Active disturbance rejection control: between the formulation in time and the understanding in frequency

With the rapid deployments of the active disturbance rejection control (ADRC) as a bonafide industrial technology in the background, this paper summarizes some recent results in the analysis of linear ADRC and offers explanations in the frequency response language with which practicing engineers are familiar. Critical to this endeavor is the concept of bandwidth, which has been used in a more general sense. It is this concept that can serve as the link between the otherwise opaque state space formulation of the ADRC and the command design considerations and concerns shared by practicing engineers. The remarkable characteristics of a simple linear ADRC was first shown in the frequency domain, followed by the corresponding analysis in time domain, where the relationship between the tracking error and the ADRC bandwidth is established. It is shown that such insight is only possible by using the method of solving linear differential equations, instead of the more traditional techniques such as the Lyapunov methods, which tend to be more conservative and difficult to grasp by engineers. The insight obtained from such analysis is further demonstrated in the simulation validation.     

Segmentation of the left ventricle in cardiac cine MRI using a shape-constrained snake model

Segmentation of the left ventricle (LV) is a hot topic in cardiac magnetic resonance (MR) images analysis. In this paper, we present an automatic LV myocardial boundary segmentation method using the parametric active contour model (or snake model). By convolving the gradient map of an image, a fast external force named gradient vector convolution (GVC) is presented for the snake model. A circle-based energy is incorporated into the GVC snake model to extract the endocardium. With this prior constraint, the snake contour can conquer the unexpected local minimum stemming from artifacts and papillary muscle, etc. After the endocardium is detected, the original edge map around and within the endocardium is directly set to zero. This modified edge map is used to generate a new GVC force filed, which automatically pushes the snake contour directly to the epicardium by employing the endocardium result as initialization. Meanwhile, a novel shape-similarity based energy is proposed to prevent the snake contour from being strapped in faulty edges and to preserve weak boundaries. Both qualitative and quantitative evaluations on our dataset and the publicly available database (e.g. MICCAI 2009) demonstrate the good performance of our algorithm.     

基于nRF24L01的主动式电子标签的设计

本文提出一种2.4G主动式RFID标签结构,设计了硬件电路及相关软件,克服被动式RFID标签识别距离短,不稳定的缺点。在主动式标签的设计中,采用低功耗单片机和射频芯片,减小标签体积。实验表明:该型标签具有扩展方便、低功耗、可靠性高的特点。     

Human eye sclera detection and tracking using a modified time-adaptive self-organizing map

This paper investigates the use of time-adaptive self-organizing map (TASOM)-based active contour models (ACMs) for detecting the boundaries of the human eye sclera and tracking its movements in a sequence of images. The task begins with extracting the head boundary based on a skin-color model. Then the eye strip is located with an acceptable accuracy using a morphological method. Eye features such as the iris center or eye corners are detected through the iris edge information. TASOM-based ACM is used to extract the inner boundary of the eye. Finally, by tracking the changes in the neighborhood characteristics of the eye-boundary estimating neurons, the eyes are tracked effectively. The original TASOM algorithm is found to have some weaknesses in this application. These include formation of undesired twists in the neuron chain and holes in the boundary, lengthy chain of neurons, and low speed of the algorithm. These weaknesses are overcome by introducing a new method for finding the winning neuron, a new definition for unused neurons, and a new method of feature selection and application to the network. Experimental results show a very good performance for the proposed method in general and a better performance than that of the gradient vector field (GVF) snake-based method.     

Dynamic Shape and Appearance Modeling via Moving and Deforming Layers

We propose a model of the shape, motion and appearance of a scene, seen through a sequence of images, that captures occlusions, scene deformations, unconstrained viewpoint variations and changes in its radiance. This model is based on a collection of overlapping layers that can move and deform, each supporting an intensity function that can change over time. We discuss the generality and limitations of this model in relation to existing ones such as traditional optical flow or motion segmentation, layers, deformable templates and deformotion. We then illustrate how this model can be used for inference of shape, motion, deformation and appearance of the scene from a collection of images. The layering structure allows for automatic inpainting of partially occluded regions. We illustrate the model on synthetic and real sequences where existing schemes fail, and show how suitable choices of constants in the model yield existing schemes, from optical flow to motion segmentation and inpainting.     

基于入侵诱骗技术的主动蜜罐系统的设计

提出了一种主动蜜罐系统的设计方法.针对传统的蜜罐的不足,主动蜜罐系统可以自动地对安全事件作出反应,能够产生匹配的目标来满足入侵者的目的,从而可以对入侵者使用的方法和技术进行研究,动态的采取防范措施,有效地保护真实系统免受攻击.     

医学院校开设《ASP动态网页设计》课程的教学探索与实践

分析了医学院校计算机基础教学的现状和存在的弊端,提出通过开设《ASP动态网页设计》课程,在课程体系、教学内容和教学模式等方面进行改革的思路,并在教学实践过程中予以贯彻和实施,建立起了一套针对医学院校计算机基础教学改革行之有效的教学体系。     

基于弹性匹配活动轮廓模型心脏超声图像分割

超声医学图像由于受成像机理的影响,图像对比度不高、边缘不明显.基于传统活动轮廓线模型(snake模型)的分割方法可能产生过分割或泄漏问题.由于医学图像中拓扑结构已知,因此基于先验知识的活动轮廓线分割方法是解决这个问题的一个有效途径.建立一种新的基于弹性匹配活动轮廓线模型,该方法将待分割曲线的形状与原型曲线用弹性匹配测量变形量或相似度.曲线在演化过程中,根据变形量或相似度,可以准确分割模糊的边缘,同时保持整体目标分割形状.通过对二维小儿超声心脏图像的左心房内壁进行分割,经比较,基于弹性匹配活动轮廓线分割比传统活动轮廓线分割的误差有显著减少,避免了传统活动轮廓线的过分割或泄漏问题.     

基于主动防御模式下蠕虫病毒特征码的提取模型及算法设计

从一般的网络攻击技术出发,分析现有网络安全技术的弱点,采用主动防御的新思想来应对当前反病毒技术远远落后病毒技术发展的局面。重点对基于动态陷阱生成技术的蠕虫病毒特征码的自动提取进行研究,对收集的新型蠕虫病毒特征扩充IDS的特征库,弥补入侵检测系统对未知病毒攻击无法识别问题,完善防御系统。