A microscopic phase-field model was used to investigate a directional coarsening mechanism caused by the anisotropic growth of long period stacking and different effects of phases on precipitation in Ni-Al-V alloy.The...A microscopic phase-field model was used to investigate a directional coarsening mechanism caused by the anisotropic growth of long period stacking and different effects of phases on precipitation in Ni-Al-V alloy.The results show that DO22 mainly coarsens along its short axis,which may press the neighboring L12,leading to the interaction among atoms.Diffusion channels of Al are formed in the direction where the mismatch between γ' and γ reduces;the occupation probabilities are anisotropic in space;and direction coarsening of L12 occurs finally.With a rise of ageing temperature,phases appear later and DO22 is much later at a higher temperature,the average occupation probabilities of Al and V reduce,and Al changes more than V.展开更多
An image magnification method with a Gradient Vector Flow(GVF)constraint-basedanisotropic diffusion model is proposed in this letter.A Low-Resolution(LR)image is first magnifiedusing bilinear interpolation,and then an...An image magnification method with a Gradient Vector Flow(GVF)constraint-basedanisotropic diffusion model is proposed in this letter.A Low-Resolution(LR)image is first magnifiedusing bilinear interpolation,and then an iterative image restoration method,with the use of an ani-sotropic diffusion model and a Gaussian moving-average constraint,is applied to the magnified image.The estimated GVF of a High-Resolution(HR)image can be used to remove the jagged effect and topreserve the textural structure in the image.Meanwhile,the use of the Gaussian moving-average LRmodel can provide a data fidelity constraint,which renders a magnified image closer to the ideal HRversion.Experimental results show that the proposed method can improve the quality of magnifiedimages in terms of both objective and subjective criteria.展开更多
Speckle noise reduction is a key problem of the image analysis of medical UltraSound images. In this paper, two important improvements have been developed to a fast anisotropic diffusion algorithm for speckle noise re...Speckle noise reduction is a key problem of the image analysis of medical UltraSound images. In this paper, two important improvements have been developed to a fast anisotropic diffusion algorithm for speckle noise reduction. The Gaussian filter is firstly used before gradient calculation, and then the adaptive algorithm of the factor k is proposed. Numerous experimental results show that the proposed model is superior to other methods in noise removal, fidelity and edge preservation. It is suitable for the preprocessing of a great number of medical UltraSound images, such as three dimen- sional reconstruction.展开更多
The structural and dynamical properties of hexafluoroacetylacetone(HFA) and acetylacetone(AA) at the water/supercritical CO2(Sc-CO2) interface at 20 MPa and 318.15 K are investigated by molecular dynamics simulations....The structural and dynamical properties of hexafluoroacetylacetone(HFA) and acetylacetone(AA) at the water/supercritical CO2(Sc-CO2) interface at 20 MPa and 318.15 K are investigated by molecular dynamics simulations.The TIP3P potential is used for water and the EPM2 model is for CO2.The water phase and SC-CO2 phase form a distinct immiscible liquid-liquid interface.The two chelating molecules show interfacial preference.Comparatively,the AA molecules show somewhat more preference for interfacial region,whereas the HFA molecules are preferably near the Sc-CO2 phase.The orientational distribution of the β-diketone molecules and the radial distribution functions between β-diketones and solvents are obtained in order to study the microscopic structural properties of the β-diketones at the water-SC-CO2 interface.It is found that the translational diffusion and rotational diffusion of HFA and AA are obviously anisotropic and decrease as the β-diketone molecules approach the interface.The anisotropic dynamic behavior for the solute molecules is related to the corresponding structural properties.展开更多
In order to reduce noise effectively in the welding defect image and preserve the minutiae information, a noise reduction method of welding defect image based on nonsubsampled contourlet transform(NSCT) and anisotropi...In order to reduce noise effectively in the welding defect image and preserve the minutiae information, a noise reduction method of welding defect image based on nonsubsampled contourlet transform(NSCT) and anisotropic diffusion is proposed. Firstly, an X-ray welding defect image is decomposed by NSCT. Then total variation(TV) model and Catte_PM model are used for the obtained low-pass component and band-pass components, respectively. Finally, the denoised image is synthesized by inverse NSCT. Experimental results show that, compared with the hybrid method of wavelet threshold shrinkage with TV diffusion, the method combining NSCT with P_Laplace diffusion, and the method combining contourlet with TV model and adaptive contrast diffusion, the proposed method has a great improvement in the aspects of subjective visual effect, peak signal-to-noise ratio(PSNR) and mean-square error(MSE). Noise is suppressed more effectively and the minutiae information is preserved better in the image.展开更多
In many image resolution enhancement applications,the blurring process of the imaging system is unknown.This paper discusses the problem of single image blind resolution enhancement without estimating the point spread...In many image resolution enhancement applications,the blurring process of the imaging system is unknown.This paper discusses the problem of single image blind resolution enhancement without estimating the point spread function(PSF).A regularization model is constructed for image enhancement based on the prior informaton of image error and image gray value,which does not need any prior information of PSF.Moreover,through the solution of Euler equations,an anisotropic nonlinear diffusion equation are obtained,which can avoid the high computational cost of regularization model.Furthermore,in order to get sub-pixel superresolved image,the regularization model for image enhancement is extended to the enlargement of image,which can enlarge and enhance image at the same time.Last,to get clearer edges,a high frequency enhancement filter is used on the superresolved image.Numerical results show that the new model can get much clearer super-resolution images than traditional methods,and the peak signal to noise ratios (PSNRs) are also higher than traditional methods.展开更多
A novel rcgularization-based approach is presented for super-resolution reconstruction in order to achieve good tradeoff between noise removal and edge preservation. The method is developed by using L1 norm as data fi...A novel rcgularization-based approach is presented for super-resolution reconstruction in order to achieve good tradeoff between noise removal and edge preservation. The method is developed by using L1 norm as data fidelity term and anisotropic fourth-order diffusion model as a regularization item to constrain the smoothness of the reconstructed images. To evaluate and prove the performance of the proposed method, series of experiments and comparisons with some existing methods including bi-cubic interpolation method and bilateral total variation method are carried out. Numerical results on synthetic data show that the PSNR improvement of the proposed method is approximately 1.0906 dB on average compared to bilateral total variation method, and the results on real videos indicate that the proposed algorithm is also effective in terms of removing visual artifacts and preserving edges in restored images.展开更多
In general there is a digital image with noise, low contrast, blnrred edges and other defects. To effectively enhance the contrast of the image blur to meet the requirements of the subsequent identification and detect...In general there is a digital image with noise, low contrast, blnrred edges and other defects. To effectively enhance the contrast of the image blur to meet the requirements of the subsequent identification and detection. This paper presents a fuzzy adaptive image contrast enhancement algorithm based on gray entropy. This method not only enhances the overall image contrast, but also effectively enrich the target image detail information, and suppress the noise amplification. Meanwhile, the paper proposes an improved K and P parameters image restoration algorithm. The algorithm combines both isotropic and anisotropic diffusion, the use of regional differences in the frequency achieved in the different regions use different iterative equation. Experimental results show that the algorithm with TV model algorithm compared with the same premise of restorative effects, avoiding the staircase effect and better than the TV model repair speed.展开更多
Molecular dynamics(MD)simulations and anisotropic thermal diffusion dynamics(ATD)simulations were performed on the wild TrpR and its 75 residue mutant(mTrpR)to investigate TrpR longrange effects.The ATD result shows t...Molecular dynamics(MD)simulations and anisotropic thermal diffusion dynamics(ATD)simulations were performed on the wild TrpR and its 75 residue mutant(mTrpR)to investigate TrpR longrange effects.The ATD result shows that the mTrpR has higher fluctuation than the wild TrpR,and its helix chainⅡF has particular disorder.It is obvious that the 75 residue of wild TrpR and mTrpR affects the protein dynamics flexibilities by the long-range effects.The ATD and MD both confirm that the differences in the size of side-chain and three-dimensional structures of two different 75 residues in the wild TrpR and mTrpR will spread to the entire protein by way of the long-range effects.Long-range effect affects the protein side chain interaction,conformational changes,flexibilities and secondary structures.Further,the ATD result also shows that each 75 residue of the symmetric homodimer has the same effect,and the two 75 residues have a positive correlation in long-range regulating processes.The residues 48,50,71,79 in chainⅠof wild TrpR and residues 45,72,80 in chainⅡof mTrpR play important roles in long-range interaction processes.展开更多
Speckle noise has long been known as a limiting factor for the quality of an ultrasound B-mode image.In this study,anisotropic diffusion filtering is proposed as an effective method for ultrasound speckle reduction.Th...Speckle noise has long been known as a limiting factor for the quality of an ultrasound B-mode image.In this study,anisotropic diffusion filtering is proposed as an effective method for ultrasound speckle reduction.This article provides a brief description of anisotropic diffusion filtering proposed by Perona and Malik,and compares its speckle filtering effects with other filtering methods including median,moving average,and frequency domain Gaussian low-pass.In this study,multiple filters are implemented in Matlab.For each filter,three different types of noisy images with speckle noise are tested.The results show that anisotropic filter can reduce the noise more effectively and meanwhile preserve the boundaries of the objects.In addition,this filter has more controllable filtering parameters and is independent on the information of the noise.展开更多
Anisotropic meshes are known to be well-suited for problems which exhibit anisotropic solution features. Defining an appropriate metric tensor and designing an efficient algorithm for anisotropic mesh gen- eration are...Anisotropic meshes are known to be well-suited for problems which exhibit anisotropic solution features. Defining an appropriate metric tensor and designing an efficient algorithm for anisotropic mesh gen- eration are two important aspects of the anisotropic mesh methodology. In this paper, we are concerned with the natural metric tensor for use in anisotropic mesh generation for anisotropic elliptic problems. We provide an algorithm to generate anisotropic meshes under the given metric tensor. We show that the inverse of the anisotropic diffusion matrix of the anisotropic elliptic problem is a natural metric tensor for the anisotropic mesh generation in three aspects: better discrete algebraic systems, more accurate finite element solution and superconvergence on the mesh nodes. Various numerical examples demonstrating the effectiveness are presented.展开更多
The effects of the Rician noise on the calculated tensors are analyzed and an affine invariant gradient (AIG) based nonlinear anisotropic smoothing strategy is presented.The AIG based smoothing strategy is a developme...The effects of the Rician noise on the calculated tensors are analyzed and an affine invariant gradient (AIG) based nonlinear anisotropic smoothing strategy is presented.The AIG based smoothing strategy is a development of the affine invariant nonlinear anisotropic diffusion(AINAD) restoration model,introduced by Guillermo Sapiro,and adopted to restore vector-valued data.To evaluate the efficiency of the presented AINAD model in accounting for the Rician noise introduced into the vector-valued data,the peak-to-peak signal-to-noise ratio(PSNR),signal-to-mean squared error ratio(SMSE) and Beta(parameter that stands for edge preservation) metrics are used.The experiment results acquired from the synthetic and real data prove the good performance of the presented filter.展开更多
基金Projects(51075335,10902086,50875217) supported by the National Natural Science Foundation of ChinaProject(JC201005) supported by the Northwestern Polytechnical University Foundation for Fundamental Research,ChinaProject(CX201007) supported by the Doctorate Foundation of Northwestern Polytechnical University,China
文摘A microscopic phase-field model was used to investigate a directional coarsening mechanism caused by the anisotropic growth of long period stacking and different effects of phases on precipitation in Ni-Al-V alloy.The results show that DO22 mainly coarsens along its short axis,which may press the neighboring L12,leading to the interaction among atoms.Diffusion channels of Al are formed in the direction where the mismatch between γ' and γ reduces;the occupation probabilities are anisotropic in space;and direction coarsening of L12 occurs finally.With a rise of ageing temperature,phases appear later and DO22 is much later at a higher temperature,the average occupation probabilities of Al and V reduce,and Al changes more than V.
基金a grant from the Research Grants Council othe Hong Kong Special Administrative Region,China(NoPolyU 5199/06E)by the National Natural ScienceFoundation of China(No.60472036,No.60431020,No60402036,No.60772069)the Natural Science Foundation of Beijing(No.4062006).
文摘An image magnification method with a Gradient Vector Flow(GVF)constraint-basedanisotropic diffusion model is proposed in this letter.A Low-Resolution(LR)image is first magnifiedusing bilinear interpolation,and then an iterative image restoration method,with the use of an ani-sotropic diffusion model and a Gaussian moving-average constraint,is applied to the magnified image.The estimated GVF of a High-Resolution(HR)image can be used to remove the jagged effect and topreserve the textural structure in the image.Meanwhile,the use of the Gaussian moving-average LRmodel can provide a data fidelity constraint,which renders a magnified image closer to the ideal HRversion.Experimental results show that the proposed method can improve the quality of magnifiedimages in terms of both objective and subjective criteria.
基金Supported by National Natural Science Foundation of China (No.60272060)Doctoral Foundation of Ministry of Education (No.20030610032)Sichuan Youth Science and Technology Foundation (No.04ZQ026-013).
文摘Speckle noise reduction is a key problem of the image analysis of medical UltraSound images. In this paper, two important improvements have been developed to a fast anisotropic diffusion algorithm for speckle noise reduction. The Gaussian filter is firstly used before gradient calculation, and then the adaptive algorithm of the factor k is proposed. Numerous experimental results show that the proposed model is superior to other methods in noise removal, fidelity and edge preservation. It is suitable for the preprocessing of a great number of medical UltraSound images, such as three dimen- sional reconstruction.
基金Supported by the National Natural Science Foundation of China (20776066, 20476044) and the Specialized Research Fund for the Doctoral Program of Higher Education of China (20060291002).
文摘The structural and dynamical properties of hexafluoroacetylacetone(HFA) and acetylacetone(AA) at the water/supercritical CO2(Sc-CO2) interface at 20 MPa and 318.15 K are investigated by molecular dynamics simulations.The TIP3P potential is used for water and the EPM2 model is for CO2.The water phase and SC-CO2 phase form a distinct immiscible liquid-liquid interface.The two chelating molecules show interfacial preference.Comparatively,the AA molecules show somewhat more preference for interfacial region,whereas the HFA molecules are preferably near the Sc-CO2 phase.The orientational distribution of the β-diketone molecules and the radial distribution functions between β-diketones and solvents are obtained in order to study the microscopic structural properties of the β-diketones at the water-SC-CO2 interface.It is found that the translational diffusion and rotational diffusion of HFA and AA are obviously anisotropic and decrease as the β-diketone molecules approach the interface.The anisotropic dynamic behavior for the solute molecules is related to the corresponding structural properties.
基金Supported by the National Natural Science Foundation of China(No.60872065)Open Foundation of State Key Laboratory of Advanced Welding and Connection,Harbin Institute of Technology(AWPT-M04)Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘In order to reduce noise effectively in the welding defect image and preserve the minutiae information, a noise reduction method of welding defect image based on nonsubsampled contourlet transform(NSCT) and anisotropic diffusion is proposed. Firstly, an X-ray welding defect image is decomposed by NSCT. Then total variation(TV) model and Catte_PM model are used for the obtained low-pass component and band-pass components, respectively. Finally, the denoised image is synthesized by inverse NSCT. Experimental results show that, compared with the hybrid method of wavelet threshold shrinkage with TV diffusion, the method combining NSCT with P_Laplace diffusion, and the method combining contourlet with TV model and adaptive contrast diffusion, the proposed method has a great improvement in the aspects of subjective visual effect, peak signal-to-noise ratio(PSNR) and mean-square error(MSE). Noise is suppressed more effectively and the minutiae information is preserved better in the image.
基金Supported by the National Natural Science Foundation of China(No.60272013) and National Excellent Doctoral DissertationFund of China(No.200140)
文摘In many image resolution enhancement applications,the blurring process of the imaging system is unknown.This paper discusses the problem of single image blind resolution enhancement without estimating the point spread function(PSF).A regularization model is constructed for image enhancement based on the prior informaton of image error and image gray value,which does not need any prior information of PSF.Moreover,through the solution of Euler equations,an anisotropic nonlinear diffusion equation are obtained,which can avoid the high computational cost of regularization model.Furthermore,in order to get sub-pixel superresolved image,the regularization model for image enhancement is extended to the enlargement of image,which can enlarge and enhance image at the same time.Last,to get clearer edges,a high frequency enhancement filter is used on the superresolved image.Numerical results show that the new model can get much clearer super-resolution images than traditional methods,and the peak signal to noise ratios (PSNRs) are also higher than traditional methods.
基金Projects(60963012,61262034)supported by the National Natural Science Foundation of ChinaProject(211087)supported by the Key Project of Ministry of Education of ChinaProjects(2010GZS0052,20114BAB211020)supported by the Natural Science Foundation of Jiangxi Province,China
文摘A novel rcgularization-based approach is presented for super-resolution reconstruction in order to achieve good tradeoff between noise removal and edge preservation. The method is developed by using L1 norm as data fidelity term and anisotropic fourth-order diffusion model as a regularization item to constrain the smoothness of the reconstructed images. To evaluate and prove the performance of the proposed method, series of experiments and comparisons with some existing methods including bi-cubic interpolation method and bilateral total variation method are carried out. Numerical results on synthetic data show that the PSNR improvement of the proposed method is approximately 1.0906 dB on average compared to bilateral total variation method, and the results on real videos indicate that the proposed algorithm is also effective in terms of removing visual artifacts and preserving edges in restored images.
文摘In general there is a digital image with noise, low contrast, blnrred edges and other defects. To effectively enhance the contrast of the image blur to meet the requirements of the subsequent identification and detection. This paper presents a fuzzy adaptive image contrast enhancement algorithm based on gray entropy. This method not only enhances the overall image contrast, but also effectively enrich the target image detail information, and suppress the noise amplification. Meanwhile, the paper proposes an improved K and P parameters image restoration algorithm. The algorithm combines both isotropic and anisotropic diffusion, the use of regional differences in the frequency achieved in the different regions use different iterative equation. Experimental results show that the algorithm with TV model algorithm compared with the same premise of restorative effects, avoiding the staircase effect and better than the TV model repair speed.
基金supported by the Innovation project of Henan Agricultural University(No.30600982)PhD Start-up Foundation of Henan Agricultural University(30600780)2023 Instrument Operator Capability lmprovement Project(SYS2023T04)
文摘Molecular dynamics(MD)simulations and anisotropic thermal diffusion dynamics(ATD)simulations were performed on the wild TrpR and its 75 residue mutant(mTrpR)to investigate TrpR longrange effects.The ATD result shows that the mTrpR has higher fluctuation than the wild TrpR,and its helix chainⅡF has particular disorder.It is obvious that the 75 residue of wild TrpR and mTrpR affects the protein dynamics flexibilities by the long-range effects.The ATD and MD both confirm that the differences in the size of side-chain and three-dimensional structures of two different 75 residues in the wild TrpR and mTrpR will spread to the entire protein by way of the long-range effects.Long-range effect affects the protein side chain interaction,conformational changes,flexibilities and secondary structures.Further,the ATD result also shows that each 75 residue of the symmetric homodimer has the same effect,and the two 75 residues have a positive correlation in long-range regulating processes.The residues 48,50,71,79 in chainⅠof wild TrpR and residues 45,72,80 in chainⅡof mTrpR play important roles in long-range interaction processes.
基金supported by the Fundamental Research Funds for the Central Universities(Grant No.NS2014060)
文摘Speckle noise has long been known as a limiting factor for the quality of an ultrasound B-mode image.In this study,anisotropic diffusion filtering is proposed as an effective method for ultrasound speckle reduction.This article provides a brief description of anisotropic diffusion filtering proposed by Perona and Malik,and compares its speckle filtering effects with other filtering methods including median,moving average,and frequency domain Gaussian low-pass.In this study,multiple filters are implemented in Matlab.For each filter,three different types of noisy images with speckle noise are tested.The results show that anisotropic filter can reduce the noise more effectively and meanwhile preserve the boundaries of the objects.In addition,this filter has more controllable filtering parameters and is independent on the information of the noise.
基金supported by National Natural Science Foundation of China(Grant Nos.11031006 and 11201397)Program for Changjiang Scholars and Innovative Research Team in University(Grant No.IRT1179)+2 种基金International Science and Technology Cooperation Program of China(Grant No.2010DFR00700)Hunan Education Department Project(Grant No.12B127)Hunan Provincial National Science Foundation Project(Grant No.12JJ4004)
文摘Anisotropic meshes are known to be well-suited for problems which exhibit anisotropic solution features. Defining an appropriate metric tensor and designing an efficient algorithm for anisotropic mesh gen- eration are two important aspects of the anisotropic mesh methodology. In this paper, we are concerned with the natural metric tensor for use in anisotropic mesh generation for anisotropic elliptic problems. We provide an algorithm to generate anisotropic meshes under the given metric tensor. We show that the inverse of the anisotropic diffusion matrix of the anisotropic elliptic problem is a natural metric tensor for the anisotropic mesh generation in three aspects: better discrete algebraic systems, more accurate finite element solution and superconvergence on the mesh nodes. Various numerical examples demonstrating the effectiveness are presented.
基金the National Basic Research Program(973)of China(No.2003CB716103)the ShanghaiNormal University Foundation(No.SK200734)
文摘The effects of the Rician noise on the calculated tensors are analyzed and an affine invariant gradient (AIG) based nonlinear anisotropic smoothing strategy is presented.The AIG based smoothing strategy is a development of the affine invariant nonlinear anisotropic diffusion(AINAD) restoration model,introduced by Guillermo Sapiro,and adopted to restore vector-valued data.To evaluate the efficiency of the presented AINAD model in accounting for the Rician noise introduced into the vector-valued data,the peak-to-peak signal-to-noise ratio(PSNR),signal-to-mean squared error ratio(SMSE) and Beta(parameter that stands for edge preservation) metrics are used.The experiment results acquired from the synthetic and real data prove the good performance of the presented filter.