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Math, OR & Optimization Modeling

Talk shop about modeling topics.

  • 119 Topics
  • 263 Replies
119 Topics
M
MZwanenburg
posted in Math, OR & Optimization Modeling
Job shop problem: capacity constraint and variable if production in time t

Hi all, I am creating a job shop scheduling model in AIMMS for my MSc thesis. The model plans jobs j of production orders i backwards from their due date. The main (nonnegative) decision variables are: StartTime(i,j) = the start time of production order i job j  EndTime(i,j) = the end time of production order i job j The only thing I still need to add is that capacity may not be exceeded. I have the following information: Capacity(j) = total capacity of job j in one time bucket Now I need some counter / variable looking like:x(i,j,t) = the amount processed of operation i, job j in time bucket t. Where time bucket 1 = [0,1], time bucket 2 = [1,2] et cetera. See the figure below for my current data, I want to retrieve the following x(i,j,t) values: x(1,COAT,1) = 0.5 (from 0 to 0.5) x(1,PRO,1) = 0.5 (from 0.5 to 1) x(1,PRO,2) = 0.7 (from 1 to 1.7) x(1,PW,2) = 0.3 (from 1.7 to 2)  x(1,PW,3) = 0.5 (from 2 to 2.5) Does someone have an idea on constraints to retrieve the values for x(i,j,t) a

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M
1 year ago
W
waishengEnthusiast
posted in Math, OR & Optimization Modeling
Problem on Solving Constraints Mapping

Good day all,I am one of the AIMMS beginners and would like to seek help upon my modelling project that I working on currently.The project is about “Production Planning Optimisation for a High Tech Company” where the company is producing 5 assemblies using 22 materials in the period of 30 weeks.The problem that I am facing while solving this model using AIMMS are as per below:Unable to solve the constraints 6 where at t=0, the onhand inventory must be equal to the input materials during the first week of assemble. The result shows infeasible solution as per below pictures.  I had attached the information of this project for better context. Note that, the similar question/model, can be solve by using python without having any error. And I had attached the reference link below for your reference and comparison. May I know the things that I should double check when running this model ?Appreciate that I can get the respond from you. Thank you. Regards,waisheng  reference link: https://medi

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MarcelRoelofs
AIMMSian
1 year ago
Jess Es
Jess EsGrand Master
published in Math, OR & Optimization Modeling
What we're reading (October 2022)

Hello everyone! Check out some interesting reads from the OR and optimization space that are making the rounds here...  Deforestation and World Population Sustainability: A Quantitative Analysis by Mauro Bologna & Gerardo Aquino (via Nature) Global Supply Chains Face Disruption Following Russia’s Invasion of Ukraine by the London business School (via Forbes) Do You Need a Prediction or a Prescription? by Zohar Strinka (via Analytics)  Feel free to share anything good you come across...especially if you or someone you know has published recently!

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Jess Es
2 years ago
L
LawrenceEnthusiast
asked in Math, OR & Optimization Modeling
How to select the maximum and minimum value of a variable

Good day All,I have a variable PW(t) where t is index from 1 to 24. What is the command to select the maximum and minimum value of PW(t) and also obtain its average.  Thank you. 

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L
2 years ago
D
DuMiExplorer
asked in Math, OR & Optimization Modeling
Gantt Chart question

Hello,I´m pretty new to Aimms. I tried to learn to create a Gantt Chart. So I downloaded th example and copied every step in my own program.My question is where can I see the created Gantt Chart after running the program ? Thx

651
gabiservidone
Administrator
2 years ago
H
HarmEnthusiast
asked in Math, OR & Optimization Modeling
Machine shop scheduling problem, how to introduce a binaray variable that shows if you have production?

Dear all,I'm quite new to Aimms, therefore I don’t know if my problem is easy to solve or a difficult one. My end goal is to be able to generate an automated production planning for a big pizza bakery. The machine shop scheduling example is in the direction for what I’m looking for, see the link below. https://how-to.aimms.com/Articles/473/473-ProductionPlanning-machinescheduling.htmlThe machine shop scheduling example determines the optimal machine and start time for each order, so that the makespan is minimized. I want to expand this model, so that more contraints can be added. An important binary variable for me is ‘DoYouHaveProductionInAPeriod(i,o,i_hc)’: do you have production at a certain machine i, for a spefic order o, at a certain time period i_hc. An example of a constraint that I want to add and using the variable ‘DoYouHaveProductionInAPeriod(i,o,i_hc)’ is if I have 4 workers available, only 4 machines can run at the same time → for each i_hc, sum((i,o),DoYouHaveProductionI

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luispinto
Administrator
2 years ago
L
LawrenceEnthusiast
posted in Math, OR & Optimization Modeling
Wind turbine Power Modeling with several mutually exclusive variables

Dear All, I want to model the power of wind turbine under different wind speeds with respect to the cut-in, cut-out and rated speeds. How can this be implemented in AIMMS. Please, kindly make your response comprehensive as i am new to AIMMS. Thank you. All the terms have been declared as parameters.  

1003
luispinto
Administrator
2 years ago
Jess Es
Jess EsGrand Master
published in Math, OR & Optimization Modeling
Topic of the Month: Using AI and ML with AIMMS

You may have noticed an item called “Incorporating AI/ML into models” in our recent Roadmap 2022 post. As you probably inferred, that’s Artificial Intelligence and Machine Learning we have in mind. For more on this topic, see also Gertjan’s post: Now we want to hear from you about this topic as we consider the possibilities. How do you (or would you) use machine learning in an AIMMS model? We would be glad to hear your real life examples or ideas as we develop this concept. The more details about your use case, the better! First 5 commenters on this post will get 10 trees planted in their name in the AIMMS Forest! And, of course, all respondents will get our heartfelt appreciation! Even if you don’t have something to say, go ahead and click “like” to let us know you were here ;)  

420
Jess Es
2 years ago
Jan-Willem
AIMMSian
Jan-WillemAIMMSian
published in Math, OR & Optimization Modeling
How the AIMMS SC app developers use automated testing

Recently I spoke about automated testing with my colleagues who are developing our off-the-shelf supply chain apps.How and how often do you run the automated tests?Each time we commit AIMMS code to our code repository in Gitlab, an automated pipelineruns our entire test collection. Around 15 minutes later we will know whether any tests failed as a result of the latest code changes.How many tests are in that test collection?We have unit tests and end-to-end tests. For the unit tests we use the AIMMS UnitTest library. For the end-to-end tests we are using a proprietary framework that has been developed in-house and that is being used by several AIMMS teams. For Network Design, for example, we currently have over 450 unit tests and over 400 end-to-end tests, offering us a coverage of about 85%.That is quite an investment, all those tests. What do you get in return?Oh, we get a lot in return. First of all, it makes us feel very confident when we are changing or refactoring code. We cannot

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Jan-Willem
AIMMSian
2 years ago
S
samloboExplorer
asked in Math, OR & Optimization Modeling
maximization argument in a minimisation objective Value

Hi All,I would like to write the following equation in my objective variable in AIMMS. I cannot manage to insert a correct notation for the max argument that works. I want to pick the v with the highest value for Zkpv, and minimize this value. My current objective (without the max argument) variable looks like this at the moment.Could somebody please help me? Kind Regards

682
S
2 years ago
D
Dick den HertogEnthusiast
published in Math, OR & Optimization Modeling
Event: Analytics for a Better World Conference (June 1, 2022)Event

Conference Analytics for a Better World | Amsterdam | June 1, 2022  The Amsterdam Business School and analytics and technology company ORTEC have founded the Analytics for a Better World (ABW) Institute in collaboration with Professor Dimitris Bertsimas of the Massachusetts Institute of Technology The institute will work with NGOs, governments and non-profit organizations to contribute to the Sustainable Development Goals of the United Nations such as no poverty, good health and well-being and climate action using data and analytics.» Register now» To the conference websiteConference Analytics for a Better World | Amsterdam | June 1, 2022 About the Conference Who should join? Why should you join? Participation and registration Programme (timezone CET) Register now To the conference website About the ConferenceOn June 1, 2022 (between 14:00-17:10 CET) we are organizing a launching conference to bring together our key partners, researchers and (potential) sponsors. Our aim is to in

440
D
2 years ago
Jan-Willem
AIMMSian
Jan-WillemAIMMSian
published in Math, OR & Optimization Modeling
Call for feedback: Machine Learning and other AI technologies with AIMMS

From quite some AIMMS app developers we have heard demand for ‘enabling AI/ML’ in AIMMS or ‘Run AI/ML, extending the AIMMS platform’. We have ideas how we could indeed deliver this to you. For example:Making it easy to ‘add’ a Python script/program to your AIMMS project that can be fed with model data and from which the results can be returned to AIMMS identifiers. We can think of various ways to run such a Python script, think of Azure Function or maybe as a Docker container, etc.. Making it easy to call ready-to-use services such as ‘Azure Machine Learning’ from your AIMMS model, including the transfer of model data to and from that service.But before we make too many assumptions and start building functionality, we would like to learn more about your needs and expectations.So please tell us: How do you expect AIMMS to support you in applying Machine Learning and other AI technologies, apart from optimization, in your projects? And there is the broader topic. AIMMS has historically f

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Jan-Willem
AIMMSian
2 years ago
Ovidiu Listes
AIMMSian
Ovidiu ListesAIMMSian
published in Math, OR & Optimization Modeling
OptiCL: A Python Package for Mixed-Integer Optimization with Constraint Learning

Herewith we would like provide some information on behalf of our partners from the OPTIMAL project introduced in one of our previous posts. More specifically, this post is about the OptiCL package developed by the researchers at OPTIMAL for Mixed-Integer Optimization with Constraint Learning. At AIMMS, we are exploring capabilities such as those provided by the OptiCL package and are looking forward to feedback on this matter from the AIMMS Community. We are especially interested in potential use cases and interests for conducting pilot studies in this area.The increasing availability of data has led to the rise in data-driven decision making. One area of data-driven decision making that is becoming increasingly popular is constraint learning [1]. Many real-life optimization problems contain one or more objectives and/or constraints for which there are no explicit formulae. In such cases, machine learning models, which are good at determining complex decision boundaries, can be used to

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Ovidiu Listes
AIMMSian
2 years ago
Ovidiu Listes
AIMMSian
Ovidiu ListesAIMMSian
posted in Math, OR & Optimization Modeling
Optimization for and with Machine Learning (OPTIMAL)

We are currently exploring opportunities for combining Optimization and Machine Learning through collaboration with the OPTIMAL consortium which carries out a large research project entitled "Optimization for and with Machine Learning".The goal of this project is to provide new analysis and tools for Optimization problems and algorithms arising in Machine Learning, but also to use insights and tools from Machine Learning in order to improve Optimization methods.For more information on the OPTIMAL project please visit the site https://optimal.uva.nlWe will try and provide updates on our exploration through more specific posts on this forum.

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Ovidiu Listes
AIMMSian
2 years ago
Z
zulfan.adiputraEnthusiast
posted in Math, OR & Optimization Modeling
Error in Softdrink planning tutorial for professional

Hi,  I’m new to AIMMS and I’m following the tutorial for professional. I’m in page 80 now and while running the procedure ‘ReadFromDatabase’, I encounter an error saying, “Executing SQL query "TotalDemand" of database procedure "TotalDemandQuery" failed: ODBC[-3500] : 42000 [Microsoft][ODBC Microsoft Access Driver] Invalid SQL statement; expected 'DELETE', 'INSERT', 'PROCEDURE', 'SELECT', or 'UPDATE'. [while calling the query TotalDemand].” I don’t understand this error as the tutorial does not say anything on this issue and I think I’ve followed the tutorial completely.  Any help, please?  

582
Z
2 years ago
Jess Es
Jess EsGrand Master
published in Math, OR & Optimization Modeling
UniSoma's Gabriela Servidone on Making the Most of WebUI Usability FeaturesInterview

Gabriela Servidone, AIMMS modeling expert at UniSoma, explains why she started studying usability and how it has changed her approach to projects with customers. She also shares how she and her colleagues transitioned customers into WebUI apps, and why she is excited about using WebUI to its full potential. A lot of developers struggle with making their model easy to use for a typical end user. How did you start learning about usability concepts? I read a few books about usability. I was able to understand the main concepts, and I use them every day in my work. When you read these, at first it seems obvious. You wonder why it needs to be written. But, in your daily work you forget these simple things. For example, if you have buttons Cancel and OK, and they are in the "wrong" or unusual position. This little detail makes it really hard for your users!  So, it's worthwhile to review these fundamentals and really try to follow them. And it doesn't just mean the UI. I presented recently a

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luispinto
Administrator
2 years ago
I
IkiniwiExplorer
asked in Math, OR & Optimization Modeling
Warning : FOR loop nested statement unnecessary.

Hi,I have the following warning : Usage of directly nested for statements is unnecessary and inefficient.How am I supposed to write this code to avoid the warning ? for gdm::iNode do    for (gdm::iTime in gdm::calHorizon) do        p1(gdm::iNode):=p2(gdm::iNode,gdm::iTime)*p3(gdm::iNode) ;     endfor;endfor; Thank you 

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I
2 years ago
G
Guus KattenbeltEnthusiast
asked in Math, OR & Optimization Modeling
Standardize link to latest version

Hi all,Every time we update our app, I get e-mails from users that they cannot enter the app and they send me a picture like the one below. We have tried to prevent this from happening by using the ‘latest’ tag option. All links in our information channels link to our app ending with the ‘/tag/latest’ such that they always end up at the right version of the app. But still I get a lot of these e-mails.Mostly this is because, once people have entered the app, they bookmark it (or store the url) and use this bookmark later on. The problem is that once they bookmark it, the url has changed to the current version name and therefore the link doesn’t consist of this latest tag anymore. And thereby causing the problem of the picture below after a new update of the app. I always reply back that they should use the link with the latest tag in there, but as we have a lot of users, this keeps happening. It would be great if there could be a solution, such that my users don’t have be annoyed by the

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Jan-Willem
AIMMSian
2 years ago
Gertjan
AIMMSian
GertjanChief AIMMSian
published in Math, OR & Optimization Modeling
Using Machine Learning in AIMMS for better Decision Making

Why this articleIn this article, we will explain how Machine Learning and AIMMS can work together to complement the mathematical modeling and optimization capabilities of AIMMS as decision support technology. Why? Because we see an increasing need by our customers to understand its potential. Also, we notice that some users feel they need to choose between one or the other when creating decision support systems. We believe the combination is more powerful. This is also why we make it possible for customers to integrate scripting languages like Python and R with AIMMS models.We will start with a brief introduction to AIMMS and the various disciplines for better decision making (optimization, machine learning and business rules). Hereafter, we explore both machine learning and optimization as techniques, followed by how optimization- and thus AIMMS and AIMMS users - can benefit from machine learning. The idea is not to fully explain the two techniques (there are various resources online)

27422
S
3 years ago
A
aims_userExplorer
asked in Math, OR & Optimization Modeling
sorting a multiple dimensional array by values with in it

Hi Aimms Community,  I’m having trouble using the Sort function in order to obtain the values of a mulit-dimensional array: For example:multi-dimensional array = foo(size,car,color,location)             size, car, color, location = some float value [ ‘small’, ‘toyota’, ‘white’, ‘usa’] = 1.25 [ ‘small’, ‘toyota’, ‘green’, ‘greenland’] = .5 [ ‘small’, ‘nissan’, ‘blue’, ‘france’’] = 1.0[ ‘small’, ‘nissan’, ‘green’, ‘france’’] = .3 In this case we are looking to sort foo by the values for all colors and locations where the size and car are the same, meaning that the result would be put into another variable  bar(size,car,row)[ ‘small’, ‘toyota’, 1] = .5[ ‘small’, ‘toyota’, 2] = 1.25[ ‘small’, ‘nissan’, 1] = .3[ ‘small’, ‘nissan’, 2] = 1.0 How do I approach this problem? I looked through the documentation but I see that the Sort operator is really trying to sort by an index of an array and not the values for given indexes.  Thanks for any help

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Chris Kuip
AIMMSian
3 years ago
B
BimboExplorer
asked in Math, OR & Optimization Modeling
Unit Commitment

Hello everyone,I am new to AIMMS, I am trying to solve a unit commitment problem with four thermal generator units and a PV unit. I have added the four generators in a set  with index (u) with all their parameters in the model. Now, I want to add another source of power supply which is PV as a fixed parameter, that is, constant power output. How do I add and index the PV  as it’s also a generating unit but with different characteristics? This would also affect my power balance constraints of sum of total power supply equal to load demand. 

762
B
3 years ago
Mstislav Simonenkov
AIMMS Champ
Mstislav SimonenkovAIMMS Champ
posted in Math, OR & Optimization Modeling
Applying AIMMS Community Edition for fire ponds and access routes layout optimisation

We solved the MIP optimization model. The characteristics of the models and solution times are given in the table below. We used SQLServer Express for data ETL purposes. Input and output data published in two datasets (Dataset: Podporozhye, Dataset: Estonia) in the MendeleyData repository. We will present the results at the IECF2021 conference in September.   Estonia Podporozhye Constraints 2904  3203 Variables 2760 3112 Binary 2759 3111 Nonzeros 36890  20174 CBC, s 1.78  3.75  What is of interest to us as AIMMS users in this case study? The use of AIMMS Community Edition with open solver CBC to find solutions for scientific problems in the first approximation. In other words, AIMMS Community Edition allows us to test different models of the problem on a small data set.    @bacherikov_iv , @anastasiiasimonenkova   Thanks to AIMMS B.V. for providing the lic

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Gertjan
AIMMSian
3 years ago
M
mglopesExplorer
asked in Math, OR & Optimization Modeling
Using a parameter as index (nested indexes)

Hi all,I’m sorry of the question is too basic, but I recently had to re-run an old code (originally developed in AIMMS 4.47) and I’m having lots of trouble correcting errors.I have a variable ( Ireal(ld) ) that uses another variable ( Vreal(bus,ph) ) in its calculation.I have an string parameter ( load_bus(ld) ) that has the “bus” value for each “ld” and a parameter ( load_ph(ld) ) that has the “ph” value for each “ld”.In  the old code I used Vreal(load_bus(ld), load_ph(ld)) to calculate the Ireal(ld), but in the new AIMMS version (4.88) I keep getting “The scope of string parameter “load_bus” has not been specified”.Can anybody please help me in what I’m missing?Thank you in advance.

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Chris Kuip
AIMMSian
3 years ago
M
mglopesExplorer
asked in Math, OR & Optimization Modeling
Lauching AIMMS through AIMMSSelector with cloud licensing

Hi all,I'm a researcher and I use AIMMS with an Academic License.AIMMS is part of a routine I developed in Python and I used the "AIMMSSelector" to launch AIMMS, but since my license is now a cloud license I've not been able to launch AIMMS that way, it does not recognize the license, and only give me option to add a stand alone license or a network license server.I've been searching for materials regarding this, but couldn't find any. Can you help me? Here is the code I used to launch AIMMS previously:#Initialize AIMMS        sys.argv = ["makepy", "AimmsSelector.Selector64"]        AimmsObj = win32com.client.Dispatch("AimmsSelector.Selector64")        self.AimmsProj = AimmsObj.GetAimmsProject(f'{self.aimmsFileDir}\\{self.aimmsFileName}')        self.AimmsProj.StartupMode = 1 #Start minimized        self.AimmsProj.ProjectOpen(f'{self.aimmsFileDir}\\{self.aimmsFileName}', 0)

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M
3 years ago
G
Gloria QuintanillaFormer AIMMSian
published in Math, OR & Optimization Modeling
Prof. Chiara Bordin Offers An Insider’s Look into the Field of Energy InformaticsInterview

AIMMS has long been in the toolbox of energy modelers. With the field undergoing a lot of change today, we were curious to hear from someone who is at the forefront of both energy modeling and one of the biggest challenges of our time: a transition to low-carbon energy systems. We had the pleasure of speaking with Chiara Bordin, Associate Professor of Energy Informatics at UiT, the Arctic University of Norway.Can you tell us a bit about yourself and your background?I am originally from a small town near Bologna, Italy. I did my master’s degree at the University of Bologna, as well as my PhD. In the last year of my PhD, I had the opportunity to spend some time as a visiting researcher in a foreign university and I decided to go to Durham University, in the UK. There was a lecturer there who was doing very interesting things in energy systems modeling. I felt that working with him would be a good experience, so I went there as a visiting student. I ended up staying there for the full yea

15550
G
3 years ago
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