4,722 research outputs found
Shape and Trajectory Tracking of Moving Obstacles
This work presents new methods and algorithms for tracking the shape and
trajectory of moving reflecting obstacles with broken rays, or rays reflecting
at an obstacle. While in tomography the focus of the reconstruction method is
to recover the velocity structure of the domain, the shape and trajectory
reconstruction procedure directly finds the shape and trajectory of the
obstacle. The physical signal carrier for this innovative method are ultrasonic
beams. When the speed of sound is constant, the rays are straight line segments
and the shape and trajectory of moving objects will be reconstructed with
methods based on the travel time equation and ellipsoid geometry. For variable
speed of sound, we start with the eikonal equation and a system of differential
equations that has its origins in acoustics and seismology. In this case, the
rays are curves that are not necessarily straight line segments and we develop
algorithms for shape and trajectory tracking based on the numerical solution of
these equations. We present methods and algorithms for shape and trajectory
tracking of moving obstacles with reflected rays when the location of the
receiver of the reflected ray is not known in advance. The shape and trajectory
tracking method is very efficient because it is not necessary for the reflected
signal to traverse the whole domain or the same path back to the transmitter.
It could be received close to the point of reflection or far away from the
transmitter. This optimizes the energy spent by transmitters for tracking the
object, reduces signal attenuation and improves image resolution. It is a safe
and secure method. We also present algorithms for tracking the shape and
trajectory of absorbing obstacles. The new methods and algorithms for shape and
trajectory tracking enable new applications and an application to one-hop
Internet routing is presented.Comment: 22 pages, 2 figures, 2 table
International Programming Systems
The emphasis in open programming lies on two things: interaction, and being dynamic. For example, a Web browser supporting plug-ins to extend its functionality (for instance to handle new content types) at run-time is open, a Web server allowing new handlers for specific resources to be added and replaced dynamically is open, and a compute server that allows clients to submit arbitrary program fragments as compute requests is open.open programming, arbitrary program fragments, interaction
The subthalamic nucleus : Part II: Modelling and simulation of activity
Part II starts with a systemic model of the basal ganglia to evaluate the position of the STN in the direct, indirect and hyperdirect pathways. A summary of in vitro studies is given, describing STN spontaneous activity as well as responses to depolarizing and hyperpolarizing inputs, and high frequency stimulation. STN bursting activity and the underlying ionic mechanisms are investigated. Deep brain stimulation used for symptomatic treatment of Parkinson's disease is discussed in terms of the elements that are influenced and its hypothesized mechanisms. This part of the monograph pays attention to the pedunculopontine-subthalamic connections and tries in cell cultures to mimic neurotransmitter actions of the pedunculopontine nucleus and high frequency stiulation on cultured dissociated rat subthalamic neurons. STN cell models: single and multi compartment, and system level models are discussed in relation to subthalamic function and dysfunction. Part I and II are mutually compared
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