Current Issue

22 October 2009, Volume 20 Issue 5
Adaptive compensating method for Doppler frequency shift using LMS and phase estimation
Jing Qingfeng & Guo Qing
2009, 20(5):  913-919. 
Abstract ( )   PDF (400KB) ( )  
Related Articles | Metrics

The novel compensating method directly demodulates the signals without the carrier recovery processes, in which the carrier with original modulation frequency is used as the local coherent carrier. In this way, the phase offsets due to frequency shift are linear. Based on this premise, the  compensation processes are: firstly, the phase offsets between the base band neighbor-symbols after clock recovery are unbiasedly estimated among the reference symbols; then, the receiving signals symbols are adjusted by the phase estimation value; finally, the phase offsets after adjusting are compensated by the least mean squares (LMS) algorithm. In order to express the compensation processes and ability clearly, the quadrature phase shift keying (QPSK) modulation signals are regarded as examples for Matlab simulation. BER simulations are carried out using the Monte-Carlo method. The learning curves are obtained to study the algorithm’s convergence ability. The constellation figures are also simulated to observe the compensation results directly.

Performance analysis and threshold selection for cooperative multiple packet reception based on NDMA
Ji Wei & Zheng Baoyu
2009, 20(5):  920-928. 
Abstract ( )   PDF (258KB) ( )  
Related Articles | Metrics

To accurately assess the performance of cooperative multiple packet reception (MPR) based on network-assisted diversity multiple access (NDMA), non-ideal collision detection is introduced in ALLIANCES (ALLow improved access in the network via cooperation and energy savings). To provide a unified analysis framework, the length of cooperative transmission epoch is fixed to the detected collision order. The mathematical analysis of potential throughput (PTP) and potential packet loss rate (PPLR) are given under a pessimistic assumption and an optimistic assumption. According to the analysis of PTP and PPLR, threshold selection is done to optimize system performances, e.g. the optimal threshold should guarantee PTP to be maximum or guarantee PPLR to be minimum. In simulations, the thresholds are selected according to PTP under the pessimistic assumption. Simulation results show that the proposed cooperative MPR scheme can achieve higher throughput than NDMA and slotted ALOHA schemes.

Knowledge-based bridge detection from SAR images
Wang Wenguang, Sun Jinping, Hu Rui & Mao Shiyi
2009, 20(5):  929-936. 
Abstract ( )   PDF (283KB) ( )  
Related Articles | Metrics

Automatic bridge detection is an important application of SAR images. Differed from the classical CFAR method, a new knowledge-based bridge detection approach is proposed. The method not only uses the backscattering intensity difference between targets and background but also applies the contextual information and spatial relationship between objects. According to bridges’ special characteristics and scattering properties in SAR images, the new knowledge-based method includes three processes: river segmentation, potential bridge areas detection and bridge discrimination. The application to AIRSAR data shows that the new method is not sensitive to rivers’ shape. Moreover, this method can detect bridges successfully when river segmentation is not very exact and is more robust than the radius projection method.

Narrowband time delay estimation based on correlation coefficient
Gao Yang, Qiu Tianshuang, Sha Lan & Zhao Yanbin
2009, 20(5):  937-942. 
Abstract ( )   PDF (184KB) ( )  
Related Articles | Metrics

The problems of time delay estimation of narrowband signals are presented. The disadvantages of the existing algorithms are analyzed, and a new narrowband time delay estimating algorithm based on correlation coefficient is proposed. The original time delay information is transfered into the delay between the autocorrelation and cross-correlation function, and the precise estimating result by wave-comparison is given. The algorithm proposed here is also compared with other algorithms and its advantages over other algorithms are proved. The theoretical analysis and simulation show the effectiveness of the proposed algorithm.

Design of complex FIR filters with arbitrary magnitude and group delay responses
Wang Xiaohua & He Yigang
2009, 20(5):  942-947. 
Abstract ( )   PDF (201KB) ( )  
Related Articles | Metrics

To design approximately linear-phase complex coefficient finite impulse response (FIR) digital filters with arbitrary magnitude and group delay responses, a novel neural network approach is studied. The approach is based on a batch back-propagation neural network algorithm by directly minimizing the real magnitude error and phase error from the linear-phase to obtain the filter’s coefficients. The approach can deal with both the real
and complex coefficient FIR digital filters design problems. The main advantage of the proposed design method is the significant reduction in the group delay error. The effectiveness of the proposed method is illustrated with two optimal design examples.

Improved direct P code acquisition technique
Xu Ying, Wang Ju & Wu Siliang
2009, 20(5):  948-953. 
Abstract ( )   PDF (230KB) ( )  
Related Articles | Metrics

P code direct acquisition is an important technology in satellite navigation system. As the P code has a long period, it is hard to directly acquire. The traditional average method can process multiple code phases in a time to shorten the acquisition time. But with the increase of average phase error of the input signal and the local code, the correlation signal-to-noise ratio (SNR) loss increases. To reduce the SNR loss, an improved average method is introduced. A new sequence is generated with a summation of phase shifting sequences to decrease correlation peak loss. Simulation results show that compared with direct average method, the improved average method effectively increases correlation SNR.

GPS short-delay multipath estimation and mitigation based on least square method
Zhang Shengkang1, Wang Hongbo, Yang Jun & He Leiming
2009, 20(5):  954-961. 
Abstract ( )   PDF (273KB) ( )  
Related Articles | Metrics

The GPS multipath signal model is presented, which indicates that the coherent DLL outputs in multipath environment are the convolution between the ideal DLL outputs and the channel responses. So the channel responses can be estimated by a least square method using the observed curve of the DLL discriminator. In terms of the estimated multipath channels, two multipath mitigation methods are discussed, which are equalization filtering and multipath subtracting, respectively. It is shown, by computer simulation, that the least square method has a good performance in channels estimation and the multipath errors can be mitigated almost completely by either of the methods. However, the multipath subtracting method has relative small remnant errors than equalization filtering.

Noise amplitude modulation jamming signal suppression based on weighted-matching pursuit
Sun Minhong & Tang Bin
2009, 20(5):  962-967. 
Abstract ( )   PDF (226KB) ( )  
Related Articles | Metrics

To suppress noise amplitude modulation jamming in a single-antenna radar system, a new method based on weighted-matching pursuit (WMP) algorithm is proposed, which can achieve underdetermined blind sources separation of the jamming and the target echo from the jammed mixture in the single channel of the receiver. Firstly, the presented method utilizes a prior information about the differences between the jamming component and the radar transmitted signal to construct two signal-adapted sub-dictionaries and to determine the weights. Then the WMP algorithm is applied to remove the jamming component from the mixture. Experimental results verify the validity of the presented method. By comparison of the pulse compression performance, the simulation results shows that the presented method is superior to the method of frequency domain cancellation (FDC) when the jamming-to-signal ratio (JSR) is lower than 15 dB.

New computing method of weighted coefficients for tracking a maneuvering target using PDAF in the presence of clutter
Liu Zongxiang, Xie Weixin & Huang Jingxiong
2009, 20(5):  968-973. 
Abstract ( )   PDF (182KB) ( )  
Related Articles | Metrics

To avoid or reduce the influence of unpredictable motion mode on data association, a new computing method of weighted coefficients of measurements for PDAF is presented in which it is assumed that the current turn rate of a maneuvering target changes within a limited range and its turn may be in arbitrary direction during data association. Thus, the predicted center for computing the weighted coefficients is a curved surface in 3-D
space, which differs from the predicted center for setting up a validation gate, namely, a point in 3-D space. The distance between a measurement and the curved surface is used to compute its weighted coefficient. To reduce the computational complexity of weighted coefficients, the formulas for computing the maneuvering direction angle and turn rate corresponding to a measurement are presented. Simulation results show the proposed method reduces the percentage of lost tracks and improves the state estimation accuracy in tracking a maneuvering target using PDAF in the presence of clutter.

Minimal feasible sets in variable resource constrained projects
Cui Wanan, Yue Chaoyuan, Chen Yingchun & Cao Xiuning
2009, 20(5):  974-984. 
Abstract ( )   PDF (315KB) ( )  
Related Articles | Metrics

To determine the reasonable resource dependent relations between activities for the purpose of exactly computing the total floats and the free floats of activities, correctly identifying critical activities and critical sequences in a project schedule with variable resource constraints, the concept of the minimal feasible set (MFS) is proposed and the properties of MFS are discussed. The methods to identify optimal MFSs and resource links are then studied. Furthermore, MFS is generalized to the situation that the preconditions of MFS are not satisfied. Contrastive results show that in establishing resource links and resolving floats, MFS is at least not inferior to other methods in all cases and is superior in most situations.

Study on the extending multi-attribute decision model of grey target
Wang Zhengxin, Dang Yaoguo, Wei Jing & Yang Hu
2009, 20(5):  985-991. 
Abstract ( )   PDF (143KB) ( )  
Related Articles | Metrics

Based on the distance of interval numbers and the two-stage decision methods, this paper expands the decision model of grey target into some situation under which the decision information and target weights are the interval numbers at the same time. It also gives the optimization method of weights in the grey target. We get the optimum coordinated vector utilizing the combination assigning method, based on the local optimization of various schemes. So it can shift the weights of interval number into real number form and sequence it according to the weighted off-target distance. Finally the effectiveness and practicality of the model is proved by a real project.

Modeling of cognitive framework in time-stressed decision making
Wang Li & Wang Mingzhe
2009, 20(5):  992-1000. 
Abstract ( )   PDF (347KB) ( )  
Related Articles | Metrics

An approach for modeling a human cognitive framework in time-stressed decision making is presented. The recognitive and metacognitive processes that represent the cognitive framework are modeled by the colored Petri nets (CPNs). A structural and behavioral analysis method is adopted to obtain the static and dynamic property used to verify the CPNs model of the cognitive framework. Finally, an example from the command and control radar recognition system is used to evaluate the feasibility and availability of the CPNs model adopted in practical systems.

Entropy-based procedures for intuitionistic fuzzy multiple attribute decision making
Xu Zeshui & Hu Hui
2009, 20(5):  1001-1011. 
Abstract ( )   PDF (186KB) ( )  
Related Articles | Metrics

The class of multiple attribute decision making (MADM) problems is studied, where the attribute values are intuitionistic fuzzy numbers, and the information about attribute weights is completely unknown. A score function is first used to calculate the score of each attribute value and a score matrix is constructed, and then it is transformed into a normalized score matrix. Based on the normalized score matrix, an entropy-based procedure is proposed to derive attribute weights. Furthermore, the additive weighted averaging operator is utilized to fuse all the normalized scores into the overall scores of alternatives, by which the ranking of all the given alternatives is obtained. This paper is concluded by extending the above results to interval-valued intuitionistic fuzzy set theory, and an illustrative example is also provided.

Quantum-inspired ant algorithm for knapsack problems
Wang Honggang, Ma Liang, Zhang Huizhen & Li Gaoya
2009, 20(5):  1012-1016. 
Abstract ( )   PDF (163KB) ( )  
Related Articles | Metrics

The knapsack problem is a well-known combinatorial optimization problem which has been proved to be NP-hard. This paper proposes a new algorithm called quantum-inspired ant algorithm (QAA) to solve the knapsack problem. QAA takes the advantage of the principles in quantum computing, such as qubit, quantum gate, and quantum superposition of states, to get more probabilistic-based status with small colonies. By updating the pheromone in the ant algorithm and rotating the quantum gate, the algorithm can finally reach the optimal solution. The detailed steps to use QAA are presented, and by solving series of test cases of classical knapsack problems, the effectiveness and generality of the new algorithm are validated.

Study of testability measurement method for equipment based on Bayesian network model
Lian Guangyao, Huang Kaoli, Chen Jianhui & Wei Zhonglin
2009, 20(5):  1017-1023. 
Abstract ( )   PDF (168KB) ( )  
Related Articles | Metrics

To analyze and evaluate the testability design of equipment, a testability analysis method based on Bayesian network inference model is proposed in the paper. The model can adequately apply testability information and many uncertainty information of design and maintenance process, so it can analyze testability by and large from Bayesian inference. The detailed procedure to analyze and evaluate testability for equipments by Bayesian network is given in the paper. Its modeling process is simple, its formulation is visual, and the analysis results are more reliable than others. Examples prove that the analysis method based on Bayesian network inference can be applied to testability analysis and evaluation for complex equipments.

Robust fault detection for a class of nonlinear network control system with communication delay
Ai Qiangyu, Liu Chunsheng & Jiang Bin
2009, 20(5):  1024-1030. 
Abstract ( )   PDF (231KB) ( )  
Related Articles | Metrics

To investigate a class of nonlinear network control system, a robust fault diagnosis method is presented based on the robust state observer. To access the objective that the designed robust filter is maximally tolerant to disturbances and sensitive to fault, the robustness and stability properties of the fault diagnosis scheme are established rigorously. Using the residual vector, a fault tolerant controller is established in order to guarantee the stability of the closed-loop system, and the controller law can be obtained by solving a set of linear matrix inequalities. Then, some relevant sufficient conditions for the existence of a solution are given by applying Lyapunov stability theory. Finally, a simulation example is performed to show the effectiveness of the proposed approach.

Robust fault detection and diagnosis for uncertain nonlinear systems
Wang Wei, Tahir Hameed, Ren Zhang & Zhou Kemin
2009, 20(5):  1031-1036. 
Abstract ( )   PDF (167KB) ( )  
Related Articles | Metrics

This paper considers robust fault detection and diagnosis for input uncertain nonlinear systems. It proposes a multi-objective fault detection criterion so that the fault residual is sensitive to the fault but insensitive to the uncertainty as much as possible. Then the paper solves the proposed criterion by maximizing the smallest singular value of the transformation from faults to fault detection residuals while minimizing the largest singular value of the transformation from input uncertainty to the fault detection residuals. This method is applied to an aircraft which has a fault in the left elevator or rudder. The simulation results show the proposed method can detect the control surface failures rapidly and efficiently.

Admissibility analysis and control synthesis for switched linear singular systems
Lin Jinxing, Fei Shumin & Shen Jiong
2009, 20(5):  1037-1044. 
Abstract ( )   PDF (163KB) ( )  
Related Articles | Metrics

The problem of admissibility analysis and control synthesis of discrete-time switched linear singular (SLS) systems for arbitrary switching laws is solved. By using the switched Lyapunov function approach, some new sufficient conditions under which the SLS system is admissible for arbitrary switching laws are derived in terms of linear matrix inequalities (LMIs). Based on the admissibility results, control synthesis is then to design switched state feedback and static output feedback controllers, guaranteeing that the resulting closed-loop system is admissible. The presented results can be viewed as the extensions of previous works on switched Lyapunov function approach from the regular switched systems to singular switched cases. Examples are provided to demonstrate the reduced conservatism and effectiveness of the proposed conditions.

Robust passive control for discrete-time T-S fuzzy systems with delays
Duan Guangren & Li Yanjiang
2009, 20(5):  1045-1051. 
Abstract ( )   PDF (139KB) ( )  
Related Articles | Metrics

This article deals with the robust stability analysis and passivity of uncertain discrete-time Takagi-Sugeno (T-S) fuzzy systems with time delays. The T-S fuzzy model with parametric uncertainties can approximate nonlinear uncertain systems at any precision. A sufficient condition on the existence of robust passive controller is established based on the Lyapunov stability theory. With the help of linear matrix inequality (LMI) method, robust passive controllers are designed so that the closed-loop system is robust stable and strictly passive.  urthermore, a convex optimization problem with LMI constraints is formulated to design robust passive controllers with the maximum dissipation rate. A numerical example illustrates the validity of the proposed method.

Novel method of improving the alignment accuracy of SINS on revolving mounting base
Qian Weixing, Liu Jianye, Zhao Wei & Zhu Yanhua
2009, 20(5):  1052-1057. 
Abstract ( )   PDF (217KB) ( )  
Related Articles | Metrics

In the process of initial alignment for a strapdown inertial navigation system (SINS) on a stationary base, the east gyro drift rate is an important factor affecting the alignment accuracy of the azimuth misalignment angle. When the Kalman filtering algorithm is adopted in initial alignment, it yields a constant error in the estimation of the azimuth misalignment angle because the east gyro drift rate cannot be estimated. To improve the alignment accuracy, a novel alignment method on revolving mounting base is proposed. The Kalman filtering algorithm of extending the measured values is studied. The theory of spectral condition number is utilized to analyze the degrees of observability of states. Simulation results show that the estimation accuracy of the azimuth misalignment angle is greatly improved through a revolving mounting base, and the proposed method is efficient in initial alignment for a medium accurate SINS.

Optimal tracking control for linear time-delay large-scale systems with persistent disturbances
Tang Ruichun, Ma Huamin, Guo Shuangle & Ren Lijie
2009, 20(5):  1058-1064. 
Abstract ( )   PDF (198KB) ( )  
Related Articles | Metrics

An optimal tracking control (OTC) problem for linear time-delay large-scale systems affected by external persistent disturbances is investigated. Based on the internal model principle, a disturbance compensator is constructed. The system with persistent disturbances is transformed into an augmented system without persistent disturbances. The original OTC problem of linear time-delay system is transformed into a sequence of linear twopoint boundary value (TPBV) problems by introducing a sensitivity parameter and expanding Maclaurin series around it. By solving an OTC law of the augmented system, the OTC law of the original system is obtained. A numerical simulation is provided to illustrate the effectiveness of the proposed method.

Discrete sliding mode prediction control of uncertain switched systems
He Zhaolan, Wang Mao & Liu Shuhuan
2009, 20(5):  1065-1071. 
Abstract ( )   PDF (184KB) ( )  
Related Articles | Metrics

The robust stabilization problem for a class of uncertain discrete-time switched systems is presented. A predictive sliding mode control strategy is proposed, and a discrete-time reaching law is improved. By applying a predictive sliding surface and a reference trajectory, combining with the state feedback correction and rolling optimization method in the predictive control strategy, a predictive sliding mode controller is synthesized, which guarantees the asymptotic stability for the closed-loop systems. The designed control strategy has stronger robustness and chattering reduction property to conquer with the system uncertainties. In addition, a unique nonswitched sliding surface is designed. The reason is to avoid the repetitive jump of the trajectories of the state components of the closed-loop system between sliding surfaces because it might cause the possible instability. Finally, a numerical example is given to illustrate the effectiveness of the proposed theory.

Robust Hfiltering for discrete-time systems with Markovian switching and time-delays
Yao Xiuming, Zhao Fu, Ling Mingxiang & Wang Changhong
2009, 20(5):  1072-1080. 
Abstract ( )   PDF (184KB) ( )  
Related Articles | Metrics

The robust H filtering problem for uncertain discrete-time Markovian jump linear systems with modedependent
time-delays is investigated. Attention is focused on designing a Markovian jump linear filter that ensures robust stochastic stability while achieving a prescribed H performance level of the resulting filtering error system, for all admissible uncertainties. The key features of the approach include the introduction of a new type of stochastic Lyapunov functional and some free weighting matrix variables. Sufficient conditions for the solvability of this problem are obtained in terms of a set of linear matrix inequalities. Numerical examples are provided to demonstrate the reduced conservatism of the proposed approach.

Novel encryption model for multimedia data
Ye Dengpan & Lian Shiguo
2009, 20(5):  1081-1085. 
Abstract ( )   PDF (168KB) ( )  
Related Articles | Metrics

A novel encryption model is proposed. It combines encryption process with compression process, and realizes compression and encryption at the same time. The model’s feasibility and security are analyzed in detail. And the relationship between its security and compression ratio is also analyzed.

Improved scheme to accelerate support vector regression
Zhao Yongping & Sun Jianguo
2009, 20(5):  1086-1090. 
Abstract ( )   PDF (134KB) ( )  
Related Articles | Metrics

The computational cost of support vector regression in the training phase is O(N3), which is very expensive for a large scale problem. In addition, the solution of support vector regression is of parsimoniousness, which has relation to a part of the whole training data set. Hence, it is reasonable to reduce the training data set. Aiming at the scheme based on k-nearest neighbors to reduce the training data set with the computational complexity 
O(kMN2), an improved scheme is proposed to accelerate the reducing phase, which cuts down the computational complexity from O(kMN2) to O(MN2). Finally, experimental results on benchmark data sets validate the effectiveness of the improved scheme.

Design and realization of threshold secret sharing scheme with random weights
Ye Zhenjun, Fang Zhenming, Wang Chunfeng & Meng Fanzhen
2009, 20(5):  1091-1095. 
Abstract ( )   PDF (111KB) ( )  
Related Articles | Metrics

A new threshold secret sharing scheme is constructed by introducing the concept of share vector, in which the number of shareholders can be adjusted by randomly changing the weights of them. This kind of scheme overcomes the limitation of the static weighted secret sharing schemes that cannot change the weights in the process of carrying out and the deficiency of low efficiency of the ordinary dynamic weighted sharing schemes for its resending process. Thus, this scheme is more suitable to the case that the number of shareholders needs to be changed randomly during the scheme is carrying out.

Detecting JPEG image forgery based on double compression
Wang Junwen, Liu Guangjie, Dai Yuewei & Wang Zhiquan
2009, 20(5):  1096-1103. 
Abstract ( )   PDF (325KB) ( )  
Related Articles | Metrics

Detecting the forgery parts from a double compressed image is very important and urgent work for blind authentication. A very simple and efficient method for accomplishing the task is proposed. Firstly, the probabilistic model with periodic effects in double quantization is analyzed, and the probability of quantized DCT coefficients in each block is calculated over the entire image. Secondly, the posteriori probability of each block is computed according to Bayesian theory and the results mentioned in first part. Then the mean and variance of the posteriori probability are to be used for judging whether the target block is tampered. Finally, the mathematical morphology operations are performed to reduce the false alarm probability. Experimental results show that the method can exactly locate the doctored part, and through the experiment it is also found that for detecting the tampered regions, the higher the second compression quality is, the more exact the detection efficiency is.

On-line linear time construction of sequential binary suffix trees
Lai Huoyao & Liu Gongshen
2009, 20(5):  1104-1110. 
Abstract ( )   PDF (171KB) ( )  
Related Articles | Metrics

Suffix trees are the key data structure for text string matching, and are used in wide application areas such as bioinformatics and data compression. Ukkonen algorithm is deeply investigated and a new algorithm, which decreases the number of memory operations in construction and keeps the result tree sequential, is proposed. The experiment result shows that both the construction and the matching procedure are more efficient than Ukkonen algorithm.

Adjustable entropy method for solving convex inequality problem
Wang Ruopeng
2009, 20(5):  1111-1114. 
Abstract ( )   PDF (112KB) ( )  
Related Articles | Metrics

To solve the inequality problem, an adjustable entropy method is proposed. An inequality problem can be transformed into a minimax problem which is nondifferentiable; then an adjustable entropy is used to smooth the minimax problem. The solution of inequalities can be approached by using a BFGS algorithm of the standard optimization method. Some properties of the new approximate function are presented and then the global convergence are given according to the algorithm. Two numerical examples illustrate that the proposed method is efficient and is superior to the former ones.

Redundant discrete wavelet transforms based moving object recognition and tracking
Gao Tao, Liu Zhengguang & Zhang Jun
2009, 20(5):  1115-1123. 
Abstract ( )   PDF (437KB) ( )  
Related Articles | Metrics

A method for moving object recognition and tracking in the intelligent traffic monitoring system is presented. For the shortcomings and deficiencies of the frame-subtraction method, a redundant discrete wavelet transform (RDWT) based moving object recognition algorithm is put forward, which directly detects moving objects in the redundant discrete wavelet transform domain. An improved adaptive mean-shift algorithm is used to track the moving object in the follow up frames. Experimental results show that the algorithm can effectively extract the moving object, even though the object is similar to the background, and the results are better than the traditional frame-subtraction method. The object tracking is accurate without the impact of changes in the size of the object. Therefore the algorithm has a certain practical value and prospect.

Vertical handoff algorithm in heterogeneous networks to maximize system benefit
Xie Shengdong & Wu Meng
2009, 20(5):  1124-1131. 
Abstract ( )   PDF (227KB) ( )  
Related Articles | Metrics

A new vertical handoff decision algorithm is proposed to maximize the system benefit in heterogeneous wireless networks which comprise cellular networks and wireless local area networks (WLANs). Firstly the block probability, the drop probability and the number of users in the heterogeneous networks are calculated in the channel-guard call admission method, and a function of the system benefit which is based on the new call arrival rate and the handoff call arrival rate is proposed. Then the optimal radius of WLAN is obtained by using simulation annealing (SA) method to maximize the benefit. All the nodes should handoff from cellular network to WLAN if they enter WLAN’s scope and handoff fromWLAN to cellular network if they leave the scope. Finally, the algorithm in different new call arrival rates and handoff call arrival rates is analyzed and results show that it can achieve good effects.

New incremental clustering framework based on induction as inverted deduction
L¨u Zonglei, Wang Jiandong & Xu Tao
2009, 20(5):  1132-1143. 
Abstract ( )   PDF (233KB) ( )  
Related Articles | Metrics

A new incremental clustering framework is presented, the basis of which is the induction as inverted deduction. Induction is inherently risky because it is not truth-preserving. If the clustering is considered as an induction process, the key to build a valid clustering is to minimize the risk of clustering. From the viewpoint of modal logic, the clustering can be described as Kripke frames and Kripke models which are reflexive and symmetric. Based on the theory of modal logic, its properties can be described by system B in syntax. Thus, the risk of clustering can be calculated by the deduction relation of system B and proximity induction theorem described. Since the new proposed framework imposes no additional restrictive conditions of clustering algorithm, it is therefore a universal framework. An incremental clustering algorithm can be easily constructed by this framework from any given nonincremental clustering algorithm. The experiments show that the lower the a priori risk is, the more effective this framework is. It can be demonstrated that this framework is generally valid.

Engineering approach for human error probability quantification
Sun Zhiqiang, Xie Hongwei, Shi Xiujian & Liu Fengqiang
2009, 20(5):  1144-1152. 
Abstract ( )   PDF (325KB) ( )  
Related Articles | Metrics

A novel approach for engineering application to human error probability quantification is presented based on an overview of the existing human reliability analysis methods. The set of performance shaping factors is classified as two subsets of dominant factors and adjusting factors respectively. Firstly, the dominant factors are used to determine the probabilities of three behavior modes. The basic probability and its interval of human error for each behavior mode are given. Secondly, the basic probability and its interval are modified by the adjusting factors, and the total probability of human error is calculated by a total probability formula. Finally, a simple example is introduced, and the consistency and validity of the presented approach are illustrated.

Application of multi-outputs LSSVR by PSO to the aero-engine model
Lu Feng, Huang Jinquan & Qiu Xiaojie
2009, 20(5):  1153-1158. 
Abstract ( )   PDF (216KB) ( )  
Related Articles | Metrics

Considering the modeling errors of on-board self-tuning model in the fault diagnosis of aero-engine, a new mechanism for compensating the model outputs is proposed. A discrete series predictor based on multi-outputs least square support vector regression (LSSVR) is applied to the compensation of on-board self-tuning model of aero-engine, and particle swarm optimization (PSO) is used to the kernels selection of multi-outputs LSSVR. The method need not reconstruct the model of aero-engine because of the differences in the individuals of the same type engines and engine degradation after use. The concrete steps for the application of the method are given, and the simulation results show the effectiveness of the algorithm.