Oriented vehicles travelling in spherical space

This paper tackles the path planning problem for oriented vehicles travelling in the non-Euclidean 3-Dimensional space; spherical space S3. For such problem, the orientation of the vehicle is naturally represented by orthonormal frame bundle; the rotation group SO(4). Orthonormal frame bundles of space forms coincide with their isometry groups and therefore the focus shifts to control systems defined on Lie groups. The oriented vehicles, in this case, are constrained to travel at constant speed in a forward direction and their angular velocities directly controlled. In this paper we identify controls that induce steady motions of these oriented vehicles and yield closed form parametric expressions for these motions. The paths these vehicles trace are defined explicitly in terms of the controls and therefore invariant with respect to the coordinate system used to describe the motion.

Travelling waves in a model of species migration

A model of species migration is presented which takes the form of a reaction-diffusion system. We consider special limits of this model in which we demonstrate the existence of travelling wave solutions. These solutions can be used to describe the migration of cells, bacteria, and some organisms. © 2000 Elsevier Science Ltd. All rights reserved.

Multi-instrument ground-based observations of a travelling convection vortices event

A coordinated ground-based observational campaign using the IMAGE magnetometer network, EISCAT radars and optical instruments on Svalbard has made possible detailed studies of a travelling convection vortices (TCV) event on 6 January 1992. Combining the data from these facilities allows us to draw a very detailed picture of the features and dynamics of this TCV event. On the way from the noon to the drawn meridian, the vortices went through a remarkable development. The propagation velocity in the ionosphere increased from 2.5 to 7.4 km s−1, and the orientation of the major axes of the vortices rotated from being almost parallel to the magnetic meridian near noon to essentially perpendicular at dawn. By combining electric fields obtained by EISCAT and ionospheric currents deduced from magnetic field recordings, conductivities associated with the vortices could be estimated. Contrary to expectations we found higher conductivities below the downward field aligned current (FAC) filament than below the upward directed. Unexpected results also emerged from the optical observations. For most of the time there were no discrete aurora at 557.7 nm associated with the TCVs. Only once did a discrete form appear at the foot of the upward FAC. This aurora subsequently expanded eastward and westward leaving its centre at the same longitude while the TCV continued to travel westward. Also we try to identify the source regions of TCVs in the magnetosphere and discuss possible generation mechanisms.

Stability of periodic travelling shallow-water waves determined by Newton`s equation

We study the existence and stability of periodic travelling-wave solutions for generalized Benjamin-Bona-Mahony and Camassa-Holm equations. To prove orbital stability, we use the abstract results of Grillakis-Shatah-Strauss and the Floquet theory for periodic eigenvalue problems.

Front End Evaluation of 'Tester' Exhibition to be Developed into a Travelling Sports Exhibition

The purpose of this evaluation is to develop a framework that will help in planning and implementing the mobile sport exhibition, increase visitor satisfaction and aid At Bristol in building successful exhibits. The evaluation mainly focuses on visitor interaction with exhibits. It is believed that learning does occur in science centres and museums. The evaluation will therefore find out if learning occurs in the Sports exhibition and if so, the nature of the learning outcomes. The evaluation also discusses advantages and disadvantages of travelling exhibitions and identifies the characteristics of good exhibits that form the basis of the framework.From the results, an indication is that children make the larger proportion of visitors to Sportastic. Their age ranges, under 10 and 10 to 15 years constituted 21% and 30% respectively. The three most enjoyed exhibits are the Sprint Challenge (running), BATAK (test your reaction and Hot Shots (football). Visitors say these exhibits are enjoyed because they are fun, competitive, entertaining, interactive and hands-on. Skateboard Challenge and Skeleton Bob are among the exhibits least enjoyed since they are reported to be boring and uncomfortable to use. The learning outcomes from the exhibits are; increased knowledge about balancing, reaction, pulse and strength.

Entropic information for travelling solitons in Lorentz and CPT breaking systems

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)