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We present the architecture and design of the IANOS scheduling framework. The goal of the new Grid scheduling system is to provide a general job submission framework allowing optimal positioning and scheduling of HPCN applications. The scheduling algorithms used to calculate best-suited resources are based on an objective cost function that exploits information on the parameterization of applications and resources. This standard-based, interoperable scheduling framework comprises four general web services and three modules. The middleware is complemented with one client and one admin console. The implementation is based on proposed Grid and Web services standards (WSRF, WS-Agreement, JSDL, and GLUE). It is agnostic to a specific Grid middleware. The beta version of IANOS has been tested and integrated with UNICORE. The validation of IANOS is in progress by running different types of HPCN applications on a large-scale Grid testbed.

"Egal ob Pump- oder Druckspeicher, Batterien oder "virtuelle" Pufferung im Netz - alle Technologien zur Stromspeicherung besitzen ihre spezifischen Vor- und Nachteile. Angesichts wachsender Marktanteile regenerativer Stromerzeugung nimmt die Bedeutung effizienter Techniken zur Energiespeicherung zu. Nur so werden "fluktuierende" Quellen wie Windkraft und Photovoltaik planbar."

Nano-scale aluminum particles are innovative materials increasingly used in energetic formulations. In this contribution, the rheological behavior of suspensions with either paraffin oil or HTPB as the matrix fluid and nano-scale aluminum (ALEX) as the dispersed phase is described and discussed. The paraffin oil/aluminum suspensions exhibit non-Newtonian flow behavior over a wide range of concentrations, whereas the HTPB/aluminum suspensions exhibitNewtonian behavior (i.e. the viscosity is independent of shear stress) up to a concentration of 50 vol.% aluminum. Both systems have unusual viscoelastic properties in that their elastic moduli are independent of the solids concentration.

AbstractFrequent failures of power converters affect the availability of wind turbines and cause considerable maintenance costs. To enhance the reliability of power converters in wind turbines, the prevailing causes and modes of failures have to be identified. This publication contributes to root‐cause analysis of the power‐converter failures in wind turbines from a statistical point of view. For this purpose, the failure behavior of power‐converters is modeled via lifetime models as well as repairable‐system models. By means of regression models, covariates are incorporated, including both design‐related and site‐specific covariates. The analysis is based on a worldwide extensive field‐data collection covering more than 9000 turbines, including different turbine designs, sites, and ages. The results obtained by means of the applied regression models indicate that the location of the power converter within the turbine, the cooling system, the converter rated power, the DC‐link voltage, the IGBT‐module manufacturer, and the commissioning date of the turbine as design‐related covariates have a significant effect on the phase‐module failure behavior and with that on converter reliability. Among the site‐specific covariates, the analysis results confirm humidity as a likely significant driver of failures.

AbstractBlack TiO2 has demonstrated a great potential for a variety of renewable energy technologies. However, its practical application is heavily hindered due to lack of efficient hydrogenation methods and a deeper understanding of hydrogenation mechanisms. Here, a simple and straightforward hot wire annealing (HWA) method is presented to prepare black TiO2 (H–TiO2) nanorods with enhanced photo‐electrochemical (PEC) activity by means of atomic hydrogen [H]. Compared to conventional molecular hydrogen approaches, the HWA shows remarkable effectiveness without any detrimental side effects on the device structure, and simultaneously the photocurrent density of H–TiO2 reaches 2.5 mA cm−2 (at 1.23 V vs reversible hydrogen electrode (RHE)). Due to the controllable and reproducible [H] flux, the HWA can be developed as a standard hydrogenation method for black TiO2. Meanwhile, the relationships between the wire temperatures, structural, optical, and photo‐electrochemical properties are systematically investigated to verify the improved PEC activity. Furthermore, the density functional theory (DFT) study provides a comprehensive insight not only into the highly efficient mechanism of the HWA approach but also its favorably low‐energy‐barrier hydrogenation pathway. The findings will have a profound impact on the broad energy applications of H–TiO2 and contribute to the fundamental understanding of its hydrogenation.

AbstractAn innovative method for heating proton exchange membrane fuel cell (PEMFC) stacks during start‐up by direct heating of the cells is presented and investigated. By imposing an alternating current on the stack, heat is generated locally depending on the internal cell resistance. It is shown, that an alternating current (AC) perturbation with a suitable high frequency mainly heats the ohmic resistors which are membrane and contact interfaces. The electrodes are protected from voltage cycling, due to (de)charging currents of the double layer capacitances at high frequency. This AC heating technique is applied on a 6‐cell low temperature (LT) PEMFC stack and a 30‐cell high temperature (HT) PEMFC stack, both with an active area of approximately 30 cm2. Both stacks are heated under realistic temperature conditions, the LTPEMFC stack from sub‐zero temperatures to 40 °C and the HTPEMFC stack from room temperature to 120 °C. Heating times are shown and discussed for different stack geometries and voltages. In both cases, this strategy leads to a short and efficient heating, as the cells are heated directly and not externally by coolant or other stack components.

In recent years, a wide range of strategies has been implemented in different EU-countries to increase the share of electricity generation from renewable energy sources. This paper evaluates the success of different regulatory strategies. The most important conclusions of this analysis are: (i) regardless of which strategy is chosen, it is of overriding importance that there should be a clear focus on the exclusive promotion of newly installed plants; (ii) a well-designed (dynamic) feed-in tariff system ensures the fastest deployment of power plants using Renewable Energy Sources at the lowest cost to society; (iii) promotion strategies with low policy risks have lower profit requirements for investors and, hence, cause lower costs to electricity customers.