Yv
Y.A.W. van den Akker
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1
Creating New Train Timetables in Case of Disruptions
Optimising a Branch & Bound Algorithm
The Dutch railway system is one of the most densely used systems worldwide and the busiest in Europe. Given the tight schedules, incidents can quickly cascade through the entire country if not handled properly. Alternative timetables are created to help train traffic controllers swiftly resolve such incidents. These schedules are currently created manually, but the team cannot keep up with demand. This is why CGI is developing VGB Solver, an application to automatically generate such timetables. The solver uses a branch and bound algorithm in which nodes are processed in best-first order, based on a heuristic value. For this thesis, different performance optimisations for this algorithm were implemented and analysed.
Various alternative formulations of the heuristic value, used to determine the likeliness of a node leading to a good solution, showed promising results.
One of these formulas resulted in solutions for 96% more scenarios than before, and improved the quality of solutions for other scenarios.
Using machine learning, a decision tree was created to predict whether applying another new formula for the heuristic value gives better results than the old formula. This classifier achieved an accuracy of 73.5% on the test data. Having the solver choose between the old and new formula based on that classification resulted in some scenarios with worse scores, but twice as many improved, and the average improvement was higher than the average deterioration.
Recommendations are made to conduct further experiments related to the heuristic value calculation. Furthermore, it is suggested to separate the scores for evaluating solution quality from the heuristic value formula, to facilitate more fine-grained changes to the calculation of the heuristic value.
...
Various alternative formulations of the heuristic value, used to determine the likeliness of a node leading to a good solution, showed promising results.
One of these formulas resulted in solutions for 96% more scenarios than before, and improved the quality of solutions for other scenarios.
Using machine learning, a decision tree was created to predict whether applying another new formula for the heuristic value gives better results than the old formula. This classifier achieved an accuracy of 73.5% on the test data. Having the solver choose between the old and new formula based on that classification resulted in some scenarios with worse scores, but twice as many improved, and the average improvement was higher than the average deterioration.
Recommendations are made to conduct further experiments related to the heuristic value calculation. Furthermore, it is suggested to separate the scores for evaluating solution quality from the heuristic value formula, to facilitate more fine-grained changes to the calculation of the heuristic value.
...
The Dutch railway system is one of the most densely used systems worldwide and the busiest in Europe. Given the tight schedules, incidents can quickly cascade through the entire country if not handled properly. Alternative timetables are created to help train traffic controllers swiftly resolve such incidents. These schedules are currently created manually, but the team cannot keep up with demand. This is why CGI is developing VGB Solver, an application to automatically generate such timetables. The solver uses a branch and bound algorithm in which nodes are processed in best-first order, based on a heuristic value. For this thesis, different performance optimisations for this algorithm were implemented and analysed.
Various alternative formulations of the heuristic value, used to determine the likeliness of a node leading to a good solution, showed promising results.
One of these formulas resulted in solutions for 96% more scenarios than before, and improved the quality of solutions for other scenarios.
Using machine learning, a decision tree was created to predict whether applying another new formula for the heuristic value gives better results than the old formula. This classifier achieved an accuracy of 73.5% on the test data. Having the solver choose between the old and new formula based on that classification resulted in some scenarios with worse scores, but twice as many improved, and the average improvement was higher than the average deterioration.
Recommendations are made to conduct further experiments related to the heuristic value calculation. Furthermore, it is suggested to separate the scores for evaluating solution quality from the heuristic value formula, to facilitate more fine-grained changes to the calculation of the heuristic value.
Various alternative formulations of the heuristic value, used to determine the likeliness of a node leading to a good solution, showed promising results.
One of these formulas resulted in solutions for 96% more scenarios than before, and improved the quality of solutions for other scenarios.
Using machine learning, a decision tree was created to predict whether applying another new formula for the heuristic value gives better results than the old formula. This classifier achieved an accuracy of 73.5% on the test data. Having the solver choose between the old and new formula based on that classification resulted in some scenarios with worse scores, but twice as many improved, and the average improvement was higher than the average deterioration.
Recommendations are made to conduct further experiments related to the heuristic value calculation. Furthermore, it is suggested to separate the scores for evaluating solution quality from the heuristic value formula, to facilitate more fine-grained changes to the calculation of the heuristic value.
FEATHER: Visual Editor for Escape Rooms
The Software behind Escape Room Games
Bachelor thesis
(2020)
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E.T. Rogers, S.J.G. Sebus, W.H. Polet, Y.Y. Angelova, Y.A.W. van den Akker, T.A.R. Overklift Vaupel Klein, Jan-Willem Manenschijn
Raccoon Serious Games develops and hosts educational activities such as escape room events and serious games. They create both physically- and digitally-based escape rooms across many different scales. These events consist of a variety of puzzles and tasks the player(s) have to solve in order to finish or `escape' the event. For their digitally hosted events, the Massive Online Reactive Serious Escape 2.0 (MORSE) system is used for creation and configuration of the needed underlying rules of the event. The system uses the `If This Then That' (IFTTT) principle for creating rules, where a trigger activated by the player/game can initiate a check about the state of the game which then results in an action by the game. In MORSE the user (usually the game host) can choose from the multiple types of triggers, conditions, and actions to create logical statements in the IFTTT format. These statements together form the rules of the game. This system, although a good improvement over the previously hard-coded procedure, has proven unintuitive to program for most of the employees at Raccoon Serious Games. The IFTTT format used is unwieldy to work with for the designers, who have little to no programming background. Furthermore this existing system provides no overview of the rules system making it challenging to visualise the whole game and its dynamics. To solve the unintuitive nature of MORSE, our team designed and developed Feather: A graph-based visual editing tool that is integrated into MORSE. It can generate rule and ruleset logic needed for the client's escape events. It uses visual components and presents the user with a graph of the whole game during the design process. The editor can be used together with all other, earlier existing, features for creating rulesets of the MORSE system. This tool has most of the functionality the current system has, with the possibility of easily extending it with new components. The product was built as an addition to MORSE over the course of 10 weeks. In the initial part of the project a thorough research was performed on the needs of the client as well as useful resources or libraries and design practices for domain specific visual languages. The second part of the project was devoted to the design and implementation of the tool. Throughout the duration of the project a number of user tests were conducted with the employees at Raccoon Serious Games to assess the understanding and usability of the product.
...
Raccoon Serious Games develops and hosts educational activities such as escape room events and serious games. They create both physically- and digitally-based escape rooms across many different scales. These events consist of a variety of puzzles and tasks the player(s) have to solve in order to finish or `escape' the event. For their digitally hosted events, the Massive Online Reactive Serious Escape 2.0 (MORSE) system is used for creation and configuration of the needed underlying rules of the event. The system uses the `If This Then That' (IFTTT) principle for creating rules, where a trigger activated by the player/game can initiate a check about the state of the game which then results in an action by the game. In MORSE the user (usually the game host) can choose from the multiple types of triggers, conditions, and actions to create logical statements in the IFTTT format. These statements together form the rules of the game. This system, although a good improvement over the previously hard-coded procedure, has proven unintuitive to program for most of the employees at Raccoon Serious Games. The IFTTT format used is unwieldy to work with for the designers, who have little to no programming background. Furthermore this existing system provides no overview of the rules system making it challenging to visualise the whole game and its dynamics. To solve the unintuitive nature of MORSE, our team designed and developed Feather: A graph-based visual editing tool that is integrated into MORSE. It can generate rule and ruleset logic needed for the client's escape events. It uses visual components and presents the user with a graph of the whole game during the design process. The editor can be used together with all other, earlier existing, features for creating rulesets of the MORSE system. This tool has most of the functionality the current system has, with the possibility of easily extending it with new components. The product was built as an addition to MORSE over the course of 10 weeks. In the initial part of the project a thorough research was performed on the needs of the client as well as useful resources or libraries and design practices for domain specific visual languages. The second part of the project was devoted to the design and implementation of the tool. Throughout the duration of the project a number of user tests were conducted with the employees at Raccoon Serious Games to assess the understanding and usability of the product.