One embodiment of the present invention provides a system that facilitates measuring quality-of-service of a computer network server or collection of servers by determining the effect that transactions in one category of service have on transactions in other categories of service. In use a rigid substrate such as a sidewalk is selected, and a primer is applied. The word clock indicates a word delimiter in the serial data. The fuel injector comprises a groove. The fan provides sufficient volumetric airflow such that a velocity of the volumetric airflow through the slits is greater than a terminal settling velocity of a predetermined particle size.