Table of Content

    30 September 2015, Volume 49 Issue 09 Previous Issue    Next Issue
    Mechanical instrumentation engineering
    Identification and Modeling of Coupling Dynamic Stiffness in Joints of Machine Tool
    DONG Guanhua,YIN Qin,YIN Guofu,XIANG Zhaowei
    2015, 49 (09):  1263-1434. 
    Abstract ( 1170 )   Save

    Abstract: In this paper, the identification and modeling of coupling dynamic stiffness in joints of machine tool was discussed. The theoretical model was built by Frequency Response Function(FRF), and the identification formulas were derived based on the mechanical equilibrium condition and the displacement compatibility condition. In the process of identification, the FRF which was difficult to be measured was considered as an intermediate variable to avoid introducing equation errors. The inconsistent equation containing the identification relationship was established, and the equivalent of coupling dynamic stiffness was obtained by using generalized inverse matrix. The coupling relationship between stiffness was probed, and the method of modeling the coupling dynamic stiffness was derived, while the models containing the coupling relationship between stiffness in varying degrees were built. Finally, field tests were conducted based on the LMS system and good results were acquired, which verified the feasibility of the proposed method. By comparing the prediction results of different dynamical models, the conclusion was made that the coupling relationship could have a significant impact on estimated performance in low frequency, and that the coupling relationship should be considered in dynamics modeling.

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    General Industrial Technology
    Coupling Relationship Between Loads on Cutterhead of Tunnel Boring Machine and Contact Stiffness of Gripper Shoes and Rocks
    XIE Qijiang,YU Haidong
    2015, 49 (09):  1269-1275. 
    Abstract ( 826 )   Save

    Abstract: The variation of cutting depth of the rolling cutter causes fluctuations of loads on the cutterhead. The variable loads result in fluctuation of stiffness after being transmitted to the contact surface between gripper and rocks, change the position and posture of the tunnel boring machine(TBM), and influence the loads on the cutterhead. The coupling of the loads and stiffness greatly influences the dynamic behaviors of TBM. Considering the fluctuation of loads on the cutterhead, the transmission of forces was analyzed using the parallel mechanism theory and the coupling of loads on the cutterhead. Besides, the stiffness on the surface between gripper shoes and rocks was studied. The results show that the stiffness on the contact surface increases with the enlargement of loads on the cutterhead. In mixed stratums, the stiffness fluctuates with the fluctuation of loads on the cutterhead. When the rocks at both sides are different, the average values and fluctuations of load on the cutterhead and stiffness of the contact surface increase compared with those of the same rocks at both sides, and the increase of stiffness on the hard contact surface is greater than the decrease on the soft contact surface.

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    Mechanical instrumentation engineering
    Static Compression Analysis of Rubber Hollow Cylinder Based on Plane Strain Assumption
    ZHONG Jianlin1,MA Dawei1,REN Jie1,LI Shijun2,WANG Xu3
    2015, 49 (09):  1276-1280. 
    Abstract ( 1028 )   Save

    Abstract: The compression mechanism of rubber hollow cylinder in damping elements was studied. First, based on the axisymmetric plane strain assumption, the geometric description of rubber hollow cylinder was conducted. Next, combined with the incompressible polynomial constitutive model, the analytical formula of stress for the rubber hollow cylinder was obtained. After that, the numerical model of rubber hollow cylinder in corresponding boundary condition was built, and the stress response obtained by simulation was compared to the results calculated by the analytical formula. Finally, the influence of the change of compression on the stress of rubber hollow cylinder was analyzed. The analysis shows that with the increase of compression, the radial stress and tangential stress increases, the increment stays the same, the stress of the boundary layer is proportional to the amount of compression, when the amount of compression is less than 1%, and the difference in tangential stress of the inner and outer surface is small.

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    Indirect Adaptive Robust Control of DC Motors with Finite-Time Disturbance Observer
    XU Zhangbao,MA Dawei,YAO Jianyong,DONG Zhenle,YANG Guichao
    2015, 49 (09):  1281-1287. 
    Abstract ( 844 )   Save

    Abstract: An indirect adaptive robust control with finite-time disturbance observer (FTDO) was proposed for DC motor servo systems with parametric uncertainties and uncertain nonlinearities. Indirect adaptive control for the parameter uncertainties and FTDO for the uncertain nonlinearities were integrated for compensation. The global uniform stability of the closed-loop system was proved by Lyapunov analysis. The simulation results reveal that the method proposed in this paper can accurately estimate the system parameters and disturbance, compared with the traditional control method, and hence it possesses the advantages of strong antidisturbance capability, good robustness and rapid response speed.

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    SAR Image Matching Algorithm Based on ImprovedKAZE
    YU Yongjun,XU Jinfaa,ZHANG Lianga,XIONG Zhib
    2015, 49 (09):  1288-1292. 
    Abstract ( 885 )   Save

    Abstract: Autonomous navigation system is the key technology of hypersonic vehicle(HV) autonomous control. As the key navigation system of the hypersonic vehicle, the synthetic aperture radar(SAR) images are affected by serious speckle noise. The SINS detecting features in nonlinear scale space are highly time consuming due to the computational burden of creating the nonlinear scale space. Based on the analysis of the characteristics of KAZE, the fast explicit diffusion was introduced to accerlarate feature detection in nonlinear scale space. Furthermore, an improved KAZE algorithm and SINS/SAR integrated scene matching algorithm was proposed. The simulation results indicate that the improved KAZE algorithm has better accuracy and robustness than SIFT, and can effectively improve the computational speed.
    Key words: synthetic aperture radar; nonlinear scale space; image matching; integrated navigation; hypersonic vehicle

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    Method of Equivalent Static Loads Based on Energy Principle and Its Application in Dynamic Optimization Design of Diesel Engine Piston
    ZHANG Yangang,MAO Huping,SU Tiexiong,DONG Xiaorui,WANG Ying,WANG Jun
    2015, 49 (09):  1293-1299. 
    Abstract ( 829 )   Save

    Abstract: Aimed at the problem of illogical time critical point and large error of the method of equivalent static loads based on displacement in structural dynamic optimization, an equivalent static loads method based on energy principle was proposed which could identify the critical time of structure by getting the spectral element discrete solution space of the structure dynamic response. The mathematical model of equivalent transformation was proposed based on the energy at the critical time, and the optimum solution of the set of equivalent static load was obtained using the global optimization algorithm. Therefore, the dynamic optimization problem could be transformed into a static structure optimization problem and solved. Finally, the effective and engineering practicability of the proposed method was proven by the effective application of the method in dynamic optimization design of a diesel engine piston oil chamber structure. The results expand the scope of the theory of equivalent static loads, providing a new way for the dynamic response optimization design of a complex structure.

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    Theoretical and Experimental Research of Frequency Tuning Characteristics of NiTi-Al MMCs Beam
    WANG Yiqinga,ZHANG Tenga,KUANG Xinbina, LU Binghenga,HONG Juna,XU Minglongb
    2015, 49 (09):  1300-1305. 
    Abstract ( 765 )   Save

    Abstract: A Timoshenko beam vibration model was built by considering the recovering stress of NiTi to predict the frequency tuning characteristics of NiTiAl beam. The recovering stress of NiTi resulted in the compressive stress in Clamped-Free (CF) beam which caused the frequency to decrease. For a 80 mm length CF beam with 8% of NiTi (prestrain 3%) embedded, the base frequency decreased by 52.1% when heated to 80 ℃, while the stress status of Clamped-Clamped (CC) beam depended on the combined effect of thermal expansion and NiTi recovering stress. At least 20% of NiTi should be embedded to increase the frequency of CC beam. Finally, theh NiTiAl MMCs beam was manufactured by ultrasonic welding process. A thermal modal experiment was conducted to study the frequency tuning characteristics of NiTi-Al CF beam. The results show that by embedding NiTi the frequency of the beam could be effectively tuned. The experimental data conforms to the theoretical data.

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    Control of  Braking Impact of Slewing MechanismBased on Magnetorheological Technology
    WANG Gongxian,ZHOU Pengzhong,HU Yong,ZHANG Yu
    2015, 49 (09):  1306-1310. 
    Abstract ( 626 )   Save

    Abstract: Aimed at the inertial impact of the crane slewing mechanism brake, a kind of magnetorheological elastomers shaft device was proposed to control the vibration frequency and amplitude of impact. Dynamics equations considering the backlash, time varying meshing stiffness and nonlinear stiffness and damping coefficient of magnetorheological elastomers were established based on the working characteristics of the slewing mechanism, and the function relation between the key parameters and the electric current was deduced. The numerical solutions to equations were obtained, and the coupling torque characteristics and damping characteristics as well as the gear meshing force and braking effect were analyzed. The results show that the magnetorheological elastomer based coupling has a strong power transmission capability. It does not affect the braking effect but it can significantly reduce the shock oscillation frequency. In addition, it can inhibit the impact load peaks.

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    Bond Graph Method for Analysis of Motion Along Coordinate Axis of Micro/Nano Transmission Platform
    LIN Chao1,JI Jiuxiang1,CAI Lizhong1,SHAO Jiming2
    2015, 49 (09):  1311-1318. 
    Abstract ( 803 )   Save

    Abstract: The pseudo-rigid-body (PRB) models of bridge type amplification mechanism (BTAM) and micro/nano transmission platform (MNTP) and the bond graph model of the MNTP moving along the coordinate axis were established. The output stiffness of the BTAM and the characteristic equations and state equations of platform moving were deduced by using the compliant mechanism, mechanics of materials, the pseudo-rigid-body (PRB) method, Castigliano’s theorem, the bond graph theory, and the working principle of 6 degrees of freedom the MNTP. By using simulation analysis of Matlab/Simulink, the displacement simulation curve of the MNTP moving along the axis and the flexible hinge angular simulation curve were acquired. The Ansys13.0 was applied to the motion simulation analysis of the platform. The experimental platform was established, and the experimental test was conducted. The Simulink simulation, finite element analysis and experimental results were analyzed, and the result changes were basically the same.  As a result, the correctness and feasibility of the bond graph model of MNTP moving along X/Y were verified, providing a new effective method for the study of flexible mechanism.

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    Dynamic Opportunistic Maintenance Policy for Complex Quayside Container Crane Systems
    ZHANG Yaozhou1,XIA Tangbin2,TAO Xinyang2,PAN Ershun2,XI Lifeng2
    2015, 49 (09):  1319-1323. 
    Abstract ( 191 )   Save

    Abstract: This paper focused on complex quayside container crane systems consisting of different machines with various degradation processes. An interactive dynamic opportunistic maintenance policy was proposed for supporting the intelligent maintenance decisionmaking. Based on  maintenance effects and environmental condition, a hybrid hazard rate recursion evolution was developed for individual machines. Besides, a multiattribute maintenance model utilizing the multiple attribute value theory and dynamic cycles was presented to optimize the maintenance schedule for each single machine. Furthermore, considering the series system structure, the combining interval timeline (CIT) programming was applied to combine related predictive maintenance actions by using the maintenance opportunities in the system level. The results of system maintenance schedules prove that the proposed methodology can effectively reduce the total maintenance cost and decrease the decisionmaking complexity.

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    Simulation of Thermal Behaviors of Motorized Spindle Based on Fractal Theory and Monte Carlo Method
    MA Chi,YANG Jun,MEI Xuesong,ZHAO Liang,WANG Xinmeng,SHI Hu
    2015, 49 (09):  1324-1331. 
    Abstract ( 143 )   Save

    Abstract: The finite element analysis thermal-structure model of a spindle was proposed at the design stage to avoid the sudden failure in actual machining caused by the high temperature rise in the spindle components. The calculation method of bearing heat power, which regarded the contact angle as the iterative variable, was proposed to avoid the disadvantages of the traditional Newton-Raphson algorithm when the bearing quasistatic was analyzed, such as the poor convergence, slow convergence speed and low accuracy. The motor efficiency analysis method was applied to calculate the heat power of the built-in motor. To avoid the inaccuracy of the statistical methods and the poor generality of the experiment methods, the fractal theory and Monte Carlo method were utilized to calculate the thermal contact conductance between joint surfaces. Besides, the convective heat transfer coefficients of different components were calculated according to the Nusselt number. Furthermore, the spindle thermal deformation and temperature distribution were simulated by applying the above boundary conditions to the FEA model. The results show that the modeling approach of high-speed spindle thermal characteristics is correct and the FEA model can accurately predict the temperature distribution and thermal deformation.

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    An Improved Discrete PSO-Based Approach for Cell Formation Problem
    FENG Hanxin1,Wang He2,YAO Jun1,PAN Ershun1,XI Lifeng1
    2015, 49 (09):  1332-1338. 
    Abstract ( 122 )   Save

    Abstract: The configuration of manufacturing cell was focused on taking into consideration alternative process routings and operation sequences of parts without predetermined number of cells, and a mathematical model was proposed with the objective of minimizing intercellular movements. An automatic clustering approach based on the improved discrete particle swarm optimization was proposed for the cell formation problem (ACPSOCF). The selfadaptive parameter for mutation was introduced to improve the diversity of particle swarm and determine the best number of cells automatically. The experimental results verify the effectiveness of the proposed approach on all test problems, which exceeds or matches the quality of the best solutions presented in the literature, without predetermination of the number of cells.

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    Three Dimensional Topography Analysis of Multi-Hole Surface Using High Definition Metrology
    SHAO Yiping1,WANG Meng1,DU Shichang1,XI Lifeng1,YANG Jia2
    2015, 49 (09):  1339-1345. 
    Abstract ( 174 )   Save

    Abstract: A filter method based on biorthogonal wavelet transform was proposed to analyze the high definition metrology data, which can separate the surface three dimensional form error and waviness of multi-hole surfaces. The effectiveness of the proposed method was demonstrated by comparing it with Gaussian filtering based on simulated continuous surfaces and multi-hole surfaces. With the results obtained from continuous surfaces as references, the deviations of three dimensional waviness parameters SWa and SWt obtained from multi-hole surfaces are 153.7% and 58.3% for Gaussian filtering, and are 0.50% and 9.69% for biorthogonal wavelet transform. Moreover, the proposed method was applied in the three dimensional topography analysis of the top surface of the engine cylinder, which showed that the evaluation results of three dimensional topography for multi-hole surfaces without border distortions are accurate.

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    Grinding Wheel Overload Criterion and Diagnosis
    WANG Siyang,XU Liming,LAI Xiaoping
    2015, 49 (09):  1346-1352. 
    Abstract ( 225 )   Save

    Abstract: Based on the acquisition of acoustic emission signal in the grinding process, two feature extraction methods for establishing grinding overload criterion were studied. The main indicators of sensitivity, stability and algorithm efficiency were proposed to evaluate the performance of different antioverload criterions. The effects of different signal processing methods on identifying the overload point between wheel and workpiece were analyzed with grinding experiments. The results show that the proposed feature extraction method of signaltonoise ratio which has high sensitivity, high algorithm efficiency and good stability, can predict the overload to some extent and can be used as the prior overload diagnosis criterion.

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    Metallography and Metallurgical Technology
    Effects of Double Ball Bar Setup Errors on Accuracy of Circular Tests of Machine Tools
    LU Hongxing,YANG Jianguo,XIANG Sitong
    2015, 49 (09):  1353-1358. 
    Abstract ( 186 )   Save

    Abstract: To improve the circular test accuracy of double ball bar (DBB), the mechanism of DBB setup errors was studied and an identification and separation model was proposed. In the first place, based on the analysis of the geometric relationship of an arbitrary position in the process of measurement, the mathematical relationship between DBB measurement and setup errors was established. The distortion rule of measured values along with setup errors was obtained in mathematical simulation, and a new identification and separation method of setup errors was put forward. The simulation results prove that the proposed method can identify setup errors with high accuracy. The noncontact laser measurement results show that the proposed method can effectively identify DBB setup errors and significantly improve the accuracy of circular tests.

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    Automatic Fall Detection Using Human Skeleton Tracking Algorithm Based on Kinect Sensor
    2015, 49 (09):  1359-1365. 
    Abstract ( 286 )   Save

    Abstract: In order to accurately and quickly detect accidental falls of the elderly who live alone, and to minimize the risk of accidental deaths and injuries caused by accidental falls, the six human skeleton joints, including head, left shoulder, right shoulder, left hip, right  hip and hip center, were chosen using the human skeleton tracking algorithm based on Kinect sensor. By realtime compution of the spatial location, relative position, kinematic velocity and static time of the six joint points, the occurrence of human falls could be determined. Meanwhile, the movements like sitting, squatting, retrieving and other nonfall movements could be accurately discriminated. As a result, the misjudgment ratio was reduced. The experiment results showed that the automatic detection of human fall was realized, and the misjudgment rate of human fall was reduced to 7%.By using the skeleton tracking technology, the privacy of the elderly could be protected in the monitoring process. The detection system did not depend on visible light and could make real time detection at 24 hours. These advantages provide a guarantee for timely security assistance for the elderly who suffer from accidental falls.

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    Aeronautics & Astronautics
    A Spare Part Configuration Scheme Model for Orbiter under Multi-Constraints and Its Optimization
    JIN Jiashan,CAI Zhiming,CHEN Yanqiao
    2015, 49 (09):  1366-1372. 
    Abstract ( 167 )   Save

    Abstract: Due to the restriction of cost, storage space and carrying ability for support resources, and aimed at the multiconstraints targets for the optimization scheme for space navigation carrying spare parts, the optimization scheme of orbiter carrying spare parts at the task preparation stage before flying was deemed as a study background. The target expected back order of configuration optimization model of spare parts was established based on multiconstraints, such as cost, mass, and volume of spare parts. The initial configuration scheme of spare parts could be obtained by setting the initial value of the initial factor. At the same time, different constraint elements were converted into the scale of spares resource constraint by introducing Lagrange constraint factor. The configuration optimization model was updated by introducing the Marginal algorithm. Finally, the configuration optimization scheme of spare parts was obtained by comparing the results of six projects. In the given example, the calculated result was analyzed, and the feasibility of the proposed method was verified.

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    Attitude Fault Tolerant Control and Active Vibration Suppression of Flexible Satellite During Orbit Control
    YANG Jing1,HOU Jianwen2,SHI Xiaoping1
    2015, 49 (09):  1373-1379. 
    Abstract ( 158 )   Save

    Abstract: An attitude fault tolerant control and flexible vibration suppression approach was proposed for the flexible satellite with actuator faults and orbit control force based on the adaptive sliding mode control method. This fault-tolerant control method does not need fault information. The adaptive control algorithm makes it estimate uncertain parameters effectively and thereby the stability and robustness of the attitude system are guaranteed in the presence of external and internal disturbance and inertia moment uncertainty. Based on this, an nonlinear state observer was designed for nonlinear term and disturbance by using the accurate robust differentiator theory, and the flexible chattering was accordingly depressed by combining adaptive control with sliding mode control methods. Finally, a simulation was conducted in actuator failure cases on the premise of reaction flywheel redundancy configuration during orbit control process. The simulation results demonstrate the validity and correctness of the designed control approaches.

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    Molding and Optimization of Injection Conditions on Shrinkage for Thin-Walled Wax Part Using RSM-GA Method
    LIU Changhuia,JIN Suna,LAI Xinmina,LI Feib
    2015, 49 (09):  1380-1386. 
    Abstract ( 208 )   Save

    Abstract: A response surface methodology(RSM) model was built to describe the relationship between the shrinkage in the thickness direction of the thinwalled wax part and injection parameters through experiments. The rationality and adequacy of the model were checked via analysis of variation(ANOVA). Besides, a sensitivity analysis for injection parameters on the dimensional shrinkage variation was conducted. Additionally, in order to reduce the shrinkage, the optimal injection conditions were also obtained by calculating the desirability and genetic algorithm(GA) approach.

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    An Improvement and Verification of Position/Attitude Estimation Algorithm Based on Binocular Vision for Unmanned Aerial Vehicle
    ZHANG Liang1,XU Jinfa1,XIA Qingyuan2,YU Yongjun1
    2015, 49 (09):  1387-1393. 
    Abstract ( 167 )   Save

    Abstract: Aimed at the problem of navigation of unmanned aerial vehicle(UAV) in a complex unknown environment, an algorithm of position and attitude estimation based on binocular vision was described and improved in this paper. The feature points in the stereo image pairs were detected and described using the KAZE features in the nonlinear scale space. The feature points were matched with the Knn algorithm. The 3D stereo information of the feature points was calculated in the camera coordinate system. The position and attitude of UAV were estimated with the RANSAC algorithm and the LM iteration algorithm. Some experiments were conducted. The result shows that KAZE features have better accuracy, realtime and repeatability than those of SIFT and SURF. The improved algorithm can meet the requirements of UAV realtime navigation.
    Key words:

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    Fusion Filtering Method Guided by Measurement Information in Integrated Navigation System
    WANG Lina1,2,HUANG Bin3,GAO Xiaoying2,KANG Guohua3,SUN Yongrong3
    2015, 49 (09):  1394-1399. 
    Abstract ( 176 )   Save

    Abstract: Aimed at the different output rates of each sub-aided navigation system in the integrated navigation system, a fusion filtering method guided by measurement information was proposed using information quality and information equivalent to register all the currently available information. Based on the additional principle, system state estimation was updated depending on the state prediction and currently available measurements, which is theoretically optimal. The simulation results show that the proposed method can handle the unequal output rates of multiple measurements, and work well when any subsystem goes wrong at any time. Compared with the federated filtering method and concentrated filtering method, the proposed method has a better realtime performance.

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    Dynamical Optimization of Satellite Structure Based on Multi-Objective Particle Swarm Optimization Algorithm
    XIA Hao1,CHEN Changya2,WANG Deyu1
    2015, 49 (09):  1400-1403. 
    Abstract ( 158 )   Save

    Abstract: Aimed at the multi-objective and dynamic optimization problem of satellite structure, a method called MOPSO was proposed. A strategy of decreasing the inertia weight was utilized, the particles that violated the constraints were punished respectively, and the mutation operator was introduced to enhance the diversity of swarms, giving this algorithm a better capability of global optimization. Combined with the support vector machine, MOPSO was applied to solve the multiobjective optimization problem of satellite structural dynamics. This approach obtained relatively better results compared with the results obtained by using the NSGA-II algorithm. Numerical results show that MOPSO can effectively and efficiently search and converge to the Pareto optimal front, which is dispersed and uniform.

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    A Numerical Simulation and Parametric Study of Z-Pin Reinforced Composite T-Joints at Tensile Load
    CHEN Shaoqing1,CHEN Xiuhua1,KONG Bin2,WANG Hai1,QIU Xueshi2
    2015, 49 (09):  1404-1410. 
    Abstract ( 135 )   Save

    Abstract: A numerical simulation model for the tensile process of Z-pin reinforced composite T-joints was established by utilizing the cohesive zone model and a parametric study was performed for the distribution of Z-pins. The force-displacement curve of the Z-pin pullout process was obtained by the experiments of Zpin bridging laws. This curve was transformed into the cohesive parameters of the pinned region to simulate the enhancement of  Z-pins to T-joints. The reliability of this model was verified by the static tensile test. Based on the proposed model, the influence of the Z-pin distribution on the tensile capability of T-joints was examined. The results show that as the column spacing decreasers, the pullout force and ultimate load increase. The row spacing has a small effect on the structural bearing capacity. The pullout force is decreased significantly when the distance between Z-pins and the axial plane is increased.

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    Design and Analysis of Super-Pressure Balloon with a Cable-Net Envelope Structure
    YANG Qi,ZHAO Haitao,WANG Quanbao,CHEN Jian,GONG Deren
    2015, 49 (09):  1411-1415. 
    Abstract ( 146 )   Save

    Abstract: In order to improve the current defect of super-pressure balloon gore design, a new approach to designing the superpressure balloon with a cablenet envelope structure was proposed. Different from the old approach, the load tapes sealed to the envelope was replaced by cables which could slid on the envelope to bear the longitudinal load. This approach combined the advantages of 2-D gore design with 3-D gore design. The controll of the initial configuration of the balloon was realized by changing the preload of the cables. According to the equal strength design criteria, the optimal initial configuration of the superpressure balloon was calculated with the ultimate strength of envelope and cable to improve the utilization efficiency of material. The influence of each parameter on the ultimate pressure of super-pressure balloon was discussed, providing reference for structure design and mechanical analysis of super-pressure balloon.

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    Off-Design Performance Prediction in a Transonic Axial Compressor Using Four-Quadrant-Analysis
    XU Xi,QIANG Xiaoqing,TENG Jinfang
    2015, 49 (09):  1416-1421. 
    Abstract ( 233 )   Save

    Abstract: Highly accurate performance prediction models based on the streamline curvature method for the through-flow analysis of transonic compressors was developed, of which the minimum loss incidence and off-design loss prediction model were modified. In addition, four-quadrant -analysis, an original method for off-design loss analysis, was proposed to redefine the composite of transonic compressor loss, to make a further exploration on the characteristic of loss at multiple operating conditions, and to reveal the loss distribution and growth law of transonic compressors to a certain extent. Detailed calculations of a highly loaded transonic compressor rotor with the newly developed model was conducted. The results show that the newly developed model and the four-quadrant-analysis method can reliably predict the overall performance and spanwise distribution of aerodynamic parameters at both design and offdesign operating conditions, providing a new idea for off-design performance prediction. In general, the newly developed model and analysis method can be of great service to engineering.

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    Mechanical Characteristic Analysis of  Flexible Airship Envelop at Unstable Configuration Stage
    CHEN Yufeng,CHEN Wujun,QIU Zhenyu
    2015, 49 (09):  1422-1428. 
    Abstract ( 189 )   Save

    Abstract: In order to reveal the mechanical characteristics of nonrigid airship at the unstable configuration stage, ABAQUS’s user material subroutine based on the iterative membrane properties (IMP) method was proposed. A rational membrane element which was used to simulate the mechanical characteristic of the flexible airship envelop at the unstable configuration stage was chosen by comparing the model results of the engineering elastic beam theory, membrane wrinkling theory and the corresponding experiment. The shape and stress of a 9 meter simplified models of the flexible airship envelop under different constraint conditions was discussed by using the explicit contact nonlinear finite element method.The net buoyant density and boundary conditions are the key factors influencing the mechanical characteristic of the flexible airship envelop at the unstable configuration stage. The nonrigid airship envelop shape varies smoothly at the initial steady state and sharply in the middle of the invariable configuration stage.In addition, the constraint parts of nonrigid airship envelops are more likely to cause strength failure in the invariable configuration phase than in the stable phase.The method proposed is valuable in disclosing the mechanical characteristics of nonrigid airship envelop at the invariable configuration stage.

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    Design of a Strong Tracing UKF for Nonlinear SelfAlignment of SINS
    XUE Haijian1,WANG Jie1,2,GUO Xiaosong1,ZHOU Zhaofa1
    2015, 49 (09):  1429-1434. 
    Abstract ( 180 )   Save

    Abstract: In order to realize fast initial alignment of the strapdown initial navigation system (SINS) in a complex circumstance, a new strong tracking unscented Kalman filter (UKF) was proposed with strict derivation based on the UKF and the two conditions of the strong tracking filter. As this algorithm took full advantage of characteristics of SINS nonlinear selfalignment, the steps of the strong tracking UKF were simplified so that the calculation was reduced significantly and the realtime performance of the algorithm was improved. The steps of the algorithm were given with proofs. The superiority of the strong tracking UKF was analyzed after the process to calculate the suboptimal fading factor given. The simulation and test of the initial alignment of large azimuth misalignment SINS based on this new algorithm show the validity and superiority of the new strong tracking UKF.
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