arXiv subjects

Neil Urquhart

Publications and source records attributed to Neil Urquhart.

5 recordsLinked to original sources

arXiv2025

Optimisation of Aircraft Maintenance Schedules

We present an aircraft maintenance scheduling problem, which requires suitably qualified staff to be assigned to maintenance tasks on each aircraft. The tasks on each aircraft must be completed within a given turn around window so that the aircraft may resume revenue earning service. This paper presents an initial study based on the application of an Evolutionary Algorithm to the problem. Evolutionary Algorithms evolve a solution to a problem by evaluating many possible solutions, focusing the search on those solutions that are of a higher quality, as defined by a fitness function. In this paper, we benchmark the algorithm on 60 generated problem instances to demonstrate the underlying representation and associated genetic operators.

cs.NE↗

arXiv2021

An Overview of Agent-based Traffic Simulators

Individual traffic significantly contributes to climate change and environmental degradation. Therefore, innovation in sustainable mobility is gaining importance as it helps to reduce environmental pollution. However, effects of new ideas in mobility are difficult to estimate in advance and strongly depend on the individual traffic participants. The application of agent technology is particularly promising as it focuses on modelling heterogeneous individual preferences and behaviours. In this paper, we show how agent-based models are particularly suitable to address three pressing research topics in mobility: 1. Social dilemmas in resource utilisation; 2. Digital connectivity; and 3. New forms of mobility. We then explain how the features of several agent-based simulators are suitable for addressing these topics. We assess the capability of simulators to model individual travel behaviour, discussing implemented features and identifying gaps in functionality that we consider important.

cs.MA↗

arXiv2021

A Conceptual Framework for Establishing Trust in Real World Intelligent Systems

Intelligent information systems that contain emergent elements often encounter trust problems because results do not get sufficiently explained and the procedure itself can not be fully retraced. This is caused by a control flow depending either on stochastic elements or on the structure and relevance of the input data. Trust in such algorithms can be established by letting users interact with the system so that they can explore results and find patterns that can be compared with their expected solution. Reflecting features and patterns of human understanding of a domain against algorithmic results can create awareness of such patterns and may increase the trust that a user has in the solution. If expectations are not met, close inspection can be used to decide whether a solution conforms to the expectations or whether it goes beyond the expected. By either accepting or rejecting a solution, the user's set of expectations evolves and a learning process for the users is established. In this paper we present a conceptual framework that reflects and supports this process. The framework is the result of an analysis of two exemplary case studies from two different disciplines with information systems that assist experts in their complex tasks.

cs.CY↗

arXiv2021

Groovy Parallel Patterns: A Process oriented Parallelization Library

A novel parallel patterns library, Groovy Parallel Patterns, is presented which, from the outset, has been designed to exploit more general process parallelism than the usual data and task parallel architectures. The library executes on a standard Java Virtual Machine. The library provides a collection of processes that can be plugged together to form a variety of parallel architectures and is intrinsically its own DSL. A network of processes is guaranteed to be deadlock and livelock free and terminate correctly and this is proved by the use of formal methods. Error capture and a basic logging mechanism have been incorporated. The library enables effective refinement of solutions between process networks which can be checked also using formal methods. A library user is only required to create the required methods as pieces of sequential code, typically taken from extant sequential solutions, which can then be invoked by the processes as required. The utility of the library is demonstrated by several examples including; Monte Carlo Methods, Concordance, Jacobi solutions, N-body problems and Mandelbrot, which is implemented on both a multicore processor and a workstation cluster. The examples are analysed for speedup and efficiency, which show good and consistent performance improvement up to the number of available processor cores and workstations.

cs.DC↗

arXiv2018

Optimisation and Illumination of a Real-world Workforce Scheduling and Routing Application via Map-Elites

Workforce Scheduling and Routing Problems (WSRP) are very common in many practical domains, and usually, have a number of objectives. Illumination algorithms such as Map-Elites (ME) have recently gained traction in application to {\em design} problems, in providing multiple diverse solutions as well as illuminating the solution space in terms of user-defined characteristics, but typically require significant computational effort to produce the solution archive. We investigate whether ME can provide an effective approach to solving WSRP, a {\em repetitive} problem in which solutions have to be produced quickly and often. The goals of the paper are two-fold. The first is to evaluate whether ME can provide solutions of competitive quality to an Evolutionary Algorithm (EA) in terms of a single objective function, and the second to examine its ability to provide a repertoire of solutions that maximise user choice. We find that very small computational budgets favour the EA in terms of quality, but ME outperforms the EA at larger budgets, provides a more diverse array of solutions, and lends insight to the end-user.

cs.AI↗