Dear authors and readers, We are completing volume 5 no. 2 with this issue. After the first four years with semestrial publication we are now moving out to trimestrial publication pace (four issues per year) starting next year. Looking back to these four years, we would like to thank you authors and readers for your contribution and interest in our new journal. Year by year, the level of the paper has increased and the content diversified. Moving to four issues per year, means that we need more paper entries. Part of them will come from OPTIM bi-annual international conferences (the next on May 19-21, 2006, www.optim.8m.com, deadline December 1st 2005). I also take this opportunity to ask potential authors to send more papers with strong experimental results, besides digital simulations. Ph.D. Students in their advanced stages and fresh Ph. Ds. are invited to send sound papers (from parts of their thesis) to the Journal. I hope you will find this issue interesting and we urge you to visit also the New books section of our site, and eventually send new books reviews for us to upload. Sincerely, Ion Boldea JEE.ro