Fault detection in configurable switched-capacitor filters using transient analysis and dynamic time warping

In this work, we address a low-cost test of switched capacitors filters embedded in configurable analog sections. The proposal improves the Transient Analysis Method (TRAM) by incorporating a similarity measure, dynamic time warping. In this way, we extend TRAM to cases that that initially were not compatible and simplify the test of filters of order higher than two. This paper performs the test evaluation by developing a new simulation model of the addressed system that supports fault injection and simulation. A comparison with experimental data in both normal and faulty behavior validates the model. We consider catastrophic faults in the switches (stuck at open and short) and capacitors (shorts and opens), and deviation faults in the capacitors. The fault simulation results validate the test proposed here.

     

Geometrical-based lip-reading using template probabilistic multi-dimension dynamic time warping

By identifying lip movements and characterizing their associations with speech sounds, the performance of speech recognition systems can be improved, particularly when operating in noisy environments. In this paper, we present a geometrical-based automatic lip reading system that extracts the lip region from images using conventional techniques, but the contour itself is extracted using a novel application of a combination of border following and convex hull approaches. Classification is carried out using an enhanced dynamic time warping technique that has the ability to operate in multiple dimensions and a template probability technique that is able to compensate for differences in the way words are uttered in the training set. The performance of the new system has been assessed in recognition of the English digits 0 to 9 as available in the CUAVE database. The experimental results obtained from the new approach compared favorably with those of existing lip reading approaches, achieving a word recognition accuracy of up to 71% with the visual information being obtained from estimates of lip height, width and their ratio.     

Efficient video sequences alignment using unbiased bidirectional dynamic time warping

In this paper, we propose an efficient technique to synchronize video sequences of events that are acquired via uncalibrated cameras at unknown and dynamically varying temporal offsets. Unlike other existing techniques that just take unidirectional alignment into consideration, the proposed technique considers symmetric alignments and compute the optimal alignment. We also establish sub-frame accuracy video alignment. The advantages of our approach are validated by tests conducted on several pairs of real and synthetic sequences. We present qualitative and quantitative comparisons with other existing techniques. A unique application of this work in generating high-resolution 4D MRI data from multiple low-resolution MRI scans is described.     

基于动态时间规整的轨道结构病害诊断方法

本文提出了一种基于动态时间规整的轨道结构病害诊断方法,利用动态时间规整算法对不同轨道结构病害下的振动响应进行特征提取,构建了基于动态时间规整的特征向量,并将其作为支持向量机的输入,利用支持向量机对轨道结构病害进行分类和诊断,实现了对不同轨道结构病害的诊断.数据的仿真结果表明,该方法取得了较好的诊断效果,且在有些列车速度...     

一种基于动态时间弯曲距离的快速子序列匹配算法

动态时间弯曲距离在用于计算时间序列间的距离时是极其耗费时间的,尤其是处理较大规模的时间序列数据库中的子序列匹配问题时,时间消耗更是难以忍受。该文提出一种新的低边界距离,能够快速滤掉不满足结果条件的时间序列,以提高查询速度,并证明该低边界距离不会丢弃真实的结果。一种基于水平边界区域的索引技术被用于进一步提高查询效率。分别以真实数据集和人造数据集作为实验数据来测试该文所提出的算法的性能,结果表明该算法在数据库规模上和序列长度上都有良好的健壮性。     

On minimizing memory in systolic arrays for the dynamic time warping algorithm

New systolic architectures have been evaluated for the Dynamic Time Warping (DTW) algorithm. This algorithm is a non-linear pattern matching technique used in isolated and continuous speech recognition systems.The proposed systolic decomposition for the DTW algorithm combines simultaneously (1) simple and regular systolic communication schemes and (2) a decomposition strategy which aims at a minimum amount of memory.This approach has led to a systolic architecture which is relatively flexible, compact and easy to test. Several arrays can be built up by keeping the same decomposition of the DTW-algorithm. This allows an easy exchange, depending on the desired application, of execution speed against chip-area.     

拒绝服务攻击及防御措施

拒绝服务攻击(DoS)是当前很常见的一种攻击,它攻击目标系统,使得被攻击系统无法给其合法用户提供正常的服务.DoS攻击的目标即可能是主机系统,也可能是网络设备或者网络本身,它主要通过消耗目标系统的CPU能力、内存、网络带宽,或者使系统死机、崩溃等来达到目的.由于DoS攻击一般不需要入侵系统,因此,经常利用UDP,ICMP等协议,DoS攻击中经常伪造源地址,这也导致了DoS攻击难于追查.     

Anatomic region-based dynamic range compression for chestradiographs using warping transformation of correlated distribution

The purpose of this paper is to investigate the effectiveness of the authors' novel dynamic range compression (DRC) for chest radiographs. The purpose of DRC is to compress the gray scale range of the image when using narrow dynamic range viewing systems such as monitors. First, an automated segmentation method was used to detect the lung region. The combined region of mediastinum, heart, and subdiaphragm was defined based on the lung region. The correlated distributions, between a pixel value and its neighboring averaged pixel value, for the lung region and the combined region were calculated. According to the appearance of overlapping of two distributions, the warping function was decided. After pixel values were warped, the pixel value range of the lung region was compressed while preserving the detail information, because the warping function compressed the range of the averaged pixel values while preserving the pixel value range for the pixels which had had the same averaged pixel value. The performance was evaluated with the authors' criterion function which was the contrast divided by the moment, where the contrast and the moment represent the sum of the differences between the pixel values and the averaged values of eight pixels surrounding that pixel, and the sum of the differences between the pixel values and the averaged value of all pixels in the region-of-interest, respectively. For 71 screening chest images from Johns Hopkins University Hospital (Baltimore, MD), this method improved our criterion function at 11.7% on average. The warping transformation algorithm based on the correlated distribution was effective in compressing the dynamic range while simultaneously preserving the detail information     

Image enhancement using warping technique

An image enhancement algorithm based on a warping technique is presented. The warping map is chosen in order to sharpen the edges of the image. In contrast to other algorithms, enhancement is performed without introducing overshoot in sharp edges and without amplifying the noise present in the original image.     

A modification over Sakoe and Chiba's dynamic time warping algorithm for isolated word recognition

A modification over Sakoe and Chiba's dynamic time warping algorithm for isolated word recognition is proposed. It is shown that this modified algorithm works better without any slope constraint. Also, this algorithm not only consumes less computation time but also improves the word recognition accuracy.     

Improving fairness using dynamic weights in ATM ABR service

A new scheme termed active fairness is proposed that substantially improves fairness in allocating bandwidth among the available bit rate (ABR) connections in ATM networks. In contrast to the one set of weights used in the generalised fairness scheme, active fairness maintains two sets of weights at each link. Simulation results prove the efficacy of the proposed scheme     

一种采用NFV架构的服务功能链动态编排与部署

随着虚拟化技术的出现,网络功能虚拟化(Network Function Virtualization,NFV) 和软件定义网络(Software Defined Networking,SDN) 技术使网络功能从硬件中抽象出来并可运行在虚拟机上,将虚拟网络功能映射部署到物理网络上,为用户提供定制化服务。服务功能链(Service Function Chaining,SFC) 由一组虚拟网络功能组成,目前其部署的一个关键问题是如何在保证为用户提供相应服务的同时降低网络资源消耗和负载压力。为此,首先介绍了一种可用于服务功能链编排的NFV 架构,并对基于SRv6 技术的SFC 编排过程进行说明;然后提出了一种有效的SFC动态编排算法——第一步使用广度优先搜索遍历网络并找到部署服务链的最短物理路径,第二步使用蚁群优化算法生成最优部署方案。仿真结果表明,该方案能够有效减轻网络负载,同时平均降低端到端延迟22%,减少带宽资源消耗18%,优化部署成功率23%。     

Dynamic time warping in classification and selection of motion capture data

Multidimensional Systems and Signal Processing - The paper is a comprehensive study on classification of motion capture data on the basis of dynamic time warping (DTW) transform. It presents both...     

Denial of service attacks on network-based control systems: impact and mitigation

Replacing specialized industrial networks with the Internet is a growing trend in industrial informatics, where packets are used to transmit feedback and control signals between a plant and a controller. Today, denial of service (DoS) attacks cause significant disruptions to the Internet, which will threaten the operation of network-based control systems (NBCS). In this paper, we propose two queueing models to simulate the stochastic process of packet delay jitter and loss under DoS attacks. The motivation is to quantitatively investigate how these attacks degrade the performance of NBCS. The example control system consists of a proportional integral controller, a second-order plant, and two one-way delay vectors induced by attacks. The simulation results indicate that Model I attack (local network DoS attack) impairs the performance because a large number of NBCS packets are lost. Model II attack (nonlocal network DoS attack) deteriorates the performance or even destabilizes the system. In this case, the traffic for NBCS exhibits strong autocorrelation of delay jitter and packet loss. Mitigating measures based on packet filtering are discussed and shown to be capable of ameliorating the performance degradation.     

Space moving target detection using time domain feature

The traditional space target detection methods mainly use the spatial characteristics of the star map to detect the targets, which can not make full use of the time domain information. This paper presents a new space moving target detection method based on time domain features. We firstly construct the time spectral data of star map, then analyze the time domain features of the main objects (target, stars and the background) in star maps, finally detect the moving targets using single pulse feature of the time domain signal. The real star map target detection experimental results show that the proposed method can effectively detect the trajectory of moving targets in the star map sequence, and the detection probability achieves 99% when the false alarm rate is about 8×10-5, which outperforms those of compared algorithms.     

基于wireshark的分布式拒绝服务攻击检测系统

wireshark是一款方便实用的网络封包分析软件,使用WinPCAP作为接口,与网卡直接进行数据报文交换。文章在使用wireshark获取网络封包的基础上,通过分析网络封包中TCP层包头在建立网络连接过程中协议标志位的特点,根据不同标志位信号在各端口的占比情况对例如SYN flood类型的分布式拒绝服务攻击进行检测。并介绍了基于wireshark的分布式拒绝服务攻击检测系统的总体设计和实现方法。     

Fast 3D video stabilization using ROI-based warping

With the rapid development of portable digital video equipment, such as camcorders, digital cameras and smart phones, video stabilization techniques for camera de-shaking are strongly required. The cutting-edge video stabilization techniques provide outstanding visual quality by utilizing 3D motion, while early video stabilization is based on 2D motion only. Recently, a content-preserving warping algorithm has been acknowledged as state-of-the-art thanks to its superior stabilization performance. However, the huge computational cost of this technique is a serious burden in spite of its excellent performance. Thus, we propose a fast video stabilization algorithm that provides significantly reduced computational complexity over the state-of-the-art with the same stabilization performance. First, we estimate the 3D information of the feature points in each input frame and define the region of interest (ROI) based on the estimated 3D information. Next, if the number of feature points in the ROI is sufficient, we apply the proposed ROI-based pre-warping and content-preserving warping sequentially to the input frame. Otherwise, conventional full-frame warping is applied. From intensive simulation results, we find that the proposed algorithm reduces computational complexity to 14% of that of the state-of-the-art method, while keeping almost equivalent stabilization performance.     

IP返回跟踪DoS攻击的压缩边界采样算法

描述了IP返回跟踪DoS(拒绝服务)攻击中的压缩边界采样算法,并在保证后向兼容性的前提下对IP数据包头部进行修改。     

Vehicle detection in aerial surveillance using dynamic Bayesian networks

We present an automatic vehicle detection system for aerial surveillance in this paper. In this system, we escape from the stereotype and existing frameworks of vehicle detection in aerial surveillance, which are either region based or sliding window based. We design a pixelwise classification method for vehicle detection. The novelty lies in the fact that, in spite of performing pixelwise classification, relations among neighboring pixels in a region are preserved in the feature extraction process. We consider features including vehicle colors and local features. For vehicle color extraction, we utilize a color transform to separate vehicle colors and nonvehicle colors effectively. For edge detection, we apply moment preserving to adjust the thresholds of the Canny edge detector automatically, which increases the adaptability and the accuracy for detection in various aerial images. Afterward, a dynamic Bayesian network (DBN) is constructed for the classification purpose. We convert regional local features into quantitative observations that can be referenced when applying pixelwise classification via DBN. Experiments were conducted on a wide variety of aerial videos. The results demonstrate flexibility and good generalization abilities of the proposed method on a challenging data set with aerial surveillance images taken at different heights and under different camera angles.