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2015 Vol. 41, No. 8

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2015 Year 41 Volume 8 Issue E-journal
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Nonlinear vibration analysis of longitudinal-transverse coupled beam
XING Yufeng, LIANG Kun
2015, 41(8): 1359-1366. doi: 10.13700/j.bh.1001-5965.2014.0556
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The coupling phenomenon of longitudinal and transverse vibration is representative in boost rocket. Taking longitudinal and transverse vibration coupling into account by using the second order term of longitudinal strain, the governing differential equations of Rayleigh beam was derived through Hamilton variational principle, and the finite element method was employed to explore the behaviors of this nonlinear coupling system. As for the inherent frequency of the corresponding linear system and the dynamic responses of nonlinear longitudinal and transverse coupling system, the obtained results were in agreement with those of NASTRAN, which validated the correctness of present method and results. According to characteristics of the viberation governing equations and the results of finite element method, the analyses focused on the time-variable property of nonlinear system frequency, the amplitude-frequency characteristic of nonlinear dynamical responses, the mutual effects of the longitudinal and transverse vibration and resonant phenomenon when the combinations of frequencies of exciting forces are closer to the frequency of the nonlinear system. The results of present study lie the theoretical foundation for the practical application of the present method.
Impulse interference mitigation method based on joint compressed sensing and whitening of interference
LIU Haitao, ZHANG Zhimei, CHENG Wei, ZHANG Xuejun
2015, 41(8): 1367-1373. doi: 10.13700/j.bh.1001-5965.2014.0545
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To mitigate the deleterious influence of distance measure equipment (DME) interference on orthogonal frequency division multiplexing (OFDM) receiver of L-band digital aeronautical communications system 1(L-DACS1) operating as an inlay system, a new DME interference suppression method was proposed based on joint compressed sensing and whitening of residual interference. Firstly, the DME impulse interference was observed via null subcarriers channel of the OFDM receiver and reconstructed with convex optimization constrained l1 norm minimization method based on the sparse property of the DME impulse interference in time domain. Then the reconstructed DME impulse interference was transformed to frequency domain and eliminated from the received signal. Finally, to avoid burst errors of demodulator, the residual impulse interference was converted to white Gaussian noise by using the de-interleaver and inverse orthogonal transformer. The computer simulation indicates that the proposed method can reduce the impact of DME interference effectively, and improve the reliability of OFDM receiver of the L-DACS1 system significantly.
Property assessment of PANS method for numerical simulation of flow around tandem cylinders
DU Ruofan, YAN Chao, LUO Dahai
2015, 41(8): 1374-1380. doi: 10.13700/j.bh.1001-5965.2014.0589
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Partially averaged Navier-Stokes (PANS) method derived from the traditional Reynolds averaged Navier-Stokes (RANS) methods by introducing controlling parameter into original RANS equations to modify these equations, is one kind of hybrid methods which can effectively simulate the separated turbulent flows. Computational results of tandem cylinders using PANS method based on Menter shear stress transport (SST) turbulence model were presented in this investigation. The flow structures around tandem cylinders were analyzed and the accuracy and reliability of PANS method were also verified. Moreover, the influence of the model parameter on numerical results was investigated and the performance of different types of PANS methods was assessed. Studies show that the unresolved-to-total ratio of turbulence kinetic energy has significant effects on the numerical results, and taking this parameter as a constant value throughout the whole computational domain can hardly tackle the complex flow problem. Furthermore, the parameter is made to change along with flow physical information and the local grid scale. The variable fk PANS method agrees well with the results from SST detached-eddy simulation (DES) and the experimental measurements, suggesting strong adaptability to complex turbulence simulation.
Control method for aircraft wake vortex based on Rayleigh-Ludwig instability
BAO Feng, LIU Jinsheng, ZHU Rui, JIANG Jianhua, WANG Junwei
2015, 41(8): 1381-1387. doi: 10.13700/j.bh.1001-5965.2014.0806
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The aircraft wake vortex is an inherent flow phenomenon due to the lift generation mechanism, which has a negative impact on the flight safety. By adding a set of specially designed spoiler, a rectangular wing was designed to generate a pair of weaker vortices, which had different sizes and opposite direction compared to main wing vortices, thereby constructing a self-destructive four-vortex wake system to induce Rayleigh-Ludwig instability. Under different experimental conditions, in terms of changing the size or shape of the spoiler, towing speed and angle of attack, the wake vortex development of the test model, that both with and without spoiler, as well as the circulation analysis, were acquired particle image velocimetry (PIV) measurements under the low Reynolds number. The study demonstrates that the decrease in circulation was 35% to 55% in 45 wingspans when spoilers are introduced, whereas the counterpart of the baseline airfoil, without spoilers, is nearly kept steadily, which reveal the application possibility of Rayleigh-Ludwig instability in alleviating the wake vortex. As the initial circulation ratio equals to -0.489 and the initial distance ratio is 0.5, the circulation of the primary vortex reduce most significantly (55.9%) in 45 wingspans. Results would provide a scheme in the design of airfoils with weaker vortices.
Radial displacement-sensorless control for bearingless induction motor
YANG Zebin, DONG Dawei, FAN Rong, SUN Xiaodong, JIN Ren
2015, 41(8): 1388-1395. doi: 10.13700/j.bh.1001-5965.2014.0779
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Aimed at rotor position identification of bearingless induction motor (BIM), a displacement-sensorless control scheme based on modified back electromotive force was proposed for the BIM. Firstly, to eliminate the flux observation error, on the basis of the back electromotive force (BEMF) method, the low pass filter was added to the flux observation model of radial suspension force winding. At the same time, the amplitude and phase deviation caused by the addition of low pass filter were compensated. Secondly, the modified flux observation model of radial suspension force winding was obtained and the rotor radial deviation was obtained according to the relationship equation between flux and displacement. Thus, the radial displacement self-detecting was achieved. Finally, a displacement-sensorless vector control system of the BIM was established using the presented position detection method. The simulation results show that the control system not only can accurately detect the rotor radial position, but also has good speed and torque characteristics. The further experimental results also show that the method had a good ability of radial displacement self-detecting. The BIM can realize stable suspension operation with displacement-sensorless.
Evaluation of network transmission performance in FC-AE-1553
FANG Liang, ZHAO Guangheng, CAO Suzhi
2015, 41(8): 1396-1402. doi: 10.13700/j.bh.1001-5965.2014.0569
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In order to improve the aerospace network transmission performance, a general network transmission efficiency calculation method based on FC-AE-1553 network was proposed and a FC-AE-1553 node card was designed. Firstly, a detailed message transmission process analysis based on FC-AE-1553 network was established, message types were analyzed, and transmission frame format proposals were given. By the time parameter analysis of all kinds of message transmission, combing the requirements of communication time in FC standard, the calculation formula of communication time was proposed in all kinds of FC-AE-1553 network exchange types. Then, calculation method of the network transmission efficiency was given according to two cases of the error free transmission and error transfer. Finally, through simulation and analysis of the effect of data frame payload length, node processing time, sequence number of exchange, transmission error rate, packet loss rate, and other parameters on transmission efficiency in FC-AE-1553 network, the design suggestions of optimizing the network were presented. Supported by an aerospace engineering task, a FC-AE-1553 node card was developed based on XC5VFX100T and MPC8536E. The experimental results indicate the packet loss rate influence on the transmission efficiency can be neglected, and the transmission efficiency is 77.2% when the data frame payload length is 2 048 B and the data frame number is 16.
TT-RMS: Communication table generation algorithm of time-triggered network
XU Xiaofei, CAO Chen, GUO Jun, LIU Zhongwei
2015, 41(8): 1403-1408. doi: 10.13700/j.bh.1001-5965.2014.0618
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According to the characteristic of communications in time-triggered network, which is data communication being triggered by a global clock, a rate monotonic scheduling (RMS) based time-triggered communication table generation algorithm was proposed, which was used to generate configurable communication schedule in the time-triggered network. The scheduling of message timeslots in time-trigger RMS (TT-RMS) algorithm included calculating link load by message period, sorting messages by RMS mechanism according to link load and message period, determining sequences of message transmission, and scheduling messages by timeslots, which optimized scheduling process. The time complexity of the TT-RMS was O(n2). And the space complexity was O(n). The time complexity of the widely used satisfiability modulo theories (SMT) method was polynomial, which did not converge sometimes. The experiment results show that to a single link, maximum bandwidth of the TT-RMS algorithm is approximate to 100% and the computing time is close to 1 millisecond. The average schedulable traffic bandwidth is twice of using SMT. The TT-RMS has better performances on computing time and schedulable traffic bandwidth, which could better satisfy the application of complex aeronautic and aerospace system which has thousands of real-time traffic in network.
Simulation analysis on oxygen partial pressure control of multi-cabin manned spacecraft
JIN Jian, XU Jin, HOU Yongqing
2015, 41(8): 1409-1415. doi: 10.13700/j.bh.1001-5965.2014.0565
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In order to ensure crew security, oxygen partial pressure of pressurized cabin should be controlled within index range using oxygen partial pressure control system. A mathematical model about oxygen partial pressure control system of multi-cabin manned spacecraft was proposed, including pressurized cabin, crew, oxygen makeup assemble, inter module ventilation (IMV) and other sub-modules. Through comparing with experiment results, veracity of the model was proved. Using this model, influence of different factors to oxygen partial pressure of manned spacecraft with two pressurized cabins all with the volume of 60 m3 was analyzed, including crew location, inter module ventilation and oxygen partial pressure monitoring mode. According to results, oxygen partial pressure peak value difference between two cabins could reach 2.2 kPa when crew of 6 stay in un-control cabin and IMV flux is 0.5 m3/min. Oxygen partial pressure difference between two cabins keep reducing as the inter module ventilation flux increasing. Monitoring mode has little effect to oxygen partial pressure of two cabins. When IMV flux is beyond 1.5 m3/min, the difference between one-cabin monitoring mode and two-cabin monitoring mode could be ignored.
Hierarchical control of engine-variable pump-variable motor drive system
ZHAO Lijun, WEI Yuying, LIU Qinghe, YIN Chengshun
2015, 41(8): 1416-1421. doi: 10.13700/j.bh.1001-5965.2014.0554
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To give full play to the working performance of engine and hydraulic system used for engineering vehicle and simultaneously increase its power transfer efficiency under dynamic working conditions, the control strategy for engine-variable pump-variable motor (three-variable) series hydraulic drive system was researched. The parameters of various components in this system were analyzed and matched to determine the rated working conditions of each link. An adaptive hierarchical control strategy was adopted, and then the operating points of engine, variable pump and variable motor can be adjusted actively to match the power of engine and load relying on the maximization of system efficiency for a given working condition. Then the backward-facing simulation model of this system was established in MATLAB/Simulink. The simulation results show that the above control strategy can effectively ensure the high power transfer efficiency and the engine working conditions can be optimized to reduce engine oil consumption.
ICT distribution-based contact model for delay tolerant networks
WANG Haiquan, MA Weijian, GU Juanjuan, LIU Dan, WANG Ya
2015, 41(8): 1422-1429. doi: 10.13700/j.bh.1001-5965.2014.0557
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Characteristics of inter contact time (ICT) are essential for delay tolerant networks (DTNs), which are beneficial to network performance analysis, routing protocol design and algorithm optimization, but existing ICT models lack general applicability. Based on the general assumptions, a reliability mathematical model was proposed, which is called ICT distribution-based contact model (IDCM), to demonstrate that the ICT between two mobile nodes was exponentially distributed and to verify that the exponential parameter of node pairs only related to the historical contact numbers and cumulative ICTs. Based on random direction (RD) mobility model dataset, random way point (RWP) mobility model dataset, Beijing taxi network dataset, pocket switch network dataset, extensive experimental simulations were conducted and comparison to parameter-aggregated exponential model was made. The simulation results show that IDCM characterizes contacts of node pairs accurately and have better accuracy than parameter-aggregated exponential model.
Design of tensile device of nanomaterials and quantitative analysis
YUE Yonghai, GONG Qihua, FAN Yuzun, KANG Jianxin, ZHAO Hewei, ZHANG Dongfeng
2015, 41(8): 1430-1434. doi: 10.13700/j.bh.1001-5965.2014.0608
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Based on a piezoelectric ceramic, a new experimental device was designed which could be used to conduct the in-situ tensile deformation test for one dimensional nanomaterials. A cantilever tip, which was used to measure the force, was also introduced to do the quantitative measurements during the mechanical properties experiments of nanomaterials, the force loaded to the sample can be calculated via the deformation of the cantilever tip. With this homemade in-situ nanomaterials tensile device, in-situ tensile experiments under both optical microscopy and scanning electron microscopy of single SiO2 nanowires prepared by thermal evaporation method were conducted. The experimental results indicate that this device can conduct the tensile deformation test effectively and give the quantitative result of the force signal loaded to the material sample itself at the same time.
Preparation of thermoelectric thin film material and numerical simulation of cooler
ZHU Wei, DENG Yuan, WANG Yao, GAO Hongli, HU Shaoxiong
2015, 41(8): 1435-1442. doi: 10.13700/j.bh.1001-5965.2014.0579
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Low dimensional thermoelectric materials and the trend of miniaturization of devices as well as the application in the field of aerospace were discussed. Then the thermoelectric thin film material was fabricated on the polymide (PI) flexible substrate using magnetron sputtering method. The microstructure and property of thin film materials were characterized. The results show that the P-type Bi-Sb-Te and N-type Bi-Te-Se all have a preferential growth of (015) plane. The numerical simulation was also conducted on the in-plane thin film thermoelectric cooler by ANSYS finite element simulation software. The effect of working current and material physical property parameter on the cooling performance was discussed. It reveals that increasing the thermal resistance of substrate in plane by the decrease of thermal conductivity and thickness benefits the directional thermal flow along the thermoelectric legs. Besides, the hollowed design of substrate and the introduction of high thermal conductive layer in cooling area facilitate the establishment of cooling temperature difference and the uniform cooling in the cooling area. These results provide guidance for the preparation of thin film devices.
Effects of operating pressure on high-speed projectile's water-entry flow
CHEN Chen, MA Qingpeng, WEI Yingjie, WANG Cong
2015, 41(8): 1443-1450. doi: 10.13700/j.bh.1001-5965.2014.0594
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In order to research the effects of operating pressure on the projectile's water-entry flow, numerical simulation for process of the high-speed water-entry induced by the cylinder body with a cone head was performed in the way of volume of fluid (VOF) model. Results of the velocity, depth and cavity shape of projectile were achieved and contrasted with the theoretical results obtained by Newton's second law of motion and the literature to verify the correctness of the numerical simulation method. Based on the method, processes with a series of operating pressure were analyzed. Results show that the effects of operating pressure on the phenomena, such as the spatter above the free liquid surface, the cavity surface closure time and the cavitation inside the cavity are great. With the operating pressure being higher, the cavity diameter near the free surface becomes smaller; the cavitation inside is more marked; the time for surface closure happens earlier.
Approach to analyzing AADL end-to-end flow latency based on timed automata
LIAN Xiaoli, ZHANG Li
2015, 41(8): 1451-1463. doi: 10.13700/j.bh.1001-5965.2014.0615
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End-to-end flow latency analysis of complex embedded system is an effective way to assess system's real-time performance. Architecture analysis and design language (AADL) is the standard language to specify the architecture of complex embedded system, end-to-end flow of which describes the components' interaction. At present, most manual latency analysis approaches could consider flow's precise semantics. However, the efficiency of this time consuming analysis is low; although automatic methods have better efficiency, the accuracy is not satisfying because of the low coverage of delay-contribution attributes. What's more, both kinds of methods only focus on the typical interactive situations such as the worst-latency analysis. The impact of design elements resulting in uncertainty cannot be analyzed. Thus, one approach to analyzing AADL end-to-end flow latency based on timed automata model was proposed. First, latency-contributed attributes meta-model of flow was constructed to improve the coverage of latency-contributed attributes. Then the transformation from AADL end-to-end flow to timed automata model was studied. Latency analyzing was performed through simulating the timed automata model. Finally, the experiments based on one case study demonstrate that our way can precisely model the transportation semantics and the latency attributes semantics of a flow, illustrating our way's sufficient expressive competence. Additionally, the experiments also show flexible analysis ability of our approach by dealing with the various interactive scenarios and even the random time factors in the transportation of information. Meanwhile, the state transition and the changing on the time factors provide a basis and suggestions for the further improvement of the original AADL model.
Steady glide trajectory planning method for hypersonic reentry vehicle
HU Jinchuan, CHEN Wanchun
2015, 41(8): 1464-1475. doi: 10.13700/j.bh.1001-5965.2014.0023
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The concept of steady glide trajectory with minimum integration of the change rate of longitudinal acceleration was proposed for the equilibrium glide problem with given angle of attack and bank angle profiles, and the planning method of the steady glide trajectory was described. First, the dynamic differential equation in the altitude direction was solved by regular perturbation, and steady glide analytical solutions with high precision, including height, flight path angle and longitudinal acceleration, were obtained. Then the dynamic behaviors of the steady glide trajectory were analyzed, the natural stability and low damping of the trajectory were found, and the expressions of natural frequency and damping were obtained. The results show that the natural frequency is only a function of velocity, while the damping depends on velocity and longitudinal lift-drag ratio. Finally, the pure differential feedback of height deviation is found to be the best scheme for restraining the oscillations of the steady glide trajectory among three feedback schemes, which are pure differential feedback, pure proportional feedback and proportion-differential feedback. The simulation results show that the control of the pure differential feedback scheme is steady, the trajectory oscillation decay fast, and the robustness of the scheme is excellent.
Heterogeneous data sharing technology based on two-layer metadata and ontology
LI Xiaotao, HU Xiaohui, LI Binquan
2015, 41(8): 1476-1484. doi: 10.13700/j.bh.1001-5965.2014.0568
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With the aim to share multi-sourced, multi-class, heterogeneous data simultaneously, an information sharing technology was proposed based on a two-layer metadata combined with ontology. Firstly, the structure of the two-layer metadata standard was analyzed. At the same time, how to implement uniform description for heterogeneous data was introduced. Secondly, due to the lack of semantic information, some important potential correlations between metadata classes may be ignored. For this reason ontology was established on the metadata layer for describing and reasoning the relationships between classes. Finally, in order to improve the recall rate and optimize the retrieval time, an improved method combining Lucene full-text search engine with SPARQL query was proposed to retrieve metadata. SPARQL retrieval was performed before the keyword queried by Lucene. Soccer match information of 2014-2015 UEFA Champions League was selected as test data. The experiment results illustrate the effectiveness on sharing heterogeneous data and improvement on recall and timeliness of the approach.
H2O impact on CO2 removal performance of 5A molecular sieve in space station
YANG Dongsheng, LIU Meng, PANG Liping, YU Qingni, HUANG Yong
2015, 41(8): 1485-1491. doi: 10.13700/j.bh.1001-5965.2014.0580
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For the further research on reliability and robustness of molecular sieve CO2 removal system applied to the space station, the problem of the humidity failure protection of 4-bed molecular sieves (4-BMS) system in the space station was proposed and studied. The experiment was set up to test the impact of the CO2 absorbing capacity under different relative humidity of gas in two kinds of molecular sieves (TC-5A and PSA-5A) for crewed space mission. Meanwhile, it compared the effect of CO2 adsorption when CO2 concentration of inlet gas, particles and temperature changed under the definite humidity, and explored the competitive adsorption between CO2 and H2O in TC-5A and PSA-5A using different measures. Results show that the PSA-5A has a better performance on CO2 adsorption, but slightly less than TC-5A on H2O adsorption capacity. And presence of H2O in the air had a great influence on molecular sieve adsorption of CO2, when the relative humidity reached the 60%, the molecular sieve has basically lose the CO2 adsorption capacity. Besides, the TC-5A and the PSA-5A CO2 adsorption capacity drop significantly when the temperature rises, but has a relatively less impact on H2O adsorption, especially when RH is high. The experimental study can play a guiding role in evaluation of system reliability and robustness for the long-term orbiting space station study.
1D-consolidation analysis based on UH model considering time effect
HU Jing, YAO Yangping
2015, 41(8): 1492-1498. doi: 10.13700/j.bh.1001-5965.2014.0583
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The soil stress-strain relationship under 1D consolidation condition was derived from the unified hardening (UH) model considering time effect. Based on this, a governing differential equation of 1D consolidation was established, which could simultaneously describe the deformation behavior of both primary and secondary consolidation. The one direction drainage consolidation problem was analyzed by the differential method. Since there is the phenomenon of relaxation that the effective stress pressure near the impermeable layer would decrease during the initiation of loading, a formula that can reflect the decrease of effective stress by time was deduced. Then, numerical analysis of the influence of secondary consolidation parameter, over consolidation ratio and the consolidation and swelling index was made and the results prove the conclusion of the formula. Besides, the laboratory tests were used to confirm the numerical prediction results of the governing equation. Depending on the condition that when the primary consolidation was almost finished, the main deformation was produced by secondary consolidation, a relationship between average degree of consolidation and time was deduced, which could be used to predict the time when primary consolidation would be finished.
Application of BN nanosheets as atom-oxygen corrosion resistant fillers
YI Min, SHEN Zhigang, LIU Lei, LIANG Shuaishuai, WANG Shuai
2015, 41(8): 1499-1504. doi: 10.13700/j.bh.1001-5965.2014.0598
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The application of boron nitride nanosheets (BNNS) as fillers to enhance the polymer's atom-oxygen corrosion resistance was investigated. Stable BNNS dispersions in polyvinylalcohol (PVA) solutions were prepared by liquid-phase exfoliation. By using a centrifugation-based size-select route, BNNS with three kinds of different lateral sizes were obtained. Their average area was about 21.4, 4.1, 1.0 μm2, respectively. The PVA/BNNS composite films were prepared by casting the PVA/BNNS dispersions. Atom-oxygen corrosion experiments indicate that all these BNNSs can enhance the atom-oxygen corrosion resistance of PVA. An addition of 1.0wt% BNNS (21.4 μm2) can lead to a reduction of 87% in PVA's mass loss. It is suggested that the bonding and barrier effects between atom oxygen and BNNS are responsible for the enhanced atom-oxygen corrosion resistance.
Method of confirming testability verification test scheme based on prior information
ZHANG Xishan, HUANG Kaoli, YAN Pengcheng, SUN Jiangsheng, LIAN Guangyao, WANG Shaoguang
2015, 41(8): 1505-1512. doi: 10.13700/j.bh.1001-5965.2014.0628
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Existing testability verification test schemes need a large number of fault samples and the engineering implementation is difficult. To solve this problem, the Bayes testability verification test scheme was proposed based on the prior information for complex equipment. Firstly, the uncertainty of testability prior information was described using Beta distribution and the prior distribution hyper-parameter was determined by the prior information from different sources. Then, the uncertainty measure and supporting degree were proposed as the weight coefficient of prior information, and the corresponded fusion algorithm was designed. Finally, the Bayes decision model was estabilished for the testability qualification test scheme of the binomial equipments using the fused prior information. Compared with the classical counterpart, the new test scheme reduces the fault sample size by up to 40% or so, and avoids the aggressive of the traditional Bayes testability verification test scheme.
Experimental analysis of wall quenching distance of a premixed Bunsen flame
HUANG Xia, HUANG Yong
2015, 41(8): 1513-1519. doi: 10.13700/j.bh.1001-5965.2014.0821
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Quenching distance is a major parameter to characterize the flame wall quenching effect. The quenching distance of a methane-air premixed Bunsen flame was measured using direct photography of the flame position. The result indicates that the quenching distance changes differently with the incoming flow velocity under different equivalence ratio ranges. While the velocity is fixed, the quenching distance decreases with the increasing equivalence ratio for the lean flame. For the rich flame the quenching distance first increases and then decreases, and keeps a constant after a certain equivalence ratio. This correlation is induced by the competition between the cooling of the wall by incoming flow and the heating of the wall by flame. The double-flame structure of a premixed rich flame especially influences the wall quenching effect very remarkably.
Accelerated testing for data integrity of Ad hoc network in complex environment
ZHANG Nan, LI Ruiying, HUANG Ning
2015, 41(8): 1520-1525. doi: 10.13700/j.bh.1001-5965.2014.0612
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In order to evaluate the data integrity of Ad hoc network under its mission scenarios in an efficient way, an accelerated testing method was proposed. The similarity models for the key parameters of data integrity, i.e. the effective signal-to-noise ratio, the traffic and the moving speed, were derived based on the similarity theory, which finally composed the similarity model of data integrity. The case study on a relief Ad hoc network verified the effectiveness of the similarity model based on OPNET simulation tools. The results show that the error between the original network and the similar one is very small, and the effectiveness of the similarity model does not change with the failure threshold, stress increase times and the topological structure.
Application of differential quadrature and precise integration methods in analysis of transient heat transfer
JIN Jing, XING Yufeng, LIAO Xuanping, ZHANG Hairui, TANG Nianhua
2015, 41(8): 1526-1531. doi: 10.13700/j.bh.1001-5965.2014.0626
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An accurate and efficient solution method of the governing equation of transient heat transfer was proposed based on the differential quadrature method (DQM) and precise integration method (PIM). DQM was applied to discretize spatial domain while PIM to temporal domain. It has been shown that DQM, with high accuracy and efficiency, also had higher flexibility than the finite element method (FEM) while dealing with complicated boundary conditions. The transient heat transfer is governed by the first-order differential equation with respect to time,while applying precise integration method in temporal domain,the same accuracy as computer can be achieved without increasing additional degrees of freedom. Numerical results were given for four kinds of boundary conditions of thermal protection structure. Then, the numerical result of the structure with constant temperature on top surface and heat insulation on other surfaces was compared with the result using the FEM. The numerical examples analysis shows that the higher precision can be achieved with fewer nodes by DQM and PIM.
Structural parameter calibration method for multiple field of view star tracker
SUN Li, JIANG Jie, LI Jian, JI Feilong
2015, 41(8): 1532-1538. doi: 10.13700/j.bh.1001-5965.2014.0575
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Based on rotation-invariant star-pair angular distances, a calibration algorithm was proposed to calibrate structural parameters of multiple field of view (FOV) star tracker. With the rotation relationships of each subfield of view were described by three Euler angels, the calibration scheme and objective function were generated by some starlight vectors of star pairs, which were obtained from the image coordinates and the corresponding celestial coordinates of observed star points. Levenberg-Marquardt (L-M) algorithm optimized the objective function and provided the relative Euler angles of each sub FOV. External attitude-measurement devices are not necessary, and the method can be used for on-obit and ground calibrations. Several attitudes were randomly selected to create star images used for calibration in the celestial sphere, then the inter star-angle statistical residual was chosen as an evaluation standard for accuracy calibration. The results show that this method is effective to calculate the accurate structural parameters. Under the positional noise level of 0.1 pixel, the inter star-angle statistical residual can reach 1.3 arc sec on average, and it can reach 6.4 arc sec on average when the method is used in outdoor experiments.
Nonlinear equivalent circuit analysis of electro-impulse de-icing system
Chen Peng, Ge Hongjuan, Ni Yiyang, Xu Yuanyuan
2015, 41(8): 1539-1545. doi: 10.13700/j.bh.1001-5965.2014.0578
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In order to design the circuit of the electro-impulse de-icing system more effectively, nonlinear equivalent load of the electro-impulse de-icing (EIDI) system was analyzed by the law of conservation of energy which was on behalf of the vibrational energy, and nonlinear equivalent circuit model related to the system parameter was established. A three-dimensional transient electromagnetic field simulation model for modeling the axisymmetric ring-type pulsed coil was presented, which based on finite element simulation software ANSOFT Maxwell, and the normal electromagnetic force expression during the complete deicing cycle was obtained by numerical fitting method; the aluminum plate deformation expression was computed which induced by the normal electromagnetic force, and the work done by the electromagnetic force was analyzed. The circuit parameter in the different coil-aluminum-plate gap was designed by using nonlinear equivalent circuit model.This parameter is consistent with experiment parameters, which verifies the correctness of the method and provides the theoretical basis for the EIDI system.
Numerical simulation and performance analysis of leaf seal
LIU Jian, WANG Zhili, DING Lei
2015, 41(8): 1546-1552. doi: 10.13700/j.bh.1001-5965.2014.0593
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In order to obtain the result of pressure and velocity distribution and leakage of the leaf seal system which is applied to high-speed rotor, a mathematical model of sealing zone flow field calculated numerically with SIMPLER method and finite difference method was established. A software based on the algorithm referred was also designed specially for the performance analysis of leaf seal system. The influence of different structure parameters and working conditions on the system's performance was discussed. Analysis result shows that the leakage increases linearly with the sealing pressure and decreases slightly with the increase of rotor speed. Increasing width, reducing spacing between front/back cover plate to rotor and decreasing length are beneficial in decreasing the leakage of the system. While changing installation angle direction of the leaf has little influence on leakage. Research on dynamic response between leaf and rotor will be carried out based on the results of the flow field.
Characteristic of air jet impingement cooling performance for electronic equipment of satellite
LIU Liangtang, WANG Anliang
2015, 41(8): 1553-1559. doi: 10.13700/j.bh.1001-5965.2014.0596
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Abstract:
On the base of the preparative stage of ventilation control system design for high power electronic equipment of satellite during ground tests, the study on optimization design of the cooling performance was done, and the numerical simulation was carried out on air jet impingement cooling system with different structural parameters. Results show that the diameter of nozzle, the distance between nozzle and heat surface, the air jet inclination angle and jet velocity directly affect the performance of the cooling system. And the optimization design results on the quantitative non dimensional parameters are analyzed. The study can be used to optimize heat dissipation for electronic equipment with a heat-flux density of about 1 kW/m2, and provide a reference for convection thermal control system design and ground tests for high-power electric equipment of satellite.
Products early failure rate evaluation based on process information fusion
ZHANG Chuanliang, DAI Wei, LIANG Peidong, ZHAO Yu
2015, 41(8): 1560-1566. doi: 10.13700/j.bh.1001-5965.2014.0604
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Abstract:
To select the appropriate technology, the assessment of early failure rate of product was carried out. To make full use of multi-source information to evaluate the early failure rate of the product in quick response manufacturing mode, an assessment method based on process information fusion was put forward. Firstly, the model of early failure rate was established and the method of parameter estimation was provided. Secondly, based on the analyzing of the forming process of product reliability, the reasonable source that influenced the early failure rate of products in the manufacturing process was determined. And then, by comparing the similar degree of current processing finished products and similar products, different prior distributions were determined. Finally, the fused distribution of the failure rate was determined based on the information entropy. And the case study on reliability evaluation of radar phase-shift unit is demonstrated to prove the feasibility and effectiveness of the proposed method.

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