List of Articles Cost optimization Open Access Article Abstract Page Full-Text 1 - Cost and sensitivity analysis of transient Markovian queue with waiting server, heterogeneous vacation policy and reneged customers Mayank Singh Madhu Jain Arumugam Azhagappan Open Access Article Abstract Page Full-Text 2 - Vacation model for Markov machine repair problem with two heterogeneous unreliable servers and threshold recovery Madhu Jain Rakesh Kumar Meena