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2014 Vol. 40, No. 8

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Enhancement of electromechanical coupling for piezoelectric system and suppression of multimode vibration
Li Lin, Liu Xue
2014, 40(8): 1011-1016. doi: 10.13700/j.bh.1001-5965.2013.0502
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Enhancing the electromechanical coupling of a piezoelectric system is an effective way to suppress the vibration of the system by the piezoelectric shunt technique. A method was proposed which can increase the multiple-mode electromechanical coupling for a piezoelectric system. From the research of piezoelectric cantilever beam model, it was found that the electromechanical coupling depends on the position of the electrode on the piezoelectric materials, as well as the way to connect to the shunted circuits. The modal electromechanical coupling function was proposed to describe this phenomenon. For the sake to get one modal coupling maximum, the best position of the electrode and the best connection ways can be obtained through optimizing the modal electromechanical coupling function. The ‘current flowing’ circuits was proposed to make multiple-mode electromechanical coupling enhancement possible and to realize multimode vibration suppression. This method was verified through numerical examples.
Classification of inverse problem of solid launch vehicle flight dynamics
Li Shipeng, Liang Xinxin, Rong Jingjing, Zhang Yan
2014, 40(8): 1017-1021. doi: 10.13700/j.bh.1001-5965.2013.0516
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To decrease the analytical difficulty and the solving complexity of the inverse problems in the development of the solid launch vehicle flight dynamics, the classification of inverse problems was investigated. By studying the characteristics of the solutions the inverse problems were divided into three classes which were described clearly by formulations. Further, two basic solving methods were proposed, which were analytical method and optimization method. Analytical method is used to solving inverse problem quickly and the precision of the solution is usually low. Optimization method is used for high precision of the solution and the calculation is usually a long time. The typical engineering problems corresponding to three classes were analyzed. The three typical problems are the required thrust design of the main engine, external force identification and error separation. The analysis and the results of the problems indicate that the classification is reasonable.
Material spectral emissivity measurement optimized by multi-spectral temperature measured
Yang Yongjun, Wang Zhongyu, Zhang Shukun, Zhang Xuecong
2014, 40(8): 1022-1026. doi: 10.13700/j.bh.1001-5965.2013.0504
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The sample surface temperature is difficult to measure in the infrared spectral emissivity measurement of high-temperature material. Optimized temperature measurement method was proposed by multi-spectral method using the spectral radiation energy data measured by spectrometer. The effect of emissivity model and measuring band selected on the accuracy of temperature measurement was analyzed. A robust calculation algorithm was recommended, and its main sources of uncertainty were evaluated. To verify the effectivity of the method, a high temperature alloy material was tested at a temperature of about 1 100 K, and its spectral emissivity relative uncertainty is less than 2% within 2-20 μm spectral range. It shows that this optimized method meets the demand of infrared stealth and radiation thermometry, and can be applied in high temperature spectral emissivity measurement of poor thermal conductivity material or coating material.
Reliability analysis modeling of manufacturing systems based on process quality data
He Yihai, Shen Zhen, Yin Chao
2014, 40(8): 1027-1032. doi: 10.13700/j.bh.1001-5965.2013.0546
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Aiming at the limitation of traditional reliability analysis of manufacturing systems neither considered product quality, nor implemented accurately comprehensive modeling, a reliability analysis modeling of manufacturing systems based on process quality data was presented. Firstly, the concept of reliability of manufacturing system was expounded and process quality data which impacted on the reliability of manufacturing system was analyzed, such as inspection data of the key quality characteristics, degradation failure data of manufacturing systems component and so on. Then the reliability analysis model of manufacturing systems was firstly proposed based on product qualified probability and manufacturing component degradation failure rate. Finally, a reliability analysis case of a cover plate machining system was given to verify the availability of the model. The results show that the proposed model can get more accurate estimated value of the reliability of manufacturing systems from the quality dada in manufacturing process conveniently.
Differential correction technique to the rotation error in autonomous navigation constellation
Meng Fanzhi, Shi Pengliang, Ou Gang
2014, 40(8): 1033-1037. doi: 10.13700/j.bh.1001-5965.2013.0544
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The rotation of the autonomous navigation constellation is unobservable while using inter-satellite measurements only. Once the rotation occurs, errors will be introduced to the positioning results of ground users. The positioning error model of ground users was established to solve this problem. According to the positioning principle and spherical coordinates transformation, the relationship was mathematically proved between the rotation error of the constellation and the positioning error of ground users. Based on this relationship, a differential correction technique to the rotation error was proposed, including the structure and correction algorithm of the technique. Simulations of the Walker 12/3/1 constellation indicate that the constellation's rotation error will cause the longitude of the ground user to have the same error. After applying the differential correction technique, the ground users will effectively correct this error. While the rotation error is less than 1'(equivalent to a 31 m horizontal error in the equator), the user's horizontal error is less than 1.5 m and the vertical error is less than 0.003 m after differential correcting.
Head pose estimation framework based on feature point detection
Qiao Tizhou, Dai Shuling
2014, 40(8): 1038-1043. doi: 10.13700/j.bh.1001-5965.2013.0530
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In order to improve the precision of head pose estimation with random regression forest, an analysis framework based on feature point recognition was proposed for head pose estimation. In view of invalid votes disturbance, this framework recognized head position point and direction point to avoid accepting abnormal voting. The decision function used depth value, normal vector, Gaussian curvature and mean curvature as image features. An approximate optimized decision function search was executed in a binary test pool generated randomly according to information gain of differential entropy. The experiments focused on performance analysis on different occlusion rates of original data. The approach got high success rate in experiments with appropriate parameters, improved accuracy after using curvature, and enhanced the capability of handling with occlusion. The proposed framework has been applied for real-time head pose estimation system in virtual cockpits successfully.
Topological space construction of flight risk probabilities during wake encountering
Xue Yuan, Xu Haojun, Li Qiang, Hou Shifang, Liu Shijie
2014, 40(8): 1044-1054. doi: 10.13700/j.bh.1001-5965.2013.0533
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Under the background of increasing wake vortex problems, wake risk probability topology was built using complex human-machine-environment theory and multivariate extreme value theory. First, three-dimensional wake extreme parameters required for assessing the risk were extracted based on Monte Carlo method. And the one-dimensional extreme parameters were verified to meet generalized extreme value (GEV) distribution. Second, the four parameters and adaptive variable weight (FPAVW) Copula was proposed for modeling three-dimensional extreme parameters. The results of fitting test show FPAVW Copula model has higher accuracy than the other models. Third, flight risk probability in each corresponding grid node was evaluated on the basis of using Copula model to describe all the extreme values in three-dimensional wake space. Then the risk's 2D and 3D topological structures at different stages of wake vortex were analyzed. The work is an effective complement to aircraft system safety assessment theory and method, which provides reference for research directions such as wake navigation control, risk aversion, airport safety interval improvement, and environmental risks visualization. It is also suitable for comparative analysis of flight risk probabilities under different circumstances.
Windage measurements for rotating disc with protrusions
Zhang Da, Luo Xiang, Xu Guoqiang, Tian Shuqing
2014, 40(8): 1055-1059. doi: 10.13700/j.bh.1001-5965.2013.0536
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A new test rig was performed to investigate the windage torque of the rotating disc with protrusions or roughness on the rotor surface. The new measurement method was verified accurately with the comparison between the free disc data and the correction in open literatures. Six configurations of protrusion were carried out. The results show that the moment coefficient of rotor increases with increasing the disc surface roughness. The increasing roughness from hydrodynamically smooth to a roughness ratio of 1 120(corresponding to a roughness height of 0.2 mm) causes a double torque value of rotor within the test range. The impact factors obtained from hydrodynamically smooth disc case were derived for the roughness disc cases. The blade shape protrusion caused the smallest friction torque of the rotor within the six configurations. Changing the protrusions orientation with respect to the direction of the fluid causes the moment coefficient a difference of approximately 10 percents. New correlations were proposed for the windage torque for the hydrodynamically smooth and the roughness rotor cases and the rotor with protrusions respectively.
Design of a controller for morphing aircraft based on backstepping/RHO
Chen Wei, Lu Jingchao, Wang Xiaoguang, Zhang Weiguo
2014, 40(8): 1060-1065. doi: 10.13700/j.bh.1001-5965.2013.0510
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In order to ensure the flight stability of morphing aircraft in the morphing process, a parallel retrofit controller was proposed. The nominal controller was designed by the backstepping technique, which was used to provide the basic flight stability as well as the tracking performance. The nonlinear dynamic equations of the morphing aircraft were linearized by the Jacobian linearization approach, and a linearized model was obtained. The retrofit controller was designed by the receding horizon optimal (RHO) algorithm based on the command filter. The retrofit value was calculated within a finite horizon in real-time to compensate for the nominal controller. The simulation results of the flight path angle control system show that the flight path angle can track the command signal regardless of morphing process, and the flight control system satisfies the requirements of real-time and robustness.
Situational awareness model based on attention allocation
Liu Shuang, Wanyan Xiaoru, Zhuang Damin, Lü Shichen
2014, 40(8): 1066-1072. doi: 10.13700/j.bh.1001-5965.2013.0512
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To predict the changes of situation awareness for the pilot, a new quantitative situation awareness model and solving method, which considered the influence of information importance on situation awareness, the characteristics of human cognition and the Bayesian conditional probability theory, was proposed based on the attention allocation model and the situation awareness model built previously. In order to verify the validity of the model, 20 subjects performed an instrument supervision task under different task conditions. Situation awareness global assessment technique (SAGAT), 3-dimensional situational awareness rating technique (3-D SART), performance measure and eye movement measure were adopted for evaluating the situation awareness under different task conditions. The integrated experimental results reveal that the changing trend of situation awareness calculated by the model is highly correlated with the practical experimental results. This new quantitative situation awareness model will provide a reference for the optimization design of the cockpit display interface and the research of reducing the human error.
Single event upset mitigation testing of SRAM-based FPGAs
Jiang Yuguang, Han Jianwei, Zhu Xiang, Cai Minghui
2014, 40(8): 1073-1077. doi: 10.13700/j.bh.1001-5965.2013.0514
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Pulsed laser and heavy ions irradiation experiment was applied to study the effectiveness of the mitigation techniques of triple modular redundancy(TMR) and dynamic scrubbing for the Virtex-Ⅱ XC2V1000. When both dynamic scrubbing and TMR methods were used, the design of data encryption standard (DES) was observed to be essentially immune to functional errors. The cross section for functional errors utilizing different mitigation techniques was obtained, and the functional error was sensitive to configuration memory upsets. According to error rates of a Virtex-Ⅱ XC2V1000 in polar orbit for configuration memory, dynamic scrubbing in combination with TMR can repair the design to maintain state information, and the only effective mitigation method for an SRAM-based field programmable gate array (FPGA) design intended for space flight is to incorporate both TMR and scrubbing. The result shows that pulsed laser can be used to evaluate the mitigation techniques of TMR and dynamic scrubbing.
3-D back projection and matching for ship recognition from SAR images
Gu Dandan, Xu Xiaojian
2014, 40(8): 1078-1084. doi: 10.13700/j.bh.1001-5965.2013.0539
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A new technique for ship recognition from synthetic aperture radar (SAR) images was proposed. First, a method of projecting SAR image back to the three-dimensional (3-D) target space was developed to obtain the 3-D distribution of the observed target scatterers, namely the 3-D back projection scattering image (BPSI). Next, the 3-D hot scattering point images (HSPIs) of candidate ships as the benchmark were predicted via the physical optics (PO) method. To classify the observed ship efficiently, a two-stage matching scheme was applied: the first stage using geometric features implemented a pre-selection to reduce the number of candidate models from the classification library; the resulting models would undergo the subsequent recognition stage, where a fuzzy matching between the 3-D BPSI and 3-D HSPI was carried out easily and also less sensitive to nonideal factors such as calculation errors than point to point matching. Experimental results for simulated and real ship SAR images display the high discrimination and better visual effect of the 3-D scattering feature, and demonstrate the effectiveness of the proposed approach.
Assessment of shock capturing methods for numerical simulations of compressible turbulence with shock waves
Qu Feng, Yan Chao, Yu Jian, Chen Jiayang
2014, 40(8): 1085-1089. doi: 10.13700/j.bh.1001-5965.2013.0556
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The direct numerical simulation (DNS) and large eddy simulation (LES) of turbulent flows raise challenges to the numerical schemes, especially when they are combined with shock waves. The two demands of the schemes seem to be contrary: the simulation of small turbulence scales requires non-dissipative schemes while the capture of shock waves requires dissipative schemes. To have a systematic comparison of some popular schemes' properties in solving the problems above, a suite of test cases were displayed,Taylor-Green vortex, Shu-Osher problem, and compressible isotropic turbulence. Through systematic analysis and comparisons, results show that the widely used high order schemes are capable of satisfying the two demands required above in some extent. However, both of them have their advantages and disadvantages compared to each other and no one can be called perfect. Thus, they are still far from the theoretic object, and their improvements are in high demands.
Hybrid time synchronization algorithm for avionics clouds
Li Zheng, Li Qiao, Zhao Luxi, Xiong Huagang
2014, 40(8): 1090-1094. doi: 10.13700/j.bh.1001-5965.2014.0038
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To meet the time synchronization requirement in avionics clouds, corresponding models were built including network model, clock model and delay model. Two synchronization operation procedures were provided for nodes in different network environments. The receiving and processing delay of the time synchronization message was compensated based on Bayesian estimation. Combining the centralized time synchronization mechanism and the distributed consensus time synchronization mechanism, the hybrid time synchronization algorithm was proposed. The performance of the proposed algorithm was compared with that of the traditional time synchronization algorithms. The results show that the proposed algorithm has the highest convergence rate and higher synchronization accuracy than the traditional time synchronization algorithms, and when the link failure rate is below 50%, the proposed algorithm also has almost the same robustness as the traditional distributed consensus time synchronization algorithm. The proposed algorithm provides a reference for solving the time synchronization problem in avionics clouds.
Orbit determination and analysis for Chang’E-2 asteroid exploration
Cao Jianfeng, Hu Songjie, Liu Lei, Liu Yong, Huang Yong, Li Peijia
2014, 40(8): 1095-1101. doi: 10.13700/j.bh.1001-5965.2013.0472
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Chang'E-2(CE-2) performed China's first asteroid exploration from April 15th, and took 243 days to fly-by with the asteroid Toutatis on December 13rd, 2012. Because of no navigation camera onboard, the navigation for CE-2 is dependent on the ground-based unified S-band (USB) and very long baseline interferometry (VLBI) tracking system. The orbit determination and orbital accuracy of CE-2 was discussed, and the tracking data from China's new built deep space network was analyzed. With only 13 days left before CE-2's encounter with the asteroid following its previous orbit correction, a new orbit determination strategy was proposed. And a better orbit accuracy can be brought by the combination of data before and after the orbit control. According to the overlap comparison, an orbit solution of 10 km accuracy can be obtained using only USB tracking data, while the joint use of USB and VLBI can improve the accuracy by one time.
Group targets tracking algorithm based on strong tracking filter and improved weighted method
Li Zhenxing, Liu Jinmang, Bai Dongying, Guo Xiangke
2014, 40(8): 1102-1108. doi: 10.13700/j.bh.1001-5965.2013.0650
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To improve the estimation performance of the existing interactive multiple models tracking algorithm for group targets, an improved group tracking algorithm was proposed. Firstly, by using the adaptive algorithm of model transition probability, the optimization of real-time matching for tracking models with the actual motion pattern was performed. And a fading factor of strong tracking filter was used to improve the estimation accuracy of the centroid state in the maneuvering stage. Then the fusion estimation of centroid state and extension state were implemented by using the probability weighted method and the scalar coefficients weighted method, respectively. Lastly, the implementation steps of the new tracking algorithm were presented in detail, which were based on variational Bayesian filtering algorithm. The computer simulations show that the estimation accuracy of the centroid state and extension state is improved in the new algorithm, and this algorithm can reduce a great deal of peak error in the maneuvering stage.
Convergence of fuzzy reliability models and an improved cut-set distribution
Zhang Meng, Lu Shan
2014, 40(8): 1109-1115. doi: 10.13700/j.bh.1001-5965.2014.0026
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The basic fuzzy reliability model of mechanical structures based on cut-set method has been applied to various engineering problems, and some specific models have been formed, such as stress-strength interference model, fatigue life model and avoid-resonance model. A convergence theorem of the model with commonly used cut-set distributions was proposed and proved, and then two corresponding inferences were obtained for the models with unilateral-infinite and bilateral-infinite safety domains respectively. The theorem indicates that when the cut-set becomes longer gradually, the reliability assessments of the fuzzy models with these commonly used cut-set distributions converge to a fixed value which has nothing to do with the specific mechanical structures and thus is unreasonable. In order to avoid this deficiency, a new cut-set distribution called modified truncated normal distribution was proposed. Meanwhile, three specific examples were carried out to verify that the fuzzy reliability model with the proposed cut-set distribution converges well to the corresponding random reliability model, which indicates it is of better convergence and wider applicability.
Improvement and application for group fuzzy analytic hierarchy process
Li Liang, Gong Guanghong, Chen Jinlei, Liu Qiongjun
2014, 40(8): 1116-1120. doi: 10.13700/j.bh.1001-5965.2013.0469
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In order to solve the consistency question of the paired comparison matrix which is constructed based on expert subjective opinion in analytic hierarchy process (AHP), an improved group fuzzy analytic hierarchy process (IGFAHP) was proposed. The AHP was extended to the field of group decision and fuzzy decision by using expert weight and triangular fuzzy numbers. The index weight counting method was designed based on fuzzy direct comparison matrix, by calculating possible degree matrix and turning it to real numbers, which was an improvement for consistency. The consistency function was defined in fuzzy sets, and tested with index number from three to nine. The method was integrated and applied to evaluate the overall design of aircraft system. The result shows that the new method is effective and alleviates the use complexity.
Multi-resolution modeling of terrain based on wavelet analysis
Wang Jiangyun, Zeng Qiong, Wang Huixia
2014, 40(8): 1121-1126. doi: 10.13700/j.bh.1001-5965.2013.0473
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Through wavelet analysis of signal, multi-resolution modeling of digital elevation model (DEM) for the purpose of improving operational efficiency and storage efficiency was studied. According to the characteristics of DEM, on the base of Mallat's multi-resolution analysis (MRA) algorithm, a method for multi-resolution modeling based on wavelet analysis was presented. Then the principles for choosing the fittest wavelet function and boundary extension mode were analyzed. Also a way and several corresponding indexes on evaluating the accuracy of modeling were given. Through simulations, the best wavelet transform parameters were found. Simulation results show that wavelet analysis can be an effective way to achieve DEM data's multi-resolution modeling while operational efficiency and storage efficiency can both be guaranteed. This method can be applied to various engineering such as terrain's quick visualization and aircraft's dynamic or static path planning.
Design of a novel folding wing mechanism
Bao Xiaoxiang, Zhang Yunfei, Yang Xiaoshu
2014, 40(8): 1127-1133. doi: 10.13700/j.bh.1001-5965.2013.0462
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In order to reduce the spanwise size of some aircraft (such as shipboard aircraft, unmanned aerial vehicle, flying car and so on) for saving the storage and transportation space, a novel folding wing mechanism was designed. It consists of three components (an inboard wing, a middle wing and an outboard wing) and can fold twice. The folding mechanism was designed with link mechanism. Then, the kinematics differential equations were established with the simplified kinematics model (without aerodynamic load on ground) to analyze its motion characteristics. The simulation software of multi-body dynamics was used to analyze its dynamics. Torsion spring was used around the hinge between inboard wing and middle wing to improve performance of the drive system. Finally, experiment was done. The result corresponds with the computer simulation very well. The novel folding wing mechanism can reduce the spanwise size of the aircraft remarkably, and the fold/extension motion is smooth and steady.
Novel method for predicting SPE flux levels based on GM(1,1) model and grey interval predictions
Wang Zhongyu, Li Qiang, Yan Hu, Wang Qian
2014, 40(8): 1134-1142. doi: 10.13700/j.bh.1001-5965.2013.0540
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Solar proton event (SPE) is the main source interfering with solar-terrestrial space, large proton event could affect the reliability of on-orbit space station experimental facilities, and sometimes it even threatens the safe operation of space station. An SPE predicting method which is based on GM(1, 1) and interval estimation was proposed. Firstly, the SPE flux levels sequence which consists of the flux data from 1976 to 2010 were preprocessed, a normal SPE flux levels sequence and an extreme SPE flux levels sequence were established according to time occurrence. Then combined with GM(1, 1) and grey interval estimation, a new forecasting method was built up. Integrated with the active adjustment coefficient that reflecting SPE flux level of cyclical fluctuation, long-term forecasting model of SPE flux level was set up. By fusing the results obtained from different SPE type, the mean value of flux levels was obtained, then SPE flux level range was given out in next year or several years. The annual average SPE data from 1976 to 2010 were selected, SPE flux mean intervals were predicted in multiple batches between 1996 to 1998, and 1999 to 2001.The results show that all the SPE flux levels are located in the prediction interval and the maximum deviation of prediction interval for many years is less than 26%. The experiment results also show that the optimum length of a single prediction is two or three years.
Gradual lightweight method of three dimensional prototypes for digital technical support
Bai Jinpeng, Liu Hu, Wu Zhe, Wang Zhenwei, Xue Jing
2014, 40(8): 1143-1148. doi: 10.13700/j.bh.1001-5965.2013.0509
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Intuitionistic three dimensional (3D) models can improve the efficiency and accuracy of civil airliner's distant maintenance support, but due to the fact that models' data size generated in computer aided design systems is usually quite huge, it is a sever challenge to make a lightweight 3D digital prototype. Based on the analysis of two lightweight ways, i.e., model format transformation and model simplification, a gradual lightweight method for digital prototype based on unit data size was proposed, which progressively simplify the 3D model of a whole plane into many different simplification levels, and a hierarchical management methods based on distortion criterion was proposed, which progressively load and use distortion model with high reduction rate and undamage model with detail characteristics according to model structure tree. An example shows that these methods can effectively reduce data size for network transmission and preserve necessary detail characteristics of the model, so that quick access to 3D model of a whole plane via internet can be realized.
Extracting process of stratospheric airship envelop fabric fiber
Meng Junhui, Zhang Yanbo, Lü Mingyun
2014, 40(8): 1149-1153. doi: 10.13700/j.bh.1001-5965.2013.0538
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Either altitude change or temperature fluctuation will cause expanding difference between the internal and external pressure on envelop of the stratospheric airship. Yarn extraction in the load-carrying ply, a microscopic process of envelop tearing, is crucial for measuring the overall pressure-proof capacity of airship. Finite element model of the load-carrying ply was employed to calculate the force change during extraction procedure. This procedure, indicated by comparison between the numerical calculations with experimental data, can be divided into linear increasing period and oscillating period. The point of transition between the two sequencing periods is a significant factor for envelop tearing. At the same time, complicate environment conditions, such as ultraviolet radiation and ozone, greatly undermine the behavior of load-carrying fabric, causing surface aging, which result in the declination of both the maximum extraction force and overall pressure-proof capacity.
Inter-stage imbalance analysis of two-stage low hysteresis brush seal
Wen Long, Wang Zhili, Ding Lei, Liu Jian, Hu Guangyang, Chen Conghui
2014, 40(8): 1154-1159. doi: 10.13700/j.bh.1001-5965.2013.0523
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The flow field of a two-stage low hysteresis brush seal with certain structure was computed with porous medium model. The relationship between seal installation angles, front and back plate gap clearance height of the second stage and partial pressure ratio were also analyzed. Based on cantilever beam theory and the pressure distribution, bristle forces and deflections were calculated with the finite element method, and the effects of parameters on friction torque and inter-stage imbalance were discussed. The result indicates that, increase of the first stage bristle angle and decrease of the second stage bristle angle could make the partial pressure tend to equilibrium. With the given structure of first stage seal, different front plate gap clearance heights of the second stage seal have little effect on inter-stage imbalance, and a specific back plate gap clearance height can make the two stages get an equilibrium state.
Post-evaluation index system for aero-engine R & D capacity building projects
Xu Chunrong, Ren Wenjing, Zhou Hong
2014, 40(8): 1160-1164. doi: 10.13700/j.bh.1001-5965.2013.0626
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According to the specific characteristics of R & D capacity building projects for aero-engines, and based on a two-stage process, a specific project evaluation index system was proposed for the post-evaluation of the aero-engine R & D capacity building projects. Firstly, a primary evaluation index system was established based on the analysis of general projects post evaluation index system and some expert interviews. In addition, an expert survey method based on Likert scale was applied to obtain the expert ratings of each index, and then the group eigenvalue method was selected for the siftings of the primary index system. Some further correlation analysis and resolution capability analysis were also realized by statistics methods to achieve a superior index system optimization.

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