The presence of speckle in ultrasound images makes it hard to segment them using active contours. Speckle causes the energy function of the active contours to have many local minima, and the gradient descent procedure used for evolving the contour gets trapped in these minima. A new algorithm, called tunnelling descent, is proposed in this paper for evolving active contours. Tunnelling descent ...

it is well known that ground-shaking site effect caused by an earthquake can vary significantly within a small distance. this is because at sites having soft soil and/or topographic and basement undulations, seismic energy gets trapped, leading to amplification of vibration that may cause considerable damage to man-made structures. theoretical analysis and observational data have shown that eac...

The purpose of this paper is to present an efficient converter circuit used to drive switched reluctance motors. It uses the C-dump topology in which the trapped energy in the phase windings is returned to the supply capacitor to be used in the following strokes. In addition to the C-dump topology, it uses two extra feedbacks. One comes from a governor mounted on the shaft of motor which contro...

S U M M A R Y The detailed structure of fault zones (FZs) plays an important role in problems related to fault mechanics, earthquake rupture, wave propagation and seismic hazard. FZs are thought to consist of an O(10–100) m wide region of decreased seismic velocity but structural details such as their depth extent, lateral and vertical variations, etc. are elusive. The small spatial scales invo...

A careful analysis of low-frequency seismic events on Soufrièere Hills volcano, Montserrat, points to a source mechanism that is non-destructive, repetitive, and has a stationary source location. By combining these seismological clues with new field evidence and numerical magma flow modelling, we propose a seismic trigger model which is based on brittle failure of magma in the glass transition....

In this paper we investigate the use of a supervised, but self-organizing, Adaptive Resonance Theory type of neural network (Fuzzy-ARTMAP), for first break picking in seismic reflection data. First break picking is the accurate location of the leading energy pulse received by a geophone in response to a seismic shot. The performance of Fuzzy-ARTMAP is compared to our previous work with multi-la...

We consider grains with superparamagnetic inclusions and report two new condensed matter effects that can enhance the internal relaxation of the energy of a wobbling grain, namely, superparamagnetic Barnett relaxation, as well as, an increase of frequencies for which nuclear relaxation becomes important. This findings extends the range of grain sizes for which grains are thermally trapped, i.e....