-Deregulation and an increasing competition in electricity markets urge energy suppliers to optimize the utilization of their equipment, focusing on technical and cost-effective aspects.As a respond to these requirements utilities introduce methods formerly used by investment managers or insurance companies. The article describes the usage of these methods, particularly with regard to asset management and risk management within electrical grids. The essential information needed to set up an appropriate asset management system and differences between asset management systems in transmission and distribution systems are discussed.The bulk of costs in electrical grids can be found in costs for maintenance and capital depreciation. A comprehensive approach for an asset management in transmission systems thus focuses on the "life-cycle costs" of the individual equipment. The objective of the life management process is the optimal utilisation of the remaining life time regarding a given reliability of service and a constant distribution of costs for reinvestment and maintenance ensuring a suitable return.In distribution systems the high number of components would require an enormous effort for the consideration of single individuals. Therefore statistical approaches have been used successfully in practical applications. Newest insights gained by a German research project on asset management systems in distribution grids give an outlook to future developments.
Magnetic transcutaneous coupling is frequently used for power and data transfer to implanted electronic devices. The proposed development of MicroImplants, small enough to be injected through a hypodermic needle suggest the need for a high-efficiency magnetic transcutaneous link. This paper describes the use of a multifrequency transmitter coil driver based upon the Class E topology. The development of a "high-Q approximation" which simplifies the design procedure is presented. A closed-loop controller to compensate for transmitter and receiver variations, and a method of data modulation, using synchronous frequency shifting are described. The closed-loop Class E circuit shows great promise, especially for circuits with unusually low coefficients of coupling. Currents of several amperes, at radio frequencies, can easily and efficiently be obtained.
In this study we present a systematic investigation of the phase behaviour of microemulsions containing near- or supercritical solvents. The starting point of this study are microemulsions of the type water/NaCl-propane-polyethyleneglycol mono-n-alkyl ether at a pressure of p = 220 bar. Replacing propane stepwise by supercritical carbon dioxide the typical phase behavior of microemulsions systems can still be observed using scCO(2) as the only nonpolar solvent. Thus, increasing the temperature a phase inversion from a CO(2)-in-water to a water-in-CO(2) microemulsion via a balanced CO(2) microemulsion is found for the first time. Such mixtures of water and scCO(2) are expected to be versatile solvents in green chemistry. In addition, the formulation of supercritical microemulsions is the initial step in the Principle Of Supercritical Microemulsion Expansion (POSME) (DE Pat., 102 60 815 B4, 2008), which is a promising new approach for the production of low-cost nanocellular foams. In contrast to conventional foaming procedures, this approach suggests the formation of nanofoams by expanding micelles swollen with a supercritical blowing agent, thereby ensuring the unhindered formation and growth of bubbles without mass transport.
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