In this paper, distributed control policies for spacecraft formations that draw inspiration from the simple idea of cyclic pursuit are studied. First studied are cyclic-pursuit control laws for both singleand double-integrator models in three dimensions. In particular, control laws are developed that only require relative measurements of position and velocity with respect to the two leading nei...

Robot formations imply the establishment and the maintenance of a predetermined geometric shape by a group of robots. In this work, we achieve formations using robots with proximity sensors of short detection range and no inter-robot communication equipment. This fact turns the synthesis problem into a hard one compared to those cases where the robot has information about the absolute location ...

Introduction: Les métropoles camerounaises concentrent un nombre croissant d'enfants cibles, non atteints par les services de vaccination de routine. Méthodes: Une étude transversale descriptive, basée sur échantillonnage exhaustif des formations sanitaires légales offrant en routine des services de vaccination a été réalisée dans le district de santé de Djoungolo, (ville de Yaoundé). L'évaluat...

The distributions of permeability and porosity are key factors that control airflow and gas phase transport in unsaturated formations. To understand the behavior of flow and transport in such formations, characterization procedure is a typical approach that has been widely applied to laboratories and fields. As is recognized by most investigations, this approach relies on accurate measurements,...

Microbial communities of two deep (1,270 and 316 m) alkaline (pH 9.94 and 8.05), anaerobic (Eh, -137 and -27 mV) aquifers were characterized by rRNA-based analyses. Both aquifers, the Grande Ronde (GR) and Priest rapids (PR) formations, are located within the Columbia River Basalt Group in south-central Washington, and sulfidogenesis and methanogenesis characterize the GR and PR formations, res...

In this paper we show how non–linear attractor dynamics can be used as a framework to control teams of autonomous mobile robots that should navigate according to a predefined geometric formation. The environment does not need to be known a priori and may change over time. Implicit to the control architecture are some important features such as establishing and moving the formation, split and jo...

Formations required to move to given destinations can be controlled to arrive to a predefined geometric shape or to self-organize. For a large number of autonomous mobile robots, geometric formations pose too many constraints to achieving inter-robot positions. Self-organizing formations are more suitable for a large number of robots and generate formation shapes while avoiding robots collision...

Statistical studies on Palynology contents of Late Cretaceous to Paleocene age Gurpi Formation in a surface section in Zagros Basin,SW Iran indicate changes in abundance, species diversity, ratio of Spiniferites to Cyclonephelium (S/C), palynological marine index(PMI) values and organic facies. These palynological variations clearly reflect fluctuations in relative sea-level and depositionalenv...

Problems of coordinated motion of vehicular formations have received much attention lately, especially in the areas of formation flight and so-called vehicular platoons. We investigate fundamental limitations that the use of only local feedback control has on the coherence of large formations that are subjected to stochastic disturbances. The notion of coherence translates roughly into how clos...

Loose, fibrillar, spherical structures have been observed during recent years in interphase nuclei of both animal and plant cells. These nuclear formations have been referred to as karyosomes, fibrillar bodies, micropuffs and centromeres. In order to gain further information on the nature of these structures, a cytochemical and radioautographic investigation was undertaken using plant meristema...