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Came across a nice set of (3) Linear Programming exercises from the Erasmus University of Rotterdam (academic year 2016/2017) that might interest you. https://www.studeersnel.nl/nl/document/erasmus-universiteit-rotterdam/lineair-programmeren/verplichte-opgaven/exercise-set-aimms-16-17/999425/view
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 workbook. Here is the error:ExcelSetActiveSheet(Input Data.xlsx, PhasingInCapital) failed: Workbook doesn't contain the specified sheet. Invalid index.I have imported a lot of data files from Excel, I am not sure what am I doing wrong this time.Please assist.
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 the lot and “simulate” charging an electric vehicle. → i tried to find a solution in the community, but i was not successful. Is there any possibility, any constraint which could make the robot not to service/drive to that parking lot while Demand(i)=0. As you can see in the picture: even if i put Demand of almost every parking lot=0, the robot drives to all the places, before going back to the depot. Another problem is, that i want to make the robots drive on a specific route, shown as yellow in the picture/simulation. → Is there any chance of making the robots drive a minimum besides the yellow route? My thought is that, despite being able to create that, later in the mathimatical pr
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 Communities: the NeatWork Tool.Abstract: NeatWork is an optimization and simulation tool for the design of water-distribution systems with the aim of providing clean water to poor rural communities. The management of such systems must be cheap and simple, a requirement which prohibits power-driven equipment, such as pumps, and man-operated devices, such as regulators. Therefore, the physical system must be driven by gravity only. It must also be endowed with self-regulation to ensure flow invariance despite stochastic intermittent water withdrawals by independent users. The formulation as a least-cost design problem belongs to the realm of two-stage stochastic optimization, in which the second stage
[i]This article, originally published in 2013, comes from our Tech Blog archives. As such, some cited data is a bit dated, but we think that the story's value illustrating practical application of OR still holds up.[/i] [b]The mathematical story behind North Star Alliance’s POLARIS[/b] More than 35 million people worldwide are infected with HIV or are living with AIDS, and approximately 70% live in Sub-Saharan Africa. Mobile populations, such as long distance truck drivers, are particularly at risk of contracting and transmitting the virus. In 2007, TNT Express and the United Nations World Food Programme joined forces to form North Star Alliance (North Star) - a public-private partnership that is working to increase access to health services along major transport corridors in sub-Saharan Africa. ORTEC, a longstanding AIMMS partner, joined North Star in 2008 to design their award-winning Corridor Medical Transfer System (COMETS), which enables North Star staff to access and mo
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 challenges. INFORMS Chicago Chapter and INFORMS Analytics Society will bring together innovative and insightful leaders across multiple industries and education for this annual conference. The goal is to have in-depth discussions and exchanges of experience and ideas related to solutions during these tough and uncertain situations. The conference will take place virtually.Areas of focus include AI & machine learning, epidemic and healthcare analytics, and election analytics. Join us to hear from experts and exchange ideas on mission critical and timely applications, strategies, and processes. Will you attend the conference? Are you working on an OR/Analytics project to help address some o
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 electricity as soon as the model makes it available for capacity allocation. I need this to change and the model should make the technology’s capacity available after the lead time has expired. Phasing in capital, which also differ for each technology. The current model assumes that the capital for a chosen technology is payable immediately. The phasing in capital are connected to lead times. For example if a technology has a lead time of 2 years, the phasing in capital is also over 2 years, say 90% of capital is payable in year 1 and 10% in year 2. I need the capital for each technology to be phased in according to the phasing in capital percentages. Life of plant (Economic life), which also dif
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
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-modeling, which I solved mathematically, into AIMMS. Can you help me with this?
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
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 converted to AIMMS.https://how-to.aimms.com/Articles/312/312-convert-gams-to-aimms.html
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.
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.
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
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
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
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.
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?
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. However, that is not happening. Ideally:The new power plants are supposed to be committed any time between 2013 and 2050. No new capacity is supposed to start at 2013 because of leading times. Those power plants with life of plant that pass 2050 are supposed to remain active until their corresponding life of plant comes to an end. Not all the capital can be taken in one year for new capacity, but a portion per each year of the leading time, according to p_phaseIn parameter.The attached model, opens on this page:One will have to:Click the input data button Select the scenario analysis, then click solve the scenario button. This solves the deterministic model. The corresponding results can be view
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