STATUS: Currently Available
GENERAL OVERVIEW:
The IMAGE tool supports the analysis of functions in support of a Top Down Function Analysis and a Mission/Function Analysis. Analysis of functions involves identifying top level functions and associated requirements, and decomposing the functions in terms of the requirements. The requirements addressed in the decomposition of functions include:
Information/knowledge requirements – what the system must know and information needed by the system to enable conduct of the function, and required characteristics of information;
performance requirements – capabilities required of the system to complete the function;
decision requirements – decisions and decision requirements.
In the Mission/Function Analysis functions are identified and decomposed for specific mission scenarios. The missions to be assessed should comprise a representative sample of the missions for which the ship system is to be designed and the totality of missions should include most of the more important system requirements. The constituent elements of a mission scenario are as follows:
• mission objectives
• mission phases
• mission conditions (threats, logistics, conditions of readiness, tactical conditions,
operational conditions, environmental conditions)
• mission events by mission phase and scheduling of mission events
• criteria for mission success
• top level functions for the mission, and associated requirements
Based on the top level functions, system functions are identified and decomposed. System functions constitute the major activities to be performed by the system, at several layers of iteration, short of the level of specificity which requires designation of the means of accomplishing the function. The ship system HSI mission/function analysis will, for each system and scenario, identify functions to be performed and provide a functional flow block diagram depicting the sequence of functions for the system completing a mission scenario. The functions will be decomposed to successively greater levels of detail in an iterative manner based on requirements associated with each function.
APPROPRIATE USES:
IMAGE supports generation of mission scenarios, function decomposition, and identification of requirements associated with individual functions.
EQUIPMENT REQUIRED:
• Apple® Macintosh running Microsoft Office 98.
• IBM PC or Clone running Windows 98.
INPUTS REQUIRED:
Mission requirements, and legacy system functions.
PROCESSING TECHNIQUES: Mission and function requirements in Excel.
OUTPUT:
Display of results of a mission function analysis in tabular or flow chart format.
USES OF OUTPUT:
Input to ROMAN and I-TASK tools.
STAGE OF DEVELOPMENT: Complete
VALIDATION:
Being implemented in CIC manning reduction as part of the S&T Manning Affordability initiative.