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28 October 2015, Volume 20 Issue 5 Previous Issue    Next Issue

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H∞ Inverse Optimal Adaptive Fault-Tolerant Attitude Control for Flexible Spacecraft with Input Saturation LONG Hai-hui (龙海辉), ZHAO Jian-kang*(赵健康), LAI Jian-qing (赖剑清) 2015, 20 (5):  513-527.  doi: 10.1007/s12204-015-1659-y Abstract ( 959 )   An adaptive inverse optimal attitude controller for flexible spacecraft with fault-free actuator is designed based on adaptive control Lyapunov function and inverse optimal methodology subjected to unknown parameter uncertainties, external disturbances and input saturation. The partial loss of actuator effectiveness and the additive faults are considered simultaneously to deal with actuator faults, and the prior knowledge of bounds on the effectiveness factors of the actuators is assumed to be unknown. A fault-tolerant control version is designed to handle the system with actuator fault by introducing a parameter update law to estimate the lower bound of the partial loss of actuator effectiveness faults. The proposed fault-tolerant attitude controller ensures robustness and stabilization, and it achieves H∞ optimality with respect to a family of cost functionals. The usefulness of the proposed algorithms is assessed and compared with the conventional approaches through numerical simulations. References | Related Articles | Metrics

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Stability Analysis of Networked Linear Systems for Multiple Sensors with Different Packet Loss Probabilities LI Jian-guoa*(李建国), LU Lia (陆丽), JIANG Yingb (蒋赢), PAN San-bob (潘三博) 2015, 20 (5):  528-534.  doi: 10.1007/s12204-015-1660-5 Abstract ( 550 )   A stability problem of the linear networked control systems (NCSs) with multisensor having different data missing rates is investigated in this paper. Each sensor of the multiple sensor-controller communication channels is assumed to have an individual stochastic data missing rate. The stochastic data missing is described by a Bernoulli binary distribution. Sufficient conditions are given for the closed-loop linear NCS which is exponentially stable in the mean square sense as the existence of random multiple data missing. The stability problem could be disposed by the MATLAB linear matrix inequality (LMI) tool easily. A simulation case is provided to illustrate the validity of the presented LMI approach. References | Related Articles | Metrics

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A Bandit Method Using Probabilistic Matrix Factorization in Recommendation TU Shi-tao* (涂世涛), ZHU Lan-juan (朱兰娟) 2015, 20 (5):  535-539.  doi: 10.1007/s12204-015-1618-7 Abstract ( 707 )   In recommendation system, sparse data and cold-start user have always been a challenging problem. Using a linear upper confidence bound (UCB) bandit approach as the item selection strategy based on the user historical ratings and user-item context, we model the recommendation problem as a multi-arm bandit (MAB) problem in this paper. Enabling the engine to recommend while it learns, we adopt probabilistic matrix factorization (PMF) in this strategy learning phase after observing the payoff. In particular, we propose a new approach to get the upper bound statistics out of latent feature matrix. In the experiment, we use two public datasets (Netfilx and MovieLens) to evaluate our proposed model. The model shows good results especially on cold-start users. References | Related Articles | Metrics

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A Novel Interference Modeling Scheme in Cognitive Networks LI Jian1,2* (李 剑), LI Sheng-hong1 (李生红) 2015, 20 (5):  540-547.  doi: 10.1007/s12204-015-1661-4 Abstract ( 554 )   In this paper, we propose a mathematical model of aggregate co-channel interference over Rayleigh fading in cognitive networks. Unlike the statistical models in the literature that aim at finding the bound or approximation of the interference, the proposed model gives an accurate expression of probability density function (PDF), cumulative distribution function (CDF) and mean and variance of the interference, which takes into account a number of factors, such as spectrum sensing scheme, and spatial distribution of the secondary users (SUs). In particular, we focus on a more general spatial structure where there are two roles of primary users (PUs) and the interfering SUs distributed in the two-dimensional space. The framework developed in this paper is easy to be applied in power control, error evaluation and other applications. References | Related Articles | Metrics

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Indoor Localization with a Crowdsourcing Based Fingerprints Collecting HUANG Zheng-yong* (黄正勇), YU Hui (俞 晖), GUAN Yun-feng (管云峰), CHEN Kun (陈 坤) 2015, 20 (5):  548-557.  doi: 10.1007/s12204-015-1662-3 Abstract ( 747 )   Fingerprint matching is adopted by a large family of indoor localization schemes, where collecting fingerprints is inevitable but all consuming. While the increasingly popular crowdsourcing based approach provides an opportunity to relieve the burden of fingerprints collecting, a number of formidable challenges for such an approach have yet been studied. For instance, querying in a large fingerprints database for matching process takes a lot of time and calculation; fingerprints collected by crowdsourcing lacks of robustness because of heterogeneous devices problem. Those are important challenges which impede practical deployment of the fingerprint matching indoor localization system. In this study, targeting on effectively utilizing and mining large amount fingerprint data, enhancing the robustness of fingerprints under heterogeneous devices’ collection and realizing the real time localization response, we propose a crowdsourcing based fingerprints collecting mechanism for indoor localization systems. With the proposed approach, massive raw fingerprints will be divided into small clusters while diverse devices’ uploaded fingerprints will be merged for overcoming device heterogeneity, both of which will contribute to reduce response time. We also build a mobile cloud testbed to verify the proposed scheme. Comprehensive real world experiment results indicate that the scheme can provide comparable localization accuracy. References | Related Articles | Metrics

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A Novel Gyrocompass Alignment Method Under Large Azimuth Misalignment Angle WEI Feng-mei1,2* (魏凤梅), ZHANG Jian-pei1 (张健沛), YANG Jing1 (杨 静),JIANG Shu-qiang3 (姜述强), XIE Song-lin3,4 (谢松霖) 2015, 20 (5):  558-564.  doi: 10.1007/s12204-015-1617-8 Abstract ( 487 )   Conventional gyrocompass alignment methods are based on relatively small azimuth misalignment angles. However, a marine strapdown inertial navigation system may face large azimuth misalignment angle caused by a failed coarse alignment algorithm. This paper provides a novel gyrocompass alignment method to solve the problem. Effects of system parameters are analyzed and the proper scenario of parameter switch based on the classic control theories is derived. Test results show that compared with the conventional methods, our method can accomplish the initial alignment quickly and accurately under large azimuth misalignment angle. References | Related Articles | Metrics

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Research on the Optimization Approach for Cargo Oil Tank Design Based on the Improved Particle Swarm Optimization Algorithm JIANG Wen-ying (姜文英), LIN Yan* (林 焰), CHEN Ming (陈 明), YU Yan-yun (于雁云) 2015, 20 (5):  565-570.  doi: 10.1007/s12204-015-1663-2 Abstract ( 627 )   Based on the improved particle swarm optimization (PSO) algorithm, an optimization approach for the cargo oil tank design (COTD) is presented in this paper. The purpose is to design an optimal overall dimension of the cargo oil tank (COT) under various kinds of constraints in the preliminary design stage. A non-linear programming model is built to simulate the optimization design, in which the requirements and rules for COTD are used as the constraints. Considering the distance between the inner shell and hull, a fuzzy constraint is used to express the feasibility degree of the double-hull configuration. In terms of the characteristic of COTD, the PSO algorithm is improved to solve this problem. A bivariate extremum strategy is presented to deal with the fuzzy constraint, by which the maximum and minimum cargo capacities are obtained simultaneously. Finally, the simulation demonstrates the feasibility and effectiveness of the proposed approach. References | Related Articles | Metrics

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Analysis of Angular Side Berthing Against a Rubber Cone Fender ESKENAZI Jean*, WANG Jian-hua (王建华) 2015, 20 (5):  571-583.  doi: 10.1007/s12204-015-1664-1 Abstract ( 487 )   This paper analyzes fender selection process in berth design and focuses on the case of a rigid berth with rubber cone fenders. Fender types and performance comparison methods are studied along with current numerical models. Berth design methods are analyzed with a focus on berthing energy calculation and fender selection. A new approach to determine the required fender capacity is suggested. A finite elements rubber cone model is tested and used in simulations of angular side berthing. Results show that the energy absorbed by the fender can be much higher than what can be calculated with the current berth design method. A new form for the expression of the energy that must be absorbed by the fender during angular berthing impact is suggested. References | Related Articles | Metrics

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Sensitivity Analysis of the Hydrodynamic Coefficients in 4 Degrees of Freedom Ship Manoeuvring Mathematical Model WANG Xue-gang1 (王雪刚), ZOU Zao-jian1,2*(邹早建), YANG Zhao-long1 (杨昭龙), XU Feng3 (徐 锋) 2015, 20 (5):  584-590.  doi: 10.1007/s12204-015-1665-0 Abstract ( 619 )   The S-type test is simulated based on a ship manoeuvring mathematical model of 4 degrees of freedom (4-DOF); simultaneously, sensitivity analysis of the hydrodynamic coefficients in the mathematical model is implemented by using an indirect method. The mathematical model is simplified by omitting the coefficients of smaller sensitivity according to the results of sensitivity analysis. The 10?/10? zigzag test and 35? turning circle manoeuvre are simulated with the original and the simplified mathematical models. The comparison of the simulation results shows the effectiveness of the sensitivity analysis and the validity of the simplified model. References | Related Articles | Metrics

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Computational Fluid Dynamics Uncertainty Analysis for Simulations of Roll Motions for a 3D Ship ZHU Ren-chuan1 (朱仁传), YANG Chun-lei1,2* (杨春蕾), MIAO Guo-ping1 (缪国平), FAN Ju1 (范 菊) 2015, 20 (5):  591-599.  doi: 10.1007/s12204-015-1666-z Abstract ( 624 )   The roll motions are influenced by significant viscous effects such as the flow separation. The 3D simulations of free decay roll motions for the ship model DTMB 5512 are carried out by Reynold averaged Navier- Stokes (RANS) method based on the dynamic mesh technique. A new moving mesh technique is adopted and discussed in details for the present simulations. The purpose of the research is to obtain accurate numerical prediction for roll motions with their respective numerical/modeling errors and uncertainties. Errors and uncertainties are estimated by performing the modern verification and validation (V&V) procedures. Simulation results for the free-floating surface combatant are used to calculate the linear, nonlinear damping coefficients and resonant frequencies including a wide range of forward speed. The present work can provide a useful reference to calculate roll damping by computational fluid dynamics (CFD) method and simulate a general ship motions in waves. References | Related Articles | Metrics

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Modeling the Completely Recrystallized Grain Growth of NiCrMoV Rotor Steel CHEN Fei*(陈 飞), LI Cui-dong (李翠冬), CUI Zhen-shan (崔振山) 2015, 20 (5):  600-605.  doi: 10.1007/s12204-015-1667-y Abstract ( 518 )   The present study focuses on the completely recrystallized grain growth of NiCrMoV steel. All the samples were austenitised at 1 250 ?C for 5min, and then were compressed with strain rate of 0.01 s?1 and finial strain of 0.8. Once the compression completed, the specimens were held for different time before water quenching. Based on the experimental results, the completely recrystallized grain growth model was established and the effects of temperature and holding time on austenite grain size were investigated. Comparison between the experimental and predicted results was carried out. A good agreement between the experimental and predicted results verifies the developed model. References | Related Articles | Metrics

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Microstructure Evolution of Different Forging Processes for 12%Cr Steel During Hot Deformation SUI Da-shan*(隋大山), GAO Liang (高 亮), CUI Zhen-shan (崔振山) 2015, 20 (5):  606-611.  doi: 10.1007/s12204-015-1668-x Abstract ( 502 )   Five forging experiments were designed and conducted to investigate the effect of process parameters on microstructure evolution during hot deformation for X12CrMoWVNbN10-1-1 steel. The experimental results indicated that average grain size became finer with the increasing number of upsetting and stretching. Especially, the size of stretching three times with upsetting twice had the most remarkable effect on refinement, and the size was only 27.36% of the original one. Moreover, the stress model was integrated into the software and finite element models were established. Simulation results demonstrated that the strain at center point of workpiece was far larger than critical strain value in each process, so that dynamic recrystallization (DRX) occurred in each workpiece, which implied DRX could occur for several times with the increasing number of upsetting and stretching, and uniform finer microstructure would be obtained. However, the results also showed that higher temperature was an unfavorable factor for grain refinement, so the times of heating should be limited for workpiece, and as many forging processes as possible should be finished in once heating. References | Related Articles | Metrics

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Smolyak Type Sparse Grid Collocation Method for Uncertainty Quantification of Nonlinear Stochastic Dynamic Equations SHI Hong-Qin1 (石红芹), HE Jun2* (何 军) 2015, 20 (5):  612-617.  doi: 10.1007/s12204-015-1621-z Abstract ( 584 )   This paper develops a Smolyak-type sparse-grid stochastic collocation method (SGSCM) for uncertainty quantification of nonlinear stochastic dynamic equations. The solution obtained by the method is a linear combination of tensor product formulas for multivariate polynomial interpolation. By choosing the collocation point sets to coincide with cubature point sets of quadrature rules, we derive quadrature formulas to estimate the expectations of the solution. The method does not suffer from the curse of dimensionality in the sense that the computational cost does not increase exponentially with the number of input random variables. Numerical analysis of a nonlinear elastic oscillator subjected to a discretized band-limited white noise process demonstrates the computational efficiency and accuracy of the developed method. References | Related Articles | Metrics

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Stability Analysis of Two-Point Mooring Autonomous Underwater Vehicle DU Xiao-xu1* (杜晓旭), LI Xin-liang1 (李新亮), HAO Cheng-zhi2 (郝承智), WANG You-jiang1 (王有江) 2015, 20 (5):  618-624.  doi: 10.1007/s12204-015-1669-9 Abstract ( 611 )   Static stability analysis of the two-point mooring autonomous underwater vehicle (AUV) is presented. The mathematic model is a set of equilibrium equations describing the attitude of the AUV. The mooring lines are regarded as inelastic catenaries, and five degrees of freedom of AUV are considered. The stability of the system is represented by inequality conditions between several physical quantities and the corresponding limitations. We analyze stability of the prime AUV and find that the AUV has a flow-following tendency, which makes the swing angle big. The result shows that the two-point mooring AUV can remain stable under 2.5 kn ocean current speed, and it will weigh anchor when the speed is greater than 3 kn. Subsequent parametric study reveals the influence of the designing parameters on the stability. References | Related Articles | Metrics

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Vibration Characteristic Analysis and Experiment of Non-Rigid Airship with Suspended Curtain CHEN Yu-feng* (陈宇峰), CHEN Wu-jun (陈务军), HE Yan-li (何艳丽), ZHANG Da-xu (张大旭) 2015, 20 (5):  625-633.  doi: 10.1007/s12204-015-1620-0 Abstract ( 465 )   In order to evaluate the vibration characteristics of non-rigid airship with suspended curtain, we introduce vibration characteristic analysis method of the inflatable membrane structure. Modal numerical method of the inflatable membrane structure under the pressure difference is validated by the model testing of the inflatable cantilever tube. The finite element model of 75m airships is established to simulate the vibration characteristics subjected to only pressure difference and the resultant force of weight and buoyancy. The nonlinear static deformation and stress analysis are investigated for two kinds of equilibrated configurations with various pressure differences, as well as the vibration characteristics. The structural efficiency of the suspended curtain is investigated through the force transfer ratio at the assumed equilibrated point. The effects of manufacture error of the suspended cable length on the structural behavior are analyzed. The results indicate that the local area of airship envelope connected to the suspended cable is a weak part. Various pressures and pressure gradients have significant effects on the global airship structure and the suspended curtain. The suspended curtain is effective to transfer the equilibrated force from the bottom to the top of airship envelope. Manufacture error of the suspended cable length could result in obvious deformation of local airship envelope. The presented work is valuable to the structural engineering design of stratospheric airship. References | Related Articles | Metrics

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Treatment of Aniline-Contaminated Wastewater by Sequencing Biofilm Batch Reactor System Under Micro-Aerobic Condition QI Pei-shi* (祁佩时), CHEN Hong-yi (陈洪一), LIU Yun-zhi (刘云芝) 2015, 20 (5):  634-640.  doi: 10.1007/s12204-015-1670-3 Abstract ( 406 )   Sequencing biofilm batch reactor (SBBR) under micro-aerobic condition was applied to the treatment of aniline-contaminated wastewater in this study. Hydraulic retention time (HRT) of 12—36 h and dissolved oxygen (DO) concentration of 0.1—0.5 mg/L were selected as the operating variables to model, analyze and optimize the process. Five dependent parameters, aniline (AN), chemical oxygen demand (COD), ammonium, total nitrogen (TN) and total phosphorus (TP) removal efficiencies as the process responses, were studied. From the results, increase in DO concentration could promote the AN, COD and ammonium removal; increase in HRT could also lead to increase of the AN and ammonium removal, but might decrease COD removal due to endogenous respiration and soluble microbial products. In the SBBR system, 24 h for HRT and 0.5 mg/L for DO concentration were chosen as the optimum operating condition. The actual removal efficiencies of COD, AN and ammonium under the optimum operating condition were 98.37%, 100% and 89.29%, respectively. The experimental findings were in close agreement with the model prediction. The presence of glucose could promote bacterial growth and has positive influence on AN degradation and ammonium removal. References | Related Articles | Metrics