This paper presents a virtual tagging framework for measuring, as well as visualising, myocardial deformation using magnetic resonance (MR) velocity imaging. Tagging grids are allocated artificially according to the deformation gradient with varying shapes and densities. The control points are then deformed such that the difference between the induced deformation velocity and that of actually measured MR data is minimum. A full three-dimensional implementation of the technique combined with the mass conservation constraint is provided. Numerical considerations of applying the proposed framework and different optimization strategies have been investigated with both simulated and phantom experiments. The accuracy of the technique in terms of following material deformation is compared with that of conventional tagging technique. Index Terms-Finite-element analysis, magnetic resonance (MR) tagging, mass conservation, myocardial deformation, myocardial velocity mapping, strain analysis.

We report a method measuring 3-Ddisplacement of cambered mirror for cryogenic optical system using white light speckle photography with double light sources and double cameras. Data acquiring and processing based on a digital image processing system is described. The 3-Ddisplacement and displacement vector distributions in two low-temperature ranges are measured.

应用图像识别与变分学原理，对数字散斑相关方法作了理论阐述，导出了测量物体表面变形场的一般过程，将力学中的变形测量问题转化为单纯的数值计算问题，避免了传统光测方法与干涉条纹有关的一系列困难。初步的实验结果表明，该方法在工程实际现场、高速冲击动态过程、细观力学变形过程以及变形测量的自动化等方面都有广泛的应用潜力，从而为光测力学拓展应用领域、实现自动化测量展现了新的前景。