public void processOtherEvent(Sim_event ev) {
    	double currentTime = GridSim.clock();
    		
    	if(ev.get_src() == myId_ && ev.get_tag() == EXPIRY_TIME) {
    		if(currentTime > lastCheckExpiryTime) { 
    			checkExpiryTime();
    			lastCheckExpiryTime = currentTime;
    		}
    	} else {
    		super.processOtherEvent(ev);
    	}
    }