Showing papers by "Michael North published in 2015"

Simulating agricultural land rental markets by combining agent-based models with traditional economics concepts

Abstract: Land exchange through rental transactions is a central process in agricultural systems. The land tenure regimes emerge from land transactions and structural and land use changes are tied to the dynamics of the land market. We introduce LARMA, a LAnd Rental MArket model embedded within the Pampas Model (PM), an agent-based model of Argentinean agricultural systems. LARMA produces endogenous formation of land rental prices. LARMA relies on traditional economic concepts for LRP formation but addresses some drawbacks of this approach by being integrated into an agent-based model that considers heterogeneous agents interacting with one another. PM-LARMA successfully reproduced the agricultural land tenure regimes and land rental prices observed in the Pampas. Including adaptive, heterogeneous and interacting agents was critical to this success. We conclude that agent-based and traditional economic models can be successfully combined to capture complex emergent land tenure and market price patterns while simplifying the overall model design. LARMA is a land rental market model with endogenous rental price formation.LARMA is embedded into the Pampas agent-based model (PM).LARMA combines traditional economics concepts with agent-based modeling.PM-LARMA successfully reproduces land tenure patterns and rental price dynamics.We discuss the advantages of combining approaches for modeling land rental markets.

The Baltic: A History

Abstract: In this overview of the Baltic region from the Vikings to the European Union, Michael North presents the sea and the lands that surround it as a Nordic Mediterranean, a maritime zone of shared influence, with its own distinct patterns of trade, cultural exchange, and conflict. Covering over a thousand years in a part of the world where seas have been much more connective than land, The Baltic: A History" transforms the way we think about a body of water too often ignored in studies of the world s major waterways.The Baltic lands have been populated since prehistory by diverse linguistic groups: Balts, Slavs, Germans, and Finns. North traces how the various tribes, peoples, and states of the region have lived in peace and at war, as both global powers and pawns of foreign regimes, and as exceptionally creative interpreters of cultural movements from Christianity to Romanticism and Modernism. He examines the golden age of the Vikings, the Hanseatic League, Gustavus Adolphus of Sweden, and Peter the Great, and looks at the hard choices people had to make in the twentieth century as fascists, communists, and liberal democrats played out their ambitions on the region s doorstep.With its vigorous trade in furs, fish, timber, amber, and grain and its strategic position as a thruway for oil and natural gas, the Baltic has been and remains one of the great economic and cultural crossroads of the world."

Repast Simphony Statecharts

Abstract: Agent states and transitions between states are important abstractions in agent-based social simulation (ABSS). Although it is common to develop ad hoc implementations of state-based and transition-based agent behaviors, 'best practice' software engineering processes provide transparent and formally grounded design notations that translate directly into working implementations. Statecharts are a software engineering design methodology and an explicit visual and logical representation of the states of system components and the transitions between those states. Used in ABSS, they can clarify a model's logic and allow for efficient software engineering of complex state-based models. In addition to agent state and behavioral logic representation, visual statecharts can also be useful for monitoring agent status during a simulation, quickly conveying the underlying dynamics of complex models as a simulation evolves over time. Visual approaches include drag-and-drop editing capabilities for constructing state-based models of agent behaviors and conditions for agent state transitions. Repast Simphony is a widely used, open source, and freely accessible agent-based modeling toolkit. While it is possible for Repast Simphony users to create their own implementations of state-based agent behaviors and even create dynamic agent state visualizations, the effort involved in doing so is usually prohibitive. The new statecharts framework in Repast Simphony, a subset of Harel's statecharts, introduces software engineering practices through the use of statecharts that directly translate visual representations of agent states and behaviors into software implementations. By integrating an agent statecharts framework into Repast Simphony, we have made it easier for users at all levels to take advantage of this important modeling paradigm. Through the visual programming that statecharts afford, users can effectively create the software underlying agents and agent-based models. This paper describes the development and use of the free and open source Repast Simphony statecharts capability for developing ABSS models.

Integrated modeling of conflict and energy

Abstract: The present paper summarizes the integration of two models, an energy security model and a national stability (conflict) model. The Energy Security Model uses system dynamics to represent national interactions in global markets for oil and natural gas. The Conflict Model employs multiscale agent-based modeling to represent international, national and subnational actors that must address complex scenarios in international relations. While this is a work in progress, the models are being integrated in order to support model interaction. So, instability in a major oil producing country can restrict global oil supplies and increase prices. Similarly, a fall in oil price might weaken a nation that is heavily dependent on oil revenue for stability. This overview provides an informative description of two alternate methods used to integrate two substantively distinct models.

Applying 3D printing and genetic algorithm-generated anticipatory system dynamics models to a homeland security challenge

Abstract: In this paper we apply 3D printing and genetic algorithm-generated anticipatory system dynamics models to a homeland security challenge, namely understanding the interface between transnational organized criminal networks and local gangs. We apply 3D printing to visualize the complex criminal networks involved. This allows better communication of the network structures and clearer understanding of possible interventions. We are applying genetic programming to automatically generate anticipatory system dynamics models. This will allow both the structure and the parameters of system dynamics models to evolve. This paper reports the status of work in progress. This paper builds on previous work that introduced the use of genetic programs to automatically generate system dynamics models. This paper's contributions are that it introduces the use of 3D printing techniques to visualize complex networks and that it presents in more detail our emerging approach to automatically generating anticipatory system dynamics in weakly constrained, data-sparse domains.