Using Hybrid Agent-Based Systems to Model Spatially-Influenced Retail Markets

One emerging area of agent-based modelling is retail markets; however, there are problems with modelling such systems. The vast size of such markets makes individual-level modelling, for example of customers, difficult and this is particularly true where the markets are spatially complex. There is an emerging recognition that the power of agent-based systems is enhanced when integrated with other AI-based and conventional approaches. The resulting hybrid models are powerful tools that combine the flexibility of the agent-based methodology with the strengths of more traditional modelling. Such combinations allow us to consider agent-based modelling of such large-scale and complex retail markets. In particular, this paper examines the application of a hybrid agent-based model to a retail petrol market. An agent model was constructed and experiments were conducted to determine whether the trends and patterns of the retail petrol market could be replicated. Consumer behaviour was incorporated by the inclusion of a spatial interaction (SI) model and a network component. The model is shown to reproduce the spatial patterns seen in the real market, as well as well known behaviours of the market such as the "rocket and feathers" effect. In addition the model was successful at predicting the long term profitability of individual retailers. The results show that agent-based modelling has the ability to improve on existing approaches to modelling retail markets.Agents, Spatial Interaction Model, Retail Markets, Networks

A Social Simulation of Housing Choice and Housing Policy in the EASEL Regeneration District, Leeds UK

Dynamics in the housing market are often discussed qualitatively but much can be explored through computer modelling. By recreating major trends in the housing market, the interplay between housing options, as dictated by policy, and housing choice, when exercised by households, can be examined. Such social simulations can be used to test the validity of policy decisions. For example, policies such as urban regeneration aim to tackle the problem of deprivation at its core by the establishing mixed communities; communities where households are mixed by socioeconomic status. Housing choice and the decision to move are a complex series of choices. Using the technique of agent-based modelling, the potential effects of this regeneration policy will be explored

GeoCrimeData:Understanding Crime Context with Novel Geo-Spatial Data

The work of crime analysts and modellers could benefit substantially from the use of new spatial data sets that are becoming more readily available. Examples include road networks (e.g. Open Street Map), building boundary datasets (e.g Ordnance Survey MasterMap) as well as under-utilised social network data (e.g. Twitter) or other volunteered sources. However, due to a lack of resources and considerable technical barriers, very few analysts exploit these types of data or understand how they could be used to offer benefits in terms of understanding crime. This paper will review the work of the GeoCrimeData Project which is exploring many novel data sources and manipulating them using geographical routines in order to generate new forms of spatial intelligence that can help to add value to the interpretation of recorded crime data. Ultimately, the project will re-release the data and methods freely for use by professionals working in the field of crime analysis. In particular, this paper will demonstrate how the use of a road network data set and a collection of geo-located 'tweets' can be used to inform an analysis of violent crime

Cavitation clusters in lipid systems - surface effects, local heating and streamer formation

Cavitation clusters and streamers are characterised in lipid materials (specifically sunflower oil) and compared to water systems. The lipid systems, which are important in food processing, are studied with high-speed camera imaging, laser scattering and pressure measurements. In these oils, clusters formed at an aged (roughened) tip of the sound source (a piston like emitter, PLE) are shown to collapse with varied periodicity in relation to the drive amplitude employed. A distinct streamer (an area of increased flow emanating from the cavitation cluster) is seen in the lipid media which is collimated directly awayfrom the tip of the PLE source whereas in water the cavitation plume is visually less distinct. The velocity of bubbles in the lipid streamer near the cluster on the order of 10 m s-1. Local heating effects, within the streamer, are detected using a dual thermocouple measurement at extended distances. Viscosity, temperature and the outgassing within the oils are suggested to play a key role in the streamer formation in these systems.<br/

Genetic algorithm optimisation of an agent-based model for simulating a retail market

Traditionally, researchers have used elaborate regression models to simulate the retail petrol market. Such models are limited in their ability to model individual behaviour and geographical influences. Heppenstall et�al presented a novel agent-based framework for modelling individual petrol stations as agents and integrated important additional system behaviour through the use of established methodologies such as spatial interaction models. The parameters for this model were initially determined by the use of real data analysis and experimentation. This paper explores the parameterisation and verification of the model through data analysis and by use of a genetic algorithm (GA). The results show that a GA can be used to produce not just an optimised match, but results that match those derived by expert analysis through rational exploration. This may suggest that despite the apparent nonlinear and complex nature of the system, there are a limited number of optimal or near optimal behaviours given its constraints, and that both user-driven and GA solutions converge on them.

Cavitation clusters in lipid systems: The generation of a bifurcated streamer and the dual collapse of a bubble cluster

Several studies have reported the use of high‐intensity ultrasound (HIU) to induce the crystallization of lipids. The effect that HIU has on lipid crystallization is usually attributed to the generation of cavities but acoustic cavitation has never been fully explored in lipids. The dynamics of a particular cavitation cluster next to a piston like emitter (PLE) in an oil was investigated in this study. The lipid systems, which are important in food processing, are studied with high‐speed camera imaging, laser scattering, and acoustic pressure measurements. A sequence of stable clusters was noted. In addition, a bifurcated streamer was detected, which exists within a sequence of clusters. This is shown to originate from two clusters on the PLE tip oscillating with a 180° phase shift in time with respect to one another. Finally, the collapse phase of the cluster is shown to involve a rapid (~10 μs) two‐stage process. These results show that the dynamics of cluster formation and collapse is driven by HIU power levels and might have implications in lipid sonocrystallization