205,094 research outputs found
Multi-level agent-based modeling with the Influence Reaction principle
This paper deals with the specification and the implementation of multi-level
agent-based models, using a formal model, IRM4MLS (an Influence Reaction Model
for Multi-Level Simulation), based on the Influence Reaction principle.
Proposed examples illustrate forms of top-down control in (multi-level)
multi-agent based-simulations
Multi-level agent-based modeling - A literature survey
During last decade, multi-level agent-based modeling has received significant
and dramatically increasing interest. In this article we present a
comprehensive and structured review of literature on the subject. We present
the main theoretical contributions and application domains of this concept,
with an emphasis on social, flow, biological and biomedical models.Comment: v2. Ref 102 added. v3-4 Many refs and text added v5-6 bibliographic
statistics updated. v7 Change of the name of the paper to reflect what it
became, many refs and text added, bibliographic statistics update
Re-engineering a nanodosimetry Monte Carlo code into Geant4: software design and first results
A set of physics models for nanodosimetry simulation is being re-engineered
for use in Geant4-based simulations. This extension of Geant4 capabilities is
part of a larger scale R&D project for multi-scale simulation involving
adaptable, co-working condensed and discrete transport schemes. The project in
progress reengineers the physics modeling capabilities associated with an
existing FORTRAN track-structure code for nanodosimetry into a software design
suitable to collaborate with an object oriented simulation kernel. The first
experience and results of the ongoing re-engineering process are presented.Comment: 4 pages, 2 figures and images, to appear in proceedings of the
Nuclear Science Symposium and Medical Imaging Conference 2009, Orland
Can geocomputation save urban simulation? Throw some agents into the mixture, simmer and wait ...
There are indications that the current generation of simulation models in practical,
operational uses has reached the limits of its usefulness under existing specifications.
The relative stasis in operational urban modeling contrasts with simulation efforts in
other disciplines, where techniques, theories, and ideas drawn from computation and
complexity studies are revitalizing the ways in which we conceptualize, understand,
and model real-world phenomena. Many of these concepts and methodologies are
applicable to operational urban systems simulation. Indeed, in many cases, ideas from
computation and complexity studiesâoften clustered under the collective term of
geocomputation, as they apply to geographyâare ideally suited to the simulation of
urban dynamics. However, there exist several obstructions to their successful use in
operational urban geographic simulation, particularly as regards the capacity of these
methodologies to handle top-down dynamics in urban systems.
This paper presents a framework for developing a hybrid model for urban geographic
simulation and discusses some of the imposing barriers against innovation in this
field. The framework infuses approaches derived from geocomputation and
complexity with standard techniques that have been tried and tested in operational
land-use and transport simulation. Macro-scale dynamics that operate from the topdown
are handled by traditional land-use and transport models, while micro-scale
dynamics that work from the bottom-up are delegated to agent-based models and
cellular automata. The two methodologies are fused in a modular fashion using a
system of feedback mechanisms. As a proof-of-concept exercise, a micro-model of
residential location has been developed with a view to hybridization. The model
mixes cellular automata and multi-agent approaches and is formulated so as to
interface with meso-models at a higher scale
Windsock memory conditioned RAM (Co-Ram) pressure effect: forced reconnection in the Earth's magnetotail
Magnetic reconnection (MR) is a key physical concept explaining the addition
of magnetic flux to the magnetotail and closed flux lines back-motion to the
dayside magnetosphere. This scenario elaborated by \citet{dung63}, can explain
many aspects of solar wind-magnetosphere interaction processes, including
substorms. However, neither the Dungey model nor its numerous modifications
were able to explain fully the onset conditions for MR in the tail. In this
paper, we introduce new onset conditions for forced MR in the tail. We call our
scenario the "windsock memory conditioned ram pressure effect". Our
non-flux-transfer associated forcing is introduced by a combination of
large-scale windsock motions exhibiting memory effects and solar wind dynamic
pressure actions on the nightside magnetopause during northward oriented IMF.
Using global MHD GUMICS-4 simulation results, upstream data from WIND,
magnetosheath data from Cluster-1 and distant-tail data from the two-probe
ARTEMIS mission, we show that the simultaneous occurrence of vertical windsock
motions of the magnetotail and enhanced solar wind dynamic pressure introduces
strong nightside disturbances, including enhanced electric fields and
persistent vertical cross-tail shear flows. These perturbations, associated
with a stream interaction region in the solar wind, drive MR in the tail during
episodes of northward oriented interplanetary magnetic field (IMF). We detect
MR indirectly, observing plasmoids in the tail and ground based signatures of
Earthward moving fast flows. We also consider the application to solar system
planets and close-in exoplanets, where the proposed scenario can elucidate some
new aspects of solar/stellar wind - magnetosphere interactions.Comment: 16 pages, 12 figure
Survey on Evaluation Methods for Dialogue Systems
In this paper we survey the methods and concepts developed for the evaluation
of dialogue systems. Evaluation is a crucial part during the development
process. Often, dialogue systems are evaluated by means of human evaluations
and questionnaires. However, this tends to be very cost and time intensive.
Thus, much work has been put into finding methods, which allow to reduce the
involvement of human labour. In this survey, we present the main concepts and
methods. For this, we differentiate between the various classes of dialogue
systems (task-oriented dialogue systems, conversational dialogue systems, and
question-answering dialogue systems). We cover each class by introducing the
main technologies developed for the dialogue systems and then by presenting the
evaluation methods regarding this class
- âŠ