Search results for "Automation"
showing 10 items of 1181 documents
Towards a Dual-mode Adaptive MAC Protocol (DMA-MAC) for Feedback-based Networked Control Systems
2014
Abstract Automated control systems play an important part in many industrial domains and the medium used for communication between devices in these systems is in transition from wired to wireless for cost reasons. Control systems have strict requirements on delay, throughput, and reliability, that vary with time during operation. Addressing these requirements requires predictable and robust protocols to be employed, and they must be adaptive to the varying states of the controlled process. In this article, we propose a dual-mode adaptive medium access control protocol that caters for two main operation modes in control systems: the steady mode operation, and the transient mode operation. We…
Introduction: Reframing Humans and Information Systems
2010
Recent development of information and communication technologies (ICT) provides information systems (IS) designers with new potentialities to build systems for various purposes. The ongoing digital convergence refers to and discloses new views on the interactive reconfiguration of technological and social arrangements on a large scale in the contemporary society (Tilson et al. 2009). In addition to work-related activities, people use new technologies for increasingly diverse purposes, for example organizing their domestic affairs, for finding information and e-services, and for staying in touch with their friends and relatives (Lyytinen and Yoo 2002; Sorensen and Yoo 2005; Iivari et al. 201…
A Review on Applications of Big Data for Disaster Management
2017
International audience; The term " disaster management " comprises both natural and man-made disasters. Highly pervaded with various types of sensors, our environment generates large amounts of data. Thus, big data applications in the field of disaster management should adopt a modular view, going from a component to nation scale. Current research trends mainly aim at integrating component, building, neighborhood and city levels, neglecting the region level for managing disasters. Current research on big data mainly address smart buildings and smart grids, notably in the following areas: energy waste management, prediction and planning of power generation needs, improved comfort, usability …
Model Free Control for muscular force by Functional Electrical Stimulation using pulse width modulation
2016
International audience; Functional Electrical Stimulation (FES) is a useful technique for restoring functions for patients with neurological disorders. Muscle activities can be artificially driven through delivery of electrical pulses to skeletal muscles. Typically, muscles are activated by using constant stimulation train with a fixed parameters (amplitude, frequency and pulse width). In addition, the FES systems do not adapt the parameters stimulation to obtain a desired force response during the rehabilitation session. The purpose of this study is to investigate a real-time FES system for adapting automatically the stimulation parameters (stimulation pulse width) to track a desired force…
Roughness evaluation of vine leaf by image processing
2013
International audience; The study of leaf surface roughness is very important in the domain of precision spraying. It is one of the parameters that allow to reduce costs and losses of phytosanitary prod- ucts and to improve the spray accuracy. Moreover, the leaf roughness is related to adhesion mechanisms of liquid on a surface. It can be used to define leaf nature surface (hy- drophilic/hydrophobic). The main goal of this study is thus to estimate and to follow the evolution of leaf roughness using image processing and computer vision. The develop- ment and application of computer vision for measurement of surface leaf roughness using artificial neural networks will be described. The syste…
Free vs. Locally Free Kleinian Groups
2015
Abstract We prove that Kleinian groups whose limit sets are Cantor sets of Hausdorff dimension < < 1 are free. On the other hand we construct for any ε > > 0 an example of a non-free purely hyperbolic Kleinian group whose limit set is a Cantor set of Hausdorff dimension < < 1 + + ε.
Stratification du secteur anormal dans la sphère de Martinet de petit rayon
2007
L’objectif de cet article est de fournir le cadre geometrique pour faire une analyse de la singularite de l’application exponentielle le long d’une direction anormale en geometrie sous-Riemannienne. Il utilise les calculs de [9], [12], et conduit dans le cas Martinet a une stratification de la singularite en secteurs Lagrangiens.
Continuous optimal control sensitivity analysis with AD
2000
In order to apply a parametric method to a minimum time control problem in celestial mechanics, a sensitivity analysis is performed. The analysis is continuous in the sense that it is done in the infinite dimensional control setting. The resulting sufficient second order condition is evaluated by means of automatic differentiation, while the associated sensitivity derivative is computed by continuous reverse differentiation. The numerical results are given for several examples of orbit transfer, also illustrating the advantages of automatic differentiation over finite differences for the computation of gradients on the discretized problem.
Optimal control of the atmospheric arc of a space shuttle and numerical simulations with multiple-shooting method
2005
This article, continuation of previous works, presents the applications of geometric optimal control theory to the analysis of the Earth re-entry problem for a space shuttle where the control is the angle of bank, the cost is the total amount of thermal flux, and the system is subject to state constraints on the thermal flux, the normal acceleration and the dynamic pressure. Our analysis is based on the evaluation of the reachable set using the maximum principle and direct computations with the boundary conditions according to the CNES research project\footnote{The project is partially supported by the Centre National d'Etude Spatiales.}. The optimal solution is approximated by a concatenat…
Une approche géométrique du contrôle optimal de l'arc atmosphérique de la navette spatiale
2002
L'objectif de ce travail est de faire quelques remarques géométriques et des calculs préliminaires pour construire l'arc atmosphérique optimal d'une navette spatiale (problème de rentrée sur Terre ou programme d'exploration de Mars). Le système décrivant les trajectoires est de dimension 6, le contrôle est l'angle de gîte cinématique et le coût est l'intégrale du flux thermique. Par ailleurs il y a des contraintes sur l'état (flux thermique, accélération normale et pression dynamique). Notre étude est essentiellement géométrique et fondée sur une évaluation de l'ensemble des états accessibles en tenant compte des contraintes sur l'état. On esquisse une analyse des extrémales du Principe du …