TY - JOUR A1 - Ritz, Thomas T1 - Personalized information services : an electronic information commodity and its production JF - International Journal of E-Business Strategy Management Y1 - 2000 SN - 1467-0305 VL - 2 IS - 2 ER - TY - CHAP A1 - Ritz, Thomas T1 - Personalized information services : an electronic information commodity and its production T2 - Electronic publishing '01 : 2001 in the digital publishing odyssey ; proceedings of an ICCC/IFIP conference held at the University of Kent at Canterbury, Kent, United Kingdom, 5 - 7 July, 2001 ; [proceedings of the Fifth Conference on Electronic Publishing] Y1 - 2001 SN - 1-58603-191-0 SP - 48 EP - 58 PB - IOS Press [u.a.] CY - Amsterdam ER - TY - JOUR A1 - Schuba, Marko A1 - Hermanns, Oliver T1 - Performance Investigations of the IP Multicast Architecture / Hermanns, Oliver ; Schuba, Marko JF - Performance of the IP Multicast Achitecture . Proceedings JENC 6. Proceedings of the 6th Joint European Networking Conference, Tel Aviv Y1 - 1995 N1 - Reprinted in Computer Networks and ISDN Systems 28 pp 429-439, 1996 SP - 121-1 EP - 121-8 ER - TY - JOUR A1 - Schuba, Marko A1 - Haverkort, Boudewijn R. A1 - Schneider, Gaby T1 - Performance evaluation of multicast communication in packet-switched networks / Schuba, Marko ; Haverkort, Boudewijn R. ; Schneider, Gaby JF - Performance Evaluation. 39 (2000), H. 1-4 Y1 - 2000 SN - 0166-5316 N1 - http://dx.doi.org/10.1016/S0166-5316(99)00058-9 SP - 61 EP - 80 ER - TY - JOUR A1 - Fiedler, Thomas M. A1 - Orzada, Stephan A1 - Flöser, Martina A1 - Rietsch, Stefan H. G. A1 - Schmidt, Simon A1 - Stelter, Jonathan K. A1 - Wittrich, Marco A1 - Quick, Harald H. A1 - Bitz, Andreas A1 - Ladd, Mark E. T1 - Performance and safety assessment of an integrated transmit array for body imaging at 7 T under consideration of specificabsorption rate, tissue temperature, and thermal dose JF - NMR in Biomedicine N2 - In this study, the performance of an integrated body-imaging array for 7 T with 32 radiofrequency (RF) channels under consideration of local specific absorption rate (SAR), tissue temperature, and thermal dose limits was evaluated and the imaging performance was compared with a clinical 3 T body coil. Thirty-two transmit elements were placed in three rings between the bore liner and RF shield of the gradient coil. Slice-selective RF pulse optimizations for B1 shimming and spokes were performed for differently oriented slices in the body under consideration of realistic constraints for power and local SAR. To improve the B1+ homogeneity, safety assessments based on temperature and thermal dose were performed to possibly allow for higher input power for the pulse optimization than permissible with SAR limits. The results showed that using two spokes, the 7 T array outperformed the 3 T birdcage in all the considered regions of interest. However, a significantly higher SAR or lower duty cycle at 7 T is necessary in some cases to achieve similar B1+ homogeneity as at 3 T. The homogeneity in up to 50 cm-long coronal slices can particularly benefit from the high RF shim performance provided by the 32 RF channels. The thermal dose approach increases the allowable input power and the corresponding local SAR, in one example up to 100 W/kg, without limiting the exposure time necessary for an MR examination. In conclusion, the integrated antenna array at 7 T enables a clinical workflow for body imaging and comparable imaging performance to a conventional 3 T clinical body coil. KW - body imaging at 7 T MRI KW - thermal dose KW - tissue temperature KW - transmit antenna arrays Y1 - 2022 U6 - https://doi.org/10.1002/nbm.4656 SN - 0952-3480 (Print) SN - 1099-1492 (Online) VL - 35 IS - 5 SP - 1 EP - 17 PB - Wiley ER - TY - JOUR A1 - Schuba, Marko T1 - Performance Analysis of Reliable Multicast Mechanisms for Widely Spread Distributed Applications in the Internet JF - International Conference on Parallel and Distributed Processing Techniques and Applications : PDPTA '99 ; June 28 - July 1, 1999, Las Vegas, Nevada, USA / ed.: Hamid R. Arabnia Y1 - 1999 SN - 1892512157 SP - 1 EP - 7 ER - TY - JOUR A1 - Fiedler, Thomas M. A1 - Orzada, Stephan A1 - Flöser, Martina A1 - Rietsch, Stefan H. G. A1 - Quick, Harald H. A1 - Ladd, Mark E. A1 - Bitz, Andreas T1 - Performance analysis of integrated RF microstrip transmit antenna arrays with high channel count for body imaging at 7 T JF - NMR in Biomedicine N2 - The aim of the current study was to investigate the performance of integrated RF transmit arrays with high channel count consisting of meander microstrip antennas for body imaging at 7 T and to optimize the position and number of transmit ele- ments. RF simulations using multiring antenna arrays placed behind the bore liner were performed for realistic exposure conditions for body imaging. Simulations were performed for arrays with as few as eight elements and for arrays with high channel counts of up to 48 elements. The B1+ field was evaluated regarding the degrees of freedom for RF shimming in the abdomen. Worst-case specific absorption rate (SARwc ), SAR overestimation in the matrix compression, the number of virtual obser- vation points (VOPs) and SAR efficiency were evaluated. Constrained RF shimming was performed in differently oriented regions of interest in the body, and the devia- tion from a target B1+ field was evaluated. Results show that integrated multiring arrays are able to generate homogeneous B1+ field distributions for large FOVs, espe- cially for coronal/sagittal slices, and thus enable body imaging at 7 T with a clinical workflow; however, a low duty cycle or a high SAR is required to achieve homoge- neous B1+ distributions and to exploit the full potential. In conclusion, integrated arrays allow for high element counts that have high degrees of freedom for the pulse optimization but also produce high SARwc , which reduces the SAR accuracy in the VOP compression for low-SAR protocols, leading to a potential reduction in array performance. Smaller SAR overestimations can increase SAR accuracy, but lead to a high number of VOPs, which increases the computational cost for VOP evaluation and makes online SAR monitoring or pulse optimization challenging. Arrays with interleaved rings showed the best results in the study. KW - body imaging at UHF MRI KW - integrated transmit coil arrays KW - VOP compression Y1 - 2021 U6 - https://doi.org/10.1002/nbm.4515 SN - 0952-3480 (ISSN) SN - 1099-1492 (eISSN) VL - 34 IS - 7 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Hagemann, Hans-Jürgen A1 - Geittner, P. T1 - PCVD hybrid technology for single mode fibres. Hagemann, H. J.; Geittner, P. JF - Proceedings : papers presented at: the 8th Annual European Fibre Optic Communications and Local Area Networks Exposition Y1 - 1990 N1 - EFOC LAN <8, 1990, München> SP - 67 EP - 72 ER - TY - JOUR A1 - Hagemann, Hans-Jürgen A1 - Geittner, P. A1 - Warnier, J. A1 - Wilson, H. T1 - PCVD at high deposition rates. Geittner, P.; Hagemann, H. J.; Warnier, J.; Wilson, H. JF - Journal of Lightwave Technology (J-LT) / Institute of Electrical and Electronics Engineers (IEEE). 4 (1986), H. 7 Y1 - 1986 SN - 0733-8724 SP - 818 EP - 822 ER - TY - JOUR A1 - Ferrein, Alexander A1 - Böhnstedt, Lutz A1 - Lakemeyer, Gerhard T1 - Options in readylog reloaded -- generating decision-theoretic plan libraries in golog / Böhnstedt, Lutz ; Ferrein, Alexander ; Lakemeyer, Gerhard JF - KI 2007: advances in artificial intelligence : 30th Annual German Conference on AI, KI 2007, Osnabrück, Germany, September 10 - 13, 2007 ; proceedings Y1 - 2007 SN - 978-3-540-74564-8 N1 - Lecture Notes in Computer Science ; 4667 SP - 352 EP - 366 PB - Springer CY - Berlin ER - TY - JOUR A1 - Benkner, Thorsten T1 - Optimum Transmission Power in High Capacity Umbrella Cell Systems JF - Multiaccess, mobility and teletraffic : advances in wireless networks ; [proceedings of the Third Workshop on Multiaccess, Mobility and Teletraffic for Personal Communications held in December 1997 in Melbourne, Australia] / ed. by David Everitt ... Y1 - 1998 SN - 0-7923-8091-6 N1 - Workshop on Multiaccess, Mobility and Teletraffic for Personal Communications <3, 1997, Melbourne> SP - 221 EP - 232 PB - Kluwer CY - Boston, Mass. [u.a.] ER - TY - JOUR A1 - Engels, Elmar A1 - Doege, E. T1 - Optimizing the number of strokes for punching machines using a fuzzy controlled electrohydraulic damping system / Doege, E. ; Engels, E. JF - ICME 98, CIRP International Seminar on Intelligent Computation in Manufacturing Engineering, Proceedings, Capri, IT, Jul 1-3, 1998 Y1 - 1998 SP - 471 EP - 478 CY - Capri ER - TY - CHAP A1 - Leise, Philipp A1 - Altherr, Lena T1 - Optimizing the design and control of decentralized water supply systems – a case-study of a hotel building T2 - EngOpt 2018 Proceedings of the 6th International Conference on Engineering Optimization N2 - To increase pressure to supply all floors of high buildings with water, booster stations, normally consisting of several parallel pumps in the basement, are used. In this work, we demonstrate the potential of a decentralized pump topology regarding energy savings in water supply systems of skyscrapers. We present an approach, based on Mixed-Integer Nonlinear Programming, that allows to choose an optimal network topology and optimal pumps from a predefined construction kit comprising different pump types. Using domain-specific scaling laws and Latin Hypercube Sampling, we generate different input sets of pump types and compare their impact on the efficiency and cost of the total system design. As a realistic application example, we consider a hotel building with 325 rooms, 12 floors and up to four pressure zones. KW - Engineering optimization KW - Energy efficiency KW - Water KW - Pump System KW - Latin Hypercube Sampling Y1 - 2018 SN - 978-3-319-97773-7 SN - 978-3-319-97772-0 U6 - https://doi.org/10.1007/978-3-319-97773-7_107 N1 - EngOpt 2018 Proceedings of the 6th International Conference on Engineering Optimization. 17-19 September 2018. Lisboa, Portugal SP - 1241 EP - 1252 PB - Springer CY - Cham ER - TY - CHAP A1 - Müller, Tim M. A1 - Altherr, Lena A1 - Ahola, Marja A1 - Schabel, Samuel A1 - Pelz, Peter F. T1 - Optimizing pressure screen systems in paper recycling: optimal system layout, component selection and operation N2 - Around 60% of the paper worldwide is made from recovered paper. Especially adhesive contaminants, so called stickies, reduce paper quality. To remove stickies but at the same time keep as many valuable fibers as possible, multi-stage screening systems with several interconnected pressure screens are used. When planning such systems, suitable screens have to be selected and their interconnection as well as operational parameters have to be defined considering multiple conflicting objectives. In this contribution, we present a Mixed-Integer Nonlinear Program to optimize system layout, component selection and operation to find a suitable trade-off between output quality and yield. KW - Mixed-integer nonlinear problem KW - MINLP KW - Process engineering KW - Paper recycling KW - Multi-criteria optimization Y1 - 2018 SN - 978-3-030-18499-5 U6 - https://doi.org/10.1007/978-3-030-18500-8_44 SP - 355 EP - 361 PB - Springer CY - Cham ER - TY - CHAP A1 - Alhwarin, Faraj A1 - Schiffer, Stefan A1 - Ferrein, Alexander A1 - Scholl, Ingrid T1 - Optimized KinectFusion Algorithm for 3D Scanning Applications T2 - Proceedings of the 11th International Joint Conference on Biomedical Engineering Systems and Technologies - Volume 2: BIOIMAGING Y1 - 2018 SN - 978-989-758-278-3 U6 - https://doi.org/10.5220/0006594700500057 SP - 50 EP - 57 ER - TY - JOUR A1 - Bank, Bart L. van de A1 - Orzada, Stephan A1 - Smits, Frits A1 - Lagemaat, Miriam W. A1 - Rodgers, Christopher T. A1 - Bitz, Andreas A1 - Scheenen, Tom W. J. T1 - Optimized (31) P MRS in the human brain at 7 T with a dedicated RF coil setup JF - NMR in Biomedicine Y1 - 2015 U6 - https://doi.org/10.1002/nbm.3422 SN - 1099-1492 VL - 28 IS - 11 SP - 1570 EP - 1578 PB - Wiley CY - Weinheim ER - TY - CHAP A1 - Müller, Tim M. A1 - Altherr, Lena A1 - Leise, Philipp A1 - Pelz, Peter F. T1 - Optimization of pumping systems for buildings: Experimental validation of different degrees of model detail on a modular test rig T2 - Operations Research Proceedings 2019 N2 - 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. KW - Experimental validation KW - MINLP KW - Engineering optimization KW - Water supply system KW - Network design Y1 - 2020 SN - 978-3-030-48438-5 U6 - https://doi.org/10.1007/978-3-030-48439-2_58 N1 - Annual International Conference of the German Operations Research Society (GOR), Dresden, Germany, September 4-6, 2019 SP - 481 EP - 488 PB - Springer CY - Cham ER - TY - JOUR A1 - Müller, Tim M. A1 - Leise, Philipp A1 - Lorenz, Imke-Sophie A1 - Altherr, Lena A1 - Pelz, Peter F. T1 - Optimization and validation of pumping system design and operation for water supply in high-rise buildings JF - Optimization and Engineering N2 - The application of mathematical optimization methods for water supply system design and operation provides the capacity to increase the energy efficiency and to lower the investment costs considerably. We present a system approach for the optimal design and operation of pumping systems in real-world high-rise buildings that is based on the usage of mixed-integer nonlinear and mixed-integer linear modeling approaches. In addition, we consider different booster station topologies, i.e. parallel and series-parallel central booster stations as well as decentral booster stations. To confirm the validity of the underlying optimization models with real-world system behavior, we additionally present validation results based on experiments conducted on a modularly constructed pumping test rig. Within the models we consider layout and control decisions for different load scenarios, leading to a Deterministic Equivalent of a two-stage stochastic optimization program. We use a piecewise linearization as well as a piecewise relaxation of the pumps’ characteristics to derive mixed-integer linear models. Besides the solution with off-the-shelf solvers, we present a problem specific exact solving algorithm to improve the computation time. Focusing on the efficient exploration of the solution space, we divide the problem into smaller subproblems, which partly can be cut off in the solution process. Furthermore, we discuss the performance and applicability of the solution approaches for real buildings and analyze the technical aspects of the solutions from an engineer’s point of view, keeping in mind the economically important trade-off between investment and operation costs. KW - Technical Operations Research KW - MINLP KW - MILP KW - Experimental validation KW - Pumping systems Y1 - 2020 U6 - https://doi.org/10.1007/s11081-020-09553-4 SN - 1573-2924 VL - 2021 IS - 22 SP - 643 EP - 686 PB - Springer ER - TY - CHAP A1 - Altherr, Lena A1 - Leise, Philipp A1 - Pfetsch, Marc E. A1 - Schmitt, Andreas T1 - Optimal design of resilient technical systems on the example of water supply systems T2 - Mastering Uncertainty in Mechanical Engineering Y1 - 2021 SN - 978-3-030-78356-3 N1 - Unterkapitel des Kapitels "Strategies for Mastering Uncertainty" SP - 429 EP - 433 PB - Springer CY - Cham ER - TY - JOUR A1 - Sun, Hui A1 - Altherr, Lena A1 - Pei, Ji A1 - Pelz, Peter F. A1 - Yuan, Shouqi T1 - Optimal booster station design and operation under uncertain load JF - Applied Mechanics and Materials N2 - Given industrial applications, the costs for the operation and maintenance of a pump system typically far exceed its purchase price. For finding an optimal pump configuration which minimizes not only investment, but life-cycle costs, methods like Technical Operations Research which is based on Mixed-Integer Programming can be applied. However, during the planning phase, the designer is often faced with uncertain input data, e.g. future load demands can only be estimated. In this work, we deal with this uncertainty by developing a chance-constrained two-stage (CCTS) stochastic program. The design and operation of a booster station working under uncertain load demand are optimized to minimize total cost including purchase price, operation cost incurred by energy consumption and penalty cost resulting from water shortage. We find optimized system layouts using a sample average approximation (SAA) algorithm, and analyze the results for different risk levels of water shortage. By adjusting the risk level, the costs and performance range of the system can be balanced, and thus the system’s resilience can be engineered KW - Stochastic Programming KW - Chance Constraint KW - Engineering Application KW - Pump System KW - Water Distribution Y1 - 2018 U6 - https://doi.org/10.4028/www.scientific.net/AMM.885.102 SN - 1662-7482 VL - 885 SP - 102 EP - 115 PB - Trans Tech Publications CY - Bäch ER -