Power Electronic Devices for Damping Torsional Vibrations
Torsional vibrations and resonance problems with synchronous machines are most frequently encountered in rotor systems with long shafts and large inertias constituting a weakly damped mechanical resonator which exhibits a low resonance frequency. It is impossible to obtain a effective mechanical damping for these torsional vibrations, but by using a power electronics device and an inductive or capacitive energy storage which is connected to the stator winding of the synchronous machine, which produce the same effect as an increased natural damping for oscillation mode in the rotating shaft assembly. This electrical method is applicable to torsional vibration problems in generators and electrical drive systems. The paper presents examples for the successful suppression of torsional resonances in synchronous machines of an isolated power system based on flywheel generators and by three phase fault in the second benchmark model of the IEEE.
Fusion as a Future Power Source: Recent Achievements and Prospects
Recent advances in high energy plasma physics show that nuclear fusion the energy source of the sun and the stars [1] may provide the corner-stone of a future sustainable energy system. Such power plants would be safe and environmentally friendly. In particular, one of the main problems of fission reactors, namely that of a possible uncontrollable nuclear reaction is banished; also the problem of radiotoxic waste is reduced by many orders of magnitude. Fusion reactors would have almost limitless supplies of fuel and could be sited anywhere in the world. Fusion is, however, still in the development stage and it is not expected that commercial power plants will start operation before the middle of this century.
Second-Generation Process Research Towards Eletriptan: A Fischer Indole Approach
The development of a second-generation process for the synthesis of eletriptan via a Fischer indole cyclisation is described. The finalised process offers several potential advantages over the current route of manufacture including cost, throughput, and safety.