, Michael A1 - Conrad, M. A1 - van Hoek, H. A1 - De Doncker, R. W. T1 - The integrated emitter turn-off thyristor (IETO) : an innovative thyristor-based high power semiconductor device using MOS assisted turn-off JF - IEEE transactions on industry applications Y1 - 2011 U6 - https://doi.org/10.1109/TIA.2011.2161432 SN - 0093-9994 VL - 47 IS - 5 SP - 2175 EP - 2182 PB - IEEE CY - New York ER - TY - CHAP A1 - Logen, Steffen A1 - Höfken, Hans A1 - Schuba, Marko T1 - Simplifying RAM Forensics : A GUI and Extensions for the Volatility Framework T2 - 2012 Seventh International Conference on Availability, Reliability and Security (ARES), 20-24 August 2012, Prague, Czech Republic N2 - The Volatility Framework is a collection of tools for the analysis of computer RAM. The framework offers a multitude of analysis options and is used by many investigators worldwide. Volatility currently comes with a command line interface only, which might be a hinderer for some investigators to use the tool. In this paper we present a GUI and extensions for the Volatility Framework, which on the one hand simplify the usage of the tool and on the other hand offer additional functionality like storage of results in a database, shortcuts for long Volatility Framework command sequences, and entirely new commands based on correlation of data stored in the database. Y1 - 2012 SN - 978-1-4673-2244-7 U6 - https://doi.org/10.1109/ARES.2012.12 SP - 620 EP - 624 PB - IEEE CY - New York ER - TY - BOOK A1 - Wosnitza, Franz A1 - Hilgers, Hans Gerd T1 - Energieeffizienz und Energiemanagement : ein Überblick heutiger Möglichkeiten und Notwendigkeiten Y1 - 2012 SN - 978-3-8348-1941-3 N1 - eISBN 978-3-8348-8671-2 PB - Springer Spektrum CY - Wiesbaden ER - TY - JOUR A1 - Hüning, Felix T1 - Using Trench PowerMOSFETs in Linear Mode JF - Power Electronics Europe (2012) N2 - If we think about applications for modern Power MOSFETs using trench technology, running them in linear mode may not be top of the priority list. Yet there are multiple uses for Trench Power MOSFETs in linear mode. In fact, even turning the device on and off in switching applications is a form of linear operation. Also, these components can be run in linear mode to protect the device against voltage surges. This article will illustrate the factors that need to be considered for linear operation and show how Trench Power MOSFETs are suited to it. Y1 - 2012 SN - 1748-3530 SP - 27 EP - 29 PB - DFA Media CY - Tonbridge ER - TY - CHAP A1 - Engels, Elmar A1 - Schnabel, Holger T1 - Rapid-control-prototyping of industrial drives for the sercos automation bus T2 - 13th International Workshop on Mechatronics (MECATRONICS), 2012 9th France-Japan & 7th Europe-Asia Congress on and Research and Education in Mechatronics (REM) N2 - This article describes the functionality of a MATLAB® library that can be used to develop motion-logic applications in MATLAB programming language for industrial drive and control systems using the well known sercos automation bus. Therewith MATLAB's functionality is extended to designing automation applications from single axis machines up to multi-kinematic robots. KW - MATLAB , MLPI , Motion control , Open Core , industrial drives , rapid control prototypin , sercos automation bus Y1 - 2012 UR - http://dx.doi.org/10.1109/MECATRONICS.2012.6451005 SN - 978-1-4673-4771-6 SP - 177 EP - 181 ER - TY - JOUR A1 - Ferrein, Alexander A1 - Steinbauer, Gerald A1 - Vassos, Stavros T1 - Action-Based Imperative Programming with YAGI N2 - Many tasks for autonomous agents or robots are best described by a specification of the environment and a specification of the available actions the agent or robot can perform. Combining such a specification with the possibility to imperatively program a robot or agent is what we call the actionbased imperative programming. One of the most successful such approaches is Golog. In this paper, we draft a proposal for a new robot programming language YAGI, which is based on the action-based imperative programming paradigm. Our goal is to design a small, portable stand-alone YAGI interpreter. We combine the benefits of a principled domain specification with a clean, small and simple programming language, which does not exploit any side-effects from the implementation language. We discuss general requirements of action-based programming languages and outline YAGI, our action-based language approach which particularly aims at embeddability. Y1 - 2012 N1 - Cognitive Robotics AAAI Technical Report WS-12-06 SP - 24 EP - 31 ER - TY - CHAP A1 - Bitz, Andreas A1 - Kraff, O. A1 - Orzada, S. A1 - Maderwald, S. A1 - Brote, I. A1 - Johst, S. A1 - Ladd, E. T1 - Assessment of RF Safety of Transmit Coils at 7 Tesla by Experimental and Numerical Procedures (490.) T2 - 19th annual ISMRM scientific meeting and exhibition 2011 : Montreal, Quebec, Canada, 7 - 13 May 2011 Y1 - 2012 SN - 978-1-61839-284-8 IS - Volume 1 SP - 475 PB - Curran CY - Red Hook, NY 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 - 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 - TY - JOUR A1 - Kobus, Thiele A1 - Bitz, Andreas A1 - Uden, Mark J. van A1 - Lagemaat, Miram W. A1 - Rothgang, Eva A1 - Orzada, Stephan A1 - Heerschap, Arend A1 - Scheenen, Tom W. J. T1 - In vivo 31P MR spectroscopic imaging of the human prostate at 7 T: safety and feasibility JF - Magnetic Resonance in Medicine N2 - 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. Y1 - 2012 U6 - https://doi.org/10.1002/mrm.24175 SN - 1522-2594 VL - 68 IS - 6 SP - 1683 EP - 1695 PB - Wiley-Liss CY - New York ER - TY - JOUR A1 - Yazdanbakhsh, Pedram A1 - Solbach, Klaus A1 - Bitz, Andreas T1 - Variable power combiner for RF mode shimming in 7-T MR imaging JF - IEEE Transaction on Biomedical Engineering N2 - 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. Y1 - 2012 U6 - https://doi.org/10.1109/TBME.2012.2205926 SN - 1558-2531 VL - 59 IS - 9 SP - 2549 EP - 2557 PB - IEEE CY - New York ER - TY - JOUR A1 - Schiffer, Stefan A1 - Ferrein, Alexander A1 - Lakemeyer, Gerhard T1 - Caesar: an intelligent domestic service robot JF - Intelligent service robotics N2 - In this paper we present CAESAR, an intelligent domestic service robot. In domestic settings for service robots complex tasks have to be accomplished. Those tasks benefit from deliberation, from robust action execution and from flexible methods for human–robot interaction that account for qualitative notions used in natural language as well as human fallibility. Our robot CAESAR deploys AI techniques on several levels of its system architecture. On the low-level side, system modules for localization or navigation make, for instance, use of path-planning methods, heuristic search, and Bayesian filters. For face recognition and human–machine interaction, random trees and well-known methods from natural language processing are deployed. For deliberation, we use the robot programming and plan language READYLOG, which was developed for the high-level control of agents and robots; it allows combining programming the behaviour using planning to find a course of action. READYLOG is a variant of the robot programming language Golog. We extended READYLOG to be able to cope with qualitative notions of space frequently used by humans, such as “near” and “far”. This facilitates human–robot interaction by bridging the gap between human natural language and the numerical values needed by the robot. Further, we use READYLOG to increase the flexible interpretation of human commands with decision-theoretic planning. We give an overview of the different methods deployed in CAESAR and show the applicability of a system equipped with these AI techniques in domestic service robotics Y1 - 2012 U6 - https://doi.org/10.1007/s11370-012-0118-y SN - 1861-2776 N1 - Special Issue on Artificial Intelligence Techniques for Robotics: Sensing, Representation and Action, Part I VL - 5 IS - 4 SP - 259 EP - 276 PB - Springer CY - Berlin ER - TY - THES A1 - Bragard, Michael T1 - The integrated emitter turn-off thyristor : an innovative MOS-gated high-power device. - (Aachener Beiträge des ISEA ; 62) N2 - This thesis introduces the Integrated Emitter Turn-Off (IETO) Thyristor as a new high-power device. Known state-of-the-art research activities like the Dual GCT, the ETO thyristor and the ICT were presented and critically reviewed. A comparison with commercialized solutions identifies the pros and cons of each type of device family. Based on this analysis, the IETO structure is proposed, covering most benefits of each device class. In particular the combination of a MOS-assisted turn-off with a thyristor-based device allows a voltage-controlled MOS switching and the low on-state voltage of the thyristors. The following synthesis of an IETO device stands on a three-dimensional field of optimization spanned by electric, mechanical and thermal aspects. From an electric point of view, the lowest possible parasitic inductance and resistance within the commutation path are optimization criteria. The mechanical construction has to withstand the required contact pressure of multiple kilo Newtons. Finally, thermal borders limit the maximum average current of the device. FEM simulations covering these three aspects are performed for several design proposals. An IETO prototype is constructed and measurements on various test benches attest thermal, mechanical and electric performance. A local decoupling of the external driver stage and the presspack housing is presented by a cable connection. This separation enables a thermal and mechanical independence, which is advantageous in terms of vibrations and thermal cycles including increased reliability. The electric pulse performance of the prototype device is a factor of 3.1 above today''s solutions. In single-pulse measurements, a current up to 1600 A was successfully turned off at 115°C with an active silicon area of 823 mm². One reason for this increased turn-off capability is the extremely low-inductive construction. Additional functionality of the IETO thyristor like over-current self-protection and defined short-circuit failure state are successfully verified. Y1 - 2012 SN - 978-3-8440-1152-4 N1 - Zugl.: Aachen, Techn. Hochsch., Diss., 2012 PB - Shaker CY - Aachen ER - TY - GEN A1 - Lindel, Tomasz Dawid A1 - Greiser, Andreas A1 - Waxman, Patrick A1 - Dietterle, Martin A1 - Seifert, Frank A1 - Fontius, Ulrich A1 - Renz, Wolfgang A1 - Dieringer, Matthias A. A1 - Frauenrath, Tobias A1 - Schulz-Menger, Jeanette A1 - Niendorf, Thoralf A1 - Ittermann, Bernd T1 - Cardiac CINE MRI at 7 T using a transmit array T2 - 2012 ISMRM Annual Meeting Proceedings N2 - With its need for high SNR and short acquisition times, Cardiac MRI (CMR) is an intriguing target application for ultrahigh field MRI. Due to the sheer size of the upper torso, however, the known RF issues of 7T MRI are also most prominent in CMR. Recent years brought substantial progress but the full potential of the ultrahigh field for CMR is yet to be exploited. Parallel transmission (pTx) is a promising approach in this context and several groups have already reported B1 shimming for 7T CMR. In such a static pTx application amplitudes and phases of all Tx channels are adjusted individually but otherwise imaging techniques established in current clinical practice 1.5 T and 3 T are applied. More advanced forms of pTx as spatially selective excitation (SSE) using Transmit SENSE promise additional benefits like faster imaging with reduced fields of view or improved SAR control. SSE requires the full dynamic capabilities of pTx, however, and for the majority of today's implemented pTx hardware the internal synchronization of the Tx array does not easily permit external triggering as needed for CMR. Here we report a software solution to this problem and demonstrate the feasibility of CINE CMR at 7 T using a Tx array. Y1 - 2012 SN - 1545-4428 N1 - ISMRM 20th Annual Meeting & Exhibition, 5-11 May 2012, Melbourne, Australia ER - TY - JOUR A1 - Ferrein, Alexander A1 - Meyer, Thomas T1 - A Brief Overview of Artificial Intelligence in South Africa JF - AI Magazine N2 - South Africa in recent years is the establishment of a number of research hubs involved in AI activities ranging from mobile robotics and computational intelligence, to knowledge representation and reasoning, and human language technologies. In this survey we take the reader through a quick tour of the research being conducted at these hubs, and touch on an initiative to maintain and extend the current level of interest in AI research in the country. Y1 - 2012 U6 - https://doi.org/10.1609/aimag.v33i1.2357 SN - 0738-4602 VL - 33 IS - 1 SP - 99 EP - 101 PB - AAAI CY - Menlo Park ER - TY - JOUR A1 - Bragard, Michael A1 - van Hoek, H. A1 - De Doncker, R. W. T1 - A major design step in IETO concept realization that allows overcurrent protection and pushes limits of switching performance JF - IEEE transactions on power electronics N2 - This paper presents the latest prototype of the integrated emitter turn-off thyristor concept, which potentially ranks among thyristor high-power devices like the gate turn-off thyristor and the integrated gate-commutated thyristor (IGCT). Due to modifications of the external driver stage and mechanical press-pack design optimization, this prototype allows for full device characterization. The turn-off capability was increased to 1600 A with an active silicon area of 823mm2 . This leads to a transient peak power of 672.1kW/cm² . Within this paper, measurements and concept assessment are presented and a comparison to state-of-the-art IGCT devices is provided. Y1 - 2012 U6 - https://doi.org/10.1109/TPEL.2012.2189136 SN - 0885-8993 VL - 27 IS - 9 SP - 4163 EP - 4171 PB - IEEE CY - New York ER - TY - GEN A1 - Tkachenko, Valeriy A1 - von Knobelsdorff-Brenkenhoff, Florian A1 - Kleindienst, Denise A1 - Winter, Lukas A1 - Rieger, Jan A1 - Frauenrath, Tobias A1 - Dieringer, Matthias A. A1 - Santoro, Davide A1 - Niendorf, Thoralf A1 - Schulz-Menger, Jeanette T1 - Cardiovasular MR at 7Tesla: assessment of the right ventricle T2 - 2012 ISMRM Annual Meeting Proceedings N2 - The assessment of the right ventricle (RV) is a challenge in today's cardiology, but of growing clinical impact regarding patient prognosis in different cardiac diseases. The detection and differentiation of small wall motion abnormalities may help to enhance the differentiation of cardiomyopathies including Arrhythmogenic Rightventricular Cardiomyopathy. Cardiovascular magnetic resonance (CMR) at 1.5T is the accepted gold standard for RV quantification. The higher spatial resolution achievable at ultrahigh field strength (UHF) offers the potential to gain new insights into the structure and function of the RV. To approach this goal accurate RV chamber quantification at 7T has to be proven. Consequently this study examines the feasibility of assessment of RV dimensions and function at 7T using improved spatial resolution enabled by the intrinsic sensitivity gain of UHF CMR. For this purpose, a dedicated 16 channel TX/RX RF coil array is used together with 2D CINE fast gradient echo (FGRE) imaging. For comparison RV chamber quantification is conducted at 1.5T using a SSFP based state of the art clinical protocol. Y1 - 2012 SN - 1545-4428 N1 - ISMRM 20th Annual Meeting & Exhibition, 5-11 May 2012, Melbourne, Australia ER - TY - GEN A1 - Gräßl, Andreas A1 - Renz, Wolfgang A1 - Hezel, Fabian A1 - Frauenrath, Tobias A1 - Pfeiffer, Harald A1 - Hoffmann, Werner A1 - Kellmann, Peter A1 - Martin, Conrad A1 - Niendorf, Thoralf T1 - Design, evaluation and application of a modular 32 channel transmit/receive surface coil array for cardiac MRI at 7T T2 - 2012 ISMRM Annual Meeting Proceedings N2 - Cardiac MR (CMR) at ultrahigh (≥7.0 T) fields is regarded as one of the most challenging MRI applications. At 7.0 T image quality is not always exclusively defined by signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). Detrimental effects bear the potential to spoil the signal-to-noise (SNR) and contrast-to-noise (CNR) benefits of cardiac MR (CMR) at 7.0 T. B₁⁺-inhomogeneities and signal voids represent the main challenges. Various pioneering coil concepts have been proposed to tackle these issues, enabling cardiac MRI at 7.0 T. This includes a trend towards an ever larger number of transmit and receive channels. This approach affords multi-dimensional B₁⁺ modulations to improve B₁⁺ shimming performance and to enhance RF efficiency. Also, parallel imaging benefits from a high number of receive channels enabling two-dimensional acceleration. Realizing the limitations of existing coil designs tailored for UHF CMR and recognizing the opportunities of a many element TX/RX channel architecture this work proposes a modular, two dimensional 32-channel transmit and receive array using loop elements and examines its efficacy for enhanced B¹+ homogeneity and improved parallel imaging performance. Y1 - 2012 SN - 1545-4428 N1 - ISMRM 20th Annual Meeting & Exhibition, 5-11 May 2012, Melbourne, Australia ER - TY - JOUR A1 - Frauenrath, Tobias A1 - Fuchs, Katharina A1 - Dieringer, Matthias A. A1 - Özerdem, Celal A1 - Patel, Nishan A1 - Renz, Wolfgang A1 - Greiser, Andreas A1 - Elgeti, Thomas A1 - Niendorf, Thoralf T1 - Detailing the use of magnetohydrodynamic effects for synchronization of MRI with the cardiac cycle: A feasibility study JF - Journal of Magnetic Resonance Imaging N2 - Purpose: To investigate the feasibility of using magnetohydrodynamic (MHD) effects for synchronization of magnetic resonance imaging (MRI) with the cardiac cycle. Materials and Methods: The MHD effect was scrutinized using a pulsatile flow phantom at B0 = 7.0 T. MHD effects were examined in vivo in healthy volunteers (n = 10) for B0 ranging from 0.05–7.0 T. Noncontrast-enhanced MR angiography (MRA) of the carotids was performed using a gated steady-state free-precession (SSFP) imaging technique in conjunction with electrocardiogram (ECG) and MHD synchronization. Results: The MHD potential correlates with flow velocities derived from phase contrast MRI. MHD voltages depend on the orientation between B0 and the flow of a conductive fluid. An increase in the interelectrode spacing along the flow increases the MHD potential. In vivo measurement of the MHD effect provides peak voltages of 1.5 mV for surface areas close to the common carotid artery at B0 = 7.0 T. Synchronization of MRI with the cardiac cycle using MHD triggering is feasible. MHD triggered MRA of the carotids at 3.0 T showed an overall image quality and richness of anatomic detail, which is comparable to ECG-triggered MRAs. Conclusion: This feasibility study demonstrates the use of MHD effects for synchronization of MR acquisitions with the cardiac cycle. J. Magn. Reson. Imaging 2012;36:364–372. © 2012 Wiley Periodicals, Inc. Y1 - 2012 U6 - https://doi.org/10.1002/jmri.23634 SN - 1522-2586 VL - 36 IS - 2 SP - 364 EP - 372 PB - Wiley-Liss CY - New York ER - TY - CHAP A1 - Niendorf, Thoralf A1 - Winter, Lukas A1 - Frauenrath, Tobias ED - Millis, Richard T1 - Electrocardiogram in an MRI environment: Clinical needs, practical considerations, safety implications, technical solutions and fFuture directions T2 - Advances in Electrocardiograms - Methods and Analysis Y1 - 2012 SN - 978-953-307-923-3 (print) SN - 978-953-51-6762-4 (eBook) U6 - https://doi.org/10.5772/24340 SP - 309 EP - 324 PB - IntechOpen CY - London ER - TY - CHAP A1 - Schopp, Christoph A1 - Nachtrodt, Frederik A1 - Heuermann, Holger A1 - Scherer, Ulrich W. A1 - Mostacci, Domiziano A1 - Finger, Torsten A1 - Tietsch, Wolfgang T1 - A novel 2.45 GHz/200 W Microwave Plasma Jet for High Temperature Applications above 3600 K T2 - Journal of Physics : Conference Series Y1 - 2012 SN - 1742-6596 VL - 406 IS - 012029 ER - TY - CHAP A1 - Fuchs, Britta A1 - Ritz, Thomas A1 - Strauch, Jakob ED - Obaidat, Mohammad S. T1 - Usability of mobile applications : dissemination of usability engineering in small and medium enterprises T2 - Proceedings of the International Conference on Data Communication Networking, e-Business and Optical Communication Systems : Rome, Italy, 24 - 27 July, 2012 ; [integrated in the ICETE (International Conference on e-Business and Telecommunications)] Y1 - 2012 SN - 978-989-8565-23-5 N1 - Nebentitel: DCNET; ICE-B; OPTICS SP - 272 EP - 277 PB - SciTePress CY - [Lissabon] ER - TY - CHAP A1 - Nötzold, K. A1 - Uphues, A. A1 - Wegener, R. A1 - Soter, S. A1 - Fink, K. A1 - Bragard, Michael A1 - Griessel, R. T1 - Inverter based test setup for LVRT verification of a full-scale 2 MW wind power converter T2 - EPE Joint Wind Energy and T&D Chapters Seminar : 28th and 29th of June 2012, in the Utzon Centre, Aalborg, Denmark ; papers, posters, presentations. - Session 2: Grid connection, compliance Y1 - 2012 PB - EPE Association CY - Brussels ER - TY - JOUR A1 - Grande, Marion A1 - Meffert, Elisabeth A1 - Schoenberger, Eva A1 - Jung, Stefanie A1 - Frauenrath, Tobias A1 - Huber, Walter A1 - Hussmann, Katja A1 - Moormann, Mareike A1 - Heim, Stefan T1 - From a concept to a word in a syntactically complete sentence: An fMRI study on spontaneous language production in an overt picture description task JF - NeuroImage N2 - Spontaneous language has rarely been subjected to neuroimaging studies. This study therefore introduces a newly developed method for the analysis of linguistic phenomena observed in continuous language production during fMRI. Most neuroimaging studies investigating language have so far focussed on single word or — to a smaller extent — sentence processing, mostly due to methodological considerations. Natural language production, however, is far more than the mere combination of words to larger units. Therefore, the present study aimed at relating brain activation to linguistic phenomena like word-finding difficulties or syntactic completeness in a continuous language fMRI paradigm. A picture description task with special constraints was used to provoke hesitation phenomena and speech errors. The transcribed speech sample was segmented into events of one second and each event was assigned to one category of a complex schema especially developed for this purpose. The main results were: conceptual planning engages bilateral activation of the precuneus. Successful lexical retrieval is accompanied – particularly in comparison to unsolved word-finding difficulties – by the left middle and superior temporal gyrus. Syntactic completeness is reflected in activation of the left inferior frontal gyrus (IFG) (area 44). In sum, the method has proven to be useful for investigating the neural correlates of lexical and syntactic phenomena in an overt picture description task. This opens up new prospects for the analysis of spontaneous language production during fMRI. Y1 - 2012 U6 - https://doi.org/10.1016/j.neuroimage.2012.03.087 SN - 1522-2586 VL - 61 IS - 3 SP - 702 EP - 714 PB - Elsevier CY - Amsterdam ER - TY - GEN A1 - Frauenrath, Tobias A1 - Pfeiffer, Harald A1 - Hezel, Fabian A1 - Dieringer, Matthias A. A1 - Winter, Lukas A1 - Gräßl, Andreas A1 - Santoro, Davide A1 - Özerdem, Celal A1 - Renz, Wolfgang A1 - Greiser, Andreas A1 - Niendorf, Thoralf T1 - Lessons learned from cardiac MRI at 7.0 T: LV function assessment at 3.0 T using local multi-channel transceiver coil arrays T2 - 2012 ISMRM Annual Meeting Proceedings N2 - Cardiac MR (CMR) is of proven clinical value but also an area of vigorous ongoing research since image quality is not always exclusively defined by signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). Recent developments of CMR at 7.0 T have been driven by pioneering explorations into novel multichannel transmit and receive coil array technology to tackle the challenges B1+-field inhomogeneities, to offset specific-absorption rate (SAR) constraints and to reduce banding artifacts in SSFP imaging. For this study, recognition of the benefits and performance of local surface Tx/Rx-array structures recently established at 7.0 T inspired migration to 3.0 T, where RF inhomogeneities and SAR limitations encountered in routine clinical CMR, though somewhat reduced versus the 7.0 T situation, remain significant. For all these reasons, this study was designed to build and examine the feasibility of a local four channel Tx/Rx cardiac coil array for anatomical and functional cardiac imaging at 3.0 T. For comparison, a homebuilt 4 channel Rx cardiac coil array exhibiting the same geometry as the Tx/Rx coil and a Rx surface coil array were used. Y1 - 2012 SN - 1545-4428 N1 - ISMRM 20th Annual Meeting & Exhibition, 5-11 May 2012, Melbourne, Australia ER - TY - CHAP A1 - Schütz, P. A1 - Breuer, M. A1 - Höfken, Hans-Wilhelm A1 - Schuba, Marko T1 - Malware proof on mobile phone exhibits based on GSM/GPRS traces T2 - The Second International Conference on Cyber Security, Cyber Peacefare and Digital Forensic (CyberSec 2013) : 04.03. - 06.03.2013, Kuala Lumpur, Malaysia Y1 - 2013 SN - 978-0-9853483-7-3 SP - 89 EP - 96 PB - The Society of Digital Information and Wireless Communication ER - TY - CHAP A1 - Engels, Elmar T1 - A field bus library for MATLAB based on open core engineering T2 - Proceedings to the 14th International Workshop on Research and Education in Mechatronics, REM 2013, Wien, 05.06.-06.06.2013. Y1 - 2013 SN - 978-3-90275-907-8 ER - TY - CHAP A1 - Stöbe, Rolf A1 - Höfken, Hans-Wilhelm A1 - Schuba, Marko A1 - Breuer, Michael T1 - Artificial ageing of mobile devices using a simulated GSM/GPRS network T2 - Eighth International Conference on Availability, Reliability and Security (ARES) : 2-6 Sept. 2013, Regensburg Y1 - 2013 SP - 493 EP - 497 PB - IEEE ER - TY - JOUR A1 - Gligorevic, Snjezana T1 - Airport surface propagation channel in the C-Band: measurements and modeling JF - IEEE transactions on antennas and propagation Y1 - 2013 SN - 0018-926x VL - Vol. 61 IS - Iss. 9 SP - 4792 EP - 4802 PB - IEEE CY - New York ER - TY - CHAP A1 - Gligorevic, Snjezana T1 - Stochastic modeling of non-stationary channels T2 - 7th European Conference on Antennas and Propagation (EuCAP) : 8 - 12 April 2013, Gothenburg, Sweden Y1 - 2013 SN - 978-1-4673-2187-7 ; 978-88-907018-1-8 SP - 1677 EP - 1681 PB - IEEE CY - Piscataway, NJ ER -