A Comparison of Modelling Systems for the Development and Revision of Water Resources Management Plans

In this paper, two modelling systems used for the simulation of water resources management are compared. These modelling systems can be used in the implementation of the European Water Framework Directive or to perform any other kind of integrated assessment with regard to water resources management. In such investigations the use of models is inevitable, as integrated water resources management demands the survey of large areas as well as the inclusion of the different functions of the water cycle and water utilisation processes. Water quantity data provides important input for hydro-chemical, hydro-ecological or hydro-economic models. If no significant water resources management activities are realised in the basin under study, these data can be provided by simple rainfall-runoff models. If significant water resources management activities are realised or planned, the effects of these water resources management activities must be taken into consideration. Then, however, the use of water resources management models becomes necessary. Two such modelling systems, WRAP and WBalMo, are compared. Both have been designed for the development and revision of water resources management plans. Due to different approaches regarding the modelling routines the models lead to different results in the calculation of water quantities. By tracking the simulation algorithms, an understanding of the detected differences becomes possible. By adapting the spatial configuration of the modelled system, equivalent results can be obtained.     

Battery sizing for serial plug-in hybrid electric vehicles: A model-based economic analysis for Germany

The battery size of a Plug-in Hybrid Electric Vehicle (PHEV) is decisive for the electrical range of the vehicle and crucial for the cost-effectiveness of this particular vehicle concept. Based on the energy consumption of a conventional reference car and a PHEV, we introduce a comprehensive total cost of ownership model for the average car user in Germany for both vehicle types. The model takes into account the purchase price, fixed annual costs and variable operating costs. The amortization time of a PHEV also depends on the recharging strategy (once a day, once a night, after each trip), the battery size, and the battery costs. We find that PHEVs with a 4 kWh battery and at current lithium-ion battery prices reach the break-even point after about 6 years (5 years when using the lower night-time electricity tariffs). With higher battery capacities the amortization time becomes significantly longer. Even for the small battery size and assuming the EU-15 electricity mix, a PHEV is found to emit only around 60% of the CO₂ emissions of a comparable conventional car. Thus, with the PHEV concept a cost-effective introduction of electric mobility and reduction of greenhouse gas emissions per vehicle can be reached.     

Detailed analysis of the self-discharge of supercapacitors

Self-discharge is an important performance factor when using supercapacitors. Voltage losses in the range of 5-60% occur over two weeks. Experiments show a dependency of the self-discharge rate on various parameters such as temperature, charge duration and short-term history. In this paper, self-discharge of three commercially available supercapacitors was measured under various conditions. Based on different measurements, the impact of the influence factors is identified. A simple model to explain parts of the voltage decay is presented.     

Nanoscaled La0.6Sr0.4CoO3−δ as intermediate temperature solid oxide fuel cell cathode: Microstructure and electrochemical performance

Lowering the operation temperature of solid oxide fuel cells to the range of 400-600 °C has generated new concepts for materials choice, interfacial design and electrode microstructures. In this study nanometer scaled and nanoporous La_0.6Sr_0.4CoO_3−δ (LSC) was derived from metal-organic precursors as thin film cathodes of about 200 nm thickness with mean grain sizes ranging from 17 to 90 nm and porosities of up to 45%. These microstructures resulted from different processing parameters such as heating rate, calcination temperature and post calcination annealing, and made it possible to study the influence of the electrode microstructure on the electrochemical performance. Microstructural characteristics were analyzed by scanning and transmission electron microscopy and the performance was evaluated in terms of area specific polarization resistance by means of electrochemical impedance spectroscopy in a temperature range of 400-600 °C. Polarization resistances as low as 0.023 Ω cm² were measured at 600 °C, facilitated by a substantial increase of the inner surface area of the nanoscaled microstructure, resulting from low temperature processing at ≤800 °C, and by enhanced catalytic properties determined for nanoscaled La_0.6Sr_0.4CoO_3−δ prepared by metal organic deposition.     

Bildung von Eisenkeimen bei der Reduktion von Wüstit

Keimbildung des Eisens bei der Reduktion von Wüstit bei 700 °C. Einfluß von Gitterstörungen und Gasatmosphäre auf die Eisenkeimbildung. Praktische Auswirkung der Hemmung der Eisenkeimbildung für die Eisenoxydreduktion im Hochofen.     

A heat stress monitoring system for fire fighters

A portable lightweight seven-channel radiotelemetry system has been developed, which is capable of monitoring environmental stresses and physiological response of fire fighters exposed to heat stress during fire fighting operations. Note: Dr. Uwe Reischl is connected with the Social Ecology Program at UC, Irvine, and Dr. Peter Reischl is a member of the Biomedical Engineering Department at USC.