49928: Design Optimisation for Manufacturing Assignment 4
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49928: Design Optimisation for Manufacturing
Assignment 4: Discrete Optimisation
Due: 11:59 pm Friday 03/11/2023
Solve the following two problems with both exhaustive enumeration and branch and bound
The assignment is worth 20 marks in total (20% of your final mark for the subject)
Exhaustive enumeration is worth 4 marks for each problem, branch and bound is worth 5.5 marks for each problem, there is also 0.5 mark for self-assessment for each problem.
Problem 1 is a mixed integer linear optimisation problem (the problem has both
discrete and continuous variables). Do not use intlinprog (from MATLAB) to solve this problem, for exhaustive enumeration solve it by enumerating through the discrete
variables and then use linprog to find the continuous variables. For branch and
bound use linprog or Excel Solver to find the partial solutions.
Problem 2 is a discrete nonlinear optimisation problem. For branch and bound use fmincon or Excel Solver to find the partial solutions.
Write a report including all of the followings for each problem:
For exhaustive enumeration method: how many evaluations were needed for exhaustive enumeration (1 mark)? Submit your MATLAB code for exhaustive
enumeration (2 mark). Find the optimal solution (1 mark).
For branch and bound method: What path did the search take for branch and bound (1 mark)? How many partial nodes were needed for branch and bound
(1 mark)? Draw the trees for branch and bound (3 mark). Find the optimal
solution (0.5 mark).
For self-assessment: after completing the assignment self-assess your work
according to the marking criteria, give a final mark and reason (require to
explain why you give this mark). (0.5 mark)
Problem 1 (10 marks)
Minimise:
f = 2x1 − 6x2 + 3x3 + 4x4 + 7x5 + 3x6 + 2x7
Subject to:
g1 = x2 + 5x3 + 3x4 − x5 + 2x6 + 3x7 ≥ 65
g2 = −6x1 − 3x2 − 2x3 + x4 + 2x5 − 2x6 ≥ −73
g3 = −7x1 − 4x2 + 3x3 − 4x4 + 3x5 − 2x6 − x7 ≤ −66
x1, x2 ∈ {2,5,7,8}, x3, x4 ∈ {3,4,6}
x5, x6 ≥ 0, x7 ∈ R
Problem 2 (10 marks)
An I-beam is shown in the figure to the right. Given the following equations and constraints, develop a mathematical model and find the dimensions of a beam with a minimal cross sectional area.
And subject to the following constraints on plate thickness and width:
x1 : 38, 40, 41
x2 : 1.9, 2.2, 2.4
x3 : 28, 30, 33
x4 : 1.1, 1.3, 1.5
2023-11-02
Discrete Optimisation