Search results for "Obstacle"
showing 10 items of 105 documents
Numerical Algorithms Based on Characteristic Domain Decomposition for Obstacle Problems
1997
A new numerical solution algorithm for obstacle problems is proposed, where the characteristic domain decomposition into active and inactive subdomains separated by the free boundary is approximated by a Schwarz method. Such an approach gives an opportunity to apply fast linear system solvers to genuinely non-linear obstacle problems. Other solution algorithms, like projected relaxation methods and active set strategies, are compared to the new solution algorithm. Numerical experiments related to the elastoplastic torsion problem are included showing the efficiency of the new approach.
A Neural Solution for a Mobile Robot Navigation into Unknown Indoor Environments Using Visual Landmarks
1998
In this paper we present a neural solution for a mobile robot navigation into unknown indoor environments by using landmarks. Robot navigation task is implemented by two groups of processes based on MLP neural networks classifiers: a Low Level Vision System performs obstacle avoidance and corridor following, while an High Level Vision System extracts landmarks contents and performs goal directed navigation. A path-planner manages the two navigation systems and interacts with the robot hardware. The proposed solution is very strong and flexible and can be used to drive a mobile robot in real indoor environments. In the paper experimental results are also reported.
Origin and Flow History of Air Parcels in Orographic Banner Clouds
2015
Abstract Banner clouds are clouds in the lee of steep mountains or sharp ridges. Previous work suggests that the main formation mechanism is vertical uplift in the lee of the mountain. On the other hand, little is known about the Lagrangian behavior of air parcels as they pass the mountain, which motivates the current investigation. Three different diagnostics are applied in the framework of large-eddy simulations of airflow past an isolated pyramid-shaped obstacle: Eulerian tracers indicating the initial positions of the parcels, streamlines along the time-averaged wind field, and online trajectories computed from the instantaneous wind field. All three methods diagnose a plume of large ve…
Niveaux, tendances et facteurs explicatifs de la non-utilisation de la contraception moderne par les femmes exposées au risque de grossesse non désir…
2021
Guinea is one of the West African countries where fertility is still high and declining little, with a worrying health situation (maternal and infant mortality levels among the highest in the world). The level of demographic growth (2.5% per year on average) associated with the low level of socioeconomic development of the country seems difficult to reconcile with the satisfaction of the objectives of sustainable development and thus makes the control of fertility a major challenge.Despite the political will displayed since the early 1980s, the adoption of a national population policy declaration in 1992 and a reproductive health policy in 2001 and the Government's efforts to promote Family…
Generación de preguntas sobre información no textual : una validación empírica del modelo obstáculo-meta en la comprensión de dispositivos experiment…
2014
RESUMEN: Los mecanismos cognitivos de la generación de preguntas no son aún bien conocidos. Recientemente, se ha propuesto el modelo obstáculo-meta que asimila la comprensión a un proceso de resolución de un problema cognitivo, cuyos obstáculos hacia la meta pretendida dan lugar a las preguntas. Una predicción del modelo es la relación entre tipos de preguntas formuladas y tipos de representación mental que los sujetos manejan durante la comprensión de la información suministrada. Hasta ahora, esta predicción ha sido validada parcialmente y solo con información textual. En este trabajo se presenta un estudio empírico de validación más fiable de esta predicción, desarrollado en dos fases y q…
Hume’s guillotine and intelligent technologies
2021
AbstractEmerging intelligent society shall change the way people are organised around their work and consequently also as a society. One approach to investigating intelligent systems and their social influence is information processing. Intelligence is information processing. However, factual and ethical information are different. Facts concern true vs. false, while ethics is about what should be done. David Hume recognised a fundamental problem in this respect, which is that facts can be used to derive values. His answer was negative, which is critical for developing intelligent ethical technologies. Hume’s problem is not crucial when values can be assigned to technologies, i.e. weak ethic…
Path Planning for Perception-Driven Obstacle-Aided Snake Robot Locomotion
2020
Development of snake robots have been motivated by the ability of snakes to move efficiently in unstructured and cluttered environments. A snake robot has the potential to utilise obstacles for generating locomotion, in contrast to wheeled robots which are unable to move efficiently in rough terrain. In this paper, we propose a local path planning algorithm for snake robots based on obstacle-aided locomotion (OAL). An essential feature in OAL is to determine suitable push-points in the environment that the snake robot can use for locomotion. The proposed method is based on a set of criteria for evaluating a path, and is a novel contribution of this paper. We focus on local path planning and…
POLARIZATION-BASED CAR DETECTION
2018
International audience; Road scene understanding is a vital task for driving assistance systems. Robust vehicle detection is a precondition for diverse applications particularly for obstacle avoidance and secure navigation. Color images provide limited information about the physical properties of the object. This results in unstable vehicle detection caused mainly from road scene complexity (strong reflexions, noises and radiometric distortions). Instead, polarimetric images, characteristic of the light wave, can robustly describe important physical properties of the object (e.g., the surface geometric structure, material and roughness etc). This modality gives rich physical informations wh…
Biologically Inspired Vision Architectures: a Software/Hardware Perspective
2007
Even tough the field of computer vision has seen huge improvement in the last few decades, computer vision systems still lack, in most cases, the efficiency of biological vision systems. In fact biological vision systems routinely accomplish complex visual tasks such as object recognition, obstacle avoidance, and target tracking, which continue to challenge artificial systems. The study of biological vision system remains a strong cue for the design of devices exhibiting intelligent behaviour in visually sensed environments but current artificial systems are vastly different from biological ones for various reasons. First of all, biologically inspired vision architectures, which are continu…
Decentralization as an incentive scheme when regional differences are large
2010
It has been suggested that large regional differences could be an obstacle to that part of the political accountability of office-holders which is based on yardstick competition among governments. The paper addresses that question and concludes that the obstacle is not too serious in general. The second part of the paper is devoted to the persistent economic underperformance of some regions in countries such as Germany, Italy and (with regard to regions overseas) France. How is it that the mechanism of yardstick competition induces a convergence of economic performance among European Union member countries, even those particularly poor initially, but fails to induce all the underperforming …