Part II of this report details the specific research accomplishments of the program on a year-to-year basis. In order to provide a consistent context and framework for understanding this detail, we have attempted to outline the major activities of the program as they unfolded over the course of the past two decades. The timeline on the following page shows the major activities broken down into two main categories—laboratory studies and outdoor testing/systems analysis. For the sake of clarity and brevity, many of the research projects and findings from the program are not presented here. Instead, only those findings that form a thread throughout the work are highlighted. There were many other studies and findings of value in the program. The reader is encouraged to review Part II of this report for a more comprehensive discussion of the research.