Author: Andrew Mason (Team OpenSolver)

On 25 May 2016, OpenSolver passed the 200,000 downloads milestone. And I remember when 10,000 was a milestone we were looking forward to.

Thanks to all our users for their support.

Andrew and the OpenSolver Team

A nice article here by Jangho Lee, Seoul National University, on a Statistical Approach for Clustering Member of Congress in South Korea. Jangho used Python, Excel and Gephi for visualizing.

Image from http://jangholee.org/?p=57

I recently received a nice email from Andrew Trapp, Assistant Professor, School of Business, Worcester Polytechnic Institute. Andrew has been using OpenSolver and SolverStudio in his student projects. He writes:

I’m writing to first of all thank you for the excellent software tools that you make, OpenSolver and SolverStudio, that I have been using and featuring for 4 years now in my optimization courses. They have also been used in a number of “senior design” projects that I have advised (specifically, OpenSolver in conjunction with VBA…)

Andrew’s OpenSolver projects look very interesting, and show how OpenSolver can be used in practical applications. The reports are available online, as follows:

Andrew

OpenSolver and COIN-OR are pleased to be part of the IFORS initiative to support operations research activities in developing countries, where access to specialist commercial software is often prohibited by licensing costs. For more on this initiative, see the IFORS Developing Countries OR Resources Website.

A nice article on using OpenSolver for Google Sheets for FanDuel optimisation…

How to make your own NBA optimizer with Google Sheets for FanDuel

One of the features that we have enjoyed in SolverStudio is support for dynamic ranges, i.e. named ranges that are created using formulae. OpenSolver 2.8 and later now supports this, and so you can use formulae to define ‘dynamic’ named ranges that are then used for the left hand side and right hand side of constraints, for the decision cells and for the objective. So for example, instead of having a constraint left hand side of A1:A4, you can defined a named range Constraint1LHS with a formula such as “=offset($A$1, 0, 0, COUNTA($A:$A),1)”. This range is dynamic in that it automatically expands as more values are entered into the A column. You can then set up a constraint in which you enter Constraint1LHS for the left hand side range. This means your model automatically works as the user changes the data on the sheet. For more information on dynamic range, see excel-easy.com or ozgrid.com. We hope you find this useful.

You may wish to view this new YouTube OpenSolver introduction by Kevin Jia (Engineering Science department, University of Auckland)

We are going to test out CloudFlare for the OpenSolver web-site; DNS propogation is happening now to switch us over. Let’s hope it goes smoothly. Andrew

http://meetings2.informs.org/wordpress/philadelphia/2015/11/04/optimal-student-volunteer-scheduling-for-the-2015-informs-annual-meeting/

“When we sat down to begin scheduling student volunteers for this year’s Annual Meeting, we recognized an opportunity to use OR methods to make the task more manageable. We realized that the problem consisted of scheduling 59 students across eight shifts (two shifts per day, four days), with each student required to work either one or two five-hour shifts (morning or afternoon). Since student volunteers are placed throughout the conference facilities, we decided to schedule students into the 74 “shift-location” combinations rather than simply assign a block of students into each shift.

A Doodle poll was set up to obtain student availability. Each student was asked to indicate five out of the eight shifts during which they were available. The availability data was translated into a cost matrix where the cost was zero if a student was available and a cost of 1,000,000 if a student was unavailable for a certain shift. The objective was to minimize the total cost of the assigned schedule, thereby creating a feasible schedule that did not assign any students to shift(s) for which they were unavailable.

The problem was set up and solved in MS Excel. The tool used was COIN-OR’s Open Solver add-in for MS Excel…”

Want to be part of our OR/Analytics team at the Department of Engineering Science, University of Auckland in NZ? Check out this job posting.

Just came across a great blog on building the best Fantasy Football team using Excel/Solver/OpenSolver by Tallys Yunes.

Read about OpenSolver being used to reduce maintenance costs in “Safety and Reliability of Complex Engineered Systems: ESREL”, 2015, edited by Luca Podofillini, Bruno Sudret, Bozidar Stojadinovic, Enrico Zio, Wolfgang Kröger.

Kenneth Baker is well known for his excellent introductory texts on optimisation modelling using spreadsheets. It is great to see that his latest edition of “Optimization Modeling with Spreadsheets” (ISBN: 978-1-118-93769-3, July 2015) now includes an online appendix on OpenSolver. I look forward to seeing a copy of this new edition when it arrives. Andrew

I am on sabbatical at DTU in Denmark, and just enjoyed meeting Aleksandr from Maersk in Copenhagen who is doing some great work with OpenSolver (and perhaps SolverStudio in the future) to help make better decisions at one of the world’s largest shipping companies. Aleksandr presented some very sophisticated OpenSolver models, and is one of the few users I know of who uses the Quick Solve feature. (Any more of you out there?) Thanks, Aleksandr, for a great talk, and giving us some challenging models to think about as we plan for faster solve times in future releases. Andrew