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In this article I describe a randomized algorithm based
on random walks with two absorbing barriers that solves the satisfiability
problem (known to be NP complete) with arbitrary high probability. As a
consequence of this algorithm, I also prove that the RSA cryptographic protocol
is not secure.
Natural gas and coal are the main primary energy resources used in the Romanian energy sector, 73.7% in 2011, taking into account the fuel imports. The objective of the article consists in analyzing all the processes along the coal and the natural gas life cycle in order to assess their overall environmental impact. Two energy technologies were analyzed, for each resource: the pulverized coal combustion with supra-critical parameters and CO2 capture unit and the natural gas combined cycle. Considering the functional unit of electricity production for 1 year, it was found that the natural gas combined cycle remains the more interesting energy technology from an environmental point of view. However, the pulverized coal with supra-critical parameters equipped with a CO2 capture unit has the lowest environmental impact on the climate change. The weakest point of the coal technology is its low efficiency.