Diodes Inc., a supplier of high-quality discrete semiconductors, announced it has signed a distribution agreement with Rutronik Electronic Components GmbH, of Ispringen, Germany.    . . .    Rafael Ramirez was appointed sales manager, Latin America northern territory, at Infinova, a Monmouth Junction, N.J., manufacturer of closed-circuit TV and fiber optic equipment. Ramirez has been in the security/surveillance industry for 10 years.    . . .    "Empower Your Next Design" is the theme of the 2005 Analog Power Management Seminar Series, hosted by National Semiconductor Corp.'s Analog University. The one-day intensive technical seminars will be held March 10 through March 22 in two locations in Japan and two in Asia-Pacific. The seminars will also be available this fall at locations in the Americas and in Europe. For details, visit: www.national.com/analogseminars