Agent Based Modelling

The interdependence and complexity of socio-technical systems and availability of a wide variety of policy measures to address policy problems make the process of policy formulation difficult. In order to formulate sustainable and efficient transport policies, development of new tools and techniques is necessary. One of the approaches gaining ground is policy packaging, which shifts focus from implementation of individual policy measures to implementation of combinations of measures with the aim of increasing efficiency and effectiveness of policy interventions by increasing synergies and reducing potential contradictions among policy measures. In this paper, we describe the development of a virtual environment for the exploration and analysis of different configurations of policy measures in order to build policy packages. By developing systematic approaches it is possible to examine more alternatives at a greater depth, decrease the time required for the overall analysis, provide real-time assessment and feedback on the effect of changes in the configurations, and ultimately form more effective policies. The results from this research demonstrate the usefulness of computational approaches in addressing the complexity inherent in the formulation of policy packages. This new approach has been applied to the formulation of policies to advance sustainable transportation.

In Agent-based Modelling and Simulation (ABMS), a system is modelled as a collection of agents, which are autonomous decision-making units with diverse characteristics. The interaction of the individual behaviours of the agents results in the global behaviour of the system. Because ABMS offers a methodology to create an artificial society in which actors with their behaviour can be designed and results of their interaction can be observed, it has gained attention in social sciences such as Economics, Ecology, Social Psychology, and Sociology.

In Economics, ABMS has been used to model many strategic situations. One of the popular strategic situations is the Public Goods Game (PGG). In the PGG, participants secretly choose how many of their private money units to put into a public pot. Social scientists can conduct laboratory experiments of PGGs to study human behaviours in strategic situations. Research findings from these laboratory studies have inspired studies using computational agents and vice versa. However, there is a lack of guidelines regarding the detailed development process and the modelling of agent behaviour for agent-based models of PGGs. We believe that this has contributed to ABMS of PGG not having been used to its full potential.

This thesis aims to leverage the potential of ABMS of PGG, focusing on the development methodology of ABMS and the modelling of agent behaviour. We construct a development framework with incorporated software engineering techniques, then tailored it to ABMS of PGG. The framework uses the Unified Modelling Language (UML) as a standard specification language, and includes a simulation development lifecycle, a step-by-step development guideline, and a short guide for modelling agent behaviour with statecharts. It utilizes software engineering methods to provide a structured approach to identify agent interactions, and design simulation architecture and agent behaviour. The framework is named ABOOMS (Agent-Based Object-Oriented Modelling and Simulation).

After applying the ABOOMS framework to three case studies, the framework demonstrates flexibility in development with two different modelling principles (Keep-It-Simple-Stupid vs. Keep-It-Descriptive-Stupid), capability in supporting complex psychological mechanisms, and ability to model dynamic behaviours in both discrete and continuous time. Additionally, the thesis developed an agent-based model of a PGG in a continuous-time setting. To the best of our knowledge such agent-based models do not exist. During the development, a new social preference, Generous Conditional Cooperators, was introduced to better explain the behavioural dynamics in continuous-time PGG. Experimentation with the agent-based model generated dynamics that are not presented in discrete-time setting. Thus, it is important to study both discrete and continuous time PGG, with laboratory experiment and ABMS. Our new framework allows to do the latter in a structured way.

With the ABOOMS framework, economists can develop PGG simulation models in a structured way and communicate them with a formal model specification. The thesis also showed that there is a need for further investigation on behaviours in continuous-time PGG. For future works, the framework can be tested with variations of PGG or other related strategic interactions.

One of the approaches gaining ground in policy design is the implementation of combinations of policy measures as policy packages with the aim of increasing efficiency and effectiveness of the designed policies. In this paper, we describe the recent advancements in the developments of a virtual environment for the exploration and analysis of policy packages. The virtual environment uses an agent-based modelling approach for the generation of different configurations of policy measures in the policy packages. The benefit of using the approach is the proactive and flexible generation of policy packages as the agents can react to the changes that occur and create packages that are more robust. The system allows faster examination of more alternatives, further exploration of the design space, and testing the effects of changes and uncertainties while formulating policies. The results demonstrate the benefit of using agent-based modelling approaches in the design of complex policies.

Remote sensing, powerful computing engines, and agent-based models offer new ways to interpret data and broaden data collection, moving archaeologists closer to their ultimate goal of approximating the individual within an extensive, interpreted, digital environment. The first Web extra is a video that demonstrates how the advanced acquisition and processing of magnetic data has led to new discoveries and insights, such as the "Henge" monument excavated near Stonehenge in 2010. The second Web extra is a video that illustrates how researchers used 3D seismic data, initially collected for use in oil and gas exploration, to reconstruct Doggerland, a lost Mesolithic landscape that was inundated by the North Sea during the last great period of global warming.

The purpose of this project was to assess the mussel (Mytilus edulis) food requirements of oystercatcher (Haematopus ostralegus) in the Exe Estuary, which has been designated a Special Protection Area for overwintering waterbirds, including oystercatcher. The overwintering oystercatcher population of the Exe Estuary has been well-studied, and the birds are known to feed predominantly upon mussels in intertidal areas. There have been recent declines in the population size of oystercatcher in the Exe Estuary, mirroring wider declines throughout Europe, the reasons for which are unknown.

The study comprised:
• The collection of new data on the area of mussel beds, the density and size distribution of mussels on these beds, and the numbers and behaviour of oystercatcher on these beds;
• The collation of existing data on the food supply of oystercatchers in the Exe Estuary;
• The development of models to predict the food requirements of oystercatcher;
• Running simulations of the models to predict whether there is / could be any effect on oystercatcher survival of the current / potential future ways of managing the mussel fishery on the Exe Estuary.

The current mussel fishery on the Exe provides a feeding resource for oystercatcher on intertidal lays that are exposed on spring tides. Two potential management options that could be effective at improving the feeding conditions of oystercatcher would be to increase the number and area of intertidal mussel lays, and / or to place mussel discards at a relatively high shore level close to the oystercatcher roost.

This project documented a number of changes that have occurred to the Exe Estuary mussel and oystercatcher populations including:
• The number and size of mussel beds have decreased since traditional methods of maintaining mussel beds in the estuary have ceased.
• The density of mussels within the size range consumed by the birds has generally decreased, but the density of the larger mussels within this size range, which are more profitable to oystercatcher, has generally increased.
• Oystercatcher lose a higher proportion of mussels to attacks by carrion crows and herring gulls than they have in the past.
• The number of oystercatcher wintering in the estuary has declined, but the number of birds feeding on the mussel beds has been relatively stable.

The models developed in the project predict that the present day mussel population is sufficient to support the number of oystercatcher that were observed to feed on mussels.

The presence of mussel lays provides extra food for oystercatcher when these lays are exposed on spring tides. The present area, or increases in the area of mussel lays could increase the survival rate of oystercatcher if the number of birds feeding on mussels was over 2000. Below this threshold, starvation was predicted to affect 0 % of the population and so additional food resources cannot further reduce the starvation. The effect over 2000 birds is relatively small because the lays are only exposed for a short time, and so oystercatcher will obtain the majority of their food from mussel beds that are higher on the shore, and hence exposed for longer. Simulations were not run in which lays were positioned higher on the shore because this would not be commercially viable from a fishery perspective; the growth rate of mussels declines as they are positioned further up the shore because they are inundated with water for less time and so have less time to feed.

Factors that would affect the beneficial effect of discards include the size of the discards, the size of the discard bed and the date from which discards are replenished. Our simulations predicted that larger discards spread at lower density over a larger bed increased oystercatcher survival by the greatest amount. This happened because interference competition excluded some birds from smaller patches, and oystercatcher can maintain high intake rate down to low mussel densities. It is unlikely that the size of discards could be increased, but the simulations suggest that the greatest benefit to oystercatchers could be achieved by spreading discards over a larger area. Our simulations predicted that making discards available from January increased oystercatcher survival by the same amount as making them available from September. This was because the feeding conditions of birds deteriorate through winter as, for example, the ash-free dry mass of prey declines, interference competition intensifies and day length shortens. The intake rate of birds feeding on discards was not measured during the study, but we recommend that this is done to between understand the potential benefit of discards. We recommend that the best place for the discard bed would be along the top of the shore on an area of gravel (and hence of relatively low food value to the birds), to the south of Cockwood. This is south of an area where discards have been laid and exploited by oystercatcher in the past, but would experience lower levels of disturbance from human activity.

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The increased complexity in our socio-economical systems requires the development of new tools to support a better understanding of the intricacies involved in addressing problems associated with such systems.  We believe that by introducing a systematic approach for exploring alternative policies we can improve the decomposition of these problems, decrease the required time for analysis and formulate more effective polices.  A case in policy formulation and analysis in the transport sector for achieving CO2 emission targets in the UK is presented; this solution is based on a previously proposed framework (Taeihagh et al., 2009a).  The results obtained from the analysis of policy measures and their relations are used in the formulation of policy alternatives (packages and clusters) through the application of agent-based modelling.  The results have the potential to further promote the use of computational approaches in the formulation of polices through the development of software systems that can support the design of policies for different sectors and geographical scopes.

The decoupling of direct payments from production represents a substantial reform of the Common Agricultural Policy (CAP). Farmers are no longer required to produce commodities to be entitled to support but only to keep land in Good Environmental and Agricultural Condition. If output declines as a result, there is concern that landscape services produced jointly with commodities will also decline. The aim of this paper is to assess the long-term effects of the 2003 reform on farm structure, landscape mosaic and biodiversity for a sample of EU regions. Impacts are quantified using a spatial agent-based modelling approach by simulating agricultural development with links to indicators of landscape value. Our results demonstrate that eliminating the link between support payments and production has possible negative consequences for the landscape, but only under particular circumstances. It is shown that these effects could be offset by strengthening (Pillar II) agri-environmental schemes. Further the single payment scheme results in higher land rental prices which reduces its ability to achieve its goal of providing income security for farmers. Implications of these results for the direction of continued CAP reform are discussed.

One of the aims of environmental education is to teach environmental knowledge and provide students with the skills to understand other environmental problems. We have built on theories of mental models in order to account for the problems that students face when learning about environmental systems. These theories relate to the role that knowledge and understanding play in such problems.

Agent-based simulation models can be used to explore the impact of policy and practice on drug use and related consequences. In a linked paper (Perez et al., 2011), we described SimAmph, an agent-based simulation model for exploring the use of psychostimulants and related harm amongst young Australians. In this paper, we use the model to simulate the impact of two policy scenarios on engagement in drug use and experience of drug-related harm: (i) the use of passive-alert detection (PAD) dogs by police at public venues and (ii) the introduction of a mass-media drug prevention campaign. The findings of the first simulation suggest that only very high rates of detection by PAD dogs reduce the intensity of drug use, and that this decrease is driven mainly by a four-fold increase in negative health consequences as detection rates rise. In the second simulation, our modelling showed that the mass-media prevention campaign had little effect on the behaviour and experience of heavier drug u...

The software agent paradigm has received considerable at- tention recently, both in research and industrial practice. However, adop- tion of this software paradigm remains elusive in software engineering practice. We claim that part of the adoption problem lies with the fact that mentalistic and social concepts underlying agents are subjective and complex for the average practitioner. Specifically, although there are many efforts related to the topic coming from philosophy, cogni- tive sciences and computer science, a uniform and well-founded semantic view on these concepts is currently lacking. This work extends an ex- isting upper-level ontology and offers it as a foundation for evaluating and designing agent-oriented modeling languages. In particular, the pa- per focuses on the concept of goal, aiming at disambiguating its defini- tion, discussing its different manifestations, and clarifying its relation to other important agent-related concepts. For that, we examine how goals are conceived and used according to some relevant literature on agent- orientation. In addition, related work on akin fields, especially philosophy and AI are used as a basis for the proposed ontological extensions.

Research on the post-occupancy stage of buildings is receiving growing interest due to the need to significantly reduce energy consumption and CO2 emissions and therefore make buildings more sustainable. The interrelationship between the building occupants (socio), the systems put in place (technical), and the building itself (technical) has added more pressure to this issue of sustainability. Building performance is therefore

This paper argues that the agent-based simulation approach is just the one appropriate to the social sciences (includ- ing economics). Although there were many predecessor ap- proaches, which tried to build formal models of social sys- tems, all of them fell short of the peculiar features of the objects of all social sciences: complex systems consisting of numerous autonomous actors