The Experts below are selected from a list of 56688 Experts worldwide ranked by ideXlab platform
Phillip Zhe Sun - One of the best experts on this subject based on the ideXlab platform.
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fast correction of b0 field Inhomogeneity for ph specific magnetization transfer and relaxation normalized amide proton transfer imaging of acute ischemic stroke without z spectrum
Magnetic Resonance in Medicine, 2020Co-Authors: Phillip Zhe SunAbstract:Purpose The magnetization transfer and relaxation normalized amide proton transfer (MRAPT) analysis is promising to provide a highly pH-specific mapping of tissue acidosis, complementing commonly used CEST asymmetry analysis. We aimed to develop a fast B0 Inhomogeneity correction algorithm for acute stroke magnetization transfer and relaxation normalized amide proton transfer imaging without Z-spectral interpolation. Methods The proposed fast field Inhomogeneity correction describes B0 artifacts with linear regression. We compared the new algorithm with the routine interpolation correction approach in CEST imaging of a dual-pH phantom. The fast B0 correction was further evaluated in amide proton transfer imaging of normal and acute stroke rats. Results Our phantom data showed that the proposed fast B0 Inhomogeneity correction significantly improved pH MRI contrast, recovering over 80% of the pH MRI contrast-to-noise-ratio difference between the raw magnetization transfer ratio asymmetry and that using the routine interpolation-based B0 correction approach. In normal rat brains, the proposed fast B0 correction improved pH-specific MRI uniformity across the intact tissue, with the ratio of magnetization transfer and relaxation normalized amide proton transfer ratio being 10% of that without B0 Inhomogeneity correction. In acute stroke rats, fast B0 Inhomogeneity-corrected pH MRI reveals substantially improved pH lesion conspicuity, particularly in regions with nonnegligible B0 Inhomogeneity. The pH MRI contrast-to-noise ratio between the ipsilateral diffusion lesion and contralateral normal tissue improved significantly with fast B0 correction (from 1.88 ± 0.48 to 2.20 ± 0.44, P Conclusions Our study established an expedient B0 Inhomogeneity correction algorithm for fast pH imaging of acute ischemia.
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fast correction of b 0 field Inhomogeneity for ph specific magnetization transfer and relaxation normalized amide proton transfer imaging of acute ischemic stroke without z spectrum
Magnetic Resonance in Medicine, 2020Co-Authors: Phillip Zhe SunAbstract:Purpose The magnetization transfer and relaxation normalized amide proton transfer (MRAPT) analysis is promising to provide a highly pH-specific mapping of tissue acidosis, complementing commonly used CEST asymmetry analysis. We aimed to develop a fast B0 Inhomogeneity correction algorithm for acute stroke magnetization transfer and relaxation normalized amide proton transfer imaging without Z-spectral interpolation. Methods The proposed fast field Inhomogeneity correction describes B0 artifacts with linear regression. We compared the new algorithm with the routine interpolation correction approach in CEST imaging of a dual-pH phantom. The fast B0 correction was further evaluated in amide proton transfer imaging of normal and acute stroke rats. Results Our phantom data showed that the proposed fast B0 Inhomogeneity correction significantly improved pH MRI contrast, recovering over 80% of the pH MRI contrast-to-noise-ratio difference between the raw magnetization transfer ratio asymmetry and that using the routine interpolation-based B0 correction approach. In normal rat brains, the proposed fast B0 correction improved pH-specific MRI uniformity across the intact tissue, with the ratio of magnetization transfer and relaxation normalized amide proton transfer ratio being 10% of that without B0 Inhomogeneity correction. In acute stroke rats, fast B0 Inhomogeneity-corrected pH MRI reveals substantially improved pH lesion conspicuity, particularly in regions with nonnegligible B0 Inhomogeneity. The pH MRI contrast-to-noise ratio between the ipsilateral diffusion lesion and contralateral normal tissue improved significantly with fast B0 correction (from 1.88 ± 0.48 to 2.20 ± 0.44, P Conclusions Our study established an expedient B0 Inhomogeneity correction algorithm for fast pH imaging of acute ischemia.
Peter Schiavone - One of the best experts on this subject based on the ideXlab platform.
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uniform stresses inside both a non parabolic Inhomogeneity and a non elliptical Inhomogeneity located in the vicinity of a circular eshelby inclusion
Mathematics and Mechanics of Solids, 2021Co-Authors: Ping Yang, Xu Wang, Peter SchiavoneAbstract:We establish the uniformity of stresses inside both a non-parabolic open Inhomogeneity and a non-elliptical closed Inhomogeneity interacting with a nearby circular Eshelby inclusion undergoing unif...
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uniformity of stresses inside a non elliptical Inhomogeneity near an irregularly shaped hole in plane elasticity
Mechanics of Materials, 2020Co-Authors: Xu Wang, Peter SchiavoneAbstract:Abstract We analyze the uniformity of stresses inside a non-elliptical elastic Inhomogeneity interacting with a nearby irregularly shaped hole when the surrounding matrix is subjected to uniform remote in-plane stresses. Using Muskhelishvili's complex variable formulation and the technique of conformal mapping for a doubly connected domain, we demonstrate that Eshelby's uniformity property is indeed valid when the Inhomogeneity and the matrix have the same shear modulus but distinct Poisson's ratios. In this case, the shapes of the Inhomogeneity and the hole are completely determined by two material, one loading and three geometric parameters.
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a screw dislocation near a non parabolic open Inhomogeneity with internal uniform stresses
Comptes Rendus Mecanique, 2019Co-Authors: Xu Wang, Peter SchiavoneAbstract:Abstract We use conformal mapping techniques and analytic continuation to prove that the stress field inside a non-parabolic open Inhomogeneity embedded in a matrix subjected to uniform remote anti-plane stresses can nevertheless remain uniform despite the presence of a screw dislocation in its vicinity. Furthermore, the internal uniform stresses inside the Inhomogeneity are found to be independent of both the shape of the Inhomogeneity and the presence of the screw dislocation. On the other hand, we find that the existence of the nearby screw dislocation exerts a significant influence on the non-parabolic shape of the Inhomogeneity.
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coated inhomogeneities of arbitrary shape with internal uniform hydrostatic stress resultants in isotropic laminated plates
Mathematics and Mechanics of Solids, 2019Co-Authors: Xu Wang, Liang Chen, Peter SchiavoneAbstract:We study the internal stress resultants inside an elastic Inhomogeneity of arbitrary shape embedded in an infinite Kirchhoff plate (matrix) via an intermediate coating. Each material phase is considered an isotropic laminated plate and the surrounding matrix is subjected to uniform remote membrane stress resultants and bending moments. We find that internal uniform hydrostatic stress resultants within the Inhomogeneity can be achieved when (i) the mapping function characterizing the shape of the Inhomogeneity is identified and specialized accordingly; (ii) the relative coating thickness should satisfy a higher-order algebraic equation; (iii) several restrictions on the remote loading should be satisfied for given material and geometric parameters of the composite plate. When all these conditions are met, the hoop membrane stress resultant and hoop bending moment on the coating side are uniform along the entire Inhomogeneity–coating interface.
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uniform stress field inside an anisotropic non elliptical Inhomogeneity interacting with a screw dislocation
European Journal of Mechanics A-solids, 2018Co-Authors: Xu Wang, Liang Chen, Peter SchiavoneAbstract:Abstract We find that an anisotropic non-elliptical Inhomogeneity interacting with a screw dislocation in a matrix subjected to remote uniform stresses and anti-plane shear deformations may still admit an internal uniform stress field. Our analysis indicates that the screw dislocation does not affect the uniform stresses inside the Inhomogeneity but does play a crucial role in determining the shape of the Inhomogeneity. In fact, we find that the influence of the screw dislocation gives rise to the possibility that the boundary of the Inhomogeneity may have up to three sharp corners. Our discussion extends to the case when multiple screw dislocations interact with the non-elliptical Inhomogeneity leading to a conjecture concerning the maximum allowable number of sharp corners in an Inhomogeneity with Eshelby's uniformity property.
Xu Wang - One of the best experts on this subject based on the ideXlab platform.
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uniform stresses inside both a non parabolic Inhomogeneity and a non elliptical Inhomogeneity located in the vicinity of a circular eshelby inclusion
Mathematics and Mechanics of Solids, 2021Co-Authors: Ping Yang, Xu Wang, Peter SchiavoneAbstract:We establish the uniformity of stresses inside both a non-parabolic open Inhomogeneity and a non-elliptical closed Inhomogeneity interacting with a nearby circular Eshelby inclusion undergoing unif...
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uniformity of stresses inside a non elliptical Inhomogeneity near an irregularly shaped hole in plane elasticity
Mechanics of Materials, 2020Co-Authors: Xu Wang, Peter SchiavoneAbstract:Abstract We analyze the uniformity of stresses inside a non-elliptical elastic Inhomogeneity interacting with a nearby irregularly shaped hole when the surrounding matrix is subjected to uniform remote in-plane stresses. Using Muskhelishvili's complex variable formulation and the technique of conformal mapping for a doubly connected domain, we demonstrate that Eshelby's uniformity property is indeed valid when the Inhomogeneity and the matrix have the same shear modulus but distinct Poisson's ratios. In this case, the shapes of the Inhomogeneity and the hole are completely determined by two material, one loading and three geometric parameters.
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a screw dislocation near a non parabolic open Inhomogeneity with internal uniform stresses
Comptes Rendus Mecanique, 2019Co-Authors: Xu Wang, Peter SchiavoneAbstract:Abstract We use conformal mapping techniques and analytic continuation to prove that the stress field inside a non-parabolic open Inhomogeneity embedded in a matrix subjected to uniform remote anti-plane stresses can nevertheless remain uniform despite the presence of a screw dislocation in its vicinity. Furthermore, the internal uniform stresses inside the Inhomogeneity are found to be independent of both the shape of the Inhomogeneity and the presence of the screw dislocation. On the other hand, we find that the existence of the nearby screw dislocation exerts a significant influence on the non-parabolic shape of the Inhomogeneity.
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coated inhomogeneities of arbitrary shape with internal uniform hydrostatic stress resultants in isotropic laminated plates
Mathematics and Mechanics of Solids, 2019Co-Authors: Xu Wang, Liang Chen, Peter SchiavoneAbstract:We study the internal stress resultants inside an elastic Inhomogeneity of arbitrary shape embedded in an infinite Kirchhoff plate (matrix) via an intermediate coating. Each material phase is considered an isotropic laminated plate and the surrounding matrix is subjected to uniform remote membrane stress resultants and bending moments. We find that internal uniform hydrostatic stress resultants within the Inhomogeneity can be achieved when (i) the mapping function characterizing the shape of the Inhomogeneity is identified and specialized accordingly; (ii) the relative coating thickness should satisfy a higher-order algebraic equation; (iii) several restrictions on the remote loading should be satisfied for given material and geometric parameters of the composite plate. When all these conditions are met, the hoop membrane stress resultant and hoop bending moment on the coating side are uniform along the entire Inhomogeneity–coating interface.
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uniform stress field inside an anisotropic non elliptical Inhomogeneity interacting with a screw dislocation
European Journal of Mechanics A-solids, 2018Co-Authors: Xu Wang, Liang Chen, Peter SchiavoneAbstract:Abstract We find that an anisotropic non-elliptical Inhomogeneity interacting with a screw dislocation in a matrix subjected to remote uniform stresses and anti-plane shear deformations may still admit an internal uniform stress field. Our analysis indicates that the screw dislocation does not affect the uniform stresses inside the Inhomogeneity but does play a crucial role in determining the shape of the Inhomogeneity. In fact, we find that the influence of the screw dislocation gives rise to the possibility that the boundary of the Inhomogeneity may have up to three sharp corners. Our discussion extends to the case when multiple screw dislocations interact with the non-elliptical Inhomogeneity leading to a conjecture concerning the maximum allowable number of sharp corners in an Inhomogeneity with Eshelby's uniformity property.
Y.w. Liu - One of the best experts on this subject based on the ideXlab platform.
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influence of dislocation on interaction between a crack and a circular Inhomogeneity
International Journal of Mechanical Sciences, 2014Co-Authors: Y S Tao, Qihong Fang, Xin Zeng, Y.w. LiuAbstract:Abstract The investigation for the interaction problem between a Griffith crack and a circular Inhomogeneity in the presence of an edge dislocation under the remote load is carried out. The expressions for the stress intensity factors (SIFs) at the crack tip are determined for different sets of geometric and material parameters with the distributed dislocation technique. The formulated singular integral equations are then solved numerically. The numerical results show that the edge dislocation can reduce the SIF or increase it, depending on the position of edge dislocation. When the distance between the edge dislocation and the Inhomogeneity is fixed, there is competition between the effects of the Inhomogeneity and the edge dislocation on the SIF. When the distance between the edge dislocation and the crack is less than a certain value, the edge dislocation is more distinct factor that influences the crack propagation. When the distance between the edge dislocation and the crack is equal to the certain value, the edge dislocation and the Inhomogeneity counteract each other's efforts. When the distance between the edge dislocation and the crack tip is more than the certain value, the effect of the Inhomogeneity is more dominant. As the remote load increases, the influence of the edge dislocation on SIF decreases, while the effect of the Inhomogeneity on it keeps unchanged.
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the interaction between a screw dislocation and a rigid line in a confocal elliptical Inhomogeneity
Applied Mathematical Modelling, 2011Co-Authors: Qihong Fang, J M Chen, Z D Luo, H P Song, Y.w. LiuAbstract:Abstract The interaction between a screw dislocation and an elastic elliptical Inhomogeneity which contains a confocal rigid line is investigated. The screw dislocation is located inside either the elliptical Inhomogeneity or the infinite matrix. By using the complex potential method, explicit series solutions of complex potentials are obtained. The image force acting on the screw dislocation and the stress intensity factor at the tip of the rigid line are derived. As a result, the analysis and discussion show that the influence of the rigid line on the interaction effects between a screw dislocation and an elliptical Inhomogeneity is significant. The rigid line enhances the repulsive force exerted on the dislocation produced by the stiff Inhomogeneity and abates the attractive force produced by the soft Inhomogeneity. For the soft Inhomogeneity, there is an unstable equilibrium position when the dislocation is inside the matrix and there is a stable equilibrium position when the dislocation is inside the Inhomogeneity. The stress intensity factor contour around the rigid line tip shows that when a dislocation with positive burgers vector is in the upper half-plane, stress intensity factor will be positive; while in the lower half-plane, stress intensity factor will be negative; and in the x-axis, it will be zero. The absolute value of the stress intensity factor will increase when the dislocation approaches the tip of the rigid line. The stress intensity factor at the rigid line tip is enhanced by a harder matrix and abated by a softer matrix.
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A Magnetoelectric Screw Dislocation Interacting with an Elliptical Inhomogeneity Containing a Confocal Rigid Line
Advanced Materials Research, 2011Co-Authors: Chun Zhi Jiang, Y.w. Liu, Chao XieAbstract:Based on the complex variable method, the magnetoelectroelastic interaction of a generalized screw dislocation with an elliptical Inhomogeneity containing a electrically conductive confocal rigid line under remote anti-plane shear stresses, in-plane electric and magnetic loads is dealt with. The generalized screw dislocation is located inside either the Inhomogeneity or the matrix. The analytical-functions of complex potentials for stresses, electric displacement fields and magnetic induction fields in both the Inhomogeneity and the matrix are derived. The image force acting on the dislocation are also calculated explicitly. The results show that the influence of the rigid line on the interaction effect between a generalized screw dislocation and an elliptical Inhomogeneity is significant. In addition, the material behavior also plays an important role on the image force.
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size dependent elastic interaction of a screw dislocation with a circular nano Inhomogeneity incorporating interface stress
Scripta Materialia, 2006Co-Authors: Y.w. LiuAbstract:Effect of interface stress upon the interaction between a screw dislocation and a nano-Inhomogeneity is investigated. By using the complex variable method, the image force acting on the screw dislocation is obtained. The results indicate that the influence of interface stress on the motion of the dislocation near the Inhomogeneity becomes significant when the radius of the Inhomogeneity is reduced to nanometer scale, leading to that the normalized image force depends on the Inhomogeneity size which differs from the size-independent classical solution.
Qihong Fang - One of the best experts on this subject based on the ideXlab platform.
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stress intensity factor of a mode i crack inside a nanoscale cylindrical Inhomogeneity
Engineering Fracture Mechanics, 2015Co-Authors: Yongshu Tao, Qihong Fang, Youwen Liu, Feng Liu, P H WenAbstract:Abstract Interior crack of a nanoscale cylindrical Inhomogeneity with interface stresses under remote load is investigated. Utilizing the distributed dislocation technique, stress intensity factor at crack tip is obtained. The results show that both positive (negative) residual interface tension and interface elasticity suppress (promote) crack propagation under remote load. The effects of residual interface tension and interface elasticity on stress intensity factor increase with decreasing Inhomogeneity radius. When Inhomogeneity radius reduces to a small value, even with remote load, the crack does not propagate due to positive residual interface tension.
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influence of dislocation on interaction between a crack and a circular Inhomogeneity
International Journal of Mechanical Sciences, 2014Co-Authors: Y S Tao, Qihong Fang, Xin Zeng, Y.w. LiuAbstract:Abstract The investigation for the interaction problem between a Griffith crack and a circular Inhomogeneity in the presence of an edge dislocation under the remote load is carried out. The expressions for the stress intensity factors (SIFs) at the crack tip are determined for different sets of geometric and material parameters with the distributed dislocation technique. The formulated singular integral equations are then solved numerically. The numerical results show that the edge dislocation can reduce the SIF or increase it, depending on the position of edge dislocation. When the distance between the edge dislocation and the Inhomogeneity is fixed, there is competition between the effects of the Inhomogeneity and the edge dislocation on the SIF. When the distance between the edge dislocation and the crack is less than a certain value, the edge dislocation is more distinct factor that influences the crack propagation. When the distance between the edge dislocation and the crack is equal to the certain value, the edge dislocation and the Inhomogeneity counteract each other's efforts. When the distance between the edge dislocation and the crack tip is more than the certain value, the effect of the Inhomogeneity is more dominant. As the remote load increases, the influence of the edge dislocation on SIF decreases, while the effect of the Inhomogeneity on it keeps unchanged.
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the interaction between a screw dislocation and a rigid line in a confocal elliptical Inhomogeneity
Applied Mathematical Modelling, 2011Co-Authors: Qihong Fang, J M Chen, Z D Luo, H P Song, Y.w. LiuAbstract:Abstract The interaction between a screw dislocation and an elastic elliptical Inhomogeneity which contains a confocal rigid line is investigated. The screw dislocation is located inside either the elliptical Inhomogeneity or the infinite matrix. By using the complex potential method, explicit series solutions of complex potentials are obtained. The image force acting on the screw dislocation and the stress intensity factor at the tip of the rigid line are derived. As a result, the analysis and discussion show that the influence of the rigid line on the interaction effects between a screw dislocation and an elliptical Inhomogeneity is significant. The rigid line enhances the repulsive force exerted on the dislocation produced by the stiff Inhomogeneity and abates the attractive force produced by the soft Inhomogeneity. For the soft Inhomogeneity, there is an unstable equilibrium position when the dislocation is inside the matrix and there is a stable equilibrium position when the dislocation is inside the Inhomogeneity. The stress intensity factor contour around the rigid line tip shows that when a dislocation with positive burgers vector is in the upper half-plane, stress intensity factor will be positive; while in the lower half-plane, stress intensity factor will be negative; and in the x-axis, it will be zero. The absolute value of the stress intensity factor will increase when the dislocation approaches the tip of the rigid line. The stress intensity factor at the rigid line tip is enhanced by a harder matrix and abated by a softer matrix.
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size dependent interaction between an edge dislocation and a nanoscale Inhomogeneity with interface effects
Acta Materialia, 2006Co-Authors: Qihong FangAbstract:The influence of the interface stress on the interaction between an edge dislocation and a circular nanoscale Inhomogeneity is investigated. The explicit solutions are given for stress fields and the image force acting on the edge dislocation. The impact of interface properties and the size of the Inhomogeneity on the glide/climb force are evaluated. The results show that the local hardening and softening effects at the interface of the nanoscale Inhomogeneity due to the interface stress are remarkable and an additional repulsive/attractive force acting on the dislocation is produced. The normalized glide/climb force increases (decreases) with the decrease of the radius of the Inhomogeneity, and the size dependence becomes significant when the radius of the Inhomogeneity is reduced to the nanometer scale which differs from the size-independent classical solutions. For some cases, the glide/climb of the edge dislocation near the nanoInhomogeneity may be more difficult because more equilibrium locations are present.
