2,395 research outputs found
Recommended from our members
Parametric Based Controller for Rapid Prototyping Applications
A methodology aiming at reproducing in Rapid Prototyping applications, exact parametric
curves from CAD data is presented. The approach consists of converting the space-based parametric
curves from the CAD system into time-base, such that the equations of the curve in terms of time are
then fed to a controller directly. Optimization is used to solve the problem, which has both Rapid
Prototyping process and scanning constraints. With information such as the equation of the curve, its
first and second derivatives with respect to time, a real-time trajectory controller can be designed.
The trajectory displays an increase in accuracy over traditional approaches using STL files, which is
ofthe order of the chordal tolerance used to generate tessellations. The system model involves
electrical and mechanical dynamics of the galvanometers and sensors. The controller, which acts on
two mirrors, deflecting the laser beam of a stereolithography machine in the x and y directions
respectively, should be easily substituted for current systems. Application of the methodology to
freeform curves shows acceptable tracking and can be improved by judicious selection ofthe equation
representing the spatial parameter as a function of time.Mechanical Engineerin
Interference and Outage in Clustered Wireless Ad Hoc Networks
In the analysis of large random wireless networks, the underlying node
distribution is almost ubiquitously assumed to be the homogeneous Poisson point
process. In this paper, the node locations are assumed to form a Poisson
clustered process on the plane. We derive the distributional properties of the
interference and provide upper and lower bounds for its CCDF. We consider the
probability of successful transmission in an interference limited channel when
fading is modeled as Rayleigh. We provide a numerically integrable expression
for the outage probability and closed-form upper and lower bounds.We show that
when the transmitter-receiver distance is large, the success probability is
greater than that of a Poisson arrangement. These results characterize the
performance of the system under geographical or MAC-induced clustering. We
obtain the maximum intensity of transmitting nodes for a given outage
constraint, i.e., the transmission capacity (of this spatial arrangement) and
show that it is equal to that of a Poisson arrangement of nodes. For the
analysis, techniques from stochastic geometry are used, in particular the
probability generating functional of Poisson cluster processes, the Palm
characterization of Poisson cluster processes and the Campbell-Mecke theorem.Comment: Submitted to IEEE Transactions on Information Theor
- …