No abstract

The uptake of airborne laser scanned (ALS) data (commonly known as airborne lidar) for heritage landscape assessment has grown rapidly in the past decade as data have become increasingly available. Likewise there has been a recent upsurge in published techniques for modelling the ground surface from ALS data to highlight archaeological features. However, many end-users of the data are not trained in remote sensing and visualization techniques and the lack of comparative assessment of techniques has increased the complexity of interpretation of the ALS-derived models. This study quantitatively compares five visualization techniques ranging from the commonly used shaded relief model to newer local relief and sky view factor modelling for a study area in the UK. Outputs are compared with the baseline data of the English Heritage National Mapping Programme aerial photographic archive transcription and assessed with respect to percentage visibility of feature length. Ancillary aspects of the outputs are discussed, such as geospatial shift of features, suitability for profile mapping, ease of interpretation and ability to combine with other data sources. It is concluded that although the overall performance of the models in terms of feature recognition is relatively even, consideration of all factors enables more transparent modelling choices to be made and facilitates critical interpretation of the features recorded.

This paper describes a pragmatic method of searching for the key inputs to a system dynamics model. This analysis is known as screening. The goal is to learn which of the many uncertain inputs stand out as most influential. The method is implemented with readily available software and relies on the simple correlation coefficient to indicate the relative importance of model inputs at different times in the simulation. The screening is demonstrated with two examples with step-by-step instructions. The paper recommends that screening analysis be used in an iterative process of screening and model expansion to arrive at tolerance intervals on model results. The appendices compare screening analysis with analytical methods to identify the key inputs to system dynamics models.

No abstract

System dynamics has been used extensively to aid in resource planning in the electric power industry. The many applications constitute a major body of work that has proven useful to large and small power companies as well as to government agencies at the local, state and federal level. The work has been performed by utility analysts, government planners, consultants and academics. One of my recent publications on electric power was honored with the 1996 Jay Wright Forrester Award. This article documents the major points in my award address to the 1996 International System Dynamics Conference. It summarizes the impressive body of work that system dynamics practitioners have accumulated over the past several decades. It gives my interpretation of the important and unique features of the system dynamics approach. I argue also that we have contributed to useful change in the electric power industry. © 1997 by John Wiley & Sons, Ltd.