TY - JOUR A1 - Blanke, Tobias A1 - Hagenkamp, Markus A1 - Döring, Bernd A1 - Göttsche, Joachim A1 - Reger, Vitali A1 - Kuhnhenne, Markus T1 - Net-exergetic, hydraulic and thermal optimization of coaxial heat exchangers using fixed flow conditions instead of fixed flow rates JF - Geothermal Energy N2 - Previous studies optimized the dimensions of coaxial heat exchangers using constant mass fow rates as a boundary condition. They show a thermal optimal circular ring width of nearly zero. Hydraulically optimal is an inner to outer pipe radius ratio of 0.65 for turbulent and 0.68 for laminar fow types. In contrast, in this study, fow conditions in the circular ring are kept constant (a set of fxed Reynolds numbers) during optimization. This approach ensures fxed fow conditions and prevents inappropriately high or low mass fow rates. The optimization is carried out for three objectives: Maximum energy gain, minimum hydraulic efort and eventually optimum net-exergy balance. The optimization changes the inner pipe radius and mass fow rate but not the Reynolds number of the circular ring. The thermal calculations base on Hellström’s borehole resistance and the hydraulic optimization on individually calculated linear loss of head coefcients. Increasing the inner pipe radius results in decreased hydraulic losses in the inner pipe but increased losses in the circular ring. The net-exergy diference is a key performance indicator and combines thermal and hydraulic calculations. It is the difference between thermal exergy fux and hydraulic efort. The Reynolds number in the circular ring is instead of the mass fow rate constant during all optimizations. The result from a thermal perspective is an optimal width of the circular ring of nearly zero. The hydraulically optimal inner pipe radius is 54% of the outer pipe radius for laminar fow and 60% for turbulent fow scenarios. Net-exergetic optimization shows a predominant infuence of hydraulic losses, especially for small temperature gains. The exact result depends on the earth’s thermal properties and the fow type. Conclusively, coaxial geothermal probes’ design should focus on the hydraulic optimum and take the thermal optimum as a secondary criterion due to the dominating hydraulics. Y1 - 2021 U6 - https://doi.org/10.1186/s40517-021-00201-3 SN - 2195-9706 N1 - Corresponding author: Tobias Blanke VL - 9 IS - Article number: 19 PB - Springer CY - Berlin ER - TY - JOUR A1 - Hartung, Frank A1 - Schieder, Andreas A1 - Kampmann, Markus A1 - Vorwerk, Marc T1 - Network Supported Media Delivery in Ambient Networks (Netzwerkunterstützte Medienverteilung) / Schieder, Andreas ; Kampmann, Markus ; Hartung, Frank ; Vorwerk, Marc ; Rembarz, René JF - it - Information Technology . 48 (2006), H. 5 Y1 - 2006 SN - 1611-2776 N1 - in der Bereichsbibliothek Eupener Str. unter der Signatur 23 Z 376 vorhanden SP - 264 EP - 273 ER - TY - JOUR A1 - Laack, Walter van A1 - Refisch, A. T1 - Neuralgic amyotrophy of the lumbar area. Case Report / Refisch, A. ; Laack, W. van JF - Archives of Orthopaedic and Trauma Surgery. 108 (1989), H. 5 Y1 - 1989 SN - 0936-8051 SP - 329 EP - 332 ER - TY - JOUR A1 - Hoyler, Friedrich A1 - Cizewski, J. A. A1 - Colvin, G. G. T1 - Neutron capture on 193Ir and σ<σ SUB>max states in 195Ir / J. A. Cizewski ; G. G. Colvin ... F. Hoyler ... JF - Journal of Physics G. 14 (1988), H. S Y1 - 1988 SN - 0305-4616 SP - S103 EP - S108 ER - TY - JOUR A1 - Grotendorst, Johannes A1 - Scott, Tony C. A1 - Aubert-Frécon, Monique T1 - New Approach for the Electronic Energies of the Hydrogen Molecular Ion / Scott, Tony C. ; Aubert-Frécon, Monique ; Grotendorst, Johannes JF - Chemical Physics. 324 (2006), H. 2/3 Y1 - 2006 SN - 0301-0104 SP - 323 EP - 338 ER - TY - JOUR A1 - Gerhards, Michael A1 - Sander, Volker A1 - Zivkovic, Miroslav A1 - Belloum, Adam A1 - Bubak, Marian T1 - New approach to allocation planning of many‐task workflows on clouds JF - Concurrency and Computation: Practice and Experience N2 - Experience has shown that a priori created static resource allocation plans are vulnerable to runtime deviations and hence often become uneconomic or highly exceed a predefined soft deadline. The assumption of constant task execution times during allocation planning is even more unlikely in a cloud environment where virtualized resources vary in performance. Revising the initially created resource allocation plan at runtime allows the scheduler to react on deviations between planning and execution. Such an adaptive rescheduling of a many-task application workflow is only feasible, when the planning time can be handled efficiently at runtime. In this paper, we present the static low-complexity resource allocation planning algorithm (LCP) applicable to efficiently schedule many-task scientific application workflows on cloud resources of different capabilities. The benefits of the presented algorithm are benchmarked against alternative approaches. The benchmark results show that LCP is not only able to compete against higher complexity algorithms in terms of planned costs and planned makespan but also outperforms them significantly by magnitudes of 2 to 160 in terms of required planning time. Hence, LCP is superior in terms of practical usability where low planning time is essential such as in our targeted online rescheduling scenario. Y1 - 2020 U6 - https://doi.org/10.1002/cpe.5404 SN - 1532-0634 VL - 32 IS - 2 Article e5404 SP - 1 EP - 16 PB - Wiley CY - Chichester ER - TY - JOUR A1 - Nam, J. A1 - Arora, D. A1 - Behbahani, Mehdi A1 - Probst, M. A1 - Benkowski, R. A1 - Behr, M. A1 - Pasquali, M. T1 - New computational method in hemolysis analysis for artificial heart pump Y1 - 2010 N1 - Posterpresentation ; American Society of Artificial Organs (ASAIO), Baltimore, USA, May 27-29, 2010 ER - TY - JOUR A1 - Simonis, A. A1 - Lüth, H. A1 - Wang, J. A1 - Schöning, Michael Josef T1 - New concepts of miniaturised reference electrodes in silicon technology for potentiometric sensor systems JF - Sensors and Actuators B. 103 (2004), H. 1-2 Y1 - 2004 SN - 0925-4005 SP - 429 EP - 435 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 - Selmer, Thorsten A1 - Pierik, Antonio J. A1 - Heider, Johann T1 - New glycyl radical enzymes catalysing key metabolic steps in anaerobic bacteria JF - Biological Chemistry. 386 (2005), H. 10 Y1 - 2005 SN - 1431-6730 SP - 981 EP - 988 ER -