An efficient and security dynamic identity based authentication protocol for multi-server architecture using smart cards

Generally, if a user wants to use numerous different network services, he/she must register himself/herself to every service providing server. It is extremely hard for users to remember these different identities and passwords. In order to resolve this problem, various multi-server authentication protocols have been proposed. Recently, Sood et al. analyzed Hsiang and Shih's multi-server authentication protocol and proposed an improved dynamic identity based authentication protocol for multi-server architecture. They claimed that their protocol provides user's anonymity, mutual authentication, the session key agreement and can resist several kinds of attacks. However, through careful analysis, we find that Sood et al.'s protocol is still vulnerable to leak-of-verifier attack, stolen smart card attack and impersonation attack. Besides, since there is no way for the control server CS to know the real identity of the user, the authentication and session key agreement phase of Sood et al.'s protocol is incorrect. We propose an efficient and security dynamic identity based authentication protocol for multi-server architecture that removes the aforementioned weaknesses. The proposed protocol is extremely suitable for use in distributed multi-server architecture since it provides user's anonymity, mutual authentication, efficient, and security.     

A power-saving data storage scheme for wireless sensor networks

In wireless sensor network (WSN), sensors are small, inexpensive, and computable. However, they are limited in power, memory, and computational capacities. A large number of tiny sensors are usually deployed randomly to monitor one or more phenomena to collect and process the sensed data, and to send the data back to the sink. Many literatures focus on developing power-saving protocols. In addition, many papers present data storage schemes but they do not take power saving into consideration. Hence, these data storage schemes cannot perform well based on power-saving protocols. Therefore, it is very critical to propose a data storage scheme to support power-saving mechanism. In this paper, we propose a power-saving data storage scheme for WSN. Our scheme adopts grid-based architecture, in which each grid guarantees that two sensors will stay in active mode while the others stay in sleep mode to save energy. Simulation results show that our power-saving data storage scheme can reduce energy consumption.     

飞行仿真系统数据可视化设计与实现

研究飞行仿真系统结果数据可视化,为验证分析飞行仿真系统结果的正确性,需要对仿真系统输出的飞行性能数据进行实时在线观测并与标准数据进行对比分析。针对飞行仿真系统对飞机飞行数据实时观测的需求,设计了一种可实时观测的飞行仿真数据可视化方案。在建立仿真系统模型的基础上,为了提高系统的可靠性和优化数据结构,提出了新的数据结构和曲线生成算法绘制实时曲线,实现了数据的可视化观测,避免了实时绘制过程屏幕的闪烁和曲线出现的锯齿。并结合飞行仿真特点,利用MapX组件技术加载了具有导航台的全国地图,对传统的电子地图显示进行了改进,实现了飞机在地图上的实时航迹观测。仿真结果表明,系统能够实时观测仿真结果并分析系统误差,实现飞行仿真数据的可视化,并可验证飞行仿真系统的正确性。     

Structure–conductivity relationships in chemical polypyrroles of low,medium and high conductivity

Chemically synthesized polypyrroles of low (σ < 75 S/cm), medium (75 < σ < 200 S/cm) and high (σ > 200 S/cm) electrical conductivity (σ) with the same dopant and degree of doping have been investigated by means of Wide Angle X-ray Scattering (WAXS), ¹³C Cross Polarized Magic Angle Spinning Nuclear Magnetic Resonance (¹³C CP/MAS NMR) spectroscopy and Fourier Transform Infrared (FTIR) Spectroscopy to establish structure–conductivity relationships useful for industrial applications. A similar amorphous structure was found by WAXS even for the higher conducting PPy (σ = 288 S/cm). WAXS spectra for polypyrroles of medium and high conductivity showed a weak peak at 2θ = 10–11° due to improved order of the counterions in these materials. The effect of the counterion size in the asymmetry of the PPy main WAXS peak was elucidated by performing ion exchange of the Cl⁻ dopant with counterions of larger size such as BF₄⁻ and ClO₄⁻. From ¹³C CP/MAS NMR measurements predominantly α–α′ bonding was found in these materials. The main ¹³C CP/MAS NMR resonance peak of PPy located at 126–128 ppm was broadened upon increasing conductivity. Interestingly, a linear relationship was observed between the half-width at half-height (HWHH) of the ¹³C CP/MAS NMR peak and conductivity where a doubling of the polypyrrole conductivity leads to an increase of HWHH by 6–7 ppm. FTIR data of these materials were analysed in the framework of the Baughman–Shacklette theory describing the dependence of conductivity on conjugation length. By comparison of model predictions and experimental results, the PPy samples were found to be in the regime of long conjugation lengths, L ≫ K₂/k_BT, where K₂ is a parameter related to the energy change on going from j − 1 to j charges on a conjugated segment of conjugation length L, k_B the Boltzman constant and T is the absolute temperature.     

Static output feedback control via PDE boundary and ODE measurements in linear cascaded ODE–beam systems

This paper addresses the problem of feedback control design for a class of linear cascaded ordinary differential equation (ODE)–partial differential equation (PDE) systems via a boundary interconnection, where the ODE system is linear time-invariant and the PDE system is described by an Euler–Bernoulli beam (EBB) equation with variable coefficients. The objective of this paper is to design a static output feedback (SOF) controller via EBB boundary and ODE measurements such that the resulting closed-loop cascaded system is exponentially stable. The Lyapunov’s direct method is employed to derive the stabilization condition for the cascaded ODE–beam system, which is provided in terms of a set of bilinear matrix inequalities (BMIs). Furthermore, in order to compute the gain matrices of SOF controllers, a two-step procedure is presented to solve the BMI feasibility problem via the existing linear matrix inequality (LMI) optimization techniques. Finally, the numerical simulation is given to illustrate the effectiveness of the proposed design method.     

超磁致伸缩作动器的率相关Hammerstein模型与H∞鲁棒跟踪控制

利用Hammerstein模型对超磁致伸缩作动器（Giant magnetostrictive actuators,GMA）的率相关迟滞非线性进行建模,分别以改进的 Prandtl-Ishlinskii（Modified Prandtl-Ishlinskii）模型和外因输入自回归模型（Autoregressive model with exogenous input,ARX）代表Hammerstein模型中的静态非线性部分和线性动态部分,并给出了模型的辨识方法. 此模型能在1～100Hz频率范围内较好地描述GMA的率相关迟滞非线性. 提出了带有逆补偿器和H∞鲁棒控制器的二自由度跟踪控制策略,实时跟踪控制实验结果证明了所提策略的有效性.     

A measure of information gained through biometric systems

We propose a measure of information gained through biometric matching systems. Firstly, we discuss how the information about the identity of a person is derived from biometric samples through a biometric system, and define the “biometric system entropy” or BSE based on mutual information. We present several theoretical properties and interpretations of the BSE, and show how to design a biometric system which maximizes the BSE. Then we prove that the BSE can be approximated asymptotically by the relative entropy D(f_G(x)∥f_I(x)) where f_G(x) and f_I(x) are probability mass functions of matching scores between samples from individuals and among population. We also discuss how to evaluate the BSE of a biometric system and show experimental evaluation of the BSE of face, fingerprint and multimodal biometric systems.     

On the design of an ECOC-Compliant Genetic Algorithm

Genetic Algorithms (GA) have been previously applied to Error-Correcting Output Codes (ECOC) in state-of-the-art works in order to find a suitable coding matrix. Nevertheless, none of the presented techniques directly take into account the properties of the ECOC matrix. As a result the considered search space is unnecessarily large. In this paper, a novel Genetic strategy to optimize the ECOC coding step is presented. This novel strategy redefines the usual crossover and mutation operators in order to take into account the theoretical properties of the ECOC framework. Thus, it reduces the search space and lets the algorithm to converge faster. In addition, a novel operator that is able to enlarge the code in a smart way is introduced. The novel methodology is tested on several UCI datasets and four challenging computer vision problems. Furthermore, the analysis of the results done in terms of performance, code length and number of Support Vectors shows that the optimization process is able to find very efficient codes, in terms of the trade-off between classification performance and the number of classifiers. Finally, classification performance per dichotomizer results shows that the novel proposal is able to obtain similar or even better results while defining a more compact number of dichotomies and SVs compared to state-of-the-art approaches.