Mathematical Problems in Engineering The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. Robust Control for Singular Time-Delay Systems via Parameterized Lyapunov Functional Approach Thu, 27 Nov 2014 08:41:39 +0000 A new version of delay-dependent bounded real lemma for singular systems with state delay is established by parameterized Lyapunov-Krasovskii functional approach. In order to avoid generating nonconvex problem formulations in control design, a strategy that introduces slack matrices and decouples the system matrices from the Lyapunov-Krasovskii parameter matrices is used. Examples are provided to demonstrate that the results in this paper are less conservative than the existing corresponding ones in the literature. Li-li Liu, Bao-wei Wu, and Yue-E Wang Copyright © 2014 Li-li Liu et al. All rights reserved. Improved Confidence Interval Estimation for Oscillometric Blood Pressure Measurement by Combining Bootstrap-After-Jackknife Function with Non-Gaussian Models Thu, 27 Nov 2014 08:22:13 +0000 Confidence intervals (CIs) are generally not provided along with estimated systolic blood pressure (SBP) and diastolic blood pressure (DBP) measured using oscillometric blood pressure devices. No criteria exist to determine the CI from a small sample set of oscillometric blood pressure measurements. We provide an extended methodology to improve estimation of CIs of SBP and DBP based on a nonparametric bootstrap-after-jackknife function and a Bayesian approach. We use the nonparametric bootstrap-after-jackknife function to reduce maximum amplitude outliers. Improved pseudomaximum amplitudes (PMAs) and pseudoenvelopes (PEs) are derived from the pseudomeasurements. Moreover, the proposed algorithm uses an unfixed ratio obtained by employing non-Gaussian models based on the Bayesian technique to estimate the SBP and DBP ratios for individual subjects. The CIs obtained through our proposed approach are narrower than those obtained using the traditional Student -distribution method. The mean difference (MD) and standard deviation (SD) of the SBP and DBP estimates using our proposed approach are better than the estimates obtained by conventional fixed ratios based on the PMA and PE (PMAE). Soojeong Lee Copyright © 2014 Soojeong Lee. All rights reserved. Nurse Scheduling Using Genetic Algorithm Thu, 27 Nov 2014 00:10:13 +0000 This study applied engineering techniques to develop a nurse scheduling model that, while maintaining the highest level of service, simultaneously minimized hospital-staffing costs and equitably distributed overtime pay. In the mathematical model, the objective function was the sum of the overtime payment to all nurses and the standard deviation of the total overtime payment that each nurse received. Input data distributions were analyzed in order to formulate a simulation model to determine the optimal demand for nurses that met the hospital’s service standards. To obtain the optimal nurse schedule with the number of nurses acquired from the simulation model, we proposed a genetic algorithm (GA) with two-point crossover and random mutation. After running the algorithm, we compared the expenses and number of nurses between the existing and our proposed nurse schedules. For January 2013, the nurse schedule obtained by GA could save 12% in staffing expenses per month and 13% in number of nurses when compare with the existing schedule, while more equitably distributing overtime pay between all nurses. Komgrit Leksakul and Sukrit Phetsawat Copyright © 2014 Komgrit Leksakul and Sukrit Phetsawat. All rights reserved. Study on Adaptive Slid Mode Controller for Improving Handling Stability of Motorized Electric Vehicles Wed, 26 Nov 2014 12:18:20 +0000 An adaptive slid mode controller was established for improving the handling stability of motorized electric vehicle (MEV). First and foremost, the structure and advantages of electric vehicle driven by in-wheel motors will be provided. Then, an ideal cornering model of vehicles will be brought and analyzed, after which a method to estimate side-slip angle was also proposed and three typical sensors were used in the theory. Besides, an idea for the recognition of road adhesion coefficient was derived based on MEV platform, which will be helpful for better control performances. Finally, the scheme of control method was given and some typical tests for observing handling properties were implemented based on Simulink and Carsim software. With the outcomes from the experiments, which vividly showed the merits of the controller, one can come to a conclusion that MEV that equips with the adaptive slid mode controller always enjoys better handling performances than the one without control. Furthermore, the controller researched is friendly to the real-time working conditions, which will hold practical values in the future. LiQiang Jin and Yue Liu Copyright © 2014 LiQiang Jin and Yue Liu. All rights reserved. Multidistribution Center Location Based on Real-Parameter Quantum Evolutionary Clustering Algorithm Wed, 26 Nov 2014 09:44:43 +0000 To determine the multidistribution center location and the distribution scope of the distribution center with high efficiency, the real-parameter quantum-inspired evolutionary clustering algorithm (RQECA) is proposed. RQECA is applied to choose multidistribution center location on the basis of the conventional fuzzy C-means clustering algorithm (FCM). The combination of the real-parameter quantum-inspired evolutionary algorithm (RQIEA) and FCM can overcome the local search defect of FCM and make the optimization result independent of the choice of initial values. The comparison of FCM, clustering based on simulated annealing genetic algorithm (CSAGA), and RQECA indicates that RQECA has the same good convergence as CSAGA, but the search efficiency of RQECA is better than that of CSAGA. Therefore, RQECA is more efficient to solve the multidistribution center location problem. Huaixiao Wang, Wanhong Zhu, Jianyong Liu, Ling Li, and Zhuchen Yin Copyright © 2014 Huaixiao Wang et al. All rights reserved. Fuzzy Based PC-PUSH in CR-MANETs Wed, 26 Nov 2014 00:10:16 +0000 In cognitive radio (CR), the secondary user (SU) needs to hand off its ongoing communication to an idle channel in order to avoid interference to the primary user (PU). Spectrum hand off issue becomes challenging in CR mobile ad hoc networks (CR-MANETs) because of the uncertainty in spectrum availability, broad range of spectrum bands and lack of central entity. The purpose of this study is to design a unified spectrum handoff (USH) scheme for CR-MANETs that considers the spectrum heterogeneity and its availability over time and space. A local flow hand off is performed when spectrum hand off cannot be carried out due to the SUs mobility. To improve further USH, preemptive unified spectrum handoff (PUSH) algorithm is proposed in which two different preemptive hand off threshold regions are defined. The PUSH algorithm also predicts the cognitive link availability considering the PU interference boundary. Although the PUSH scheme improves the hand off performance, the number of spectrum hand offs due to the PU activity should be reduced in this scheme. Therefore, the PC-PUSH (Power Controller-PUSH) scheme is proposed in which the fuzzy logic is used to improve the PUSH in terms of the number of spectrum handoffs because of the PU activity. The PC-PUSH decreases the interference to the PUs, while reducing the number of spectrum handoffs. The results show that the proposed scheme improves the link maintenance probability, decreases the hand off delay, and reduces the number of spectrum handoffs. S. Nejatian, S. K. Syed Yusof, N. M. Abdul Lattif, V. Rezaie, and V. Asadpour Copyright © 2014 S. Nejatian et al. All rights reserved. An Adaptive Nonlinear Control for Gyro Stabilized Platform Based on Neural Networks and Disturbance Observer Tue, 25 Nov 2014 12:54:02 +0000 In order to improve the tracking performance of gyro stabilized platform with disturbances and uncertainties, an adaptive nonlinear control based on neural networks and reduced-order disturbance observer for disturbance compensation is developed. First the reduced-order disturbance observer estimates the disturbance directly. The error of the estimated disturbance caused by parameter variation and measurement noise is then approximated by neural networks. The phase compensation is also introduced to the proposed control law for the desired sinusoidal tracking. The stability of the proposed scheme is analyzed by the Lyapunov criterion. Experimental results show the validity of the proposed control approach. Jiancheng Fang and Rui Yin Copyright © 2014 Jiancheng Fang and Rui Yin. All rights reserved. The Schur Multiplier of Pairs of Groups of Order Tue, 25 Nov 2014 12:29:08 +0000 Let be a pair of groups where is a group and is a normal subgroup of . Then the Schur multiplier of pairs of groups is a functorial abelian group . In this paper, for groups of order where and are prime numbers are determined. S. Rashid, A. A. Nawi, N. M. Mohd Ali, and N. H. Sarmin Copyright © 2014 S. Rashid et al. All rights reserved. Upper-Lower Bounds Candidate Sets Searching Algorithm for Bayesian Network Structure Learning Tue, 25 Nov 2014 12:28:31 +0000 Bayesian network is an important theoretical model in artificial intelligence field and also a powerful tool for processing uncertainty issues. Considering the slow convergence speed of current Bayesian network structure learning algorithms, a fast hybrid learning method is proposed in this paper. We start with further analysis of information provided by low-order conditional independence testing, and then two methods are given for constructing graph model of network, which is theoretically proved to be upper and lower bounds of the structure space of target network, so that candidate sets are given as a result; after that a search and scoring algorithm is operated based on the candidate sets to find the final structure of the network. Simulation results show that the algorithm proposed in this paper is more efficient than similar algorithms with the same learning precision. Guangyi Liu, Ou Li, Dalong Zhang, and Tao Song Copyright © 2014 Guangyi Liu et al. All rights reserved. Fluid Dynamics and Computational Engineering Tue, 25 Nov 2014 11:39:16 +0000 Benchawan Wiwatanapataphee, Yonghong Wu, I. Ming Tang, and Shaoyong Lai Copyright © 2014 Benchawan Wiwatanapataphee et al. All rights reserved. A Novel Guidance Law with Line-of-Sight Acceleration Feedback for Missiles against Maneuvering Targets Tue, 25 Nov 2014 11:15:31 +0000 Terminal guidance law design and its implementation are considered for homing missiles against maneuvering targets. The lateral acceleration dynamics are taken into account in the design. In the guidance law design, the line-of-sight acceleration signals are incorporated into the acceleration reference signals to compensate for the targets’ maneuvers. Then the commanded accelerations are designed and the convergent tracking of the lateral accelerations to these signals is proven theoretically. In the guidance implementation, a linear high-gain differentiator is used to estimate the line-of-sight rates and the line-of-sight acceleration signals. To avoid the magnifying effects of higher order differentiation, a practical design of commanded accelerations is given to realize approximate tracking of the lateral accelerations to the given reference signals. Simulation is conducted for both cases with and without measurement noises. The simulation results justify the feasibility of the design and the implementation. Kemao Ma and Xiaoyu Zhang Copyright © 2014 Kemao Ma and Xiaoyu Zhang. All rights reserved. Non-Gaussian Stochastic Equivalent Linearization Method for Inelastic Nonlinear Systems with Softening Behaviour, under Seismic Ground Motions Tue, 25 Nov 2014 11:13:33 +0000 A non-Gaussian stochastic equivalent linearization (NSEL) method for estimating the non-Gaussian response of inelastic non-linear structural systems subjected to seismic ground motions represented as nonstationary random processes is presented. Based on a model that represents the time evolution of the joint probability density function (PDF) of the structural response, mathematical expressions of equivalent linearization coefficients are derived. The displacement and velocity are assumed jointly Gaussian and the marginal PDF of the hysteretic component of the displacement is modeled by a mixed PDF which is Gaussian when the structural behavior is linear and turns into a bimodal PDF when the structural behavior is hysteretic. The proposed NSEL method is applied to calculate the response of hysteretic single-degree-of-freedom systems with different vibration periods and different design displacement ductility values. The results corresponding to the proposed method are compared with those calculated by means of Monte Carlo simulation, as well as by a Gaussian equivalent linearization method. It is verified that the NSEL approach proposed herein leads to maximum structural response standard deviations similar to those obtained with Monte Carlo technique. In addition, a brief discussion about the extension of the method to muti-degree-of-freedom systems is presented. Francisco L. Silva-González, Sonia E. Ruiz, and Alejandro Rodríguez-Castellanos Copyright © 2014 Francisco L. Silva-González et al. All rights reserved. Stereo-Vision-Based Relative Pose Estimation for the Rendezvous and Docking of Noncooperative Satellites Tue, 25 Nov 2014 08:01:38 +0000 Autonomous on-orbit servicing is expected to play an important role in future space activities. Acquiring the relative pose information and inertial parameters of target is one of the key technologies for autonomous capturing. In this paper, an estimation method of relative pose based on stereo vision is presented for the final phase of the rendezvous and docking of noncooperative satellites. The proposed estimation method utilizes the sparse stereo vision algorithm instead of the dense stereo algorithm. The method consists of three parts: (1) body frame reestablishment, which establishes the body-fixed frame for the target satellite using the natural features on the surface and measures the relative attitude based on TRIAD and QUEST; (2) translational parameter estimation, which designs a standard Kalman filter to estimate the translational states and the location of mass center; (3) rotational parameter estimation, which designs an extended Kalman filter and an unscented Kalman filter, respectively, to estimate the rotational states and all the moment-of-inertia ratios. Compared to the dense stereo algorithm, the proposed method can avoid degeneracy when the target has a high degree of axial symmetry and reduce the number of sensors. The validity of the proposed method is verified by numerical simulations. Feng Yu, Zhen He, Bing Qiao, and Xiaoting Yu Copyright © 2014 Feng Yu et al. All rights reserved. Modeling and Performance Analysis for Cell Access and Handoff Schemes in Two-Tier Cellular Networks Mon, 24 Nov 2014 12:37:46 +0000 We investigate the effects of handoff on system performance in two-tier cellular networks. Two of the main performance metrics are new call blocking probability and handoff drop rate. We develop analytical models to evaluate the performance of two different handoff schemes. One scheme considers only femto-to-macrocell handoff while the other is bidirectional including macro-to-femtocell handoff. Our model is more elaborate than existing ones which have not considered the mobility of mobile stations. Numerical results show that the bidirectional scheme performs better than the femto-to-macrocell handoff as it achieves lower blocking probability and drop rate. Kyungkoo Jun and Sijung Kim Copyright © 2014 Kyungkoo Jun and Sijung Kim. All rights reserved. A High-Precision Registration Technology Based on Bundle Adjustment in Structured Light Scanning System Mon, 24 Nov 2014 09:44:41 +0000 The multiview 3D data registration precision will decrease with the increasing number of registrations when measuring a large scale object using structured light scanning. In this paper, we propose a high-precision registration method based on multiple view geometry theory in order to solve this problem. First, a multiview network is constructed during the scanning process. The bundle adjustment method from digital close range photogrammetry is used to optimize the multiview network to obtain high-precision global control points. After that, the 3D data under each local coordinate of each scan are registered with the global control points. The method overcomes the error accumulation in the traditional registration process and reduces the time consumption of the following 3D data global optimization. The multiview 3D scan registration precision and efficiency are increased. Experiments verify the effectiveness of the proposed algorithm. Jianying Yuan, Qiong Wang, Xiaoliang Jiang, and Bailin Li Copyright © 2014 Jianying Yuan et al. All rights reserved. Static Eccentricity Fault Recognition in Three-Phase Line Start Permanent Magnet Synchronous Motor Using Finite Element Method Mon, 24 Nov 2014 09:38:04 +0000 This paper is dedicated to investigating static eccentricity in a three-phase LSPMSM. The modeling of LSPMSM with static eccentricity between stator and rotor is developed using finite element method (FEM). The analytical expression for the permeance and flux components of nonuniform air-gap due to static eccentricity fault is discussed. Various indexes for static eccentricity detection using stator current signal of IM and permanent magnet synchronous motor (PMSM) are presented. Since LSPMSM is composed of a rotor which is a combination of these two motors, the ability of these features is evaluated for static eccentricity diagnosis in LSPMSM. The simulated stator current signal of LSPMSM in the presence of static eccentricity is analyzed in frequency domain using power spectral density (PSD). It is demonstrated that static eccentricity fault generates a series of low frequency harmonic components in the form of sidebands around the fundamental frequency. Moreover, the amplitudes of these components increase in proportion to the fault severity. According to the mentioned observations, an accurate frequency pattern is specified for static eccentricity detection in three-phase LSPMSM. Mahdi Karami, Norman Mariun, Mohammad Rezazadeh Mehrjou, Mohd Zainal Abidin Ab Kadir, Norhisam Misron, and Mohd Amran Mohd Radzi Copyright © 2014 Mahdi Karami et al. All rights reserved. Multiple Adaptive Fading Schmidt-Kalman Filter for Unknown Bias Mon, 24 Nov 2014 06:24:50 +0000 Unknown biases in dynamic and measurement models of the dynamic systems can bring greatly negative effects to the state estimates when using a conventional Kalman filter algorithm. Schmidt introduces the “consider” analysis to account for errors in both the dynamic and measurement models due to the unknown biases. Although the Schmidt-Kalman filter “considers” the biases, the uncertain initial values and incorrect covariance matrices of the unknown biases still are not considered. To solve this problem, a multiple adaptive fading Schmidt-Kalman filter (MAFSKF) is designed by using the proposed multiple adaptive fading Kalman filter to mitigate the negative effects of the unknown biases in dynamic or measurement model. The performance of the MAFSKF algorithm is verified by simulation. Tai-Shan Lou, Zhi-Hua Wang, Meng-Li Xiao, and Hui-Min Fu Copyright © 2014 Tai-Shan Lou et al. All rights reserved. Joint Application of Bilinear Operator and F-Expansion Method for ()-Dimensional Kadomtsev-Petviashvili Equation Sun, 23 Nov 2014 13:51:25 +0000 The bilinear operator and F-expansion method are applied jointly to study ()-dimensional Kadomtsev-Petviashvili (KP) equation. An exact cusped solitary wave solution is obtained by using the extended single-soliton test function and its mechanical feature which blows up periodically in finite time for cusped solitary wave is investigated. By constructing the extended double-soliton test function, a new type of exact traveling wave solution describing the assimilation of solitary wave and periodic traveling wave is also presented. Our results validate the effectiveness for joint application of the bilinear operator and F-expansion method. Shaolin Li, Yinghui He, and Yao Long Copyright © 2014 Shaolin Li et al. All rights reserved. A Strategy Optimization Approach for Mission Deployment in Distributed Systems Sun, 23 Nov 2014 09:55:44 +0000 In order to increase operational efficiency, reduce delays, and/or maximize profit, almost all the organizations have split their mission into several tasks which are deployed in distributed system. However, due to distributivity, the mission is prone to be vulnerable to kinds of cyberattacks. In this paper, we propose a mission deployment scheme to optimize mission payoff in the face of different attack strategies. Using this scheme, defenders can achieve “appropriate security” and force attackers to jointly safeguard the mission situation. Liu Xiaojian, Yuan Yuyu, Fang Binxing, and Gao Yi Copyright © 2014 Liu Xiaojian et al. All rights reserved. Two Modified Three-Term Type Conjugate Gradient Methods and Their Global Convergence for Unconstrained Optimization Sun, 23 Nov 2014 07:52:56 +0000 Two modified three-term type conjugate gradient algorithms which satisfy both the descent condition and the Dai-Liao type conjugacy condition are presented for unconstrained optimization. The first algorithm is a modification of the Hager and Zhang type algorithm in such a way that the search direction is descent and satisfies Dai-Liao’s type conjugacy condition. The second simple three-term type conjugate gradient method can generate sufficient decent directions at every iteration; moreover, this property is independent of the steplength line search. Also, the algorithms could be considered as a modification of the MBFGS method, but with different . Under some mild conditions, the given methods are global convergence, which is independent of the Wolfe line search for general functions. The numerical experiments show that the proposed methods are very robust and efficient. Zhongbo Sun, Yantao Tian, and Hongyang Li Copyright © 2014 Zhongbo Sun et al. All rights reserved. An Improved Method of Training Overcomplete Dictionary Pair Sun, 23 Nov 2014 07:13:46 +0000 Training overcomplete dictionary pair is a critical step of the mainstream superresolution methods. For the high time complexity and susceptible to corruption characteristics of training dictionary, an improved method based on lifting wavelet transform and robust principal component analysis is reported. The high-frequency components of example images are estimated through wavelet coefficients of 3-tier lifting wavelet transform decomposition. Sparse coefficients are similar in multiframe images. Accordingly, the inexact augmented Lagrange multiplier method is employed to achieve robust principal component analysis in the process of imposing global constraints. Experiments reveal that the new algorithm not only reduces the time complexity preserving the clarity but also improves the robustness for the corrupted example images. Zhuozheng Wang, John R. Deller, Kebin Jia, and Wenli Zhang Copyright © 2014 Zhuozheng Wang et al. All rights reserved. Stability and Linear Quadratic Differential Games of Discrete-Time Markovian Jump Linear Systems with State-Dependent Noise Sun, 23 Nov 2014 00:00:00 +0000 We mainly consider the stability of discrete-time Markovian jump linear systems with state-dependent noise as well as its linear quadratic (LQ) differential games. A necessary and sufficient condition involved with the connection between stochastic -stability of Markovian jump linear systems with state-dependent noise and Lyapunov equation is proposed. And using the theory of stochastic -stability, we give the optimal strategies and the optimal cost values for infinite horizon LQ stochastic differential games. It is demonstrated that the solutions of infinite horizon LQ stochastic differential games are concerned with four coupled generalized algebraic Riccati equations (GAREs). Finally, an iterative algorithm is presented to solve the four coupled GAREs and a simulation example is given to illustrate the effectiveness of it. Huiying Sun, Meng Li, Shenglin Ji, and Long Yan Copyright © 2014 Huiying Sun et al. All rights reserved. Extension of Matched Asymptotic Method to Fractional Boundary Layers Problems Thu, 20 Nov 2014 14:07:28 +0000 We were concerned with the description of the boundary layers problems within the scope of fractional calculus. However, we will note that one of the main methods used to solve these problems is the matched asymptotic method. We should mention that this was not achievable via the existing fractional derivative definitions, because they do not obey the chain rule. In order to accommodate the matched asymptotic method to the scope of fractional derivative, we proposed a relatively new derivative called the beta-derivative. We presented some useful information for this operator. With the reward of this operator, we presented the idea of matched asymptotic method in finding solutions of the fractional boundary layers problems. The method was illustrated with an example. Abdon Atangana and Emile Franc Doungmo Goufo Copyright © 2014 Abdon Atangana and Emile Franc Doungmo Goufo. All rights reserved. Dynamic Response of Underground Circular Lining Tunnels Subjected to Incident P Waves Thu, 20 Nov 2014 10:48:38 +0000 Dynamic stress concentration in tunnels and underground structures during earthquakes often leads to serious structural damage. A series solution of wave equation for dynamic response of underground circular lining tunnels subjected to incident plane P waves is presented by Fourier-Bessel series expansion method in this paper. The deformation and stress fields of the whole medium of surrounding rock and tunnel were obtained by solving the equations of seismic wave propagation in an elastic half space. Based on the assumption of a large circular arc, a series of solutions for dynamic stress were deduced by using a wave function expansion approach for a circular lining tunnel in an elastic half space rock medium subjected to incident plane P waves. Then, the dynamic response of the circular lining tunnel was obtained by solving a series of algebraic equations after imposing its boundary conditions for displacement and stress of the circular lining tunnel. The effects of different factors on circular lining rock tunnels, including incident frequency, incident angle, buried depth, rock conditions, and lining stiffness, were derived and several application examples are presented. The results may provide a good reference for studies on the dynamic response and aseismic design of tunnels and underground structures. Hua Xu, Tianbin Li, Jingsong Xu, and Yingjun Wang Copyright © 2014 Hua Xu et al. All rights reserved. Plastic Deformation of Metal Tubes Subjected to Lateral Blast Loads Thu, 20 Nov 2014 10:23:52 +0000 When subjected to the dynamic load, the behavior of the structures is complex and makes it difficult to describe the process of the deformation. In the paper, an analytical model is presented to analyze the plastic deformation of the steel circular tubes. The aim of the research is to calculate the deflection and the deformation angle of the tubes. A series of assumptions are made to achieve the objective. During the research, we build a mathematical model for simply supported thin-walled metal tubes with finite length. At a specified distance above the tube, a TNT charge explodes and generates a plastic shock wave. The wave can be seen as uniformly distributed over the upper semicircle of the cross-section. The simplified Tresca yield domain can be used to describe the plastic flow of the circular tube. The yield domain together with the plastic flow law and other assumptions can finally lead to the solving of the deflection. In the end, tubes with different dimensions subjected to blast wave induced by the TNT charge are observed in experiments. Comparison shows that the numerical results agree well with experiment observations. Kejian Song, Yuan Long, Chong Ji, and Fuyin Gao Copyright © 2014 Kejian Song et al. All rights reserved. Fractal-Based Methods and Inverse Problems for Differential Equations: Current State of the Art Thu, 20 Nov 2014 08:33:20 +0000 We illustrate, in this short survey, the current state of the art of fractal-based techniques and their application to the solution of inverse problems for ordinary and partial differential equations. We review several methods based on the Collage Theorem and its extensions. We also discuss two innovative applications: the first one is related to a vibrating string model while the second one considers a collage-based approach for solving inverse problems for partial differential equations on a perforated domain. Herb E. Kunze, Davide La Torre, Franklin Mendivil, Manuel Ruiz Galán, and Rachad Zaki Copyright © 2014 Herb E. Kunze et al. All rights reserved. Robust FDI for a Class of Nonlinear Networked Systems with ROQs Thu, 20 Nov 2014 06:35:36 +0000 This paper considers the robust fault detection and isolation (FDI) problem for a class of nonlinear networked systems (NSs) with randomly occurring quantisations (ROQs). After vector augmentation, Lyapunov function is introduced to ensure the asymptotically mean-square stability of fault detection system. By transforming the quantisation effects into sector-bounded parameter uncertainties, sufficient conditions ensuring the existence of fault detection filter are proposed, which can reduce the difference between output residuals and fault signals as small as possible under framework. Finally, an example linearized from a vehicle system is introduced to show the efficiency of the proposed fault detection filter. An-quan Sun, Lin Zhang, Wen-feng Wang, Jun Wang, Tian-lin Niu, and Jia-li Zhang Copyright © 2014 An-quan Sun et al. All rights reserved. Synchronizing Spatiotemporal Chaos via a Composite Disturbance Observer-Based Sliding Mode Control Thu, 20 Nov 2014 00:00:00 +0000 The sliding mode control schemes are investigated to synchronize two spatiotemporal chaotic systems, which are two arrays of a large number of coupled chaotic oscillators. Firstly, sliding mode manifolds with the desired performance are designed. The asymptotic convergence to the origin of the synchronization errors is also proved. However, the terms from parameter fluctuations in equivalent controls are usually impossible to be measured directly. So we regard them as lumped disturbances, but, for practical application, it is difficult to obtain the upper bound of lumped disturbances in advance which often results in a conservative sliding mode control law with large control effort, causing a large amount of chattering. To reduce the chattering and improve the performance of the system, a disturbance observer is designed to estimate the lumped disturbances. A composite synchronization controller that consists of a sliding mode feedback part and a feedforward compensation part based on disturbance observer is developed. The numerical simulation results are presented to show the effectiveness of the proposed methods. Congyan Chen and Shi Qiu Copyright © 2014 Congyan Chen and Shi Qiu. All rights reserved. Modeling of Piezoelectric Energy Harvesting from Freely Oscillating Cylinders in Water Flow Thu, 20 Nov 2014 00:00:00 +0000 A concept of energy harvesting from vortex-induced vibrations of a rigid circular cylinder with two piezoelectric beams attached is investigated. The variations of the power levels with the free stream velocity are determined. A mathematical approach including the coupled cylinder motion and harvested voltage is presented. The effects of the load resistance, piezoelectric materials, and circuit combined on the natural frequency and damping of the vibratory system are determined by performing a linear analysis. The dynamic response of the cylinder and harvested energy are investigated. The results show that the harvested level in SS and SP&PS modes is the same with different values of load resistance. For four different system parameters, the results show that the bigger size of cylinder with PZT beams can obtain the higher harvested power. Min Zhang, YingZheng Liu, and ZhaoMin Cao Copyright © 2014 Min Zhang et al. All rights reserved. Secure Certificateless Signature with Revocation in the Standard Model Wed, 19 Nov 2014 14:15:25 +0000 Certificateless public key cryptography is very attractive in solving the key escrow problem which is inherent in identity- (ID-) based public key cryptography. In the past, a large number of certificateless cryptographic schemes and protocols were presented, but a secure certificateless signature in the standard model (without random oracles) is still not accessible until now. To the best of our knowledge, all the previously proposed certificateless signature schemes were insecure under a considerably strong security model in the sense that they suffered from outsiders’ key replacement attacks or the attacks from the key generation center (KGC). In this paper, we propose a certificateless signature scheme without random oracles. Moreover, our scheme is secure under the strong security model and provides a public revocation mechanism, called revocable certificateless signature (RCLS). Under the standard computational Diffie-Hellman assumption, we formally demonstrate that our scheme possesses existential unforgeability against adaptive chosen-message attacks. Tung-Tso Tsai, Sen-Shan Huang, and Yuh-Min Tseng Copyright © 2014 Tung-Tso Tsai et al. All rights reserved.