Synchronization of complex dynamical networks under recoverable attacks

In this paper, the synchronization of complex dynamical networks (CDNs) under ‘successful’ but recoverable attacks is studied by utilizing the framework of switching systems. ‘Successful’ attacks refer to a class of attacks that break a network into a group of isolated clusters. Recoverable attacks refer to a class of attacks that the network can recover from after a period of time. To facilitate the investigation of the synchronization of a CDN under ‘successful’ but recoverable attacks, the attack frequency and the average recovering time are introduced. By using a piecewise Lyapunov function, the upper bounds of the attack frequency and the average recovering time are obtained to ensure that the whole network can achieve global synchronization under attacks.     

嵌入式系统芯片的软硬件协同仿真环境设计

针对嵌入式系统芯片SoC开发验证阶段的需求,介绍了一种通用的SoC软硬件协同仿真平台。软件仿真由C／C＋＋和汇编语言编写,硬件仿真基于VMM验证方法学所搭建,SoC设计代码由RTL代码编写而成。将SoC设计代码中的ARM由DSM模型替代,通过VCS编译器将软硬件协同起来进行信息交互,实现一种速度快、真实性高、调试方便的...     

Optimized element positions for prescribed radar cross section pattern of linear dipole arrays

Approximate closed‐form expression is derived for the scattering from dipole arrays based on the equivalent circuit theory. Then, a method is proposed for synthesis of dipole arrays to produce desired scattering pattern using genetic algorithm (GA). In the synthesis method, the element positions in an array are considered as the optimization parameter and the derived expression is used to evaluate the fitness function of GA. To assess the validity and efficiency of the proposed method, several linear dipole arrays are designed to obtain scattering pattern with low sidelobe level (SLL). A good agreement between the patterns calculated using the expression and simulated by FEKO validates the accuracy of the presented expression. In addition, the numerical results show that the maximum SLL of the scattering pattern is considerably reduced by optimization. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.     

Algorithms for computing the optimal transitive approximation of a proximity relation

Three ways for generating the optimal transitive approximations or a suboptimal transitive approximation are given in this paper. The first one can obtain all the optimal transitive approximations for any proximity relation. However, trying to find all the optimal transitive approximations can be very expensive. The second one gives a method to obtain a suboptimal transitive approximation which can frequently generate an optimal transitive approximation. Furthermore, starting from the transitive closure the third method is proposed which can obtain a locally optimal transitive approximation. Finally, numerical experiments are carried out to show the abilities of these algorithms and compare them to other existing approximation algorithms.     

基于FPGA的同步时钟报文检测电路的设计

时钟同步技术是解决基于网络的分布式测控系统完成同步测控任务的关键技术,IEEE-1588协议是一种应用于分布式测量和控制系统中的精准时钟同步协议.提出了一种基于IEEE-1588协议在以太网物理层和MAC层之间的介质无关接口(MII/RMII)处检测同步报文的策略和实现精确时间标记方案[1],在此硬件支持方案和方法的基础之上,充分利用FPGA宏模块资源采用较为简便实用的方法设计实现了同步报文检测电路,该部分电路的设计是采用硬件时间标记方案实现IEEE1588高精度时钟同步的基础.在QuartsII 7.2平台下对设计电路进行优化综合和时序仿真,通过在线实时检测验证了电路设计的正确性.初步验证结果表明设计达到课题要求,应用性能良好.     

基于模式映射的GML文档存储

随着地理信息系统GIS(Geography Markup Language)的广泛应用,GML己经成为事实上的空间数据编码、传输、共享和发布的一种国际标准。近年来,大量GML数据以文档形式出现,对如何高效地存储和管理GML数据提出了新的挑战。根据GML文档的特点,提出了一种基于模式映射的存储方法。首先,根据映射规则将GML模式生成对象-关系数据库模式;其次,解析GML文档并根据映射信息构造相应的SQL语句,将数据存储于数据库。实验表明,提出的存储方法是可行、高效的。     

Pricing and inventory management in a system with multiple competing retailers under (r, Q) policies

We consider a multi-retailer system operated on an infinite horizon, in which each retailer faces stochastic demand following a Poisson process and adopts a continuous-review (r, Q) policy for replenishing inventory to satisfy customer demand. The system involves decisions of pricing and inventory management with the goal of maximizing profit, which equals the sales revenue minus the purchase and inventory costs. Taking Cournot competition into account, models are formulated to optimize simultaneously the expected sales volumes and (r, Q) policies of all retailers. An efficient approach is proposed to calculate the approximate inventory cost. Based on this approach, solution methods for centralized and decentralized scenarios are developed. A great number of numerical computations are provided to evaluate the efficiency of the solution methods, and their performance in the two scenarios. Moreover, system performance under sequential decisions (first pricing and then inventory management) is also investigated.     

Identifying mislabeled training data with the aid of unlabeled data

This paper presents a new approach for identifying and eliminating mislabeled training instances for supervised learning algorithms. The novelty of this approach lies in the using of unlabeled instances to aid the detection of mislabeled training instances. This is in contrast with existing methods which rely upon only the labeled training instances. Our approach is straightforward and can be applied to many existing noise detection methods with only marginal modifications on them as required. To assess the benefit of our approach, we choose two popular noise detection methods: majority filtering (MF) and consensus filtering (CF). MFAUD/CFAUD is the new proposed variant of MF/CF which relies on our approach and denotes majority/consensus filtering with the aid of unlabeled data. Empirical study validates the superiority of our approach and shows that MFAUD and CFAUD can significantly improve the performances of MF and CF under different noise ratios and labeled ratios. In addition, the improvement is more remarkable when the noise ratio is greater.     

Advancements in technology and design of NEMS vector hydrophone

This paper reports on recent developments to improve the performance of hair vector hydrophone by means of several technological advancements in the fabrication procedures and corresponding sensor design. With fish’s lateral line organs as prototypes, NEMS (Nano-Electromechanical System) vector hydrophone with directivity has been designed. This paper describes the meso-piezoresistance effect of resonant tunneling thin-film, and the NEMS hydrophone based on this effect is highly sensitive and small size. The application of bionics structure may improve the low-frequency sensitivity of hydrophone. The calibration test shows that NEMS vector hydrophone’s receiving sensitivity is up to −170 dB (0dB = 1 V/μPa), has a good directional pattern in the form of “8” shape. The sea test shows that the direction of target can be detected by single NEMS vector hydrophone. In the anechoic tank, it has been verified that NEMS vector hydrophone can track the trajectory of the moving target.