Sensor-Driven, Spatially Explicit Agent-Based Models

Conventionally, agent-based models (ABMs) are specified from well-established theory about the systems under investigation. For such models, data is only introduced to ensure the validity of the specified models. In cases where the underlying mechanisms of the system of interest are unknown, rich datasets about the system can reveal patterns and processes of the systems. Sensors have become ubiquitous allowing researchers to capture precise characteristics of entities in both time and space. The combination of data from in situ sensors to geospatial outputs provides a rich resource for characterising geospatial environments and entities on earth. More importantly, the sensor data can capture behaviours and interactions of entities allowing us to visualise emerging patterns from the interactions. However, there is a paucity of standardised methods for the integration of dynamic sensor data streams into ABMs. Further, only few models have attempted to incorporate spatial and temporal data dynamically from sensors for model specification, calibration and validation. This chapter documents the state of the art of methods for bridging the gap between sensor data observations and specification of accurate spatially explicit agent-based models. In addition, this work proposes a conceptual framework for dynamic validation of sensor-driven spatial ABMs to address the risk of model overfitting

Modeling Spatio-Temporal Evolution of Urban Crowd Flows

Metropolitan cities are facing many socio-economic problems (e.g., frequent traffic congestion, unexpected emergency events, and even human-made disasters) related to urban crowd flows, which can be described in terms of the gathering process of a flock of moving objects (e.g., vehicles, pedestrians) towards specific destinations during a given time period via different travel routes. Understanding the spatio-temporal characteristics of urban crowd flows is therefore of critical importance to traffic management and public safety, yet it is very challenging as it is affected by many complex factors, including spatial dependencies, temporal dependencies, and environmental conditions. In this research, we propose a novel matrix-computation-based method for modeling the morphological evolutionary patterns of urban crowd flows. The proposed methodology consists of four connected steps: (1) defining urban crowd levels, (2) deriving urban crowd regions, (3) quantifying their morphological changes, and (4) delineating the morphological evolution patterns. The proposed methodology integrates urban crowd visualization, identification, and correlation into a unified and efficient analytical framework. We validated the proposed methodology under both synthetic and real-world data scenarios using taxi mobility data in Wuhan, China as an example. Results confirm that the proposed methodology can enable city planners, municipal managers, and other stakeholders to identify and understand the gathering process of urban crowd flows in an informative and intuitive manner. Limitations and further directions with regard to data representativeness, data sparseness, pattern sensitivity, and spatial constraint are also discussed. Document type: Articl

A Study of Colloquial Place Names through Geotagged Social Media Data

Place is a rich but vague geographic concept. Much work has been done to explore the collective understanding and perceived location of place. The last few decades have seen rapid expansion in the use of online social media and data sharing services, which provide a large amount of valuable data for research of colloquial place names. This study explored how geotagged social media data can be used to understand geographic place names, and delimit the perceived geographic extent of a place. The author proposes a probabilistic method to map the perceived geographic extent of a place using Kernel Density Estimation (KDE) based on the geotagged data uploaded by users. The author also used spatio-temporal analysis methods in GIS to explore characteristics, hidden patterns, and trends of the places. Flickr, a popular online social networking service that features image hosting and sharing, was selected as the main data source for this project. The results show that outcomes of KDE with different functions and parameters differ from each other; therefore, it is crucial to select the proper KDE bandwidth in order to obtain appropriate geographic extents. Official boundaries and reference boundaries can be used to assess the geographic extents. Google Maps Street View is another useful source to examine the visual characteristics of places. Spatio-temporal analysis of the geographic extents over time reveals significant location changes of the places composed of man-made structures. Besides names and variations of place names, related colloquial terms, like Cades Cove of the Great Smoky Mountains National Park, are also useful sources when delimiting a place. Several examples are analyzed and discussed. Studies like this research can improve our understanding of geotagged Online Social Network (OSN) data in the study of colloquial place names as well as provide a temporal perspective to the analysis of their perceived geographic extents

Vector Zonal Operations for Spatiotemporal Analysis

Cartographic modeling (also known as map algebra) is a powerful set of operations for manipulating raster geographic data. Zonal operations are one type of cartographic modeling operations where the spatial scopes of the operations are defines by zones. The conventional zonal operations only work with raster data and lack the capability of performing spatiotemporal analysis. This research developed zonal operations for spatiotemporal analysis where spatiotemporal zones can be defined in the vector data model. The zonal operations were used to extract watershed hourly or daily precipitation for use in non-point source pollution models and to explore the effects of antecedent precipitation on water quality samples. The case studies demonstrated the usefulness of the operations. A software tool, NexTool was also developed to process and build NEXRDA precipitation database, which was used in the case studies

Swarm Intelligence

Swarm Intelligence has emerged as one of the most studied artificial intelligence branches during the last decade, constituting the fastest growing stream in the bio-inspired computation community. A clear trend can be deduced analyzing some of the most renowned scientific databases available, showing that the interest aroused by this branch has increased at a notable pace in the last years. This book describes the prominent theories and recent developments of Swarm Intelligence methods, and their application in all fields covered by engineering. This book unleashes a great opportunity for researchers, lecturers, and practitioners interested in Swarm Intelligence, optimization problems, and artificial intelligence

Context-based routing in road networks

Mestrado em Engenharia de Computadores e TelemáticaA utilização de sistemas de geo-localização já faz parte do quotidiano das pessoas, através dos mais variados equipamentos de recepção de dados posicionais. Com o aumento de utilização deste tipo de equipamentos, a estruturas de armazenamento associadas a dados geográficos foram aperfeiçoadas de forma a permitir uma gestão mais eficiente. Neste trabalho é apresentado uma Data Warehouse espacial orientado ao contexto para o armazenamento de dados relativos ao tráfego automóvel. Esses dados são obtidos através de dados posicionais e representados num mapa rodoviário digital. O mapeamento é analisado através da comparação das similaridades de trajectos criados a partir de dados posicionais de veiculos em Aalborg (Dinamarca), usando diferentes períodos de amostragem. Após o armazenamento dos trajectos, dos dados posicionais e dos troços percorridos em três Data Marts distintas, foi feita uma análise de rotas em zonas residenciais, estradas secundárias e em pontos turísticos em Pequim (China). Através da análise faz-se a relação entre as rotas mais rápidas, as mais curtas, o número de paragens e o contexto em que esses dados foram registados. A análise mostra que, nas zonas de estradas secundárias as rotas utilizadas com mais frequência são na maioria dos casos a rota mais rápida, o que não acontece nas zonas residenciais e nas zonas turísticas. A análise mostrou que a relevância temporal influenciou o nível de tráfego e que o factor meteorológico não teve influência na escolha das rotas.The use of Geographic Information Systems is part of today's people's lives. As the use of these systems keeps growing, data storage and management structures are improving in order to allow a better use of spatio-temporal data. In this dissertation a Data Warehouse for traff ic and contextual storage is presented. The main data sources are GPS datasets and digital road maps. A map matching algorithm was implemented and evaluated using data from vehicles in Aalborg (Denmark). The data stored in three Data Marts, a route analysis in severa1 zones of Beijing city was presented. With this analysis, we show the relationship between the shortest routes, the fastest routes, the number of stoppages and the contextual data. The analysis shows that in secondary road zones, the routes used more frequently are usually the fastest routes. In residential zones and in turistic locations this conslusion was not found valid. It was concluded that time is a dimension that influences traffic levels, but no pattern was found beetween route selection and weather condition influenced the traffic level

Extraction de relations spatio-temporelles à partir des données environnementales et de la santé

Thanks to the new technologies (smartphones, sensors, etc.), large amounts of spatiotemporal data are now available. The associated database can be called spatiotemporal databases because each row is described by a spatial information (e.g. a city, a neighborhood, a river, etc.) and temporal information (e.g. the date of an event). This huge data is often complex and heterogeneous and generates new needs in knowledge extraction methods to deal with these constraints (e.g. follow phenomena in time and space).Many phenomena with complex dynamics are thus associated with spatiotemporal data. For instance, the dynamics of an infectious disease can be described as the interactions between humans and the transmission vector as well as some spatiotemporal mechanisms involved in its development. The modification of one of these components can trigger changes in the interactions between the components and finally develop the overall system behavior.To deal with these new challenges, new processes and methods must be developed to manage all available data. In this context, the spatiotemporal data mining is define as a set of techniques and methods used to obtain useful information from large volumes of spatiotemporal data. This thesis follows the general framework of spatiotemporal data mining and sequential pattern mining. More specifically, two generic methods of pattern mining are proposed. The first one allows us to extract sequential patterns including spatial characteristics of data. In the second one, we propose a new type of patterns called spatio-sequential patterns. This kind of patterns is used to study the evolution of a set of events describing an area and its near environment.Both approaches were tested on real datasets associated to two spatiotemporal phenomena: the pollution of rivers in France and the epidemiological monitoring of dengue in New Caledonia. In addition, two measures of quality and a patterns visualization prototype are also available to assist the experts in the selection of interesting patters.Face à l'explosion des nouvelles technologies (mobiles, capteurs, etc.), de grandes quantités de données localisées dans l'espace et dans le temps sont désormais disponibles. Les bases de données associées peuvent être qualifiées de bases de données spatio-temporelles car chaque donnée est décrite par une information spatiale (e.g. une ville, un quartier, une rivière, etc.) et temporelle (p. ex. la date d'un événement). Cette masse de données souvent hétérogènes et complexes génère ainsi de nouveaux besoins auxquels les méthodes d'extraction de connaissances doivent pouvoir répondre (e.g. suivre des phénomènes dans le temps et l'espace). De nombreux phénomènes avec des dynamiques complexes sont ainsi associés à des données spatio-temporelles. Par exemple, la dynamique d'une maladie infectieuse peut être décrite par les interactions entre les humains et le vecteur de transmission associé ainsi que par certains mécanismes spatio-temporels qui participent à son évolution. La modification de l'un des composants de ce système peut déclencher des variations dans les interactions entre les composants et finalement, faire évoluer le comportement global du système. Pour faire face à ces nouveaux enjeux, de nouveaux processus et méthodes doivent être développés afin d'exploiter au mieux l'ensemble des données disponibles. Tel est l'objectif de la fouille de données spatio-temporelles qui correspond à l'ensemble de techniques et méthodes qui permettent d'obtenir des connaissances utiles à partir de gros volumes de données spatio-temporelles. Cette thèse s'inscrit dans le cadre général de la fouille de données spatio-temporelles et l'extraction de motifs séquentiels. Plus précisément, deux méthodes génériques d'extraction de motifs sont proposées. La première permet d'extraire des motifs séquentiels incluant des caractéristiques spatiales. Dans la deuxième, nous proposons un nouveau type de motifs appelé "motifs spatio-séquentiels". Ce type de motifs permet d'étudier l'évolution d'un ensemble d'événements décrivant une zone et son entourage proche. Ces deux approches ont été testées sur deux jeux de données associées à des phénomènes spatio-temporels : la pollution des rivières en France et le suivi épidémiologique de la dengue en Nouvelle Calédonie. Par ailleurs, deux mesures de qualité ainsi qu'un prototype de visualisation de motifs sont été également proposés pour accompagner les experts dans la sélection des motifs d'intérêts