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    28 December 2020, Volume 25 Issue 6 Previous Issue    Next Issue

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    Particle Swarm Optimization Based on Hybrid Kalman Filter and Particle Filter 
    PENG Pai, CHEN Cong , YANG Yongsheng
    2020, 25 (6):  681-688.  doi: 10.1007/s12204-020-2229-5
    Abstract ( 458 )   PDF (516KB) ( 8 )  
    The combination of particle swarm and filters is a hot topic in the research of particle swarm optimization (PSO). The Kalman filter based PSO (K-PSO) algorithm is efficient, but it is prone to premature convergence. In this paper, a particle filter based PSO (P-PSO) algorithm is proposed, which is a fine search with fewer premature problems. Unfortunately, the P-PSO algorithm is of higher computational complexity. In order to avoid the premature problem and reduce the computational burden, a hybrid Kalman filter and particle filter based particle swarm optimization (HKP-PSO) algorithm is proposed. The HKP-PSO algorithm combines the fast convergence feature of K-PSO and the consistent convergence performance of P-PSO to avoid premature convergence as well as high computational complexity. The simulation results demonstrate that the proposed HKP-PSO algorithm can achieve better optimal solution than other six PSO related algorithms.

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    New Approach for Information Security Evaluation and Management of IT Systems in Educational Institutions
    WANG Mingzheng, WANG Yijie, WANG Tianyu, HOU Linzao, LI Mian
    2020, 25 (6):  689-699.  doi: 10.1007/s12204-020-2231-y
    Abstract ( 284 )   PDF (233KB) ( 7 )  
    Security evaluation and management has become increasingly important for Web-based information technology (IT) systems, especially for educational institutions. For the security evaluation and management of IT systems in educational institutions, determining the security level for a single IT system has been well developed. However, it is still difficult to evaluate the information security level of the entire educational institution considering multiple IT systems, because there might be too many different IT systems in one institution, educational institutions can be very different, and there is no standard model or method to provide a justifiable information security evaluation among different educational institutions considering their differences. In light of these difficulties,a security evaluation model of educational institutions’ IT systems (SEMEIS) is proposed in this work to facilitate the information security management for the educational institutions. Firstly, a simplified educational industry information system security level protection rating (EIISSLPR) with a new weight redistribution strategy for a single IT system is proposed by choosing important evaluation questions from EIISSLPR and redistributing the weights of these questions. Then for the entire educational institution, analytic hierarchy process (AHP) is used to redistribute the weights of multiple IT systems at different security levels. Considering the risk of possible network security vulnerabilities, a risk index is formulated by weighting different factors, normalized by a utility function, and calculated with the real data collected from the institutions under the evaluation. Finally,the information security performance of educational institutions is obtained as the final score from SEMEIS. The results show that SEMEIS can evaluate the security level of the education institutions practically and provide an efficient and effective management tool for the information security management.

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    Safety Evaluation Method for Long-Term Operation of Metro Based on Combination Weighting Method
    CAO Weiwei, LI Mingguang, WU Wei, XIA Xiaohe, SHI Yujin
    2020, 25 (6):  700-705.  doi: 10.1007/s12204-020-2230-z
    Abstract ( 257 )   PDF (243KB) ( 4 )  
    Metros are critical infrastructure in big cities and evaluation of their safe operation is of increasing importance.To make a reasonable safety evaluation for the metro during operation, this paper establishes a rational safety evaluation model based on long-term monitoring data of Shanghai Metro Line 2. Four evaluation indicators,i.e., absolute settlement, relative curvature, deformation rate and curvature radius, are adopted. Analytic hierarchy process (AHP) and entropy method are combined to determine the weights of the indicators. The risk level values at different mileage are calculated and five danger levels are defined accordingly to determine the safety state of Shanghai Metro Line 2, i.e., safe, relatively safe, critical, relatively dangerous, and dangerous. Safety evaluation of Shanghai Metro Line 2 shows that: 83.81% areas of Shanghai Metro Line 2 are in safe, relatively safe and critical states, while 15.63% and 0.57% areas are in relatively dangerous and dangerous states, respectively;the parts of Shanghai Metro Line 2 where the risk level values exceed the critical value are mainly distributed around the mileage at 6.0—7.5 km and 8.5—11.0 km, and the risk level value peaks around the mileage at 7.3 km,to which much attention should be attached and relevant protective measures be taken; the sections with the high risk level values coincide with the distinctly deforming areas of the metro, indicating that this evaluation method is valid.

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    Fixture Locating Modelling and Optimization Research of Aluminum Alloy Sidewall in a High-Speed Train Body
    WANG Xianjin, GAO Xu, YU Kuigang
    2020, 25 (6):  706-713.  doi: 10.1007/s12204-020-2212-1
    Abstract ( 287 )   PDF (1411KB) ( 9 )  
    The high-speed train body is welded with aluminum alloy assemblies or parts. Due to the material properties, the welding deformation is much significant. In order to control the welding deformation, this paper takes the sidewall welding of a high-speed train body as the research objective, and carries out the fixture locating modelling and optimization research of the aluminum alloy sidewall. Firstly, a finite element model of the sidewall is established and verified by the comparison between the analysis results and the actual measurement data. Then the residual stress and deformation of the sidewall after welding are analyzed. By selecting the longitudinal parameters of different fixture locating layouts for welding analysis, models describing the relationship between the maximum welding residual stress and maximum welding deformation and the longitudinal fixture locating distance of the sidewall are established. Finally, the fixture locating model of welding deformation is used to optimize the longitudinal fixture locating distance. And the transverse fixture locating distance is also optimized by comparing different locating positions. The result shows that the welding residual stress and the welding deformation have been decreased in the optimal fixture locating layout.

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    Critical Velocity of Short Floating Slab Track Using Alterable Element Method Considering Wheel-Rail Contact Loss 
    ZHANG Jingwei, LIU Xuewen, WANG Yansong, WANG Yingyi, LI Ke
    2020, 25 (6):  714-720.  doi: 10.1007/s12204-020-2213-0
    Abstract ( 259 )   PDF (319KB) ( 5 )  
    In actual line operation, the critical velocity is one of the key physical quantities of rail design owing to its great influence on the riding comfort and safety of vehicles due to the wheel-rail contact loss caused by the abrupt change of rail foundation rigidity, rail wear, or abruptness irregularities on rail. In this study, the short floating slab track (SFST) structure is regarded as a double-layer system. The Euler beam and the rigid body model are adopted for the rail and the floating slab, respectively, and the dispersion equation and the theoretical critical velocity of the rail structure under ideal conditions are deduced. Besides, this study considers the implementation of the SFST in the vehicle-structure coupling system. The alterable element method is introduced for accurately simulating the change of the wheel-rail contact state and coding a vehicle-structure dynamic analysis program (VSDAP) to calculate the critical velocity of rail structures from the dynamic response of vehicles and rail structures. The principle of its design at the beginning of the design is given on the basis of the theoretical value of the critical velocity and the simulation of the dynamic response, which can provide reference for practical engineering design.

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    Emergency Evacuation Path Planning of Passenger Ship Based on Cellular Ant Optimization Model
    WANG Peiliang, ZHANG Ting, XIAO Yingjie
    2020, 25 (6):  721-726.  doi: 10.1007/s12204-020-2215-y
    Abstract ( 250 )   PDF (437KB) ( 5 )  
    Aiming at the problem of emergency evacuation path planning of passenger ships, the cellular ant algorithm is applied to path planning on the basis of the grid map. Firstly, a grid map based on hexagonal cells is established to equalize the moving length between the grids. Then, the static field function is introduced into the optimization design of the heuristic function to make the heuristic function adapt to the hexagonal grid map. Finally, the segmented update rule is applied to pheromone update. In order to verify the feasibility and rationality of the proposed method, the simulation of an exhibition hall in a passenger ship is carried out, and the path planning performed by the cellular ant algorithm and the traditional model is compared. The results show that when the cellular ant algorithm is used to plan the path, it not only accelerates the search speed, but also increases the understanding space, which can effectively avoid falling into the localy optimal solution.

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    Multi-Objective Optimization for Structure Crashworthiness Based on Kriging Surrogate Model and Simulated Annealing Algorithm
    SUN Xilong, WANG Dengfeng, LI Ruheng, ZHANG Bin
    2020, 25 (6):  727-738.  doi: 10.1007/s12204-020-2223-y
    Abstract ( 277 )   PDF (3445KB) ( 10 )  
    Multi-objective optimization of crashworthiness in automobile front-end structure was performed, and finite element model (FEM) was validated by experimental results to ensure that FEM can predict the response value with sufficient accuracy. Seven design variables and four crashworthiness indicators were defined. Through orthogonal design method, 18 FEMs were established, and the response values of crashworthiness indicators were extracted. By using the variable-response specimen matrix, Kriging surrogate model (KSM) was constructed to replace FEM to reflect the function correlation between variables and responses. The accuracy of KSM was also validated. Finally, the simulated annealing optimization algorithm was implemented in KSM to seek optimal and reliable solutions. Based on the optimal results and comparison analysis, the 9096-th iteration point was the optimal solution. Although the intrusion of firewall and the mass of optimal structure increased slightly, the vehicle acceleration of the optimal solution decreased by 6.9%, which effectively reduced the risk of occupant injury.
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    Prediction Method of Ice Resistance and Propulsion Power for Polar Ships
    DING Shifeng, ZHOU Li, WANG Zhengrong, TSUPRIK Vladimir G.
    2020, 25 (6):  739-745.  doi: 10.1007/s12204-020-2216-x
    Abstract ( 265 )   PDF (463KB) ( 7 )  
    Polar ships need to meet stringent safety and environmental requirements. Usually those ships are classified by different ice classes based on ice operation capability. However, the polar ships are also trapped by severe ice condition due to low propulsion power. Therefore, it is a realistic question to design the appropriate minimum propulsion power for ice operation. This paper focuses on the ice resistance and its related propulsion power for the ships with polar code (PC) classes. In consideration of seven typical polar ice conditions related to the PC rule of International Association of Classification Societies (IACS), a prediction method of ice resistance is developed by Lindqvist’s model. The results are compared with those of Lindqvist’s model and Riska’s model by using two real ship lines. The comparison among propulsion requirements of representative classification societies is made, and a formula of minimum propulsion power is presented on the basis of ice resistance by revised Finnish-Swedish Ice Class Rules (FSICR) method. The results are verified by the actual values from seven ice class ships. A relatively good agreement is achieved. As a conclusion, the presented prediction method of ice resistance and minimum propulsion power is recommended for evaluation of ice resistance and its related propulsion power during the process of developing polar ships.

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    Prediction of Formation Quality of Inconel 625 Clads Using Support Vector Regression
    GUO Longlong, WU Zebing, HE Yutian, WEI Wenlan, XIA Shengyong, JU Luyan, WANG Bo , ZHANG Yong
    2020, 25 (6):  746-754.  doi: 10.1007/s12204-020-2225-9
    Abstract ( 231 )   PDF (697KB) ( 3 )  
    The process parameters of pulsed tungsten inert gas (PTIG) have a significant influence on the formation quality, mechanical properties and corrosion resistance of the weld overlay. The PTIG was utilized to deposit Inconel 625 clads with various combinations of the process parameters, which were determined by the central composite design (CCD) method. Based on the experimental results, the relationship between process parameters of PTIG and formation quality of the Inconel 625 clads was established using support vector regression (SVR) with different kernel functions, including polynomial kernel function, radial basis function (RBF) kernel function, and sigmoid kernel function. The results indicate that the kernel functions have a great influence on the prediction of height, width and dilution. The models with RBF kernel function feature the best goodness of fitting and the most accurate against the other SVR models for estimating the height and the dilution. However, the model with polynomial kernel function is superior to the other SVR models for predicting the width. Meanwhile, the prediction performance of the SVR models was compared with the general regression analysis. The results demonstrate that the optimized SVR model is much better than the general regression model in the prediction performance.

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    Lifetime Prediction of Wind Turbine Blade Based on Full-Scale Fatigue Testing  
    KOU Haixia, AN Zongwen, MA Qiang, GUO Xu
    2020, 25 (6):  755-761.  doi: 10.1007/s12204-020-2174-3
    Abstract ( 288 )   PDF (269KB) ( 3 )  
     In order to predict the lifetime of products appropriately with long lifetime and high reliability, the accelerated degradation testing (ADT) has been proposed. Composite wind turbine blade is one of the most important components in wind turbine system. Its fatigue cycle is very long in practice. A full-scale fatigue testing is usually used to verify the design of a new blade. In general, the full-scale fatigue testing of blade is accelerated on the basis of the damage equivalent principle. During the full-scale fatigue testing, blade is subjected to higher testing load than normal operating conditions; consequently, the performance degradation of the blade is hastened over time. The full-scale fatigue testing of blade is regarded as a special ADT. According to the fatigue failure criterion, we choose blade stiffness as the characteristic quantity of the blade performance, and propose an accelerated model (AM) for blade on the basis of the theories of ADT. Then, degradation path of the blade stiffness is modeled by using Gamma process. Finally, the lifetime prediction of full-scale megawatt (MW) blade is conducted by combining the proposed AM and blade stiffness degradation model. The prediction results prove the reasonability and validity of this study. This can supply a new approach to predict the lifetime of the full-scale MW blade.

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    Indirect-Inversion Algorithm via Precise Integration for Ill-Conditioned Matrix in Ambiguity Resolution
    ZHAO Fang, SUN Jin, ZHAO Jianjun, YANG Libin
    2020, 25 (6):  762-768.  doi: 10.1007/s12204-020-2200-5
    Abstract ( 217 )   PDF (165KB) ( 2 )  
    Global navigation satellite system (GNSS) positioning depends on the correct integer ambiguity resolution (AR). If the double difference equation for solving the float solution remains ill-conditioned, often happening due to the environment complexity and the equipment mobility, the correct AR is difficult to achieve. Concerningthe ill-conditioned problem, methods of modifying the equation coefficient matrix are widely applied, whose effects are heavily dependent on modifying parameters. Besides, the direct-inversion of the ill-conditioned coefficient matrix can lead to a reduction in the accuracy and stability of the float solution. To solve the problem of ill-conditioned matrix inversion and further improve the accuracy, the present study for the first time proves the positive definite symmetry of the coefficient matrix in AR model and employs precise integration method to the indirect inverse of coefficient matrix. AR model for the GNSS positioning and the general resolving strategies introduction are briefly introduced. An indirect-inversion algorithm via precise integration for ill-conditioned coefficient matrix is proposed. According to the simulations and comparisons, the proposed strategy has higher precision and stability on float solution, and less dependence on modifying parameters.

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    Stability and Numerical Analysis of a Standby System
    QIAO Xing, MA Dan, YAO Xuliang, FENG Baolin
    2020, 25 (6):  769-778.  doi: 10.1007/s12204-020-2217-9
    Abstract ( 303 )   PDF (260KB) ( 4 )  
    A model for repairable standby parallel system consisting of two identical components with common cause failure (CCF) and human error is introduced in this article by a semigroup approach. The stability of the system is verified by the pure analysis technique, the co-final related theory and functional analysis method. It is discussed that four different reliability indices of the studied model are consistent with each other both analytically and numerically. The simulations and comparisons demonstrate the validity of the proposed technique.

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    Nonlinear Distributed Model Predictive Control for Multiple Missiles Against Maneuvering Target with a Trajectory Predictor
    ZHANG Xue, CUI Hao, LUO Qianyue, ZHANG Hui
    2020, 25 (6):  779-789.  doi: 10.1007/s12204-020-2233-9
    Abstract ( 241 )   PDF (1299KB) ( 3 )  
    This study aims to solve the problem of multi-missile simultaneous attacks on maneuvering target. The challenges include multi-missile cooperative control and target’s trajectory prediction. A controller based on nonlinear distributed model predictive control (NDMPC) is designed for multiple missiles against a maneuvering target, and a trajectory prediction method based on particle swarm optimization (PSO) algorithm is proposed. This study has mainly completed the following three aspects of work. Firstly, the cost function of the controller is constructed to optimize the accuracy and synchronization of the multi-missile system with consideration of collision avoidance. Secondly, the velocity control of the leading missile is designed by using the range-to-go information in real time to ensure the attack efficiency and the control of the terminal velocity difference. Finally, a kinematic model of the target is estimated by using short-term real-time data with the PSO algorithm. The established model is employed to predict the target trajectory in the interval between radar scans. Numerical simulation results of two different scenarios demonstrate the effectiveness of the proposed cooperative guidance approach.

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    Reconstruction of Antenna Radiation Pattern Based on Compressed Sensing
    ZHANG Haoping, JIANG Yilin, LI Xiaoyu
    2020, 25 (6):  790-794.  doi: 10.1007/s12204-020-2222-z
    Abstract ( 242 )   PDF (290KB) ( 3 )  
    The measurement of the far-field radiation pattern is an important factor in describing the characteristics of the antenna. The measurement process is time consuming and expensive. Therefore, this paper proposes a novel method to reduce the number of samples required for radiation pattern measurement by adopting compressed sensing theory. This method reconstructs the radiation pattern from data measured by a few sensors, and the positions of these sensors are generated via the m-sequence. Simulation results demonstrate that the proposed algorithm can effectively reconstruct the complete radiation pattern by using the 50% samples.

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    Fractional Fourier Transform Based M-ary Chirp Modulation
    SHA Jiajun, ZHENG Guoxin, YANG Liu
    2020, 25 (6):  795-801.  doi: 10.1007/s12204-020-2191-2
    Abstract ( 285 )   PDF (317KB) ( 3 )  
    In this paper, a novel M-ary chirp modulation scheme is proposed on the basis of the energy concentration property of chirp signals in fractional domain. In the proposed scheme, chirp signals with different phases are multiplexed in the same time-frequency bandwidth through reverse chirp-rate to increase information rate. In addition, fractional filters based on fractional Fourier transform (FRFT) are designed to separate chirp signals of different chirp-rates in the receiver. Moreover, the theoretical performance of fractional filters and the error probability of M-ary chirp system are derived. Both theoretical analysis and simulation prove that the proposed scheme outperforms M-ary quadrature amplitude modulation (QAM) system in the anti-noise performance.

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    Collaborative Tracking Method in Multi-Camera System
    ZHOU Zhipeng, YIN Dong, DING Jinwen, LUO Yuhao, YUAN Mingyue, ZHU Chengfeng
    2020, 25 (6):  802-810.  doi: 10.1007/s12204-020-2188-x
    Abstract ( 329 )   PDF (2111KB) ( 3 )  
    Visual tracking has been a popular task in computer vision in recent years, especially for long-term tracking. A novel object tracking framework is proposed in this paper. For surveillance cameras with overlapping areas, the target area is divided into several regions corresponding to each camera, and a simple re-matching method is used by matching the colors according to the segmented parts. For surveillance cameras without overlapping areas, a time estimation model is employed for continuously tracking objects in different fields of view (FoVs). A demonstration system for collaborative tracking in real time situation is realized finally. The experimental results show that compared with current popular algorithms, the proposed approach has good effect in accuracy and computation time for the application of continuously tracking the pedestrians.

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