SUBJECT: Ph.D. Dissertation Defense
   
BY: Aleksandr Kerzhner
   
TIME: Monday, April 23, 2012, 9:00 a.m.
   
PLACE: Love Building, 210
   
TITLE: Using Logic-Based Approaches to Explore System Architectures for Systems Engineering
   
COMMITTEE: Dr. Chris Paredis, Chair (ME)
Dr. Leon McGinnis (ME)
Dr. Bert Bras (ME)
Dr. Godfried Augenbroe (COA)
Dr. Charles Eastman (COA)
 

SUMMARY

This research is focused on helping engineers design better systems by supporting their decision making. Current systems engineering practices try to simplify the design process by providing practical approaches to managing the large amount of knowledge and information needed during the process. Although these methods make designing a system more practical, they do not support a structured decision making process and instead rely on designers using ad-hoc frameworks. A framework for performing architecture exploration at early stages of the design process is presented. The goal is to support more rational and self-consistent design making by allowing designers to explicitly represent their architecture exploration problem then use computational tools to perform this exploration. To represent the architecture exploration problem, an information modeling language is presented which explicitly models it as an architecture selection decision. This language is based on the principles of decision-based design and decision theory, where alternatives are selected based on most preferred expected outcome. The language is designed to capture potential alternatives in a compact form, analysis knowledge to predict the quality of a particular alternative, and evaluation criteria to rank outcomes. This language is based on the Object Management Groupís System Modeling Language (SysML). A framework for modeling an architecture selection decision in mixed-integer linear programming (MIP) is also presented. MIP solvers can then solve the problem to identify candidate architectures. Mathematical programming is a common optimization domain, but it is rarely used for architecture selection because of the difficulty of manually formulating an architecture selection problem as a mathematical program. To address this issue, the formulation is presented in a modular fashion along with model transformations that transform the more compact SysML representation into the MIP formulation. The overall framework is demonstrated on the design of an actuation subsystem for an excavator. This example is chosen because of the variety of potential architecture embodiments and also a plethora of well-known configurations which can be used to verify the results.