in this paper, we obtain a necessary and sufficient condition for a conformal mapping between two weyl manifolds to preserve einstein tensor. then we prove that some basic curvature tensors of $w_n$ are preserved by such a conformal mapping if and only if the covector field of the mapping is locally a gradient. also, we obtained the relation between the scalar curvatures of the weyl manifolds r...

The detection of dipole-like sources, such as unexploded ordnances (UXO) and other metallic objects, based on a magnetic gradiometer system, has been increasingly applied in recent years. In this paper, a novel dipole-like source detection algorithm, based on eigenvector analysis with magnetic gradient tensor data interpretation is presented. Firstly, the theoretical basis of the eigenvector de...

The tangential equilibria are characterized by a bulk plasma velocity and a magnetic field that are perpendicular to the gradient direction. Such equilibria can be spatially periodic (like waves), or they can separate two regions with asymptotic uniform conditions (like MHD tangential discontinuities). It is possible to compute the velocity moments of the particle distribution function. Even in...

Consider the following consistent Sylvester tensor equation[mathscr{X}times_1 A +mathscr{X}times_2 B+mathscr{X}times_3 C=mathscr{D},]where the matrices $A,B, C$ and the tensor $mathscr{D}$ are given and $mathscr{X}$ is the unknown tensor. The current paper concerns with examining a simple and neat framework for accelerating the speed of convergence of the gradient-based iterative algorithm and ...

Heterogeneity of magnetic susceptibility within brain tissues creates unique contrast between gray and white matter in magnetic resonance phase images acquired by gradient echo sequences. Detailed understanding of this contrast may provide meaningful diagnostic information. In this communication, we report an observation of extensive anisotropic magnetic susceptibility in the white matter of th...

This paper investigates the iterative reconstruction of tensor fields in diffusion tensor magnetic resonance imaging (MRI). The gradient constraints on eigenvalue and tensor component images of the diffusion tensor were exploited. A computer-generated phantom was used in order to simulate the diffusion tensor in a cardiac MRI study with a diffusion model that depends on the fiber structure of t...

In order to improve the stability of second-order magnetic gradient tensor data under interference, a optimization algorithm based on improved central difference method is proposed in this paper, and new measuring device designed according algorithm. simulation, root mean square error (RMSE) old methods different noise conditions studied, results show that more stable. experiment, measurement w...

The clinical ability to measure molecular diffusion non­ invasively and in vivo using magnetic resonance imag­ ing (MRI) has generated great interest (1). In tissues, the effective diffusivity depends upon tissue anatomy, microstructure, and gradient pulse parameters. Diffu­ sion MR spectroscopy (2-4), 2DFT spin-echo imaging (5-7), and echo-planar imaging (EPI) (8-11), of in vivo isotropic medi...

Introduction: High-angular resolution diffusion imaging (HARDI) is a powerful extension of MRI that maps the directional diffusion of water in the brain, based on applying diffusion-sensitized gradients in 30-100 or more different directions. In the Diffusion Tensor (DT) model, a tensor is fitted to the set of diffusion images, and maps of fiber integrity such as fractional or relative anisotro...