Probabilistic pseudo-morphology for grayscale and color images

Mathematical morphology offers popular image processing tools, successfully used for binary and grayscale images. Recently, its extension to color images has become of interest and several approaches were proposed. Due to various issues arising from the vectorial nature of the data, none of them imposed as a generally valid solution. We propose a probabilistic pseudo-morphological approach, by estimating two pseudo-extrema based on Chebyshev inequality. The framework embeds a parameter which allows controlling the linear versus non-linear behavior of the probabilistic pseudo-morphological operators. We compare our approach for grayscale images with the classical morphology and we emphasize the impact of this parameter on the results. Then, we extend the approach to color images, using principal component analysis. As validation criteria, we use the estimation of the color fractal dimension, color textured image segmentation and color texture classification. Furthermore, we compare our proposed method against two widely used approaches, one morphological and one pseudo-morphological.     

一类非线性随机时滞系统的故障诊断

针对一类非线性随机时滞系统提出了一种新的故障检测算法,该方法不同于传统的故障检测方法,是通过构建一种带有Consensus滤波器的故障诊断滤波器的方法来进行故障诊断.首先采用一组传感器测量系统实际输出,然后根据传感器的测量值构建一组残差生成器,将每个残差生成器看作一个小世界网络模型中的一个节点,采用动态Consensus算法计算出残差生成器的残差,并根据残差来判断系统是否有故障发生.仿真结果表明了本文所提出方法的可行性和有效性.     

Content-aware optimization on rate-distortion and network traffic for scalable video multicast networks

This paper aims to optimize the content-aware prioritization of scalable video multicast, which is coupled with multipath streaming and network coding based routing. It constructs multiple layer distribution meshes for the scalable video stream to minimize the total video distortion at all the receivers, determines the base layer meshes with minimum costs to maintain application-layer QoS and the layer synchronization of SVC streaming, and improves the network throughput by encouraging path-overlapping transmissions and thus allowing bandwidth sharing among different receivers for the same video layer by utilizing network coding. The targeted problem is formulated into a minimization programming in which the quality variation between layers, the transmission cost of the base layer, as well as the efficient resource utilization are jointly considered. By decomposition and dual approach, the global convex problem is solved by a two-level decentralized iterative algorithm. The implementation of the distributed algorithm is discussed with regard to the communication overhead, and the convergence performance is validated by numerical experiments. Packet-level simulations demonstrate that the proposed algorithm could approximately achieve the maximum flow rates determined by Max-Flow Min-Cut Theorem and benefit the overall received video quality.     

Multidisciplinary design modeling and optimizationfor satellite with maneuver capability

According to the mission of a satellite with maneuver capability, the collaborative optimization (CO) method was introduced for the satellite system design, and the related multidisciplinary design optimization (MDO) model was established. The possessing and needed velocity increments Δv and Δv _{n e e d} were taken as the measurement of maneuvering capability of the studied satellite, which were then combined with total mass of the satellite to form the optimization objective in the systematic level of the MDO problem. The design variables and constraints of the MDO problem dealt with disciplines or subsystems as guidance, navigation and control (GNC), power, and structure, and corresponding engineering analysis models were also built. A program system to solve the MDO problem wasdeveloped by integrating a non-nested CO method, the commercial and user-supplied codes on framework software iSIGHT. The result showed that the satellite performance could be obviously improved, which also indicates MDO technique is feasible and effective for the spacecraft design problem. The modeling and optimization procedure of the work can be referred for further research and engineering design.     

Polyimide/montmorillonite nanocomposites based on thermally stable, rigid-rod aromatic amine modifiers

The preparation and processing of most of polymer/clay nanocomposites need high temperature. This limited the application of commonly used organic modifiers of long carbon-chain alkyl ammonium salts because of their low thermal stability. In this study, we synthesized two novel thermally stable, rigid-rod aromatic amines. Montmorillonite (MMT) treated by these amines exhibited larger layer-to-layer spacing, higher thermal stability than that treated by commonly used 1-hexadecylamine and also high ion-exchange ratio (>95%). They were applied to prepare nanocomposites with polyimide (PI) by in situ polymerization. XRD, TEM were used to obtain the information on morphological structure of PI/MMT nanocomposites. DMA, TGA, DSC, universal tester were applied to characterize the mechanical and thermal properties of the nanocomposites. When the MMT content was below 3 wt%, the PI/MMT nanocomposites were strengthened and toughened at the same time. The introduction of a small amount of MMT also led to improvement in thermal stability, slight increase in glass transition temperature, marked decrease in coefficient of thermal expansion and decrease in solvent uptake. MMT treated by these aromatic amines exhibited better dispersibility and (probably) interfacial interaction with PI matrix than that treated by 1-hexadecylamine. The nanocomposites based on these MMT resultantly exhibited better mechanical, thermal and solvent resistance properties than those based on 1-hexadecylamine treated MMT.     

一种车载自组织网络路况信息的数据信任模型

动态寻路是解决城市交通拥堵的重要手段。在动态寻路中,一些车辆产生和转发路况信息,使其他车辆能够避开拥堵路段。但一般车载自组织网络寻路算法缺乏验证路况信息的真实性的措施,导致恶意车辆能轻易篡改路况信息,误导其他车辆选择错误路线。提出了一种路况信息鉴别模型,该模型将基于数据的信任模型应用到路况信息真伪的鉴别中,并在一般投票算法的基础上利用D-S理论增加不确定情况下的鲁棒性。仿真实验表明,该算法在不增加额外信息交互的前提下,有效规避了恶意伪造信息,改进了车辆的行程时间。     

特定事件微博与新闻报道话题对比研究

该文描述了基于特定事件的新闻报道和微博在话题层面的对比研究。首先利用LDA话题模型抽取两种媒体上关于特定事件的话题,然后提出了话题关注度、差异度、演化度的定义和计算公式,改进了不同媒体话题差异度的计算方法,最后,选取四个不同种类的事件,进行实验对比与分析,结果显示,关于同一事件,1)微博上评论性话题较多,话题关注度值比较接近;新闻报道上事实性话题较多,话题关注度值差异较大;2)微博与新闻报道对评论性话题词汇差异度大,事实性话题词汇差异度小;3)微博上评论性话题持续时间较长,内容变化较少;新闻报道上事实性话题持续时间较长,内容变化较少。     

Preparation and characterization of a series of polyamides with long alkylene segments: Nylons 12 20, 10 20,s 20,6 20, 4 20 and 2 20

Summary A series of nylons with long alkylene segments between amide groups were newly prepared by step-heating melt-polycondensation of 1,lS-octadecanedicarboxylic acid with various diamines. The prepared polyamides were characterized carefully. The results show that many properties of the prepared nylons change regularly with the length of methylene segments in diamines. In addition, nylon 2 20 has a relatively low molecular weight and much different melting and thermal decomposition behaviors in comparison with other nylons. Received: 21 June 2OO2/Revised version: 18 September 2002/ Accepted: 18 September 2002 Correspondence to Deyue Yan E-mail: dyyan@mail.sjtu.edu.cn Tel: 0086-21-54742863 Fax: 0086-21-54741297