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2012 Vol. 38, No. 10

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Calculation of wing-body junction flow using Gao-Yong turbulence equations
Gao Ge, Jiang Lijun, Gao Lin
2012, 38(10): 1271-1274.
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The derivation of Gao-Yong turbulence equations was based on a partial statistical average scheme proposed in the past by the first author in an attempt to capture the drift flow, a first-order statistical moment of turbulent fluctuations. Continuity and momentum equations of turbulent fluctuations were obtained as a result of this valuable first statistical information. Orthotropic turbulence and momentum transfer chain were formulated in the modeling of correlation terms, eventually, led to a complete set of equations of turbulent flow with no empirical coefficients and wall functions. Numerical simulations in the past preliminarily verified the adaptability of Gao-Yong equations to a wide range of complex benchmark turbulent flows. In order to further application of these equations to engineering flows, the Gao-Yong turbulence equations were implemented into OpenFOAM and applied to the calculation of wing-body junction flow. The wing-body junction flow involves very complex feathers, such as a 3-D separation and a horseshoe vortex. The results of numerical simulation of this flow compared to experimental data show that all these main characteristics have been captured, both qualitatively and quantitatively.
Linear regression analysis for normal distribution-valued data based on complete information
Wang Huiwen, Li Nan
2012, 38(10): 1275-1279.
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In light of normal distribution-valued symbolic data, a new method for building linear regression model was proposed. To reflect all the original information of the normal distribution-valued data, definition and calculation principle were proposed for first moments, second original moment and second mixed original moment of normal distribution-valued variables. On this basis, linear regression model for normal distribution-valued data and the sum of squares of the residual information were defined and least-squares regression coefficients were derived. Simulation results show that the explanatory power and predictive ability of the regression model derived by the proposed method are effective and outperform the "Centre Method". The definition and calculation principle of numerical characteristics laid the foundation for extending the other classical multivariate statistical method to distribution-valued data.
Experiments of contact stiffness and fretting wear on coating material of blade shroud
Hong Jie, Yang Xin, Chen Lulu, Zhang Dayi
2012, 38(10): 1280-1284.
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The experimental facilities, which could be used to measure the hysteresis curve caused by fretting during contact surface, were adopted in order to test the contact stiffness and fretting wear of the test pieces with the coating material under different contact styles. The contact stiffness test results indicate the impact of vibration force amplitude and frequency as well as contact pressure on the contact stiffness; the fretting wear test results manifest the influence on the contact stiffness when contact styles and loading conditions on the contact surface vary under different working hours. After analyzing the test results, the protective measures against fretting wear of dry friction damping structures were proposed, contributing to enhance the aero-engine reliability and offer the theoretical basis and technical support.
Evaluating SEU effects in SRAM-based FPGA with bit-by-bit upset fault injection
Song Ningfang, Qin Jiaomei, Pan Xiong, Jiang Yuntian
2012, 38(10): 1285-1289.
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Static random access memory (SRAM)-based field programmable gate arrays (FPGAs) are extremely sensitive to single event upsets (SEUs) induced by radiation particles. In order to evaluate the dependability of the obtained designs, a bit-by-bit upset fault injection methodology based on run-time reconfiguration was proposed. The methodology can detect the sensitive bits in various logic designs. The configuration memories’ dynamic cross section, failure rate and reliability change curve can be counted with the number of sensitive bits. The reliability parameters and curves of triple modular redundancy (TMR) multiplier and non-TMR multiplier were obtained with this method, and the correctness of sensitive bits was validated.
Localized adaptive control for a class of MIMO nonlinear systems
Zheng Hong, Liu Dong, Guo Jun, Dong Xinmin
2012, 38(10): 1290-1294.
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Localized robust adaptive control was proposed for a class of uncertain multiple-input-multiple-output nonlinear systems. The proposed method used command filtering backstepping method to design virtual control law. Localized approximators were used to approximate unknown functions online. Spectral radius introduction avoided the assumption that the control coefficient matrix estimation must be nonsingular. The inherent approximation errors and external disturbances were compensated by adaptive bounding control. Localized σ-modification guaranteed boundedness of bounding parameter estimation and overcame the global forgetting. It was proved that the proposed control method can guarantee boundedness of all signals in the closed-loop system. Simulation examples demonstrated the effectiveness of the proposed method.
Method of MSPC fault detection and diagnosis based on variable contributions
Du Fuzhou, Tang Xiaoqing
2012, 38(10): 1295-1299.
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Fault detection and diagnosis is one of the key technologies on the effective application of multivariate statistical process control(MSPC). In order to overcome the historical fault information using shortage, considering the influence of principal components variable contributions and the reconstructive errors, the synthetical variable contributions were calculated by normalizing and summing these two different variable contributions. A novel MSPC fault detection and diagnosis method was proposed based on the integrated variable contributions, and the relevant algorithm and program were presented and implemented. A case study was illustrated through the Tennessee Eastman challenge process simulation platform. The experimental results demonstrate that the proposed method is feasible and valid.
Fault prediction for aircraft control surface damage based on SMO-SVR
Dong Lei, Ren Zhang, Li Qingdong
2012, 38(10): 1300-1305.
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In order to predict changes more accurately when the surface of aircraft damaged, an algorithm based on improved sequential minimal optimization support vector regression (SMO-SVR) was presented. This algorithm reconstructed the phase space of multivariate and nonlinear time series using improved C-C average method to determine the embedding dimension m and the delay time τd. Then, a weighted SVR model was built according to m and τd, and in which the halt criterion of SMO was modified. The parameters of SVR were optimized by interval adaptive particle swarm optimization (IAPSO) to improve the efficiency of parameter optimization. In order to verify the validity of the algorithm, the prediction and analysis of surface damage trend were performed. Comparing with the radial basis function neural network (RBFNN) method, the simulation result demonstrates that the improved SMO-SVR prediction model has good predictive ability.
Elastic effects on flight mechanics of waverider
Xiang Jinwu, Zeng Kaichun, Nie Lu
2012, 38(10): 1306-1310.
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The impact of structural elasticity on the static properties and dynamic stability of a typical air-breathing hypersonic vehicle was investigated. An integrated aeropropulsive/aeroelastic model was developed for the longitudinal dynamics of hypersonic vehicles, with local piston theory for unsteady aerodynamics. A comparative analysis of level-flight trim control, trimmable region, open-loop poles and non-minimum phase zeros was performed when the fuselage was subjected to different bending stiffness. The results show that the structural elasticity has a significant influence on the flight mechanics of hypersonic waverider. The elevator operation mode of vehicles with flexible fuselage is reversed in high Mach number zone. As the fuselage bending stiffness decreases, the lift-drag ratio drops and dynamic stability deteriorates.
Pulsed electron beam welding grid power supply design
Qi Bojin, Xu Guoning, Liu Fangjun, Xiao Pan
2012, 38(10): 1311-1316.
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A new pulsed electron beam welding grid power supply was developed, which includes gridbias base circuit and gridbias pulse circuit. The power supply can produce both direct current gridbias and pulse gridbias, in another word, it can realize not only direct current electron beam welding but also pulsed beam welding at one equipment. The gridbias base circuit controls gridbias pulse base, while the gridbias pulse circuit controls gridbias pulse peak, gridbias pulse frequency and gridbias duty ratio. The pulsed electron beam welding grid power supply can realize beam current pulsed welding, at the same time, gridbias pulse frequency, pulse duty ratio, pulse base value and pulse peak value can be adjusted continuously, and beam current pulse frequency and pulse base value can be adjusted correspondingly. The test proves that the pulsed electron beam welding impulsion effect made electron beam welding keyhole effect much more evident than direct current beam welding at the same beam current.
Feature extraction method based on multifractal parameters for hyperspectral imagery
Zhao Huijie, Cai Hui, Li Na
2012, 38(10): 1317-1320.
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Multi-fractal parameter extraction method based on spectral probability measurement was proposed to resolve the problem that the local absorption characteristics of hyperspectral data can not be described by the single fractal dimension. The method of spectral information measurement was used to calculate the spectral probability. The scaling function was estimated with the partition function. The differential coefficient of scaling function was calculated to obtain Holder exponent, and the multi-fractal spectrum was computed with Legendre transformation of scaling function. Four multi-fractal parameters can be extracted from multi-fractal spectrum and Holder exponent. The minimum Euclidean distance rule with the characteristic extraction based on multi-fractal parameters was applied to hyperspectral image supervised classification. The hyperspectral image was collected by airborne push-broom hyperspectral imager (PHI). The applied results show that the efficiency and reliability of the proposed method and its classification accuracy are about 94.789%, which is better than the classification accuracy of information fractal dimension and multi-fractal spectrum.
Balanced external gust loads computation and analysis for elastic aircraft
Yan De, Yang Chao, Xiao Zhipeng
2012, 38(10): 1321-1325.
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Continuous turbulence is one of gust models for gust loads analysis needed in various aviation regulations. But there exit some difficulties when the loads induced by continuous turbulence applied to aircraft structural design. Based on stationary random process assumption, utilizing power spectral density (PSD) method and von Karman continuous turbulence model, external gust loads were obtained by using force summation method. An approach was presented by introducing correlations and multiple sets of external load distributions due to continuous turbulence was generated. The results from an elastic aircraft encountering vertical continuous turbulence demonstrate that the external gust load distributions are strictly in banlance. These load distributions can be applied to structural stress analysis or design when the design conditions are identified through load envelope concept which is frequently applied in maneuvering flight loads analysis.
FED:high performance industrial fieldbus based on Ethernet devices
Hu Xing, Huan Ji, Liu Zhe
2012, 38(10): 1326-1330.
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A kind of high-speed real-time fieldbus used in automation equipment named fieldbus based on Ethernet devices(FED) was studied. FED is based on Ethernet components and FPGA chip. System on chip(SOC) technology was used to develop a kind of practical FED device. Without complex driver, media access control layer communication was realized. The application layer protocol can be designed for different control tasks. FED performs at 100 Mbit/s on summation frame and employs "data operation on fly" technology. Master-slave structure is used in FED which supports one master and 255 slaves. The prototype system proves that FED can meet the high-speed and real-time requirement of industrial automation equipment.
Six-position rotation rate calibration and piecewise linear interpolation compensation for INS in full temperatures
Li Jianli, Fang Jiancheng, Ma Yanhai, Cheng Junchao
2012, 38(10): 1331-1335.
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For decreasing measurement error of inertial navigation system(INS), a novel scheme was proposed in which a six-position rotation calibration and piecewise linear interpolation compensation in full temperatures. A six-position rotation rate calibration experiment was implemented in a series of constant temperature. Moreover, a piecewise linear interpolation algorithm was used to compensate for bias and scale factor temperature errors of gyroscopes and accelerometers, and to improve the measurement precision of INS. The experimental results show that the inertial navigation average errors are reduced to 0.393 n mile/h and 0.681 n mile/h from 1.501 n mile/h and 5.811 n mile/h for vehicle and airborne experiments. The proposed method is helpful to further improving image resolution of synthetic aperture radar (SAR).
Pressure sensing valve plate mechanism for ripple reduction of variable pressure piston pump
Huang Bochao, Wang Shaoping
2012, 38(10): 1336-1340.
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The silencing structure of the valve plate is the most effective approach to reduce the pressure ripple in the hydraulic system via reducing the source flow ripple. To endue the piston pump with self-adaptability at the operating pressures over a wide range, a novel pressure sensing silencing structure based on the hole-groove combination was developed for the valve plate. A one-way throttle valve, with its opening in conformity to the operating pressure, was inserted into the passageway between the communication hole and the delivery port to obtain required pre-pressurization (pre-relief) characteristic. A novel pressure sensing silencing valve plate was designed and optimized, and a simulation model of the novel valve plate was produced. The simulation results demonstrate that the novel valve plate achieves an obvious silencing effect and excellent self-adaptability under the condition of variable operating pressures, and its reduced value of pressure ripple is up to 27.7% over that of traditional valve plate with V-type relief groove.
Orthogonal test on environmental effects of fatigue life of CFRP composite laminates
Sun Chongqiang, Zhang Jianyu, Fei Binjun
2012, 38(10): 1341-1345.
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In order to research the environmental effects on fatigue performance of CFRP composite laminates, an orthogonal test was carried out for T300/QY8911 composite laminates. Standard specimens were prepared and then the tension fatigue life was tested in the given condition. To obtain the significance of the environmental effects such as coating, ultraviolet, humidity and their interactions on the tension fatigue life of T300/QY8911 composite laminates, the variance analysis method was applied. The results indicate that the environments of coating have highly significant effect on the fatigue life of the composite laminates. The environments of ultraviolet, interaction of coating and humidity have significant effect on the fatigue life of the composite laminates. Humidity, interaction of coating and ultraviolet, interaction of ultraviolet and humidity have no significant effect on the fatigue life of the composite laminates.
Ascent trajectory optimization for stratospheric airships with thermal effects
Guo Xiao, Zhu Ming, Wu Zhe
2012, 38(10): 1346-1351.
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In respect for ascent trajectory optimization of stratospheric airship, a research was conducted with the thermal effects. Basic thermal characteristics of the stratospheric airship and the energy equations about the ship film and the internal gas were introduced. Besides, the equations of motion for the airship were described in detail. To minimum the flight time, a trajectory optimization problem was constructed and then converted into a parameter optimization problem by a direct collocation method. In different scenarios, the optimal trajectories were developed by a numerical nonlinear solver, sparse nonlinear optimizer (SNOPT). It shows that the solutions are greatly affected by the thermal behaviors. Solar irradiation is the most important factor during ascent, and in addition, the natural wind also affects the thermal transfer of convection.
Locating variable message signs under ATIS environment
Lu Xiaoshan, Huang Haijun, Shang Huayan
2012, 38(10): 1352-1357.
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The variable message signs (VMS) location problem under the advanced traveler information system (ATIS) environment was studied using the link transmission model. A method for estimating link travel times was proposed for serving the information release of ATIS. Simulation results show that there exists a critical value about the ATIS market penetration. The VMS should be located more away from the intersection with the increase of the ATIS market penetration when the penetration is less than the critical value, closer to the intersection otherwise. It is also shown that the total congestion delay of the system can be further reduced if determining the VMS location with consideration of the ATIS market penetration. This method can help well understand the drivers’ route choice behavior under multiple traffic information and evaluate the impact of VMS location on system performance.
Impact analysis on frequency hopping to carrier tracking precision in DS/FH hybrid spread spectrum receiver
Zhan Wei, Zhang Xiaolin, Chang Xiaoming, Meng Bochao
2012, 38(10): 1358-1362.
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Facing the increasingly complex electromagnetic environment, it is an attempt to introduce DS/FH hybrid spread spectrum technology to the field of TT&C. According to the characteristics of DS/FH signal, mathematical model of several key nodes in DS/FH hybrid spread spectrum receiver was derived in the context of TT&C. Effect to acquisition and tracking in the hybrid spread spectrum receiver caused by hopped Doppler frequency and initial carrier phase transition attached to the carrier brought by adjacent hopped frequency’s difference was analyzed, especially effect to carrier tracking precision. A method to lower the accumulated energy loss caused by initial carrier phase uncertainty of hopped carrier was proposed. The receiver employed hopping pattern to reduce the impact of hopped frequency to tracking precision in the DS/FH hybrid spread spectrum receiver, and the effectiveness of the method was verified through simulation.
Modeling and collaborative optimization of remote sensing satellite system parameters design
Wu Wenrui, Huang Hai, Wu Beibei
2012, 38(10): 1363-1368.
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Focusing on system design problem of remote sensing satellite, optimization problem with comprehensive objective combined by coverage width, ground sample distance and total mass was set up. Considering subsystems of guidance, navigation and control (GNC), power, structure and thermal control (TCS) and sorting the coupled relationship between them, multidisciplinary design optimization (MDO) model based on collaborative optimization (CO) method architecture was established and solved with penalty function method. Compatible results of improved performance were obtained. The rationality of the model and the efficiency of MDO method applying to satellite system design were verified. The analysis models of the subsystems and employed solving method can be referenced by engineering application of MDO method.
Modeling of electromagnetic environment and radiation distribution analysis for aircraft approaching and landing
Wang Lei, Su Donglin, Xie Shuguo, Zhao Zihua
2012, 38(10): 1369-1374.
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Electromagnetic field, terrain and obstacle are three vital elements which constitute electromagnetic environment in aerodrome terminal. Because of their inhomogeneity in topology, physics and semanteme, it is difficult to express the characteristic of the electromagnetic environment for aircraft approaching and landing with determined model. Based on the attribute of hierarchy and the coupling interrelation of those three elements, a multi-layer fused electromagnetic environment model frame for aerodrome terminal was put forward. In order to reduce the computation error induced by the non-regulation boundary variation of electromagnetic field, a combination of method of moment(MoM) and ray tracing methods was used to simulate the radiation pattern and wave propagation, and radiation intensity expression and distribution computation flow in approaching and landing area were described. Simulation experiment of the radiation computation in approaching area based on one aerodrome dataset shows the validity of the modeling method.
Cell-center ADT algorithm based on ghost cell
Yuan Wu, Yan Chao, Yu Jian, Du Ruofan
2012, 38(10): 1375-1379.
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For the point search problem in Chimera gird generation, an alternating digital tree(ADT) method based on ghost cells was presented, which operated directly on the cell-centered grid system. The problem caused by the covering area incompleteness of cell-centered grids when constituting ADT data structure can be avoided by introducing ghost cells through extension of the original grid. The result of ADT searching with this method is a list of cell-centered cells, which can be directly traversed to obtain the exact donor cell. Therefore, the Stencil Walk method can be omitted. The use of ghost cells makes point search procedures near the boundary more flexible, providing exact information of donor cell near boundaries, and simplifying the construction of ghost cell system. One major application of the proposed method is expanding the types of the overset boundaries, as the constructed searching space is able to cover the entire grid, resolving the problem for the symmetry plane overset. The test case shows that the method is very reliable, feasible for boundaries, and greatly improves the flexibility of the Chimera grid for complex configurations.
Interdiffusion behavior in Nb/α-Ti3Al ternary system
Wang Wenbo, Zhou Chungen
2012, 38(10): 1380-1383.
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The α2 single phase interdiffusion behavior in Ti3Al-Nb ternary system was studied at the temperature of 1 273 K, 1 423 K, 1 573 K, using Ti3Al/Nb single phase diffusion couples. The uniform β-(Ti, Nb) phase was formed in mid of the diffusion couple after 120 hours diffusion annealing in the high temperature. On the contrary, the nonuniform diffusion layers, including Ti3Al(Nb), β-(Ti,Nb) and Nb2Al, were formed in low temperature.The interdiffusion coefficients were calculated by the method of Dayananda, which can evaluate by the concentration dependence in one couple only. The calculation results show that the interdiffusion coefficients of Ti and Al is five order of magnitude larger than Nb, and Nb atoms are considered to occupy Ti sites in Ti3Al, the exchanges with vacancies on Ti sublattice played a leading role in the diffusion of Ti3Al. These results can provide a theoretical basis for the mechanisms of Nb improving the oxidation resistance of Ti3Al.
Modification of SA model for predicting airfoil flow separation
Zhou Dagao, Liu Yangwei, Wen Xiaoqing, Lu Lipeng
2012, 38(10): 1384-1388.
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Two-dimensional numerical simulation of airfoil S825 with Spalart-Allmaras(SA) turbulent model was presented. The simulation results were compared with the experiment results. As SA turbulent model could not simulate the flow separation accurately at the rear region of the airfoil, the strongly non-equilibrium turbulence transport nature in the separate region was analyzed. The non-equilibrium turbulence transport nature was closely related to the constant Cb1 in SA model. A method of modifying the constant Cb1 was adopted in SA model, and the simulation results show that the method simulates the flow separation more accurately.
Decision-making of failure modes mitigation program considering coupling relationship among failure modes
Yang Dezhen, Ren Yi, Wang Zili, Liu Linlin
2012, 38(10): 1389-1394.
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During the development stage of complex products, failure modes mitigation program often decided by experience, without considering the failure modes’ coupling relationship. Aiming at solving this problem, a decision process of failure modes mitigation program was proposed. Firstly, a new concept of failure modes correlation set(FMCS) was presented, including the determination approach based on deductive theory. Secondly, according to changes about failure modes occurrence probabilities, models depicting the varying relationship between failure modes mitigation and quantitative achievement of reliability were constructed to decide failure modes mitigation sequence orienting to the requirements achievement. Finally, a case study of helicopter fuel system demonstrated the feasibility of approaches and models, proved the existence of the relationship between reliability quantitative achievement and qualitative design, and the failure modes mitigation could be controlled orienting to the quantitative achievement of reliability availably to satisfy the design requirements with minimal cost of resources and time. Furthermore, the approaches could be applied in real engineering scenarios due to the practicality.
Design and efficiency analysis for loading actuator used in aircraft structure test
Luo Caijin, Shang Yaoxing, Jiao Zongxia
2012, 38(10): 1395-1399.
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Based on the characteristics of low speed and low system flow in plane structure test especially in the static loading test, a new type of valve-control electro-hydraulic actuator for aircraft structure loading test was designed. The system components and working principle was described, and the efficiency of valve-control system was analyzed. A scheme of reducing the oil source pressure setting was proposed in order to improve the system efficiency, while modeling and simulation work of the electro-hydraulic actuator system was completed through the AMESim platform, and the effectiveness of proposed scheme in improving the system efficiency was proved. The simulation results demonstrate that the designed electro-hydraulic actuator can totally meet the expected design requirements, and can be widely used in aircraft structural loading test system.
Intelligent verticality-adjustment method of end-effector in aeronautical drilling robot
Gong Maozhen, Yuan Peijiang, Wang Tianmiao, Zhang Rui
2012, 38(10): 1400-1404.
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Based on the requirement of robotic drilling for aircraft fuselage, a novel verticality adjustment method of drill bit in aeronautical drilling robot system was proposed, which is composed of surface-normal measurement and adjustment of drill bit-s attitude. Three laser range sensors were used in surface-normal measurement to measure the distances between sensors and three measurement positions around the drilling point. Thus the normal vector can be calculated from the cross product of any two vectors that are tangent to the surface at the drilling point. Meanwhile, the angle between normal vector and drill bit was obtained, which was fed back to the control system. Finally, the attitude of drill bit was adjusted using the binary angular adjustment mechanism (BAAM) to correct drill bit in line with the normal vector, which ensures to drill along the normal direction of drilling point. The high-accuracy, high-efficiency and practicability of the verticality adjustment method were tested by the experiments conducted on the aeronautical drilling robot, which meet the requirements of the auto-drilling for aircraft manufacturing.
Accelerated degradation mechanism modeling method for accelerometers
Wang Qiancheng, Chen Yunxia, Kang Rui
2012, 38(10): 1405-1409.
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To deal with the difficulties of lacking mechanism model for traditional accelerated degradation test design, a modeling method was proposed based on main mechanism test, key part simulation, parameters analysis and system identification. The main mechanism was identified and its test was carried out next. The key output parameters were obtained through finite element analysis. Then the relationship between key output parameters and product performance parameters was gained by parameters analysis. Finally, the accelerated degradation mechanism model was got through system identification. Taking account of the accelerometer, the accelerated degradation mechanism model and the results of scaling factor stability analysis at constant temperature were given. The conclusion of comparing the model results with historical data at constant temperature proved that the method is feasible.
Infrared radiation characteristic ground test of ballistic flying projectile
Ke Weina, Zhu Dingqiang, Cai Guobiao, Wang Weidong
2012, 38(10): 1410-1414.
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An experimental system based on the laboratory equipments was designed and set up to simulate the mid-course flying condition of projectile, and measured the infrared radiation characteristic data of flying projectile. Based on the conductive and radiant theory, the influences of simulation parameters on experimental results were analyzed, and the changing rules of radiation characteristic during the flying conditions were concluded. The initialize temperature of flying projectile and the radiation sources were the important parameters to the infrared radiation temporal characteristic of flying projectile, and the spin station has effects on the infrared radiation spatial characteristic. Comparing the results between the experiment, the numeric simulation and academic analysis, the results are correct and accordant, which sustain that the infrared radiation characteristic simulation experiment of flying projectile carried on the laboratory is feasible.
Improvement on ABDOM with normalized and discrete parameters
He Zhitao, Yan Haihua, Liu Chao
2012, 38(10): 1415-1419.
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In order to describe, predict and evaluate the true software defects discovery process more accurately with accumulative bi-damped oscillation model(ABDOM), on the basis of proposing ideal sequential process of software defects discovery(ISPSDD), software defects discovery damp a and software defects discovery cycle damp b of ABDOM were studied with normalized and discrete parameters and a software defects discovery process quality evaluation coefficient Q was proposed as well as its typical values and corresponding significances. With Q introduced into ABDOM, finally an improved model ABDOM-Qd with normalized and discrete parameters was gotten and its validity was verified with the software defect data from a true test project.
Traffic impact analysis of highway accident based on the shockwave theory
Yu Guizhen, Liu Yumin, Jin Maojing, Wang Yunpeng
2012, 38(10): 1420-1424.
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The study on traffic impact of highway accident plays an important role in highway incident management. In the study, the shockwave theory as a foundation, the accumulation and dissipation process of the accident upstream location on two-lane highway was analyzed. According to the numbers of impacted lanes, the clean up time and the upstream traffic flow, a mathematical model named highway traffic accident impact model was established. By numerical models analysis and professional microscopic traffic simulation software under the same traffic conditions, the result shows that the model is ideal for evaluating traffic impact of highway accident for its small deviation about 5% and efficient calculating.

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