An improved binarization algorithm of wood image defect segmentation based on non-uniform background

2019 ◽  
Vol 30 (4) ◽  
pp. 1527-1533 ◽  
Author(s):  
Wei Luo ◽  
Liping Sun
Keyword(s):  
Uniform Background ◽  
Image Defect ◽  
Binarization Algorithm

scholarly journals Vortex–Vortex Interactions for the Maintenance of Blocking. Part II: Numerical Experiments

2013 ◽  
Vol 70 (3) ◽  
pp. 743-766 ◽  
Author(s):  
Akira Yamazaki ◽  
Hisanori Itoh
Keyword(s):  
Numerical Experiments ◽  
Channel Model ◽  
Spherical Model ◽  
Zonal Flow ◽  
Selective Absorption ◽  
Absorption Mechanism ◽  
Vortex Interactions ◽  
Maintenance Mechanism ◽  
Uniform Background

Abstract The selective absorption mechanism (SAM), newly proposed in Part I of this study on the maintenance mechanism of blocking, is verified through numerical experiments. The experiments were based on the nonlinear equivalent-barotropic potential vorticity equation, with varying conditions with respect to the shape and amplitude of blocking, and characteristics of storm tracks (displacement and strength) and background zonal flow. The experiments indicate that the SAM effectively maintains blocking, irrespective of the above conditions. At first, by applying a channel model on a β plane, numerical experiments were conducted using a uniform background westerly with and without a jet. The results show that the presence of a jet promotes the effectiveness of the SAM. Then, two types of spherical model experiments were also performed. In idealized experiments, the SAM was as effective as the β-plane model in explaining the maintenance of blocking. Moreover, experiments performed under realistic meteorological conditions showed that the SAM maintained a real block, demonstrating that the SAM is effective. These results, and the case study in Part I, verify that the SAM is the effective general maintenance mechanism for blocking.

Background Synaptic Activity as a Switch Between Dynamical States in a Network

2003 ◽  
Vol 15 (7) ◽  
pp. 1439-1475 ◽  
Author(s):  
Emilio Salinas
Keyword(s):  
Random Network ◽  
Red Light ◽  
Theoretical Models ◽  
Reciprocal Inhibition ◽  
Synaptic Activity ◽  
Dynamic State ◽  
Motor Action ◽  
Sustained Activity ◽  
Uniform Background ◽  
Background Input

A bright red light may trigger a sudden motor action in a driver crossing an intersection: stepping at once on the brakes. The same red light, however, may be entirely inconsequential if it appears, say, inside a movie theater. Clearly, context determines whether a particular stimulus will trigger a motor response, but what is the neural correlate of this? How does the nervous system enable or disable whole networks so that they are responsive or not to a given sensory signal? Using theoretical models and computer simulations, I show that networks of neurons have a built-in capacity to switch between two types of dynamic state: one in which activity is low and approximately equal for all units, and another in which different activity distributions are possible and may even change dynamically. This property allows whole circuits to be turned on or off by weak, unstructured inputs. These results are illustrated using networks of integrate-and-fire neurons with diverse architectures. In agreement with the analytic calculations, a uniform background input may determine whether a random network has one or two stable firing levels; it may give rise to randomly alternating firing episodes in a circuit with reciprocal inhibition; and it may regulate the capacity of a center-surround circuit to produce either self-sustained activity or traveling waves. Thus, the functional properties of a network may be drastically modified by a simple, weak signal. This mechanism works as long as the network is able to exhibit stable firing states, or attractors.

scholarly journals The nonlinear electromigration of analytes into confined spaces

2012 ◽  
Vol 468 (2146) ◽  
pp. 3139-3152 ◽  
Author(s):  
Zhen Chen ◽  
Sandip Ghosal
Keyword(s):  
Electric Field ◽  
Background Electrolyte ◽  
Ionic Transport ◽  
Wave Shape ◽  
One Dimensional ◽  
Sample Concentration ◽  
Confined Spaces ◽  
Electrokinetic Injection ◽  
Sudden Contraction ◽  
Uniform Background

We consider the problem of electromigration of a sample ion (analyte) within a uniform background electrolyte when the confining channel undergoes a sudden contraction. One example of such a situation arises in microfluidics in the electrokinetic injection of the analyte into a micro-capillary from a reservoir of much larger size. Here, the sample concentration propagates as a wave driven by the electric field. The dynamics is governed by the Nerst–Planck–Poisson system of equations for ionic transport. A reduced one-dimensional nonlinear equation, describing the evolution of the sample concentration, is derived. We integrate this equation numerically to obtain the evolution of the wave shape and determine how the injected mass depends on the sample concentration in the reservoir. It is shown that due to the nonlinear coupling of the ionic concentrations and the electric field, the concentration of the injected sample could be substantially less than the concentration of the sample in the reservoir.

Vector fields created by Fourier transform of video signals

2021 ◽  
Author(s):  
A.V. Bogoslovsky ◽  
V.A. Sukharev ◽  
I.V. Zhigulina ◽  
M.A. Pantyukhin
Keyword(s):  
Vector Field ◽  
Power Spectrum ◽  
Vector Fields ◽  
Amplitude Spectrum ◽  
Power Spectra ◽  
Field Work ◽  
Signal Process ◽  
Video Signals ◽  
Uniform Background ◽  
Pixel Brightness

The power spectrum and autocorrelation are widely used in video signals processing. The phase-frequency spectrum contains more information than the amplitude spectrum. However, the amplitude spectrum is used more often in the video signal process. It is possible to combine the advantages of these two spectra to obtain a vector function such as phase-energy spectrum. This spectrum is sensitive even to a small difference in pixel brightness but at the same time it is as stable as the power spectrum. In this paper, we explored the properties of the phase-power spectrum and related amplitude of partials vector field. We showed that phase-power spectrum has conservative as well as solenoidal components and so it creates curl’s vector field. We also found the components of phase-power spectra that contain pixels with a different degree of contrast on the uniform background. We showed the possibility to use solenoidal component of the phase-power vector field to find the circulation (i.e. field work). We concluded that the circulation along any of brightness contour constants, which is symmetrical to the origin, is equal zero. We explored two-dimensional vector field of the phase-power spectrum. Finally, we determined an effect of pixels with different degree of brightness and their relative position to the image’s edges on vector field’s components formation.

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