Using underwater gliders we have identified canyon driven upwelling across the Celtic Sea shelf-break, in the vicinity of Whittard Canyon. The presence of this upwelling appears to be tied to the direction and strength of the local slope current, which is in itself highly variable. During typical summer time equatorward flow, an unbalanced pressure gradient force and the resulting disruption of...

We present the combination of a sensor based on “Phase-Measuring Deflectometry” and a new numerical algorithm to obtain the shape of specular free-form surfaces. The sensor measures the local slope of the surface which then is used to reconstruct the object’s shape. The sensor is calibrated and yields absolute slope data. We solved the inherent ambiguity of deflectometric sensors using a novel ...

BACKGROUND The contribution of vegetation to shallow-slope stability is of major importance in landslide-prone regions. However, existing slope stability models use only limited plant root architectural parameters. This study aims to provide a chain of tools useful for determining the contribution of tree roots to soil reinforcement. METHODS Three-dimensional digitizing in situ was used to ob...

We introduce ”microdeflectometry”, a novel technique for measuring the microtopography of specular surfaces. The primary data is the local slope of the surface under test. Measuring the slope instead of the height implies high information efficiency and extreme sensitivity to local shape irregularities. The lateral resolution can be better than 1μm, whereas the resulting height resolution is in...

We introduce ”microdeflectometry”, a novel technique for measuring the microtopology of specular surfaces. The primary data is the local slope of the surface under test. Measuring the slope instead of the height implies high information efficiency and extreme sensitivity to local shape irregularities. The lateral resolution can be better than one micron whereas the resulting height resolution i...

This memo describes the results of Shack-Hartmann wavefront sensor measurements of the 48” mirror at the Whipple Observatory, Mount Hopkins, AZ. The observations show significant errors in the figure of the primary mirror. Visual inspection of the data shows spots that are significantly shifted, distorted in shape, and some spots that are missing entirely from the images. Local slope errors on ...

In this Letter, we introduce a wavefront slope sensor based on a diffractive element. The diffractive element wavefront sensor (DEWS) produces four double overlapping copies of the incoming wavefront acting like a combination of shearing and pyramidal sensors. The DEWS allows a simple and fast slope estimate. The wavefront sampling can be as high as the number of pixel assigned to cover a wavef...

We construct a driven sandpile slope model and study it by numerical simulations in one dimension. The model is specified by a threshold slope σc, a parameter α, governing the local current-slope relation (beyond threshold), and jin, the mean input current of sand. A nonequilibrium phase diagram is obtained in the α − jin plane. We find an infinity of phases, characterized by different mean slo...