计算机辅助外科手术空间配准技术的研究

医学图像和实际手术空间的配准问题是计算机辅助外科手术技术的一个重要的研究热点,它能够帮助医生选择最佳手术路径和减小手术损伤,实现手术的方便快捷和微创,提高手术成功率。主要研究了一种基于ICP算法的计算机辅助外科手术中空间配准技术,通过获取实验模型的空间坐标信息,进行点集配准,找到最优旋转矩阵和最优平移向量。并通过仿真实验给出了模拟的配准结果,仿真试验结果表明,ICP算法配准精度高,适用于计算机辅助外科手术。     

信息系统开发的牛头模型

本文提出了信息系统开发的牛头模型,并对模型的内容进行了说明。     

改进遗传算法搜索性能的研究

本文针对改进遗传算法的搜索性能,提出了一种新的变异算子－自适应多位变异算子,它根据每一代的每一个体在当代中的优劣程度,自适应地控制其发生变异的位数。适应度差的个体变异的位数多,一方面使差的模式生存机会少,另一方面增加了种群的多样性,同时也扩大了搜索范围。我们用模式定理证明了该算子的有效性,并且我们作的仿真实验也同样表明该算子能大大改进遗传算法的搜索性能。     

An Analysis of Edge Detection by Using the Jensen-Shannon Divergence

This work constitutes a theoretical study of the edge-detection method by means of the Jensen-Shannon divergence, as proposed by the authors. The overall aim is to establish formally the suitability of the procedure of edge detection in digital images, as a step prior to segmentation. In specific, an analysis is made not only of the properties of the divergence used, but also of the method's sensitivity to the spatial variation, as well as the detection-error risk associated with the operating conditions due to the randomness of the spatial configuration of the pixels. Although the paper deals with the procedure based on the Jensen-Shannon divergence, some problems are also related to other methods based on local detection with a sliding window, and part of the study is focused to noisy and textured images.     

实现动态网页的一种新技术ColdFusion

介绍了ColdFusion技术的定义、工作原理、具体实例、应用前景。     

3D-QSAR and molecular docking studies of selective agonists for the thyroid hormone receptor beta

Three-dimensional quantitative structure-activity relationship (3D-QSAR) models were developed using comparative molecular field analysis (CoMFA) and comparative molecular similarity analysis (CoMSIA) on a series of agonists of thyroid hormone receptor beta (TRbeta), which may lead to safe therapies for non-thyroid disorders while avoiding the cardiac side effects. The reasonable q(2) (cross-validated) values 0.600 and 0.616 and non-cross-validated r(2) values of 0.974 and 0.974 were obtained for CoMFA and CoMSIA models for the training set compounds, respectively. The predictive ability of two models was validated using a test set of 12 molecules which gave predictive correlation coefficients (r(pred)(2)) of 0.688 and 0.674, respectively. The Lamarckian Genetic Algorithm (LGA) of AutoDock 4.0 was employed to explore the binding mode of the compound at the active site of TRbeta. The results not only lead to a better understanding of interactions between these agonists and the thyroid hormone receptor beta but also can provide us some useful information about the influence of structures on the activity which will be very useful for designing some new agonist with desired activity.     

Evaluation of amplitude-based sorting algorithm to reduce lung tumor blurring in PET images using 4D NCAT phantom

PURPOSE: develop and validate a PET sorting algorithm based on the respiratory amplitude to correct for abnormal respiratory cycles. METHOD AND MATERIALS: using the 4D NCAT phantom model, 3D PET images were simulated in lung and other structures at different times within a respiratory cycle and noise was added. To validate the amplitude binning algorithm, NCAT phantom was used to simulate one case of five different respiratory periods and another case of five respiratory periods alone with five respiratory amplitudes. Comparison was performed for gated and un-gated images and for the new amplitude binning algorithm with the time binning algorithm by calculating the mean number of counts in the ROI (region of interest). RESULTS: an average of 8.87+/-5.10% improvement was reported for total 16 tumors with different tumor sizes and different T/B (tumor to background) ratios using the new sorting algorithm. As both the T/B ratio and tumor size decreases, image degradation due to respiration increases. The greater benefit for smaller diameter tumor and lower T/B ratio indicates a potential improvement in detecting more problematic tumors.     

High-pressure plastic flow in silicon: A first-principles theoretical study

Summary Microindentation experiments have recently shown that silicon can exhibit plastic flow when subjected to high pressure. Assuming that under these conditions the relevant reference structure is the -Sn high-pressure phase of silicon, we apply the magic-strain concept to explore the space of configurations that could describe the observed behavior. We use first-principles total-energy calculations (including full relaxation of the atomic basis for every structure) to evaluate the relevance of strained configurations. Using this approach, we were able to identify a low-energy path that corresponds to planar flow of the atoms. The atomic configurations along this path provide insight into possible microscopic motions under high pressure that may be relevant to plastic flow in silicon.     

Définition théorique des paramètres en fort niveau d’un multipôle actif non linéaire

In this paper, large signal non linear P parameters are rigorously defined, allowing the characterization of non linear active n-port circuits in the frequency domain with the aim of computer aided design of power microwave devices. No a priori conditions bind the parameters to the variables describing the input signal. However the following rules apply to the parameters: they may be function of any input variables of the n-port circuit; the expression of the large-signal parameters should become identical to the expression of the linear parameters characterizing the n-port circuit under linear operating conditions when the values of the input variables tend to zero. An application of the definition to afet is demonstrated.