Setup SCORE

SCORE, short for Simulation-based COnstraint REmoval, is a methodology developed for identifying and sequencing bottlenecks of production systems while at the same time suggesting counter measures of how to remove those bottlenecks. Using Simulation-based Multi-objective Optimization (SMO) constraints of a system are systematically relaxed (i.e. an improvement is done that elimiates the constraint) while the performance of the system is measured with the goal of maximizing the performance (e.g. throughput) of the system with as few improvements as possible.

In it's simplest form processing times, availabilities and repair times are considered as potential causes for bottlenecks. However, the methodology is applicable to a wide range of other causes of bottlenecks, e.g. quality deficiencies and lack of resources. These parameters are added as optimization input variables with two levels, the original value and an improved value where the constraint is removed.

The SCORE optimization problem can be described as follows:

max

Throughput

min

Sum_i I_i

subject to

`I_i ∈ {0, 1}, where`	`I_i = 0 iff x_i = original value_i`
	`I_i = 1 iff x_i = improved value_i`

x_i ∈ {original value_i, improved value_i}

i = 1,...,N, where N is the total number of improvements

Upon exit from this dialog (using the -button) this optimization problem will be added to the optimization dialog, where variables x_i will be added as inputs and variables I_i will be added as Custom Outputs under Formulas.

This dialog will help with the setup of such an optimization problem by creating SCORE Groups.

Note: Results from a SCORE optimization is visualized with a SCORE Frequency Diagram.

-button adds default SCORE Groups for processing time (20 % reduction), availability (set to 100 %) and repair time (reduced by 50 %).

-button removes all default SCORE Groups.

-button adds a new SCORE Group.

-button removes all SCORE Groups.

-button enabled once all defined SCORE Groups are valid and once pressed it will setup the SCORE optimization problem.

-button used to Cancel the setup of SCORE.

SCORE Group

A SCORE Group is used to define improvements used as optimization inputs in the SCORE optimization problem described above. In general terms an improvement is a change from an original value to an improved value where the direction of the change is depended on the type of variable that is being improved. Improvements are defined by the settings seen in the image to the right and described below.

Note: If a SCORE Group is red as in the image at the top of the page it indicates that some setting is missing. By hovering over the red part a tooltip will appear including informaiton about what is missing.

Setting

Description

Object type	Selection of the object type for this improvement, i.e. what type of object that this improvement should be added for.
Variable type	List of all optimization variables available for the selected object type. This selection will determine what variable that should be improved.
Improvment type	This will determine the type of improvement as one out of three types: ABSOLUTE - The `improved value` is calculated as an absolute offset from the `original value`. RELATIVE - The `improved value` is calculated as a relative offset from the `original value`. FIXED - The `improved value` is fixed (same for all input variables of this SCORE Group) and independent of the `original value`.
Improvement direction	Determines what direction is considered an improvement for the selected variable type. POSITIVE - An increase of the `original value` is considered an improvement, e.g. the case for availability. NEGATIVE - An decrease of the `original value` is considered an improvement, e.g. the case for processing time.
Improvement	Parameter used to calculate the `improved value`. It's meaning is determined by the selected Improvement type: Improvement type = ABSOLUTE - This parameter is the absolute offset used to calculate the `improved value`. Improvement type = RELATIVE - This parameter is a percentage value used to calculate the size of the improvement as a percentage of the `original value`. Improvement type = FIXED - This parameter is the actual `improved value`.
Steps	The number of incremental steps the improvement should be split in, i.e. how many steps of improvements it should be from the `original value` to the `improved value`. Default value 1. In the optimzation problem these improvement steps are normalized between 0 and 1, where 0 represents the `original value` and 1 represents the `improved value`.
Limit	Optional parameter used to limit the improvement and possibly exclude variables from improvement. If the `improved value` is better than this limit it will be capped to this limit parameter. On the other hand if the `original value` is all ready better than this limit the variable will not be added as an improvement.
	Button used to delete the SCORE Group.