Teodor-Viorel Chelaru and Mircea Cernat
The purpose of this paper is to solve the Dynamic Launch Zone (DLZ) problem for air-to-air homing missiles, by finding a numerical solution through integration of the nonlinear equations of the motion of the missile and target. To build the mathematical model of the real process we used experimental data of missile aerodynamic and thrust, mechanical measurements. The complex mathematical model includes a dynamic equation system with six degrees of freedom (DOF) and a guidance law, experimentally validated. By integrating the complex mathematical model we obtained the flight parameters for some significant cases and the DLZ for several tactical situations of aerial combat. The conclusions point to the altitude influence on DLZ configuration and the relevance of the input data on model precision.
Ron Caro, John Quinn, Douglas Harvey, and Lisa Mentz
This study describes the effects that knowledge flows had on a community of practice (CoP) that consisted of a highly distributed network of monitors tasked with maintaining a very large, dynamic, and complex communication network during Operation Iraqi Freedom. This communication network spanned hundreds of square miles and supported U.S. forces and coalition forces that went from 700 to over 80,000 personnel in four months. Prior to the commencement of Operation Iraqi Freedom, these network monitors were communicating and sharing information via different media in combination with an obsolete physical logbook-based knowledge management System (KMS). This caused the CoP to be reactive in maintaining this vast communication network. In addressing this problem, the First Marine Expeditionary Force communication Marines developed a virtual real-time KMS that collected over 8,000 log entries in 5 months. This KMS, called the MEL (Marine Air Ground Task Force Communication Control Center Event Log) was utilized in raising and troubleshooting network issues that are prevalent in maintaining any large communication network. Triangulation and analysis of the multiple interviews, audiovisual material, archival records, and documents formed the basis for the four findings of this study. First, the CoP utilized the MEL as an initial troubleshooting forum and as a starting point for sharing information and problem solving strategies regarding the operation of the network. Second, the CoP did not display social interactions in the use of the MEL throughout the study. Third, the CoP significantly relied on other media outside the use of the MEL, making the MEL one of a number of ways to communicate within the CoP. Fourth, the reliance on other forms of communications increased during the stress of combat operations..
Michael Tyson, Carlo Kopp, and Ronald Pose
Urban canyon environments represent a significant challenge to wireless communications, a satisfactory solution for which remains to be proven. We present RF Propagation Environment Awareness (RPEA), utilising ‘smart’ ad hoc, or self-forming and self-healing networks that are capable of storing and exploiting local propagation geometry information. An empirical radio propagation environment model, comprising a loss model specific to the local urban topology, is used to optimise network operation. This model is constructed over time from prior experience operating in the area of interest, and can be used to estimate the lifetime of a wireless connection, given current node kinematic behaviour, and location relative to attenuating objects in the environment. This lifetime can in turn be used to evaluate Quality of Service parameters for network routes, and to select optimal routes with the longest lifetime. We propose one technique to learn about the RF propagation environment, and evaluate the utility of RPEA.
Alan C. McLucas
Despite the growing body of knowledge regarding software engineering and management of projects involving software development or integration, such projects frequently overrun cost and schedule estimates by a factor of two or more. In the first part of this two-part series, it was argued that conventional methods of estimating the effort involved in software development projects are flawed because they do not take rework into account, or at the very least are unable to accommodate reliably the need for rework effort. Rework impacts upon almost every aspect of software projects, from the earliest stage when requirements are being captured, through to final acceptance testing. How rework impacts upon each phase of the project, and the project overall, is identified through the use of a dynamic simulation coupled with scenario planning. Using the approach described in this article, managers of projects involving software development can identify where management and engineering efforts are best directed, before committing to delivering a project which subsequently proves unexpectedly costly or involves undue risk.
