Extending the DEVS Formalism with Initialization Information

DEVS is a popular formalism to model system behaviour using a discrete-event abstraction. The main advantages of DEVS are its rigourous and precise specification, as well as its support for modular, hierarchical construction of models. DEVS frequently serves as a simulation "assembly language" to which models in other formalisms are translated, either giving meaning to new (domain-specific) languages, or reproducing semantics of existing languages. Despite this rigourous definition of its syntax and semantics, initialization of DEVS models is left unspecified in both the Classic and Parallel DEVS formalism definition. In this paper, we extend the DEVS formalism by including an initial total state. Extensions to syntax as well as denotational (closure under coupling) and operational semantics (abstract simulator) are presented. The extension is applicable to both main variants of the DEVS formalism. Our extension is such that it adds to, but does not alter the original specification. All changes are illustrated by means of a traffic light example

Mimosa: Using ontologies for modeling and simulation

Modeling is the shared activity for both modeling and simulation, and knowledge representation. At the same time, the objectives of these two domains are not the same and both seem necessary when dealing with modeling highly structured and complex systems. To face the complexity of the systems we are trying to model and to simulate nowadays, the challenge addressed in this paper is to mix both approaches in a common framework. We first describe separately the recent advances made in the modeling and simulation community as well as in the knowledge representation community. We show that, despite the same goal to describe a reality, or at least a part of it, it results in very different, although related concepts. This difference is due to the focus taken by these communities. The first community is centered on dynamics, and the second one on static descriptions. From the analysis of the differences and similarities, we propose an architecture which is being tested in a modeling and simulation platform: Mimosa. The outcome is a formal way to pave the path from conceptual to running models which is sketched in this paper. The achievements and the perspectives are discussed in the conclusion. (Résumé d'auteur

Multi-modal gated recurrent units for image description

Using a natural language sentence to describe the content of an image is a challenging but very important task. It is challenging because a description must not only capture objects contained in the image and the relationships among them, but also be relevant and grammatically correct. In this paper a multi-modal embedding model based on gated recurrent units (GRU) which can generate variable-length description for a given image. In the training step, we apply the convolutional neural network (CNN) to extract the image feature. Then the feature is imported into the multi-modal GRU as well as the corresponding sentence representations. The multi-modal GRU learns the inter-modal relations between image and sentence. And in the testing step, when an image is imported to our multi-modal GRU model, a sentence which describes the image content is generated. The experimental results demonstrate that our multi-modal GRU model obtains the state-of-the-art performance on Flickr8K, Flickr30K and MS COCO datasets.Comment: 25 pages, 7 figures, 6 tables, magazin

DEVS-based intelligent control of space adapted fluid mixing

The development is described of event-based intelligent control system for a space-adapted mixing process by employing the DEVS (Discrete Event System Specification) formalism. In this control paradigm, the controller expects to receive confirming sensor responses to its control commands within definite time windows determined by its DEVS model of the system under control. The DEVS-based intelligent control paradigm was applied in a space-adapted mixing system capable of supporting the laboratory automation aboard a Space Station

Etching-dependent reproducible memory switching in vertical SiO2 structures

Vertical structures of SiO$_{2}$ sandwiched between a top tungsten electrode and conducting non-metal substrate were fabricated by dry and wet etching methods. Both structures exhibit similar voltage-controlled memory behaviors, in which short voltage pulses (1 $\mu$s) can switch the devices between high- and low-impedance states. Through the comparison of current-voltage characteristics in structures made by different methods, filamentary conduction at the etched oxide edges is most consistent with the results, providing insights into similar behaviors in metal/SiO/metal systems. High ON/OFF ratios of over 10$^{4}$ were demonstrated.Comment: 6 pages, 3 figures + 2 suppl. figure

Modelling the Minsky triad: A framework to perform reflexive MandS studies

In this paper, we propose a general framework to evaluate models of systems that are ill defined, incompletely known, and furthermore, which cannot be experimented in real conditions, such as the economical systems at the country scale, epidemics (for obvious ethical reasons) or any natural disasters, for instance where human lives are the main issue. Our framework relies on the generic Marvin Minsky's definition of a model and its specification in the frame of the Theory of Modelling and Simulation, initiated by B.P. Zeigler. Such a dynamic system implementation of the Marvin Minsky's model definition, we called the Minsky triad model, enables to address original questions. The Minsky triad model is a coupled model composed of the model of a real system, the model of this later model, and, in between, the model of the user of the later model. We argue that the Minsky triad model is very promising as a framework to design and to evaluate decision support systems for crisis management. (Résumé d'auteur

The Numerical Sausage

The renormalization group equation describing the evolution of the metric of the non linear sigma models poses some nice mathematical problems involving functional analysis, differential geometry and numerical analysis. We describe the techniques which allow a numerical study of the solutions in the case of a two-dimensional target space (deformation of the $O(3)\; \sigma$--model. Our analysis shows that the so-called sausages define an attracting manifold in the U(1) symmetric case, at one-loop level. The paper describes i) the known analytical solutions, ii) the spectral method which realizes the numerical integrator and allows to estimate the spectrum of zero--modes, iii) the solution of variational equations around the solutions, and finally iv) the algorithms which reconstruct the surface as embedded in $R^3$.Comment: 15 pages, uuencoded postscript fil

Pterodactyl: Trade Study for an Integrated Control System Design of a Mechanically Deployable Entry Vehicle

This paper presents the trade study method used to evaluate and downselect from a set of guidance and control (G&C) system designs for a mechanically Deployable Entry Vehicle (DEV). The Pterodactyl project was prompted by the challenge to develop an effective G&C system for a vehicle without a backshell, which is the case for DEVs. For the DEV, the project assumed a specific aeroshell geometry pertaining to an Adaptable, Deployable Entry and Placement Technology (ADEPT) vehicle, which was successfully developed by NASAs Space Technology Mission Directorate (STMD) prior to this study. The Pterodactyl project designed three different entry G&C systems for precision targeting. This paper details the Figures of Merit (FOMs) and metrics used during the course of the projects G&C system assessment. The relative importance of the FOMs was determined from the Analytic Hierarchy Process (AHP), which was used to develop weights that were combined with quantitative design metrics and engineering judgement to rank the G&C systems against one another. This systematic method takes into consideration the projects input while simultaneously reducing unintentional judgement bias and ultimately was used to select a single G&C design for the project to pursue in the next design phase