Separation

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==Definition==
==Definition==
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Separation is an [[optimization]] approach that replaces a design optimization problem with a set of subproblems.  It then solves each
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Separation is an [[optimization]] approach that replaces a design optimization problem with a set of subproblems.  Thus, it is a type of problem [[decomposition]].  It then solves each
subproblem once in order to generate a feasible solution.  Ideally, separation produces an optimal solution to the original problem. However, not all separations do.
subproblem once in order to generate a feasible solution.  Ideally, separation produces an optimal solution to the original problem. However, not all separations do.
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The concept of separation is similar to the idea of [[decomposition]]. Both replace a large design optimization
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Separations are similar to decomposition-based design optimization methods, because they all replace a large design optimization
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problem with a set of subproblems.  In a typical decomposition approach, a second-level problem must be solved to coordinate the
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problem with a set of subproblems.  Decomposition-based design optimization methods solve a second-level problem to coordinate the
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subproblem solutions in an iterative manner.  Separation does not require this iteration.
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subproblem solutions in an iterative manner.  Separations do not require this iteration or coordination.
A separation may use a simple sequence of subproblems, a set of subproblems that are solved in parallel, or a more complex network of subproblems.  
A separation may use a simple sequence of subproblems, a set of subproblems that are solved in parallel, or a more complex network of subproblems.  

Current revision

Definition

Separation is an optimization approach that replaces a design optimization problem with a set of subproblems. Thus, it is a type of problem decomposition. It then solves each subproblem once in order to generate a feasible solution. Ideally, separation produces an optimal solution to the original problem. However, not all separations do.

Separations are similar to decomposition-based design optimization methods, because they all replace a large design optimization problem with a set of subproblems. Decomposition-based design optimization methods solve a second-level problem to coordinate the subproblem solutions in an iterative manner. Separations do not require this iteration or coordination.

A separation may use a simple sequence of subproblems, a set of subproblems that are solved in parallel, or a more complex network of subproblems.

A separation provides a way to reformulate a design optimization problems and find a good solution. It is important to carefully design the separation to provide a valuable solution, and the quality of the solution that results depends upon the constraints and objectives used in the subproblems. A separation may be able to find a feasible solution in less time.

References

  • Karimian, Peyman, and Jeffrey W. Herrmann, "Separating Design Optimization Problems into Decision-Based Design Processes," Journal of Mechanical Design, Volume 131, Issue 1, 011007, January 2009. [1]
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