Kronecker product approximation for preconditioning in three-dimensional imaging applications.

We derive Kronecker product approximations, with the help of tensor decompositions, to construct approximations of severely ill-conditioned matrices that arise in three-dimensional (3-D) image processing applications. We use the Kronecker product approximations to derive preconditioners for iterative regularization techniques; the resulting preconditioned algorithms allow us to restore 3-D images in a computationally efficient manner. Through examples in microscopy and medical imaging, we show that the Kronecker approximation preconditioners provide a powerful tool that can be used to improve efficiency of iterative image restoration algorithms.     

Kinematics of the heart: strain-rate imaging from time-resolved three-dimensional phase contrast MRI

A four-dimensional mapping (three spatial dimensions + time) of myocardial strain-rate would help to describe the mechanical properties of the myocardium, which affect important physiological factors such as the pumping performance of the ventricles. Strain-rate represents the local instantaneous deformation of the myocardium and can be calculated from the spatial gradients of the velocity field. Strain-rate has previously been calculated using one-dimensional (ultrasound) or two-dimensional (2-D) magnetic resonance imaging) techniques. However, this assumes that myocardial motion only occurs in one direction or in one plane, respectively. This paper presents a method for calculation of the time-resolved three-dimensional (3-D) strain-rate tensor using velocity vector information in a 3-D spatial grid during the whole cardiac cycle. The strain-rate tensor provides full information of both magnitude and direction of the instantaneous deformation of the myocardium. A method for visualization of the full 3-D tensor is also suggested. The tensors are visualized using ellipsoids, which display the principal directions of strain-rate and the ratio between strain-rate magnitude in each direction. The presented method reveals the principal strain-rate directions without a priori knowledge of myocardial motion directions.     

针对三维动画中关键帧数据的数字水印算法

提出一种针对三维动画中关键帧数据的数字水印算法。算法中水印的嵌入对象是运动对象的运动坐标,将运动坐标形成一个方阵,将具有惟一性的水印信息嵌入到方阵的特征向量的特定元素中,形成含有水印的动画。当动画的版权出现争议时,利用提取算法从动画中提取出水印,以证明版权。通过仿真实验表明,该算法的隐蔽性、抗攻击性较好,可以推广到其他形式或用其他软件制作的CG作品中。     

Simultaneous usage of homologous points, lines, and planes for optimal, 3-D, linear registration of multimodality imaging data

The authors have extended point-based registration to include simultaneous registration of points, lines, and planes, to permit accurate and easily implemented three-dimensional (3-D) registration of multimodal data sets for fusion of clinical anatomic and functional imaging modalities. Constructive geometry is used to define user-identified features where each feature's role in the reconstruction is weighted based on its relative statistical quality, i.e., variance. The algorithm employs singular value decomposition (SVD) and optimization techniques to find the minimum weighted least mean square error (LMSE) affine solution. The new method is generally more accurate due to the availability of more features to register. Notably the error surface contains only one minimum. Different subclasses of affine solutions can be obtained based on appropriateness and sufficiency of the number and type of input features. Preliminary results indicate that this method is useful in multimodal diagnostic image fusion.     

距离选通技术在三维成像激光雷达中的应用研究

距离选通技术在三维成像激光雷达中有着重要应用,是一种解决水下微光成像和抑制后向散射问题的简单有效方法之一。文中概述了距离选通技术的原理和应用范围,根据实时成像的需求,提出了一种实时距离选通成像系统的设计方案,该方案只需要一次成像就可以完成距离选通成像并求解出目标距离。根据质心法求解距离的原理,详细推导了成像系统的距离像和距离精度,并用仿真软件仿真分析了该系统距离像的距离精度和目标距离、时间切片数量、信噪比之间的关系。仿真结果表明:距离精度受系统信噪比的影响很大,当信噪比大于2 000时,测距精度优于0.2 m。     

高分辨雷达/红外成像复合系统的空间配准方法

为实现高分辨雷达/红外成像复合制导系统的空间配准,首先提出了一种基于无偏转换测量的精确极大似然坐标变换法来完成由球坐标系到笛卡尔坐标系的坐标转换,然后提出了一种通过标定雷达和红外相机实现空间配准的方法.为提高空间配准的精度,用提出的坐标变换法估计目标在笛卡尔坐标系下的真实位置,在红外图像处理中提出了一种多灰度细分质心算...     

干涉成像光谱仪高光谱数据信息质量评估

从信噪比和信息熵两个方面对干涉成像光谱仪(IIM)高光谱数据的信息质量进行了评估,以期为IIM高光谱数据的深入应用提供参考依据.结果显示,IIM高光谱数据整体信息质量良好,中间波段影像信息质量优于两端波段,750 nm附近作为月表斜长石、辉石光谱曲线反射峰,表现出较好的信噪比和信息熵,这对提取月表元素与矿物具有重要意义,但作为辉石、斜长玻璃矿物吸收谷的930 nm波段附近则信息质量较差;前9个波段信息质量上升趋势明显,但整体较差,建议在使用时对噪声做着重处理;第一波段和最后一个波段信息质量较差,建议舍去.     

A recursive algorithm for the three-dimensional imaging of brain electric activity: Shrinking LORETA-FOCUSS

Estimation of intracranial electric activity from the scalp electroencephalogram (EEG) requires a solution to the EEG inverse problem, which is known as an ill-conditioned problem. In order to yield a unique solution, weighted minimum norm least square (MNLS) inverse methods are generally used. This paper proposes a recursive algorithm, termed Shrinking LORETA-FOCUSS, which combines and expands upon the central features of two well-known weighted MNLS methods: LORETA and FOCUSS. This recursive algorithm makes iterative adjustments to the solution space as well as the weighting matrix, thereby dramatically reducing the computation load, and increasing local source resolution. Simulations are conducted on a 3-shell spherical head model registered to the Talairach human brain atlas. A comparative study of four different inverse methods, standard Weighted Minimum Norm, L1-norm, LORETA-FOCUSS and Shrinking LORETA-FOCUSS are presented. The results demonstrate that Shrinking LORETA-FOCUSS is able to reconstruct a three-dimensional source distribution with smaller localization and energy errors compared to the other methods.     

A Computationally Efficient Method for Determining the Size and Location of Myocardial Ischemia

The purpose of this paper is to introduce a new method for solving the inverse problem of locating ischemic regions in the heart. The electrical activity in the human heart is modeled by the bidomain equations, which can be expanded to compute the potentials on the body surface. The associated inverse problem is to use ECG recordings to gain information about ischemias. We propose an algorithm for doing this, combining the level set method with a simpler minimization problem. Instead of trying to determine the shape, as in the level set method, we simply make the approximation that the ischemia is spherical. The effects of ischemia on the electrical attributes of heart tissue are examined. The new method is tested with computer simulations on synthetic body surface potential maps (BSPMs) in a realistic geometry, using realistic values for the parameters. It is shown to be, in some respects, superior to the level set approach and may be a step toward a practical algorithm useful in medical diagnostics.     

基于测量报告数据优化CSFB频点配置的方法

中国移动TD-LTE语音业务当前主流解决方案采用R8盲重定向CSFB回落到2G的方式,本文基于对TD-LTE MR周期性测量报告的研究运用,给出了一种基于MR周期性测量报告数据优化CSFB回落频点配的方案。     

Image stabilization and registration for tracking cells in the microvasculature

We propose a registration system to be used for tracking cells in intravital video microscopy that 1) stabilizes jitter-the undesired translational displacement of frames due to respiratory movement, etc., and 2) registers frames in a moving field of view (FOV) to allow for cell tracking over an extended range. For the first time, tracking of rolling leukocytes in vivo over a moving FOV is demonstrated. In a fixed FOV, stable background regions are located using a morphological approach. Template subregions are then selected from the stable regions and matched to corresponding locations in a reference frame. We show the effectiveness of the stabilization algorithm by using an active contour to track 15 leukocytes previously untrackable due to jitter. For 30 fixed FOV sequences containing rolling leukocytes, the resulting root-mean-square error (RMSE) is less than 0.5 microm. To align frames in a moving FOV, we present a modified correlation approach to estimate the common region between two consecutive fixed FOVs. We correlate the overlapping regions of the initial frame of the current fixed FOV and the final frame of the previous fixed FOV to register the images in the adjoining moving FOV. The RMSE of our moving FOV registration technique was less than 0.6 mmicrom. In 10 sequences from different venules, we were able to track 11 cells using an active contour approach over moving FOVs.     

Method for analytic subscriber traffic data acquisition in telephone networks

A method for fast and economic acquisition of analytic subscriber traffic data in conventional electromechanical telephone exchanges is described. The method is based on a specially designed microprocessor-controlled scanning device and on algorithms constructed according to the statistics of the registered call phases. The method has been successfully implemented in the local telephone network of Patras, Greece.     

提高遥感相机电子学成像质量方法

影响遥感相机成像质量的因素很多,为了提高遥感相机电子学成像质量,对核心元器件的信噪比、电路带宽、抑制高频信号干扰和暗电平箝位等影响因素进行了分析,提出了改进方法,并进行了实验验证。达到空间实际应用的要求。     

Method for replica creation in data grids based on complex networks

In order to reduce makespan and storage consumption in data grids,a node selection model for replica creation is proposed.The model is based on the degree distribution of complex networks.We define two candidate replica nodes: a degree-based candidate pool and a frequency-based candidate pool,through which a degree-based candidate pool is defined m consideration of onsidering the access frequency,a candidate pool-based frequency is also defined.The data replica is copied to the node with the minimum local cost in the two pools.Further,this paper presents and proves a replica creation theorem.A dynamic multi-replicas creation algorithm(DMRC)is also provided.Simulation results show that the proposed method may simultaneously reduce makespan and data used in space storage consumption.     

Method of obtaining accurate transistor data for the evaluation of computer models

The conventional manual method of obtaining simultaneous, measurements of Vce, Vbe and Ic for transistor modelling requires that the current gain be maintained at a fixed value over a wide range of collector current. A method is presented for accurately maintaining the current gain of the transistor constant to the required accuracy for over more than four decades of collector current.     

On the a priori identifiability of the two-compartment distributed parameter model from residual tracer data acquired by dynamic contrast-enhanced imaging

Tracer kinetics models are commonly employed to estimate physiological parameters related to blood transport and capillary-tissue exchange. A priori identifiability addresses the question of whether the parameters in a model can be uniquely determined from a given experiment. It has been previously shown that the one- and two-compartment distributed parameter (DP) models are nonidentifiable from tracer outflow data obtained by arterial-venous sampling. In this correspondence, we show that both DP models are a priori identifiable from residual tracer data obtained by dynamic contrast-enhanced (DCE) imaging. We list the various parameters of the DP models that can be uniquely estimated from DCE imaging data, and discuss this seemingly different outcome for DCE imaging experiments, as compared with the arterial-venous sampling experiments.     

Convergence of the Red-TOWER method for removing noise from data

By coupling the wavelet transform with a particular nonlinear shrinking function, the Red-telescopic optimal wavelet estimation of the risk (TOWER) method is introduced for removing noise from signals. It is shown that the method yields convergence of the L₂ risk to the actual solution with optimal rate. Moreover the method is proved to be asymptotically efficient when the regularization parameter is selected by the generalized cross validation criterion (GCV) or the Mallows criterion. Numerical experiments based on synthetic data are provided to compare the performance of the Red-TOWER method with hard-thresholding, soft-thresholding, and neigh-coeff thresholding. Furthermore, the numerical tests are also performed when the TOWER method is applied to hard-thresholding, soft-thresholding, and neigh-coeff thresholding, for which the full convergence results are still open     

An automated system for the registration and comparison of photographic images in medicine

A system is presented for digitization and automated comparison of photographic images of patients obtained at different times using a high-precision video camera. The images can be acquired either directly or from slides. The two images to be compared are registered using a complex geometrical and gray-level registration model including six parameters (planar, translation, rotation, magnification, linear transformation of the gray levels). The values of the registration parameters are automatically calculated by maximizing an integer similarity measure selected for robustness. The optimization of this function with respect to the registration parameters is performed using an adaptive random search strategy. The analysis of the differences between the registered images can be carried out through visual inspection of the subtraction image in which artifacts due to remaining infrapixel shifts have been suppressed.