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Share your favorite OR Blogs

Good afternoon!I would like to invite the community to share their favorite blogs on mathematical programming, operations research, and data manipulation.My favorite blog is http://yetanothermathprogrammingconsultant.blogspot.com/The author of the blog uses GAMS. Models created in GAMS can be conver...

Developers (Math, OR, programming)

How to write Floor or ceiling Function?

Hi,I want to write a floor function in my model.Or how to get floor value of a fractional number?how can i write that in AIMMS?

Developers (Math, OR, programming)

Not getting correct results for leading times, phasing in capital and life of plant

The data for leading times, phasing in capital and life of plant was imported to the model. A new declaration called Lead times was added. It looks like this: All the identifiers in the Lead Times declaration are supposed to take care of the leading times, phasing in capital and economic life. Howev...

Developers (Math, OR, programming)

Error when importing percentage data from Excel to an AIMMS model

I have been trying to import the phasing in capital data which is in the attached Excel file. I have added the identifiers on the attached word file. The data I am importing has numbers which I want AIMMS to convert to percentages.On my side the PhasingInCapital is a worksheet inside the Input Data...

Developers (Math, OR, programming)

Article Improve Solve Times for your AIMMS Models with ODH-CPLEX

ODH-CPLEX is a high performance solver for Mixed Integer Programming (MIP) and Mixed Integer Quadratic Programming (MIQP/MIQCP) problems. ODH-CPLEX uses the CPLEX solver underneath and is made to run on modern multiprocessor machines. While it is designed for scheduling problems, it’s been deployed...

Developers (Math, OR, programming)

Stop in the middle of run

Hi, My model took more than 14 days to run on i7 core computer with 16GB RAM. And it still does not give an optimal solution yet. What will happen if we stop AIMMS during the middle of running a model when the solution is not optimal yet? The gap in progress window shows 38.2% for 10 days (see attac...

Developers (Math, OR, programming)

Adding leading time, phasing in capital and economic life to a generation capacity expansion planning model

Good day, I have an electricity capacity expansion planning model which was developed in AIMMS and is working fine. However, now I need to add the following:Lead times, which differ for each technology. Currently, the model assumes that if a technology is selected by the model, it can produce electr...

Developers (Math, OR, programming)

Supply Chain uncertainty

Dear All,I’m writing to inquire about the application of uncertainty on a supply chain model. My Supply chain model has three echelons that target the production, warehousing, and distribution of medication products. The deterministic version of my model works perfectly, but is far from reality as p...

Supply Chain

Determine where the robot has to drive

Hello dear AIMMS Community, currently im working on a simulation of robots driving in a parking garage and charging electric vehicles.The first step is done and it is kind of working, but i have currently two major problems. even if i am not putting any demand on the parking lot the robots drive to...

Developers (Math, OR, programming)

Errors with constraint programming

Hello,I am a beginner with aimms programmation. I added a constraint which is :sum[t,BackLog(i,t)|t>14]=0But when i compile my model, it gives me this message error: Constraint programming constraints cannot be used in combination with real valued variables, only with integer valued variables, el...

Supply Chain

Simplex task solved mathematically - how to program it in AIMMS?

Hello, I am a Master Student at the University of Applied Sciences. I found your website by chance, because you have knowledge in production management. Recently we started working in production management with the software AIMMS. However, I don't know how to transfer or programming the simplex-mode...

Developers (Math, OR, programming)

solveFixed using AIMMS

Dear Community; We are working with some MILP problems where we need to identify the ShadowPrice of some constraints. These constraints are made up of both binary and continuous variables. As the duality is not well defined for MILP problems, one method to find the ShadowPrice is to run a LP fixed m...

Developers (Math, OR, programming)

Very long execution time with BARON solver

Hello,I am solving small MINLP problem using BARON solver to find the ‘optimal’ solution. But for such a small system, 8 hours passed and I have not got the solution yet. My question is: why this solver cannot find the solution after such a long time? Is this because of the way I implemented the mod...

Developers (Math, OR, programming)

MIP Start with CPLEX

Hi, I would like to know how I can give an initial integer solution to a MIP solved with CPLEX. I found this link on the topic but I’m not convinced about the option it suggests for CPLEX in particular “Advanced basis” sounds like a setting to warm start an LP, not a MIP. I’m also not sure how to ac...

Developers (Math, OR, programming)

Article How OnLocation Analyzes the Impact of Renewables and Energy Storage on the U.S. Power Grid

OnLocation is an energy consulting company based in the Washington, D.C. area. They have extensive experience using integrated energy modeling to assess the costs and benefits of energy policies and technologies and provide insights into potential implementation challenges. OnLocation’s primary inte...

Developers (Math, OR, programming)

Article 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,...

Developers (Math, OR, programming)

Next Analytics for a Better World is on October 28

1. The next Analytics for a Better World Webinar (ABW-W) is on Wednesday, October 28, 2020, EDT 12:00 PM (Boston time), CET 5:00 PM (Amsterdam time). Speaker: Jean-Philippe Vial (Geneva, Switzerland)Title: Analytics for the Design of Gravity-Driven Water Distribution Systems for Poor Rural Communiti...

Developers (Math, OR, programming)

Subset creation/formulation

Hello all,I am trying to create a subset of a main set for a constraint. See the attached figure of the constraint*. The index k should be a subset of its set. The main set consists for example of three classes {1,2,3}, then its subset should consist be{1,2}, so the main (ordered) set minus the last...

Developers (Math, OR, programming)

Memory ram manage

We have 2 aimms licenses, we would like to place them on the same server, is it possible to use one license for each project? Is it possible to manage ram memory used by the program being run by each license?

Developers (Math, OR, programming)

Article Analytics to the Rescue: Join AIMMS' N.S. Krishnan at INFORMS' Virtual Regional Conference

Join us this month at INFORMS' virtual regional conference! AIMMS' N.S. Krishnan (@nsk) will participate on the Panel Discussion "Analytics to the Rescue" on September 24, 12:25pm CST.About the conferenceThe conference will address the relevance of analytics to solve emerging issues, problems and ch...

Developers (Math, OR, programming)

How to delete all elements from a set prior to each execution

Hi,as the title indicates I’d like to delete all elements from a set prior to each execution. Otherwhise elements from the previous execution are messing up my results. Basically I have a set that will only contain elements under a certain condition, but if it doesn’t it still keeps the elements fro...

Developers (Math, OR, programming)

Article Suggested reading: Academic paper about Constraint Programming with AIMMS

Some of you may find this paper interesting - published 2013 but still relevant! “Developing Constraint Programming Applications with AIMMS” by Prof. Willem-Jan van Hoeve of Carnegie Mellon University Download the full paper in PDF from https://www.andrew.cmu.edu/user/vanhoeve/papers/aimms_cp_app.pd...

Developers (Math, OR, programming)

New initiative: Webinar for Analytics Practitioners

New initiative! Webinar for Analytics Practitioners (WAP) Back to School For Analytics practitioners it is difficult to remain up-to-date with respect to the newest scientific developments that are relevant for practice. There are at least two reasons why this is difficult for them: There...

Developers (Math, OR, programming)

How to define a set as empty under a certain condition

Hi,I think it would be helpful to provide a little bit of background regarding my problem first. I’m currently working on a project where a given set of volunteers should be assigned to a given set of people in need. So basically a simple transport problem, where the demand of all people in need is...

Developers (Math, OR, programming)

Minimize (max-min)

Hi, In my model I want to minimize the (maximum_t of a function) - (minimum_t of that function) and I have solved this issue by setting: k >= function for all tp <= function for all tand adding (k-p) to the objective of my model. When I do this for one variable, it works, but: when I do this t...

Developers (Math, OR, programming)

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