power system blackouts have become a serious problem for electric utilities especially in recent years. different forms of system instability have emerged in recent blackouts, such as voltage instability and frequency instability. to counteract each form of system instability, special algorithms have been designed in the protection system, e.g. under frequency load shedding (ufls) and under vol...

Many procedures require size selection of DNA molecules for subsequent cloning or for other procedures. If the desired DNA fragments are of a known specific size, then one can easily cut the required band from a gel and extract the DNA; there are many effective methods to purify DNA from the small piece of agarose that contains the band. It is much less convenient if one needs to select molecul...