TY - JOUR A1 - Streun, M. A1 - Brandenburg, G. A1 - Brökel, M. A1 - Fuss, L. A1 - Larue, H. A1 - Parl, C. A1 - Zimmermann, E. A1 - Ziemons, Karl A1 - Halling, H. T1 - The ClearPET data acquisition JF - 2003 IEEE Nuclear Science Symposium Conference Record, Vol. 5 N2 - Within the Crystal Clear Collaboration a modular system for a small animal PET scanner (ClearPET™) has been developed. The modularity allows the assembly of scanners of different sizes and characteristics in order to fit the specific needs of the individual member institutions. Now a first demonstrator is being completed in Julich. The system performs depth of interaction detection by using a phoswich arrangement combining LSO and LuYAP scintillators which are coupled to multi-channel photomultipliers (PMTs). A free-running ADC digitizes the signal from the PMT and the complete scintillation pulses are sampled by an FPGA and sent with 20 MB/S to a PC for preprocessing. The pulse provides information about the gamma energy and the scintillator material which identifies the interaction layer. Furthermore, the exact pulse starting time is obtained from the sampled data. This is important as no hardware coincidence detection is implemented. All single events are recorded and coincidences are identified by software. An advantage of that is that the coincidence window and the dimensions of the field of view can be adjusted easily. The ClearPET™ demonstrator is equipped with 10240 crystals on 80 PMTs. This paper presents an overview of the data acquisition system. Y1 - 2004 SN - 1082-3654 SP - 3097 EP - 3100 ER - TY - JOUR A1 - Christ, D. A1 - Hollendung, A. A1 - Larue, H. A1 - Parl, C. A1 - Streun, M. A1 - Weber, S. A1 - Ziemons, Karl A1 - Halling, H. T1 - Homogenization of the MultiChannel PM gain by inserting light attenuating masks JF - 2003 IEEE Nuclear Science Symposium Conference Record, Vol. 4 N2 - MultiChannel Photomultipliers (PM), like the R7600-00-M64 or R5900-00-M64 from Hamamatsu, are often chosen as photodetectors in high-resolution positron emission tomography (PET). A major problem of this PM is the nonuniform channel gain. In order to solve this problem, light attenuating masks were created. The aim of the masks is a homogenization of the output of all 64 channels using different hole sizes at the channel positions. The hole area, which is individually defined for the different channels, is inversely proportional to the channel gain. The measurements by inserting light attenuating masks improved a homogenization to a ratio of 1:1.2. Y1 - 2004 SN - 1082-3654 SP - 2382 EP - 2385 ER - TY - JOUR A1 - Ziemons, Karl A1 - Heinrichs, U. A1 - Streun, M. A1 - Pietrzyk, U. T1 - Validation of GEANT3 simulation studies with a dual-head PMT ClearPET™ prototype JF - 2003 IEEE Nuclear Science Symposium Conference Record, Vol. 5 N2 - The ClearPET™ project is proposed by working groups of the Crystal Clear Collaboration (CCC) to develop a 2nd generation high performance small animal positron emission tomograph (PET). High sensitivity and high spatial resolution is foreseen for the ClearPET™ camera by using a phoswich arrangement combining mixed lutetium yttrium aluminum perovskite (LuYAP:Ce) and lutetium oxyorthosilicate (LSO) scintillating crystals. Design optimizations for the first photomultiplier tube (PMT) based ClearPET camera are done with a Monte-Carlo simulation package implemented on GEANT3 (CERN, Geneva, Switzerland). A dual-head prototype has been built to test the frontend electronics and was used to validate the implementation of the GEANT3 simulation tool. Multiple simulations were performed following the experimental protocols to measure the intrinsic resolution and the sensitivity profile in axial and radial direction. Including a mean energy resolution of about 27.0% the simulated intrinsic resolution is about (1.41±0.11)mm compared to the measured of (1.48±0.06)mm. The simulated sensitivity profiles show a mean square deviation of 12.6% in axial direction and 3.6% in radial direction. Satisfactorily these results are representative for all designs and confirm the scanner geometry. Y1 - 2004 SN - 1082-3654 SP - 3053 EP - 3056 ER - TY - JOUR A1 - Auffray, E. A1 - Bruyndonckx, P. A1 - Devroede, O. A1 - Fedorov, A. A1 - Ziemons, Karl T1 - The ClearPET project JF - Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment N2 - The Crystal Clear Collaboration has designed and is building a high-resolution small animal PET scanner. The design is based on the use of the Hamamatsu R7600-M64 multi-anode photomultiplier tube and a LSO/LuYAP phoswich matrix with one to one coupling between the crystals and the photo-detector. The complete system will have 80 PM tubes in four rings with an inner diameter of 137 mm and an axial field of view of 110 mm. The PM pulses are digitized by free-running ADCs and digital data processing determines the gamma energy, the phoswich layer and even the pulse arrival time. Single gamma interactions are recorded and coincidences are found by software. The gantry allows rotation of the detector modules around the field of view. Simulations, and measurements a 2×4 module test set-up predict a spatial resolution of 1.5 mm in the centre of the field of view and a sensitivity of 5.9% for a point source in the centre of the field of view. Y1 - 2004 SN - 0168-9002 N1 - Proceedings of the 2nd International Conference on Imaging Technologies in Biomedical Sciences VL - 527 IS - 1-2 SP - 171 EP - 174 ER - TY - JOUR A1 - Dilthey, Ulrich A1 - Brandenburg, Annette A1 - Schleser, Markus T1 - Dispensing and application of unfilled adhesives in the micro range JF - Welding and cutting. 3 (2004), H. 4 Y1 - 2004 SN - 1612-3433 SP - 250 EP - 254 ER - TY - JOUR A1 - Hellwig, Angelika A1 - Volkmann, Lutz T1 - Maximally local-edge-connected graphs and digraphs JF - Ars combinatoria Y1 - 2004 SN - 0381-7032 VL - Vol. 72 SP - 295 EP - 306 ER - TY - JOUR A1 - Hellwig, Angelika A1 - Volkmann, Lutz T1 - Neighborhood and degree conditions for super-edge-connected bipartite digraphs JF - Results in mathematics Y1 - 2004 SN - 1420-9012 (E-Journal); 1422-6383 (Print) VL - Vol. 45 IS - Iss. 1-2 SP - 45 EP - 58 ER - TY - JOUR A1 - Hellwig, Angelika A1 - Volkmann, Lutz T1 - Sufficient conditions for λ′-optimality in graphs of diameter 2 JF - Discrete mathematics Y1 - 2004 SN - 1872-681X (E-Journal); 0012-365X (Print) VL - Vol. 283 IS - Iss. 1-3 SP - 113 EP - 120 ER - TY - JOUR A1 - Hellwig, Angelika A1 - Rautenbach, Dieter A1 - Volkmann, Lutz T1 - Note on the connectivity of line graphs JF - Information processing letters Y1 - 2004 SN - 1872-6119 (E-Journal); 0020-0190 (Print) VL - Vol. 91 IS - Iss. 1 SP - 7 EP - 10 ER - TY - JOUR A1 - Staat, Manfred T1 - Plastic collapse analysis of longitudinally flawed pipes and vessels N2 - Improved collapse loads of thick-walled, crack containing pipes and vessels are suggested. Very deep cracks have a residual strength which is better modelled by a global limit load. In all burst tests, the ductility of pressure vessel steels was sufficiently high whereby the burst pressure could be predicted by limit analysis with no need to apply fracture mechanics. The relative prognosis error increases however, for long and deep defects due to uncertainties of geometry and strength data. KW - Druckbehälter KW - Stahl KW - Druckbelastung KW - Druckbeanspruchung KW - Rohr KW - Rohrbruch KW - Druckbehälter KW - Stahl KW - Druckbelastung KW - Druckbeanspruchung KW - Rohrbruch KW - Fehlerstellen KW - pipes KW - vessels KW - load limit KW - burst tests KW - burst pressure KW - flaw Y1 - 2004 ER - TY - JOUR A1 - Vu, Duc-Khoi A1 - Staat, Manfred T1 - An algorithm for shakedown analysis of structure with temperature dependent yield stress N2 - This work is an attempt to answer the question: How to use convex programming in shakedown analysis of structures made of materials with temperature-dependent properties. Based on recently established shakedown theorems and formulations, a dual relationship between upper and lower bounds of the shakedown limit load is found, an algorithmfor shakedown analysis is proposed. While the original problem is neither convex nor concave, the algorithm presented here has the advantage of employing convex programming tools. KW - Einspielen KW - Temperaturabhängigkeit KW - Fließgrenze KW - Shakedown KW - shakedown analysis KW - yield stress Y1 - 2004 ER - TY - JOUR A1 - Kühn, Raoul-Roman A1 - Haugner, Werner A1 - Staat, Manfred A1 - Sponagel, Stefan T1 - A Two Phase Mixture Model based on Bone Observation N2 - An optimization method is developed to describe the mechanical behaviour of the human cancellous bone. The method is based on a mixture theory. A careful observation of the behaviour of the bone material leads to the hypothesis that the bone density is controlled by the principal stress trajectories (Wolff’s law). The basic idea of the developed method is the coupling of a scalar value via an eigenvalue problem to the principal stress trajectories. On the one hand this theory will permit a prediction of the reaction of the biological bone structure after the implantation of a prosthesis, on the other hand it may be useful in engineering optimization problems. An analytical example shows its efficiency. KW - Knochen KW - Knochenbildung KW - Knochenchirugie KW - Strukturanalyse KW - Schwammknochen KW - Knochendichte KW - Wolffsches Gesetz KW - bone structure KW - bone density KW - Wolff's Law KW - cancellous bone Y1 - 2004 ER - TY - JOUR A1 - Dersch, Jürgen A1 - Geyer, Michael A1 - Herrmann, Ulf A1 - Jones, Scott A. A1 - Kelly, Bruce A1 - Kistner, Rainer A1 - Ortmanns, Winfried A1 - Pitz-Paal, Robert A1 - Price, Henry T1 - Trough integration into power plants—a study on the performance and economy of integrated solar combined cycle systems JF - Energy : the international journal Y1 - 2004 U6 - http://dx.doi.org/10.1016/S0360-5442(03)00199-3 SN - 0360-5442 N1 - SolarPACES 2002, Zürich, Switzerland, 4–6 September 2002 VL - 29 IS - 5-6 (Special Issue SolarPaces) SP - 947 EP - 959 ER - TY - JOUR A1 - Cesari, Francesca A1 - Rennekampff, Verena A1 - Vintersten, Kristina A1 - Vuong, Lam Giang A1 - Seibler, Jost A1 - Bode, Jürgen A1 - Wiebel, Franziska F. A1 - Nordheim, Alfred T1 - Elk-1 knock-out mice engineered by Flp recombinase-mediated cassette exchange JF - Genesis : The Journal of Genetics and Development Y1 - 2004 U6 - http://dx.doi.org/10.1002/gene.20003 SN - 1526-968X VL - 38 IS - 2 SP - 87 EP - 92 ER - TY - JOUR A1 - Chudoba, Rostislav A1 - Butenweg, Christoph A1 - Peiffer, F. T1 - Technical information system for collaborative material research JF - Advances in engineering software Y1 - 2004 U6 - http://dx.doi.org/10.1016/j.advengsoft.2004.03.021 SN - 1873-5339 (E-Journal); 0965-9978 (Print) VL - Volume 35 IS - Issue 10-11 SP - 747 EP - 756 ER - TY - JOUR A1 - Holler, S. A1 - Butenweg, Christoph A1 - Noh, S.-Y. A1 - Meskouris, Konstantin T1 - Computational model of textile-reinforced concrete structures JF - Computers & structures : an international journal Y1 - 2004 U6 - http://dx.doi.org/10.1016/j.compstruc.2004.03.076 SN - 1879-2243 (E-Journal); 0045-7949 (Print) VL - Volume 82 IS - Issues 23-26 SP - 1971 EP - 1979 ER - TY - JOUR A1 - Ndoumbè Mbonjo Mbonjo, H. A1 - Streckert, J. A1 - Bitz, Andreas A1 - Hansen, V. A1 - Glasmachers, A. A1 - Gencol, S. A1 - Rozic, D. T1 - Generic UMTS test signal for RF bioelectromagnetic studies JF - Bioelectromagnetics Y1 - 2004 U6 - http://dx.doi.org/10.1002/bem.20007 SN - 1521-186X VL - 25 IS - 6 SP - 415 EP - 425 ER - TY - JOUR A1 - Sommer, Angela M. A1 - Streckert, Joachim A1 - Bitz, Andreas A1 - Hansen, Volkert W. A1 - Lerchl, Alexander T1 - No effects of GSM-modulated 900 MHz electromagnetic fields on survival rate and spontaneous development of lymphoma in female AKR/J mice JF - BMC Cancer Y1 - 2004 U6 - http://dx.doi.org/10.1186/1471-2407-4-77 VL - 77 IS - 4 ER - TY - JOUR A1 - Hans, Stefan A1 - Scheer, Nico A1 - Riedl, Iris A1 - Weizäcker, Elisabeth von A1 - Blader, Patrick A1 - Campos-Ortega, José A. T1 - her3, a zebrafish member of the hairy-E(spl) family, is repressed by Notch signalling JF - Development Y1 - 2004 U6 - http://dx.doi.org/10.1242/dev.01167 SN - 1477-9129 VL - 131 IS - 12 SP - 2957 EP - 2969 ER -