EIGENVALUES OF A SPECIAL KIND OF SYMMETRIC BLOCK CIRCULANT MATRICES

In this paper, the spectrum and characteristic polynomial for a special kind of symmetric block circulant matrices are given.

Non-Blind Image Deblurring via Shear Total Variation Norm

In this paper, we propose a novel shear gradient operator by combining the shear and gradient operators. The shear gradient operator performs well to capture diverse directional information in the image gradient domain. Based on the shear gradient operator, we extend the total variation(TV) norm to the shear total variation(STV) norm by adding two shear gradient terms. Subsequently, we introduce a shear total variation deblurring model. Experimental results are provided to validate the ability of the STV norm to capture the detailed information. Leveraging the Block Circulant with Circulant Blocks(BCCB) structure of the shear gradient matrices, the alternating direction method of multipliers(ADMM) algorithm can be used to solve the proposed model efficiently. Numerous experiments are presented to verify the performance of our algorithm for non-blind image deblurring.

BAROTROPIC AND BAROCLINIC ENSTROPHY EQUATIONS WITH THEIR APPLICATIONS TO A BLOCKING CIRCULATION

After the manner for studying atmospheric kinetic energy,concepts of atmospheric enstrophy (ζ~2/2)_m and barotropic and baroclinic enstrophy (ζ_m^2/2,ζ_s^2/2) are developed with their relations investigated,whereupon are established,separately,equations for the 1000- 100 hPa extent- averaged ζ_m^2/2 and ζ_s^2/2 over a limited area and on a local basis.Study shows that controlling their changes are the following factors:the terms of their fluxes (viz.,divergences).β effect,their mutual conversions,production and dissipation.Analysis is undertaken of these terms-dependent physical mechanisms for the variations in barotropic and baroclinic enstrophy and by means of the equations,calculation is conducted of the terms during the development of an Okhotsk blocking circulation,indicating that the total,harotropic and haroclinic enstrophies experience noticeable variations,from which we see that the latter two factors can really characterize the development as a whole,thus revealing the mechanisms at different stages of the circulation history.

Non-Blind Image Deblurring Method Using Shear High Order Total Variation Norm

In this paper,we propose a shear high-order gradient(SHOG)operator by combining the shear operator and high-order gradient(HOG)operator.Compared with the HOG operator,the proposed SHOG operator can incorporate more directionality and detect more abundant edge information.Based on the SHOG operator,we extend the total variation(TV)norm to shear high-order total variation(SHOTV),and then propose a SHOTV deblurring model.We also study some properties of the SHOG operator,and show that the SHOG matrices are Block Circulant with Circulant Blocks(BCCB)when the shear angle isπ/4.The proposed model is solved efficiently by the alternating direction method of multipliers(ADMM).Experimental results demonstrate that the proposed method outperforms some state-of-the-art non-blind deblurring methods in both objective and perceptual quality.

The Large Scale Circulation of the Snow Disaster in Southern China in the Beginning of 2008

This study analyzed the heaviest snowfalls or icy-rainfalls occurring in southern China from January to the beginning of February 2008.The results are summarized as follows：the disaster was induced by the persistent front of warm/cold air masses in southern China,which displayed an interaction between the weather systems in higher and lower latitudes.There was an adjustment for circulation at hemisphere scale during mid January by a variation of sign of the Arctic Oscillation（AO）index from negative to positive.The long lasting precipitation well coincided with a blocking situation centered near 80°E from mid January to the beginning of February.A diagnostic analysis indicates that stationary waves with an energy dispersion accompanying the blocking high propagated from upstream region in high latitudes to the south of the Yangtze River,which formed a maintaining energy source for the cyclonic circulation in situ.This resulted in that the large mass of cold air in high latitudes could not easily invade into the south but slowly shifted southward.On the other hand,the sea surface temperature（SST）over the warm pool of the western Pacific increased with a new history record due to the effect of the strong La Nina episode,which also blocked the cold air mass from the north.The blocking high collapsed around 30 January and the energy source for the local cyclonic circulation was cut off.Thus,the precipitation in southern China ceased after 1 February.