Color classification using color vision models

According to recent physiological research results, there are many individual differences already at the detection level of our color vision system. It is not completely clear yet, how the other levels of color vision system compensate the detection differences. Instead of detecting and analyzing colors exactly in the same way, we all just have learned to classify colors in a certain way, which seems to lead almost always to the same result independent of the individual differences in the color vision system. In this article, we experiment with four models developed for replicating certain properties of human color vision. We examine the color classification abilities of these models and show the differences and similarities in their behavior. © 2010 Wiley Periodicals, Inc. Col Res Appl, 2010.     

Particle Entrapment in Hybrid Lubricated Point Contacts

This study proposes an innovative approach for the study of particle entrapment in rolling element bearings (REBs). Two couples of contacting materials were considered, the classical steel–steel and silicon nitride–steel used in hybrid bearings. Numerical simulations, as well as experiments, combine theoretical trajectories for incoming contaminant particles and effective entrapment ratios observed within a twin-disc machine. Linking both approaches allows the highlighting of some key parameters leading to particle entrapment under pure rolling conditions in elastohydrodynamic point contacts.     

Activelets: Wavelets for sparse representation of hemodynamic responses

We propose a new framework to extract the activity-related component in the BOLD functional magnetic resonance imaging (fMRI) signal. As opposed to traditional fMRI signal analysis techniques, we do not impose any prior knowledge of the event timing. Instead, our basic assumption is that the activation pattern is a sequence of short and sparsely distributed stimuli, as is the case in slow event-related fMRI.We introduce new wavelet bases, termed “activelets”, which sparsify the activity-related BOLD signal. These wavelets mimic the behavior of the differential operator underlying the hemodynamic system. To recover the sparse representation, we deploy a sparse-solution search algorithm.The feasibility of the method is evaluated using both synthetic and experimental fMRI data. The importance of the activelet basis and the non-linear sparse recovery algorithm is demonstrated by comparison against classical B-spline wavelets and linear regularization, respectively.     

Ships as a sensor network to observe ice field properties

This paper introduces a concept and a prototype system of using ships and coastal stations as a sensor network to obtain additional information about the ice field. The system collects marine radar images and ship performance observations, forms mosaics of images from multiples radars, calculates ice drift from subsequent radar images, analyzes trafficability in different sea areas using performance observations, and delivers processed images, trafficability estimation, and ice drift information to end-users. The prototype was developed and tested during the winters of 2008 and 2009 in the Baltic Sea. In this paper, we describe the prototype and discuss the usability of a ship sensor network. The concept appears to be feasible, and such a system would provide additional information about prevailing ice conditions.     

Polyharmonic smoothing splines and the multidimensional Wiener filtering of fractal-like signals.

Motivated by the fractal-like behavior of natural images, we develop a smoothing technique that uses a regularization functional which is a fractional iterate of the Laplacian. This type of functional was initially introduced by Duchon for the approximation of nonuniformily sampled, multidimensional data. He proved that the general solution is a smoothing spline that is represented by a linear combination of radial basis functions (RBFs). Unfortunately, this is tedious to implement for images because of the poor conditioning of RBFs and their lack of decay. Here, we present a much more efficient method for the special case of a uniform grid. The key idea is to express Duchon's solution in a fractional polyharmonic B-spline basis that spans the same space as the RBFs. This allows us to derive an algorithm where the smoothing is performed by filtering in the Fourier domain. Next, we prove that the above smoothing spline can be optimally tuned to provide the MMSE estimation of a fractional Brownian field corrupted by white noise. This is a strong result that not only yields the best linear filter (Wiener solution), but also the optimal interpolation space, which is not bandlimited. It also suggests a way of using the noisy data to identify the optimal parameters (order of the spline and smoothing strength), which yields a fully automatic smoothing procedure. We evaluate the performance of our algorithm by comparing it against an oracle Wiener filter, which requires the knowledge of the true noiseless power spectrum of the signal. We find that our approach performs almost as well as the oracle solution over a wide range of conditions.     

Intraabdominal pyloromyotomy through the umbilical route: a technical improvement

BACKGROUND/PURPOSE: Performing a pyloromyotomy through a supraumbilical skin fold incision will leave an almost invisible scar and therefore has definitive cosmetic advantages. This alternative approach may be related to technical difficulties in delivering a large pyloric tumor when compared with the conventional pyloromyotomy through a right upper quadrant incision. However, in situ (intraabdominal) myotomy can help overcome this inconvenience. METHODS: Of 122 cases of infantile hypertrophic pyloric stenosis operated on between January 1990 and August 1996, 29 underwent a pyloromyotomy performed intraabdominally through the umbilical route. The medical records of these babies were reviewed. RESULTS: Twenty-three boys and six girls (median age, 30 days; range, 17 to 70 days) underwent surgery. The median hospital stay was 2.5 days. There were two intraoperative technical complications (small mucosal perforation) and one postoperative wound complication (abcess formation) requiring local drainage. CONCLUSIONS: In situ pyloromyotomy through the umbilical route is an elegant alternative in cases of a large pyloric tumor.