4,919 research outputs found
May 2010 - Digital Minute Issue 2
This issue features information about global repositories, as well as visits to our Digital Commons by country
Asymptotic formulas for solitary waves in the high-energy limit of FPU-type chains
It is well established that the solitary waves of FPU-type chains converge in
the high-energy limit to traveling waves of the hard-sphere model. In this
paper we establish improved asymptotic expressions for the wave profiles as
well as an explicit formula for the wave speed. The key step in our approach is
the derivation of an asymptotic ODE for the appropriately rescaled strain
profile.Comment: revised version with corrected typos; 25 pages, several figure
Sparse bayesian polynomial chaos approximations of elasto-plastic material models
In this paper we studied the uncertainty quantification in a functional approximation form of elastoplastic models parameterised by material uncertainties. The problem of estimating the polynomial chaos coefficients is recast in a linear regression form by taking into consideration the possible sparsity of the solution. Departing from the classical optimisation point of view, we take a slightly different path by solving the problem in a Bayesian manner with the help of new spectral based sparse Kalman filter algorithms
Should I Bug You? Identifying Domain Experts in Software Projects Using Code Complexity Metrics
In any sufficiently complex software system there are experts, having a
deeper understanding of parts of the system than others. However, it is not
always clear who these experts are and which particular parts of the system
they can provide help with. We propose a framework to elicit the expertise of
developers and recommend experts by analyzing complexity measures over time.
Furthermore, teams can detect those parts of the software for which currently
no, or only few experts exist and take preventive actions to keep the
collective code knowledge and ownership high. We employed the developed
approach at a medium-sized company. The results were evaluated with a survey,
comparing the perceived and the computed expertise of developers. We show that
aggregated code metrics can be used to identify experts for different software
components. The identified experts were rated as acceptable candidates by
developers in over 90% of all cases
Near real-time stereo vision system
The apparatus for a near real-time stereo vision system for use with a robotic vehicle is described. The system is comprised of two cameras mounted on three-axis rotation platforms, image-processing boards, a CPU, and specialized stereo vision algorithms. Bandpass-filtered image pyramids are computed, stereo matching is performed by least-squares correlation, and confidence ranges are estimated by means of Bayes' theorem. In particular, Laplacian image pyramids are built and disparity maps are produced from the 60 x 64 level of the pyramids at rates of up to 2 seconds per image pair. The first autonomous cross-country robotic traverses (of up to 100 meters) have been achieved using the stereo vision system of the present invention with all computing done onboard the vehicle. The overall approach disclosed herein provides a unifying paradigm for practical domain-independent stereo ranging
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