46,396 research outputs found
Coarse-grained description of thermo-capillary flow
A mesoscopic or coarse-grained approach is presented to study
thermo-capillary induced flows. An order parameter representation of a
two-phase binary fluid is used in which the interfacial region separating the
phases naturally occupies a transition zone of small width. The order parameter
satisfies the Cahn-Hilliard equation with advective transport. A modified
Navier-Stokes equation that incorporates an explicit coupling to the order
parameter field governs fluid flow. It reduces, in the limit of an infinitely
thin interface, to the Navier-Stokes equation within the bulk phases and to two
interfacial forces: a normal capillary force proportional to the surface
tension and the mean curvature of the surface, and a tangential force
proportional to the tangential derivative of the surface tension. The method is
illustrated in two cases: thermo-capillary migration of drops and phase
separation via spinodal decomposition, both in an externally imposed
temperature gradient.Comment: To appear in Phys. Fluids. Also at
http://www.scri.fsu.edu/~vinals/dj1.p
Going Deeper into Action Recognition: A Survey
Understanding human actions in visual data is tied to advances in
complementary research areas including object recognition, human dynamics,
domain adaptation and semantic segmentation. Over the last decade, human action
analysis evolved from earlier schemes that are often limited to controlled
environments to nowadays advanced solutions that can learn from millions of
videos and apply to almost all daily activities. Given the broad range of
applications from video surveillance to human-computer interaction, scientific
milestones in action recognition are achieved more rapidly, eventually leading
to the demise of what used to be good in a short time. This motivated us to
provide a comprehensive review of the notable steps taken towards recognizing
human actions. To this end, we start our discussion with the pioneering methods
that use handcrafted representations, and then, navigate into the realm of deep
learning based approaches. We aim to remain objective throughout this survey,
touching upon encouraging improvements as well as inevitable fallbacks, in the
hope of raising fresh questions and motivating new research directions for the
reader
Method and apparatus for predicting the direction of movement in machine vision
A computer-simulated cortical network is presented. The network is capable of computing the visibility of shifts in the direction of movement. Additionally, the network can compute the following: (1) the magnitude of the position difference between the test and background patterns; (2) localized contrast differences at different spatial scales analyzed by computing temporal gradients of the difference and sum of the outputs of paired even- and odd-symmetric bandpass filters convolved with the input pattern; and (3) the direction of a test pattern moved relative to a textured background. The direction of movement of an object in the field of view of a robotic vision system is detected in accordance with nonlinear Gabor function algorithms. The movement of objects relative to their background is used to infer the 3-dimensional structure and motion of object surfaces
Reflectance Hashing for Material Recognition
We introduce a novel method for using reflectance to identify materials.
Reflectance offers a unique signature of the material but is challenging to
measure and use for recognizing materials due to its high-dimensionality. In
this work, one-shot reflectance is captured using a unique optical camera
measuring {\it reflectance disks} where the pixel coordinates correspond to
surface viewing angles. The reflectance has class-specific stucture and angular
gradients computed in this reflectance space reveal the material class.
These reflectance disks encode discriminative information for efficient and
accurate material recognition. We introduce a framework called reflectance
hashing that models the reflectance disks with dictionary learning and binary
hashing. We demonstrate the effectiveness of reflectance hashing for material
recognition with a number of real-world materials
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