Sabrin Rashwan
I am currently pursuing a Master`s degree in operation research. In particular, my Master is about optimizing a variant of vehicle routing problem (VRPs).
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Activity overview
Latest activity by Sabrin Rashwan-
Sabrin Rashwan commented,
@Xianbang and @ Jaromił , thanks a lot for your prompt response. Jaromił, thanks to your reply I paid attention to a specific point in my model in general. As Jaromił has mentioned and by try and...
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Sabrin Rashwan created a post,
How to get a more compacted version of some constraints?!
AnsweredDear all, I have the next information: R = [1,2,3,4,5] # no of requests rb = {1:1,2:-1,3:-1,4:1,5:1} # takes 1 or -1Cr1 = {1: C[0:3], 2:C[3:6], 3:C[6:9], 4:C[9:12], 5:C[12:15] }Cr2 = {1: C[15:18],2...
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Sabrin Rashwan commented,
Dear Jaromil, I have some good news. My basic model is working perfectly now and so is the Arc-elimination-based model. with arc elimination I realized higher speed reaching a gap of 8% within 600 ...
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Sabrin Rashwan commented,
Dear Jaromil, That is great. I have got your idea Jaromil and will use M = 3000. With my best wishes, Sabreen
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Sabrin Rashwan commented,
Dear Jaromil, Now I got all the bounds: max min t[I,j] 824 0 B 1745 50 Bk 2000 0 d 30 15 D 529 0 I isolated M for each constraint, in order as follows: M ...
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Sabrin Rashwan commented,
Dear Jaromil, hereafter are the perfect constraints that include the Big-M. I succeeded to calculate the bounds of the variables but failed to get the values of the D variable. If you can help me g...
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Sabrin Rashwan commented,
Many many thanks Jaromil, you always support me. I am preparing the required data. Will come soon. Regards, Sabreen
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Sabrin Rashwan created a post,
DARP: How to correctly calculate the Big-M value that exists in two inequalities?
AnsweredThe formulation includes a Big-M . Actually I am not sure of how to calculate it perfectly. I am sharing my calculations hereafter. This Big-M does exist in two inequalities. I can share the ineq...
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Sabrin Rashwan created a post,
Saved Log File of a MIP model: Read, Recall, Analyze
AnsweredI have programmed code for optimizing a vehicle routing problem. I have limited the runtime to 2 hours and saved the log to a file ''L2.log''. After obtaining the result I closed the spyder interfa...
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Sabrin Rashwan commented,
Dear Jaromil, Thanks a lot for your support. I will find how to understand that .lp file to analyze it correctly. For now, I think I have to return a step back to the basic model. I discovered an i...