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共有20条相似文献,以下是第1-20项 搜索用时 268 毫秒

1.  Security for cyber-physical systems: Secure control against known-plaintext attack  
   《中国科学:技术科学(英文版)》,2020年第9期
   There has been a surge of interests in the security of cyber-physical systems(CPSs), yet it is commonly assumed that the adversary has a full knowledge of physical system models. This paper argues that such an unrealistic assumption can be relaxed: the adversary might still be able to identify the system model by passively observing the control input and sensory data. In such a setup, the attack with knowledge of input-output data can be categorized as a Known-Plaintext Attack. A necessary and sufficient condition has been provided, under which the adversary can uniquely obtain the knowledge of the underlying physical system.From the defender's perspective, a secure controller design—which exhibits a low rank structure—is proposed which renders the system unidentifiable to the adversary, while trading off the control system's performance. Finally, a numerical example has been provided to demonstrate the effectiveness of the proposed secure controller design.    

2.  基于自适应神经模糊推理系统的间歇反应精馏组分估算  被引次数:1
   S.M. Khazraee  A.H. Jahanmiri《中国化学工程学报》,2010年第18卷第4期
   Composition estimation plays very important role in plant operation and control. Extended Kalman filter (EKF) is one of the most common estimators, which has been used in composition estimation of reactive batch distillation, but its performance is heavily dependent on the thermodynamic modeling of vapor-liquid equilibrium, which is difficult to initialize and tune. In this paper an inferential state estimation scheme based on adaptive neuro-fuzzy inference system (ANFIS), which is a model base estimator, is employed for composition estimation by using temperature measurements in multicomponent reactive batch distillation. The state estimator is supported by data from a complete dynamic model that includes component and energy balance equations accompanied with thermodynamic relations and reaction kinetics. The mathematical model is verified by pilot plant data. The simulation results show that the ANFIS estimator provides reliable and accurate estimation for component concentrations in reactive batch distillation. The estimated states form a basis for improving the performance of reactive batch distillation either through decision making of an operator or through an automatic closed-loop control scheme.    

3.  Unknown inputs observer for a class of nonlinear uncertain systems: An LMI approach  
   Kamel Mohamed  Mohammed Chadli  Mohamed Chaabane《国际自动化与计算杂志》,2012年第9卷第3期
   This paper deals with the simultaneous estimation of states and unknown inputs for a class of Lipschitz nonlinear systems using only the measured outputs. The system is assumed to have bounded uncertainties that appear on both the state and output matrices. The observer design problem is formulated as a set of linear constraints which can be easily solved using linear matrix inequalities (LMI) technique. An application based on manipulator arm actuated by a direct current (DC) motor is presented to evaluate the performance of the proposed observer. The observer is applied to estimate both state and faults.    

4.  Game Theory Based False Negative Probability of Embedded Watermark Under Unintentional and Steganalysis Attacks  
   HU Ziquan  ;SHE Kun  ;WANG Jianghua  ;TANG Jianguo《中国通信》,2014年第5期
   Steganalysis attack is to statistically estimate the embedded watermark in the watermarked multimedia,and the estimated watermark may be destroyed by the attacker.The existing methods of false negative probability,however,do not consider the influence of steganalysis attack.This paper proposed the game theory based false negative probability to estimate the impacts of steganalysis attack,as well as unintentional attack.Specifically,game theory was used to model the collision between the embedment and steganalysis attack,and derive the optimal building embedding/attacking strategy.Such optimal playing strategies devote to calculating the attacker destructed watermark,used for calculation of the game theory based false negative probability.The experimental results show that watermark detection reliability measured using our proposed method,in comparison,can better reflect the real scenario in which the embedded watermark undergoes unintentional attack and the attacker using steganalysis attack.This paper provides a foundation for investigating countermeasures of digital watermarking community against steganalysis attack.    

5.  Compressed sensing of superimposed chirps with adaptive dictionary refinement  
   HU Lei  ZHOU JianXiong  SHI ZhiGuang  FU Qiang《中国科学:信息科学(英文版)》,2013年第12期
   The compressed sensing (CS) theory shows that accurate signal reconstruction depends on presetting an appropriate signal sparsifying dictionary. For CS of superimposed chirps, this dictionary is typically taken to be a waveform-matched dictionary formed by blindly diseretizing the frequency-chirp rate plane. However, since practical target parameters do not lie exactly on gridding points of the assumed dictionary, there is always mismatch between the assumed and the actual sparsifying dictionaries, which will cause the performance of conventional CS reconstruction methods to degrade considerably. To address this, we model the waveform- matched sparsifying dictionary as a parameterized one by treating its sampled frequency-chirp rate grid points as the underlying parameters. As a consequence, the sparsifying dictionary becomes refinable and its refinement can be achieved by optimizing the underlying parameters. Based on this, we develop a novel reconstruction algorithm for CS of superimposed chirps by utilizing the variational expectation-maximization (EM) algorithm. By alternating between steps of sparse coefficients estimation and dictionary parameters optimization, the algorithm integrates the process for dictionary refinement into that of signal reconstruction, and thus can achieve sparse reconstruction and dictionary optimization simultaneously. Experimental results demonstrate that the algorithm effectively deals with the performance degradation incurred by dictionary mismatch, and also outperforms the state-of-the-art CS reconstruction methods both in compressing the signal measurements and in suppressing the measurement noise.    

6.  A NOVEL LINK ADAPTATION SCHEME TO ENHANCE PERFORMANCE OF IEEE 802.11G WIRELESS LAN  
   Chen Liquan HuAiqun《电子科学学刊(英文版)》,2006年第23卷第3期
   A novel link adaptation scheme using linear Auto Regressive (AR) model channel estimation algorithm to enhance the performance of auto rate selection mechanism in IEEE 802.11g is proposed. This scheme can overcome the low efficiency caused by time interval between the time when Received Signal Strength (RSS) is measured and the time when rate is selected. The best rate is selected based on data payload length, frame retry count and the estimated RSS, which is estimated from recorded RSSs. Simulation results show that the proposed scheme enhances mean throughput performance up to 7%, in saturation state, and up to 24% in finite load state compared with those non-estimation schemes, performance enhancements in average drop rate and average number of transmission attempts per data frame delivery also validate the effectiveness of the proposed schelne.    

7.  System identification with binary-valued observations under both denial-of-service attacks and data tampering attacks: defense scheme and its optimality  
   Jin Guo  Xuebin Wang  Yanling Zhang  Wenchao Xue  Yanlong Zhao《控制理论与应用(英文版)》,2022年第20卷第1期
   In this paper, we investigate the defense problem against the joint attacks of denial-of-service attacks and data tampering attacks in the framework of system identification with binary-valued observations. By estimating the key parameters of the joint attack and compensating them in the identification algorithm, a compensation-oriented defense scheme is proposed. Then the identification algorithm of system parameter is designed and is further proved to be consistent. The asymptotic normality of the algorithm is obtained, and on this basis, we propose the optimal defense scheme. Furthermore, the implementation of the optimal defense scheme is discussed. Finally, a simulation example is presented to verify the effectiveness of the main results.    

8.  Event-triggered state estimation for T-S fuzzy affine systems based on piecewise Lyapunov-Krasovskii functionals  
   Meng WANG  Jianbin QIU  Gang FENG《控制理论与应用(英文版)》,2019年第17卷第1期
   This paper investigates the problem of event-triggered ${\rm H}_\infty$ state estimation for Takagi-Sugeno (T-S) fuzzy affine systems. The objective is to design an event-triggered scheme and an observer such that the resulting estimation error system is asymptotically stable with a prescribed ${\rm H}_{\infty}$ performance and at the same time unnecessary output measurement transmission can be reduced. First, an event-triggered scheme is proposed to determine whether the sampled measurements should be transmitted or not. The output measurements, which trigger the condition, are supposed to suffer a network-induced time-varying and bounded delay before arriving at the observer. Then, by adopting the input delay method, the estimation error system can be reformulated as a piecewise delay system. Based on the piecewise Lyapunov-Krasovskii functional and the Finsler''s lemma, the event-triggered ${\rm H}_{\infty}$ observer design method is developed. Moreover, an algorithm is proposed to co-design the observer gains and the event-triggering parameters to guarantee that the estimation error system is asymptotically stable with a given disturbance attenuation level and the signal transmission rate is reduced as much as possible. Simulation studies are given to show the effectiveness of the proposed method.    

9.  Prediction-based manufacturing center self-adaptive demand side energy optimization in cyber physical systems  
   Xinyao Sun  Xue Wang  Jiangwei Wu  Youda Liu《机械工程学报(英文版)》,2014年第27卷第3期
   Cyber physical systems(CPS) recently emerge as a new technology which can provide promising approaches to demand side management(DSM), an important capability in industrial power systems. Meanwhile, the manufacturing center is a typical industrial power subsystem with dozens of high energy consumption devices which have complex physical dynamics. DSM, integrated with CPS, is an effective methodology for solving energy optimization problems in manufacturing center. This paper presents a prediction-based manufacturing center self-adaptive energy optimization method for demand side management in cyber physical systems. To gain prior knowledge of DSM operating results, a sparse Bayesian learning based componential forecasting method is introduced to predict 24-hour electric load levels for specific industrial areas in China. From this data, a pricing strategy is designed based on short-term load forecasting results. To minimize total energy costs while guaranteeing manufacturing center service quality, an adaptive demand side energy optimization algorithm is presented. The proposed scheme is tested in a machining center energy optimization experiment. An AMI sensing system is then used to measure the demand side energy consumption of the manufacturing center. Based on the data collected from the sensing system, the load prediction-based energy optimization scheme is implemented. By employing both the PSO and the CPSO method, the problem of DSM in the manufac~ring center is solved. The results of the experiment show the self-adaptive CPSO energy optimization method enhances optimization by 5% compared with the traditional PSO optimization method.    

10.  A novel covert speech communication system and its implementation  
   Zongyuan Deng  Xi Shao  Zhen Yang  Baoyu Zheng《电子科学学刊(英文版)》,2008年第25卷第6期
   In this paper, a Covert Speech Telephone (CST) is designed and implemented based on the information hiding technique, which works on the internet. To solve the large embedding capacity problem for real-time information hiding, a steganographic system combined with a watermarking scheme is proposed, which skillfully transfers the secret speech into watermarking information. The basic idea is to use the speech recognition to significantly reduce the size of information that has to be transmitted in a hidden way. Furthermore, an improved DFT watermarking scheme is proposed which adaptively chooses the embedding locations and applies the multi-ary modulation technique. Based on the GUI (Graphical User Interface) software, the CST operates on both ordinary and secure mode. It is a completely digital system with high speech quality. Objective and subjective tests show that the CST is robust against normal signal processing attacks and steganalysis. The proposed scheme can be used in terms of military applications.    

11.  线性多胞型不确定连续系统故障检测滤波器设计  
   王恒  居鹤华  杨光红《自动化学报》,2010年第36卷第5期
   The paper studies the problem of fault detection filter design for uncertain linear continuous-time systems. A design procedure dealing with parameter uncertainties is proposed for residual generation, the sensitivity to fault and the robustness against disturbances are both enhanced on residual outputs through satisfying some performance indexes. By the aid of the generalized Kalman-Yakubovich-Popov (GKYP) lemma, the fault sensitivity performance index can be dealt with in the given frequency range directly, which avoids approximations associated with frequency weights of the existing techniques. An iterative algorithm based on linear matrix inequality (LMI) is given to obtain the solutions. A numerical example is given to illustrate the effectiveness of the proposed methods.    

12.  Control of systems with sector-bounded nonlinearities: robust stability and command effort minimization by disturbance rejection  
   C. Novar  E. Canuto  D. Carlucci《控制理论与应用(英文版)》,2016年第14卷第3期
   The paper shows that a control strategy with disturbance rejection is able to reduce the control effort to a minimum, ensuring at the same time a desired performance level. The disturbance to be rejected is completely unknown, except for a sectorial bound. The control unit is endowed with an extended state observer which includes a disturbance dynamics, whose state tracksthe unknown disturbance to be rejected. In summary, the novel contributions of the paper are the following. First, we derive a robust stability condition for the proposed control scheme, holding for all the nonlinearities that are bounded by a known (or estimated) maximum slope. Second, we propose a novel approach for designing the observer and state feedback gains, whichguarantee robust closed-loop stability. Third, we show that the designed control system yields, with a minimum control effort, the same control performance as a robust state feedback control, which on the contrary may require a larger command activity.Two simulated case studies are presented to show the effectiveness of the proposed approach.    

13.  甘油生物歧化为1, 3-丙二醇过程的优化控制  
   徐恭贤  邵诚  修志龙《中国化学工程学报》,2008年第16卷第1期
   An iterative optimization strategy is proposed and applied to the steady state optimizing control of the bio-dissimilation process of glycerol to 1,3-propanediol in the presence of model-plant mismatch and input constraints. The scheme is based on the Augmented Integrated System Optimization and Parameter Estimation (AI- SOPE) technique, but a linearization of some performance function in the modified model-based optimization problem of AISOPE is introduced to overcome the difficulty of determining an appropriate penalty parameter. When carrying out the iterative optimization, the penalty coefficient is set to a larger value at the current iteration than at the previous iteration, which can promote the evolution rate of the iterative optimization. Simulation studies illustrate the potential ofthe approach presented for the optimizing control of the bioTdissimilation process of glycerol to 1,3-propanediol. The effects of measurement noise, measured and unmeasured disturbances on the proposed algorithm are also investigated.    

14.  Data‑driven disturbance observer‑based control: an active disturbance rejection approach  
   Harvey Rojas?Cubides  John Cortés?Romero  Jaime Arcos?Legarda《控制理论与应用(英文版)》,2021年第19卷第1期
   In this paper, a data-driven method for disturbance estimation and rejection is presented. The proposed approach is divided into two stages: an inner stabilization loop, to set the desired reference model, together with an outer loop for disturbance estimation and compensation. Inspired by the active disturbance rejection control framework, the exogenous and endogenous disturbances are lumped into a total disturbance signal. This signal is estimated using an on-line algorithm based on a data#2;driven predictor scheme, whose parameters are chosen to satisfy high robustness-performance criteria. The above process is presented as a novel enhancement to design a disturbance observer, which constitutes the main contribution of the paper. In addition, the control strategy is completely presented in discrete time, avoiding the use of discretization methods for its digital implementation. As a case study, the voltage control of a DC-DC synchronous buck converter afected by disturbances in the input voltage and the load is considered. Finally, experimental results that validate the proposed strategy and some comparisons with the classical disturbance observer-based control are presented.    

15.  Design and Application of a Robust Vision Tracking System for Unmanned Rotorcraft  
   FAN Baojie  DU Yingkui《机器人》,2014年第5期
   In order to satisfy the requirements of UAV’s aerial safety monitoring and surveillance of sensitive areas,a robust vision system for the rotor UAV is designed and implemented,which includes visual airborne subsystem,ground station subsystem and wireless communication subsystem.Complete sky-ground and human-computer interaction loops are constructed.Based on the developed UAV vision platform,a real-time target tracking algorithm under the mean shift tracking framework is developed.The joint color-texture histogram is used to represent the target robustly.With the help of moment information,the scale and the orientation of the tracked target is estimated adaptively during the tracking process.A model updating scheme for the target and the background is introduced to reduce the interferences from background and the locating biases.Numerical simulation and real flight tracking experiments demonstrate that the overall visual tracking system is effective and has superior performance against several state-of-the-art algorithms.    

16.  无线传感器网络在智能建筑中的优化实现与评估(英文)  
   段俊奇  张思东  郑涛《中国通信》,2011年第8卷第8期
   A complete study for the implementation of wireless sensor networks in the intelligent building is presented. We carry out some experiments to find out the factors affecting the network performance. Several vital parameters which are related to the link quality are measured before deploying the actual system. And then, we propose an optimized routing protocol based on the analysis of the test data. We evaluate the deployment strategies to ensure the excellent performance of the wireless sensor networks unde...    

17.  Electromagnetic Tomography System for Defect Detection of High-Speed Rail Wheel  
   Yu Miao  Xianglong Liu  Ze Liu  Yuanli Yue  Jianli Wu  Jiwei Huo  Yong Li《北京理工大学学报(英文版)》,2020年第29卷第4期
   A novel electromagnetic tomography(EMT) system for defect detection of high-speed rail wheel is proposed, which differs from traditional electromagnetic tomography systems in its spatial arrangements of coils. A U-shaped sensor array was designed, and then a simulation model was built with the low frequency electromagnetic simulation software. Three different algorithms were applied to perform image reconstruction, therefore the defects can be detected from the reconstructed images. Based on the simulation results, an experimental system was built and image reconstruction were performed with the measured data. The reconstructed images obtained both from numerical simulation and experimental system indicated the locations of the defects of the wheel, which verified the feasibility of the EMT system and revealed its good application prospect in the future.    

18.  Generation and Display System of Measurement Matrix Based on DMD  
   Wenzhao Gu  Fu Zheng  Guangjie Zhai《北京理工大学学报(英文版)》,2018年第27卷第4期
   A measurement matrix is the key to sampling and signal reconstruction during the process of compressed sensing. On the basis of digital light processing (DLP) technology, a generation and display system of measurement matrix based on digital micro-mirror device (DMD) is proposed and well designed. In this system, the generation and controlling of measurement matrix are implemented on a PC, which reduces the hardware requirement to generate a random matrix and overcomes the difficulty of the hardware implementation for the random matrix. It can set up the display number of the measurement matrix, the mode of display and display time according to the requirements from users. The display information can be designed to complete the display of measurement matrix with a better adaptability. The system can be easily embedded into a variety of compressed sensing applications, which can be used to generate and display the corresponding measurement matrice with strong portability. In addition, the DMD of this system will be used as a spatial optical modulator to manipulate near-infrared light in a fast, accurate and efficient way in several applications such as in 3D scanning devices and spectrometers.    

19.  Compressed wide spectrum sensing scheme based on BP network  
   WANG Lu-yu    ZHU Qi    ZHAO Su《中国邮电高校学报(英文版)》,2012年第19卷第3期
   This paper proposes a compressed sensing (CS) scheme to reconstruct and estimate the signals. In this scheme, the framework of CS is used to break the Nyquist sampling limit, making it possible to reconstruct and estimate signals via fewer measurements than that is required traditionally. However, the reconstruction algorithms based on CS are normally non-deterministic polynomial hard (NP-hard) in mathematics, which makes difficulties in obtaining real-time analysis-results. Therefore, a new compressed sensing scheme based on back propagation (BP) neural network is proposed under an assumption that every sub-band is the same. In this new scheme, BP neural network is added into detection process, replacing for signal reconstruction and decision-making. By doing this, heavy calculation cost in reconstruction is moved into pre-training period, which can be done before the real-time analysis, bringing about a sharp reduction in time consuming. For simplify, 1-bit quantification is taken on compressed signals. Simulations demonstrate the performance enhancement in the proposed scheme: compared with normal CS-based scheme, the proposed one presents a much shorter response time as well as a better robustness performance to noise via fewer measurements.    

20.  MMSE based joint Tomlinson-Harashima source and linear relay precoder design in non-regenerative MIMO relay system  
   LI Nan    CHEN Peng    HE Zhi-qiang    LIN Jia-ru《中国邮电高校学报(英文版)》,2012年第19卷第4期
   This paper proposes a joint nonlinear transceiver design scheme based on minimum mean square error(MMSE) criterion for non-regenerative multiple input multiple output(MIMO) relay system.The proposed scheme decomposes the error covariance matrix,reformulates the original joint design problem as two separate optimization problems,and then provides a closed-form solution with only local channel state information(CSI) available at the source and destination.Performance evaluation shows that the proposed scheme significantly outperforms linear schemes,and has a competitive performance compared with existing global CSI based nonlinear schemes,both iterative and non-iterative.    

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