An efficient image encryption algorithm based on a novel chaotic map

Multimedia Tools and Applications - In this paper, we propose a novel low dimensional chaotic map, namely, compounded piecewise linear map (CPLM) in order to balance between security and...     

Image compression-encryption scheme combining 2D compressive sensing with discrete fractional random transform

Multimedia Tools and Applications - Most of the existing image encryption algorithms based on compressive sensing are too complex to operate. An image compression-encryption scheme with simple...     

HD-GDD: high dimensional graph dominance drawing approach for reachability query

Efficiently answering reachability queries, which checks whether one vertex can reach another in a directed graph, has been studied extensively during recent years. However, the size of the graph that people are facing and generating nowadays is growing so rapidly that simple algorithms, such as BFS and DFS, are no longer feasible. Although Refined Online Search algorithms can scale to large graphs, they all suffer from the false positive problem. In this paper, we analyze the cause of false positive and propose an efficient High Dimensional coordinate generating method based on Graph Dominance Drawing (HD-GDD) to answer reachability queries in linear or even constant time. We conduct experiments on different graph structures and different graph sizes to fully evaluate the performance and behavior of our proposal. Empirical results demonstrate that our method outperforms state-of-the-art algorithms and can handle extensive graphs.     

Discriminant error correcting output codes based on spectral clustering

Error correcting output codes (ECOCs) is a powerful framework to solve the multi-class problems. Finding the optimal partitions with maximum class discrimination efficiently is a key point to improve its performance. In this paper, we propose an alternative and efficient approach to obtain the partitions which are discriminative in the class space. The main idea of the proposed method is to transform the partition in the class space into the cut for an undirected graph using spectral clustering. In addition to measuring the class similarity, the confusion matrix with a pre-classifier is used. Our method is compared with the classical ECOC and DECOC over a synthetic dataset, a set of UCI machine learning repository datasets and one face recognition application. The results show that our proposal is able to obtain comparable or even better classification accuracy while reducing the computational complexity in comparison with the state-of-the-art coding methods.     

On Convergence of Volterra Series Expansion of a Class of Nonlinear Systems

A fundamental issue in conducting the analysis and design of a nonlinear system via Volterra series theory is how to ensure the excitation magnitude and/or model parameters will be in the appropriate range such that the nonlinear system has a convergent Volterra series expansion. To this aim, parametric convergence bounds of Volterra series expansion of nonlinear systems described by a NARX model, which can reveal under what excitation magnitude or within what parameter range a given NARX system is able to have a convergent Volterra series expansion subject to any given input signal, are investigated systematically in this paper. The existing bound results often are given as a function of the maximum input magnitude, which could be suitable for single‐tone harmonic inputs but very conservative for complicated inputs (e.g. multi‐tone or arbitrary inputs). In this study, the output response of nonlinear systems is expressed in a closed form, which is not only determined by the input magnitude but also related to the input energy or waveform. These new techniques result in more accurate bound criteria, which are not only functions of model parameters and the maximum input magnitude but also consider a factor reflecting the overall input energy or wave form. This is significant to practical applications, since the same nonlinear system could exhibit chaotic behavior subject to a simple single‐tone input but might not with respect to other different input signals (e.g. multi‐tone inputs) of the same input magnitude. The results provide useful guidance for the application of Volterra series‐based theory and methods from an engineering point of view. The Duffing equation is used as a benchmark example to show the effectiveness of the results.     

Mean square detectability of LTI systems over finite-state digital block-fading channels

This paper studies the mean square quadratic (MSQ) detectability for multi-output networked systems over finite-state digital block-fading channels. The packet-loss rate of each digital fading channel depends on the channel power gain, as well as packet length and power level used for transmission. A finite-state random process is introduced to model time-varying fading channels, which characterizes various configurations of physical communication environment and/or different channel fading amplitudes. Necessary and sufficient conditions for MSQ detectability over finite-state Markov digital block-fading channels are given in the form of algebraic Riccati equations or linear matrix inequalities (LMIs). The estimation gain is given as a function of estimated/observed channel state. In addition, explicit conditions on network for MSQ detectability over finite-state independent identically distributed (i.i.d.) digital block-fading channels are presented in terms of the unstable poles of the multi-output plant. Finally, an application to Gilbert-Elliott channels (GECs) is provided to demonstrate the derived results.     

基于SVM的粉末冶金零件的多类分类器的研究

传统的SVM特别适合解决两类分类问题,而对于多类分类,则需将其转化为多个两类分类问题,相应地需要构造多个两类子分类器,这样不但使得分类器结构复杂,而且分类速度受到很大的影响。为了快速地进行多类分类,本文使用LIBSVM中的svmtrain实现对训练数据集的训练,从而获取SVM多分类模型,利用获取的模型进行测试与预测,不仅使得子分类器数目大大减少,而且使分类速度明显提高。最后从粉末冶金零件图库中选取的8张图像进行了分类实验,取得较好的分类结果。     

基于收益率门槛限制考虑的网格资源拍卖问题

基于收益率门槛限制的视角,通过建立效用函数模型并结合动态博弈理论,对网格资源的拍卖问题进行了探讨.在对网格资源提供者与竞标网格资源使用者的动态博弈过程进行分析时发现,网格资源提供者的最优策略选择决定于其对货币收益与非货币收益的偏好程度,以及网格资源使用者的最高报价.在收益率门槛给定的条件下,当参与竞标的网格资源使用者具有较低的生产利润或付出较高的努力成本时,网格资源使用者将会选择价格较低的投标策略.研究结果表明收益率门槛机制的引入,在一定程度上可以使得参与双方的效用达到最大化.     

Comparison between Two Spectral Mixture Analysis Methods based on IDL and MATLAB

Interactive Data Language (IDL) is a language in the development of application based on multiplatform and object\|oriented,which has significant advantages in data analysis and visualization.The MATLAB is a software with powerful features in the image of processing and programming in complex numerical analysis,which based on matrix calculation.Programming in combining the IDL with MATLAB,meanwhile using the Extended Linear Mixed Model for endmember unmixing in Hyperion images.To verify the results of endmember unmixing,adopted the Fully Constrained Least Squares for comparative analysis.The results showed that：The method of programming in combining the IDL with MATLAB not noly possess the advantages of both but also enhance the efficiency in programming,it is conducive to remote sensing image processing.Meanwhile endmember unmixing results show that：the Extended Linear Mixing Model unmixing has a higher accuracy when the proportion of local category in the image is large.On the contrary,the Fully Constrained Least Squares unmixing has a higher accuracy.     

The Ground Process Segment of SAR Altimeter

The key innovation technology of SAR Altimeter (Synthetic Aperture Radar Altimeter)are Doppler\|beam sharpen and delay/Doppler range compensation.The cooperation of these two technologies makes it has high along track resolution and high precision in height measurement.The ground processor is the key hinge to make sure that SAR altimeter could obtain these superiorities.Many key technologies for SAR altimeter processor,such as Doppler beam\|sharpen,delay/Doppler compensation and the second range correction,multilook,echo model and gradient function for retracker,are introduced in the paper.Based on the processor and related work,some simulation work and airborne experiment were tested by the processor,and both of the quantity results show that the SAR altimeter has more potential superiorities.