Archives de catégorie : Project 4

GeoDiverCity at AAG Annual Meeting 2014 in Tampa, Florida

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Various contributions of GeoDiverCity team are scheduled for the Annual Meeting of the Association of American Geographers in Tampa, Florida :

Tuesday, 4/8/2014

> Session : 1654 European Research Council – Top European grants for brilliant minds from across the world, from 4:40 PM – 6:20 PM in Grand Salon C, Marriott, Second Floor. Organizer : Katja Meinke.

17:15-17:30    Denise Pumain, « ERC from an Advanced Grantee’s perspective. »

Wednesday, 4/9/2014

> Session : 2268 Urban systems and scaling laws: Functional diversity and urban economic trajectories, from 10:00 AM – 11:40 AM in Meeting Room 1, Marriott, Second Floor. Organizer : Céline Vacchiani-Marcuzzo.

10:00-10:20    Elfie Swerts, Céline Vacchiani-Marcuzzo, Fabien Paulus, « Scaling laws as a tool for characterising the functional evolution in urban systems »

10:20-10:40    Olivier Finance, « Transnational firms in the French system of cities and scaling laws »

> Session : 2239 Geosimulation Models 1: Methodological Advances, from 10:00 AM – 11:40 AM in Room 39, TCC, Fourth Floor. Organizers : Paul Torrens, Suzana Dragicevic, Andrew Crooks.

11:20-11:40    Mathieu Leclaire, Romain Reuillon, « Simpuzzle/Janet tools or how to build a step by step modular ABM ? »

> Session : 2539 Geosimulation Models 3 : Applications – Macro, from 2:40 PM – 4:20 PM in Room 39, TCC, Fourth Floor. Organizers : Paul Torrens, Suzana Dragicevic, Andrew Crooks.

14:00-14:20    Clémentine Cottineau, Paul Chapron, « Evaluation & Calibration for the comparison of ABMs of cities’ trajectories »

16:00-16:20  Denise Pumain, Clara Schmitt, Sébastien Rey-Coyrehourcq, Romain Reuillon, « Building and exploring an agent-based model with OpenMOLE »

Complex Systems and Geography

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GeoDiverCity Team was active at presenting their work to a diverse and large audience at the inauguration of the Complex Systems Institute in Paris.

Here are some documents we presented :

> A selection of visual results in geographical modeling

[gview file= »http://geodivercity.parisgeo.cnrs.fr/blog/wp-content/uploads/2014/03/GeoModelingok1.pdf »]

Paul Chapron, Clémentine Cottineau, Robin Cura, César Ducruet, Julie Fen-Chong, Sébastien Haule, Marion Le Texier, Nora Marei and Clara Schmitt

Picture Refs : 1. C. Cottineau, 2. D. Holten & J. W. Jarke, 3. R. Cura, 4.5. C. Ducruet, 6. M. Le Texier, 7. C. Cottineau, 8. P. Chapron, 9.10. C. Schmitt

> Netlogo models of systems of cities

  • SimpopNet

Clara Schmitt

 

  • MARIUS : Modeling of Agglomerations of Imperial Russia and the Soviet Union

Clémentine Cottineau and Paul Chapron

 

> A poster about a method to conceive, build and evaluate models at the intersection of generic systems of cities and the specific case of post-Soviet cities

Clémentine Cottineau, Paul Chapron, Denise Pumain and Romain Reuillon

 

> Accessing the European Grid computing power

Mathieu Leclaire and Romain Reuillon

 

From SimpopLocal to SimpopClim: Three stages of urban growth dynamics under resource accessibility constraints

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  The aim of this series of models [ref] PhD project of Clara Schmitt, under the supervision of Denise Pumain (founded by ADEME, The French Agency for Environment and Energy) [/ref] is to study growth regimes of systems of cities, which are defined by the nature of the interaction between the cities. Three different stages of urbanisation are considered as resource accessibility, which plays a major role in growth dynamics, takes different forms. For each stage, a set of stylized facts characterizing the state of the system and urban growth dynamics is proposed and defines the structure of an ABM model.

The SimpopLocal model tries to characterise a stylised dynamics of urban emergence.  This first urban regime is defined by the role of local environmental constraints on growth. Central to this model is the notion of landscape carrying capacity. Settlement sizes and their growth are controlled by the amount of resources locally available.  But innovations and their diffusion in the system thanks to interactions between settlements help to overcome those limitations, eventually producing the proto-structure of urban systems.

The SimpopNet model characterise the progressive networking of urban economies. Innovations in communication and transport networks allow the trade and long distance diffusion of goods and techniques which enables cities to overcome, by importing what was lacking, the local constraints and climatic hazards that limited their growth. In this regime, the resource accessibility of each city is defined by its situation in the network. The SimpopNet model simulates the co-evolution of urban systems and transportation networks.

The SimpopClim model will represent a dynamic regime that takes into account the impact of global environmental constraints on urban dynamics.

This PhD is made possible thanks to interdisciplinary work with computer researchers participating in the GeoDiverCity programme, hired after previous collaboration with ISC-PIF (Romain Reuillon and Mathieu Leclaire, http://www.iscpif.fr/) and a PhD in geomatics conducted by Sébastien Rey Coyrehourcq. The SimpopLocal and SimpopNet models are used as case studies for the development of grid exploration procedures and protocols with OpenMole (http://www.openmole.org/). Those explorations and validating tools are designed to meet the validation and reproducibility requirements and to be generic and adapted to the exploration of spatial simulation models.

Clara Schmitt

100 years of computation

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It’s what it takes to calibrate the SimpopLocal model, that simulates the dynamical hierarchical and spatial organization of settlements at the time when cities emerged, a few thousand years after the emergence of agriculture. Even if this model has been built using a few simple mechanisms, 7 parameters have no known empirical value. To find suitable values for those parameters, an automated calibration algorithm has been designed. In doing so, three quantitative goals have been defined in order to measure the quality of the output of a simulation, hence the quality of a set of parameters. One goal targets the shape of the distribution of the size of settlements, another one the size of the biggest settlement of the distribution and a last one the length of the simulation, or number of iterations, required to achieve those goals. These criteria are evaluated by computing 30 replications (independent execution) of the model (due to its stochasticity). Using the OpenMOLE framework (www.openmole.org) a genetic algorithm (a global optimization algorithm) has been distributed on the European grid EGI, federating computing power all over the world. After running about 10 million model executions, which would take more than 100 years of computation on a bleeding edge computer, the algorithm has finally converged after one week of computation and found suitable sets of parameters for the model calibration. The modelers have validated them and are now taking benefit from the calibrated model to better understand the implications of the mechanisms chosen to simulate a stylized emergence of urbanism.

Romain Reuillon, Sébastien Rey-Coyrehourcq and Clara Schmitt