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Submitted on: 13 May 2011.
Revised on: 29 August 2011.
Accepted on: 13 October 2011.
___________________ELECTRIC POWER SYSTEMS RESEARCH
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Submitted on: 04 June 2011.
Revised on: 12 August 2011.
Accepted on: 23 September 2011.
___________________ELECTRIC POWER SYSTEMS RESEARCH
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