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2011 Vol. 37, No. 5

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Thermodynamic model and numerical simulation of high altitude balloon ascending process
Lü Mingyun, Wu Zichun
2011, 37(5): 505-509.
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Based on the analysis of the high-altitude balloon thermodynamic environment, a coupling dynamic model was established to describe its thermodynamics and kinetics. The model was used to simulate the ascending and floating processes of a high altitude balloon. The results show that the inner helium temperature will present "supercool" during its ascending process, and "supercool" is more pronounced during the stratosphere region, with the inner helium temperature 19 K below the surrounding air temperature. Because of "supercool", its ascending velocity profile take on double "V" shape. The inner helium temperature presents "superheat" during the daytime floating process due to strong sun radiation and weak convection with air, and the inner helium average temperature is 39 K higher than that of the surrounding air, with 648.8 Pa super-pressure. The ascending velocity profile and inner helium temperature profile of the numerical simulation good agreement with experimental flight data shows that the established model is accurate.
Fault diagnosis for satellite attitude control system based on FDDPB
Wang Xinsheng, Ma Lei, Liang Bin
2011, 37(5): 510-514.
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For satellite attitude control system fault diagnosis, step type and slow drift type output bias of actor and sensor were considered as parameter bias fault. Fault detection and diagnostics of parameter bias(FDDPB) algorithm and its application on actor and sensor of satellite attitude control system were introduced. The simulation models were proposed after describing satellite attitude dynamics model and wheel model. Simulations were finished on the assumption that step type fault and slow drift type fault occurred. Simulation results show that FDDPB algorithm could detect system fault and was able to estimate fault amplitude accurately.
Cooperative traffic alarming method based on epidemic model
Wang Yunpeng, Yi Zhenguo, Xia Haiying, Tian Daxin
2011, 37(5): 515-518.
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Based on the characteristics of high speed, the movement was constrained by roads, and the vehicle networking topology changed frequently, a cooperative traffic safety alarming method based on epidemic model was presented, and the transmitting delay was analyzed with Markov chain. The method was tested with NS2 network simulator. The simulation scenario contains a 2 000 meters long and 20 meters wide highway, which allows two-way movements of vehicles. The experimental results prove that the transmitting delay is consistent with the theory analysis.
Simulation and ergonomics analysis of pilot visual information flow intensity
Zhang Huishu, Zhuang Damin, Ma Ding, Sun Jian
2011, 37(5): 519-523,527.
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In order to determine the reasonable information flow intensity of the flight task, a simulation model of aircraft information display interface was developed, in which the correct response rate and reaction time of subjects were used to evaluate the task performance. According to the experiments and data analysis, the results show that the intensity curve of visual information flow was consistent with the normal distribution in the established visual information flow model. The task performance is greatly influenced by different information flow. When the visual information flow increases to certain intensity, the identification become slow and the possibility of making errors increase. Under the same information flow, there are significant differences of identification and performance between the daytime operation and night operation, as well as between the static operation and dynamic operation. The identification and performance is better in the daytime than at night, and is better at static state than dynamic state.
Experimental validation for axial-symmetric plume numerical simulation
Zhang Jianhua, He Bijiao, Cai Guobiao
2011, 37(5): 524-527.
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To solve effect problem of spacecraft lifetime caused by on-orbit spacecraft plume effect, numerical simulation and experimental validation were used. Based on the experiment studies of DFH series satellite attitude control thruster nozzle plume, axial-symmetric nozzle model was established. Rectangle calculation region was chosen, and a certain boundary condition and calculation condition were assumed. The calculations were carried out by axial-symmetric single gas direct simulation Monte Carlo (DSMC) method for plume of corresponding experiment state. By comparing numerical simulation results with experimental results, the calculation results of plume agree well with the experiment flow characteristics. It shows that the program of axial-symmetric single gas DSMC method designed is accurate and effective.
Design and implementation of a simulator for wireless communication nonlinear distortion
Lu Cheng, Zhang Xiaolin, Li You
2011, 37(5): 528-533.
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The non-linear distortion should be considered in aeronautics and astronautics communication applications due to high spectrum utilization and power efficiency. Numerous studies have been carried out on the non-linear distortion modeling and linearization of power amplifier. A design of nonlinear distortion simulator was presented. The simulator can be used in testing on anti-aliasing capabilities of wireless communication, testing on adaptive pre-distortion performance and providing specified amplifier conditions of communication systems. The coordinate rotation digital computer(CORDIC) pipeline and look-up-table (LUT) structure were utilized to realize the AM-AM and AM-PM conversion of amplifier in digital signal processing devices inside the emulator. Simulation and experiment results demonstrate the validity and feasibility of the design.
Target observability criteria from bearing-rate-only measurements
Tian Hongliang, Liang Xiaogeng, Jia Xiaohong, Guo Xiaonan
2011, 37(5): 534-537.
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Target observability criteria previously established for bearing-only tracking in two dimensions was extended to that for bearing-rate-only tracking. For unobservability of Nth-order dynamics target from bearing-rate-only measurements, by an analysis of the relative movement equation of missile and target, the necessary and sufficient conditions (target unobservability criteria) were presented in Cartesian coordinates.The unobservability criteria has two simple forms, one is the restriction of relative distance of missile and target,and the other is the restriction of line-of-sight angle. For observability of constant acceleration target from bearing-rate-only measurements, by an analysis of the system fisher information matrix, the necessary and sufficient conditions were obtained in modified polar coordinates. Result shows that the target unobservability criteria is identical with the necessary and sufficient conditions established in modified polar coordinates , and is consistent with the target observability criteria for bearing-only tracking, besides which, is derived easily without examination of an observability matrix and nonlinear differential equations,which fits it for appliance.
Numerical simulation of minor geometry characteristics and small orifice water mist swirl injector
Fan Wenhong, Ling Zongyu, Fu Qingfei, Yang Jie
2011, 37(5): 538-544.
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Due to the deficiency of the maximum discharge principle with regard to the design of the minor geometry characteristics and small orifice water mist swirl injector, a numerical investigation on it was performed by simulating the inner flow field of two phase flow injector using the mixture model in Fluent, from which the flow rate and spray angel α were obtained and compared with the experimental data and the theoretical calculation results. The gas-liquid phase distribution, axial velocity and tangential velocity, pressure distribution in the injector were also investigated. The discrepancy between the investigation and the traditional design theory was discussed and the mechanism was concluded. The viscosity of liquid and the friction of wall were taken into account which made the simulation can describe the inner flow field of injector accurately and the numerical simulation provides a reference for the design of minor geometry characteristics and small orifice water mist swirl injector.
Performance comparison among three super resolution direction finding algorithms based on virtual element interpolation
Chen Wensheng, Xu Xiaojian
2011, 37(5): 545-550,555.
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Three super resolution direction finding algorithms based on virtual element interpolation were studied. On the basis of mutually cohering the signals from multiple smaller arrays of different radars, three super resolution algorithms, namely, the nonlinear least squares (NLS) algorithm, the iterative deconvolution algorithm based on minimum entropy criterion (IDMEC), and the minimum weighted norm (MWN) algorithm were applied to interpolate the virtual elements between the physical radar arrays. As a result, the effective aperture size was increased, thus super resolution direction finding was achieved. Simulations were made to validate the techniques as well as compare the super resolution performance and calculation burden among the three algorithms. Results demonstrate that the MWN algorithm has not only the lowest virtual element construction error level and calculation complexity, but also the best direction finding performance. Therefore, the MWN algorithm generally outperforms the NLS and IDMEC algorithms.
Effect of jet mixing enhancement by pulsed blowing on infrared radiation of plume
Zhu Xijuan, Eriqitai Li, Jiajun Wang
2011, 37(5): 551-555.
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A three-dimensional infrared (IR) radiation code of the plume was developed by the finite volume method (FVM) coupled with narrow band model in non-gray absorbing-emitting media. The infrared radiation of the unforced plume and the forced plume, which is mixed by injecting high amplitude and low mass flux plused slot jets into subsonic shear layer were simulated by the code. The 3-D flow field of the jet was simulated numerically by FVM, renormalization group(RNG) k-ε turbulence model. The results indicate that small injection flow rates (about 3%) can make sharp increases in both velocity and temperature decay rates at middle Mach number. At the zenithal angle of 90°, the IR radiation of the plume at each azimuth angle has tremendous reduction, and the decreases in the plane parallel with the actuators are larger than those in the plane perpendicular to the actuators.
Piezoresistivity of cement based material with small amount of graphite
Gan Weimin, Huang Xin, Chen Pengfei
2011, 37(5): 556-559,578.
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Graphite-cement specimens were made by adding water reducing agent in cement, and the specimens- piezoresistivity in a destructive overload experiment was mensurated by a series connected AC circuit. The results present that, if a small amount of graphite was mixed in, the cement material-s uniaxial compressive strength will decrease, at the same time the material-s piezoresistence coefficient will ascend. As the amount of graphite was increased within a small range, the deviation of specimens- relative resistivity decreases, and the piezoresistivity of the material increases. Furthermore, the resistivity of the specimens becomes stable while being loaded. By examining the piezoresistivity curves of the graphite-cement material, similar shape with the stress-strain curves can be got in these experiments. There are three stages while the material-s relative resistivity is changing along with the increase of stress imposed on it which are undulate stage, slowly descend stage and rapidly descend stage. These stages are accordant to the three stages of the failure of cement based material, which are elastic stage, elastic-plastic stage and failure stage.
Robust adaptive control for hypersonic vehicle based on dynamic inversion
Huang Xiyuan, Wang Qing, Dong Chaoyang
2011, 37(5): 560-563.
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For the feature that hypersonic vehicle motion model is highly nonlinear, multivariable coupled and includes uncertain parameters, a robust adaptive control strategy based on nonlinear dynamic inversion for the hypersonic vehicle was proposed. By decomposing the vehicle motion equations into two subsystems, namely, a velocity subsystem and an altitude subsystem, and incorporating the design of virtual control commands and nonlinear dynamic inversion technology, the stable velocity and altitude tracking were achieved. To eliminate the effect of the model uncertainties and external disturbances, the robust adaptive sliding mode control method was adopted. Simulation results show that the proposed method not only satisfies the velocity and altitude tracking performance requirements, but also is robust to model uncertainties and external disturbances.
Construction of fault-tolerant synopsis over data stream based on prefix-tree
You Yuyang, Zhang Jianpei, Yang Zhihong, You Yong
2011, 37(5): 564-568.
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Complexity of data mining algorithm over data stream is the most important and it should be more focused on algorithm efficiency because of the great consumption of algorithm resources. Fault-tolerant frequent pattern mining is more generalized and suitable for extracting interesting knowledge from real-world data stream polluted by noise. An algorithm, called data stream fault-tolerant frequent pattern tree(DSFT-tree ), was proposed. It could achieve a frequency-descending and highly compact prefix-tree structure with a single-pass to capture fault-tolerant frequent itemsets in recent sliding window. To completely and efficiently perform the tree restructuring operation, an efficient mechanism based on sliding window pointer and bit-vector representation were utilized to restructure the tree. The efficient reconstruction mechanism greatly reduced the consumption of calculation resources and achieved fault-tolerant frequent itemsets mining. Experimental transaction database was generated by IBM synthetic data generator. The number of frequent itemsets extracted by DSFT-tree is 1.5 fold greater than that extracted by FP-stream. Experimental results show that developed algorithm is an efficient fault-tolerant synopsis.
Analysis of multi-parameters effect on Shupe error in fiber optic gyroscope fiber coil
Song Ningfang, Guan Yueming, Jia Ming
2011, 37(5): 569-573.
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The element model of the fiber coil with the quadrupole (QAD) winding pattern was built based on the discrete mathematics formulae of the Shupe error in the fiber optic gyroscope (FOG), and the comprehensive physical parameters of the fiber coil with multi-material composition were analyzed for the next simulation. Combining of the thermal loads and boundary conditions in the FOG working environment, the numerical simulation of the fiber coil was done to analyze the Shupe error in the fiber coil at the FOG operating temperature quantitatively. It also verified the correctness of the model building comparing with the experimental results. On this condition, the effects of structural parameters, thermal parameters and temperature disturbed parameters on Shupe error in the fiber coil were analyzed. The results show that by optimizing the winding layers, increasing thermal conductivity, and arranging heat source rationally, the Shupe error of fiber coils can be inhibited, thereby enhancing the FOG thermal performance.
Regression testing method of UAV flight and management software
Tian Feng, Ding Wenrui, Li Hongguang, Li Xinjun
2011, 37(5): 574-578.
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In order to solve the large embedded software testing problems,an automated regression testing method based on system snapshot was proposed. Taking unmanned aerial vehicle(UAV) flight control software as a case study, some key technology researching, system architecture designing and experiment analyzing were carried out by degrees. The system snapshot technology was used to decouple the test cases which had complex relationship with each others, then transformed complex systems testing into some flexible unit testing. With CPPUnit testing framework, an automated regression testing system structure was established, and the function and implementation process of each part were deeply analyzed. Furthermore, based on the system snapshot technology, the process of automated regression testing and the preparation of test cases were designed. Two kinds of experimental result of a large UAV flight control software testing using different method was given. Through comparative analysis of the evidence-based data, test system-s effectiveness was verified.
AC load semi-physical simulation technology for aircraft electric power system
Wu Shiyu, Zhou Yuanjun
2011, 37(5): 579-583.
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To facilitate alternating current (AC) load power performance research in aircraft electric power system, the AC load semi-physical simulation technology was proposed. The technology was based on pulse width modulation rectifier topology and three-phase current decoupling control. Complex compensation structure was used to ensure rapid tracking; a one-leg was added to provide access to the neutral current; the power filter was added to reduce the switch harmonic current for obtaining the more real load characteristics in the aircraft power system side. In 115 V, 400 Hz aircraft electric power system, by using the semi-physical simulation technology, the function that AC side current tracked the given current generated by the computer digital simulation was completed. The simulation of the AC load dynamic process of power factor, current harmonics and unbalanced currents was realized. The experiment results of the semi-physical simulation show that both accuracy and speed meet requirements. The semi-physical simulation provides a design and verification tool for aircraft electric power system.
AHP ultra weight for simulation credibility evaluation
Fang Ke, Ma Ping, Yang Ming
2011, 37(5): 584-588.
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Analytic hierarchy process (AHP) is widely applied to simulation systems credibility evaluation, but the traditional AHP can not solve the step problem of credibility evaluation result. In order to resolve this problem, the main cause of step problem was pointed out to be AHP relative weight-s fault. With the reference of Petri net definitions, the AHP net concepts and mathematical basis were proposed. To the question of traditional AHP relative weight-s fault, the enhanced AHP net and its definitions, legends etc. were established. Based on the net definitions, the AHP ultra weight concept and mathematical expression were proposed. The evaluation node value and priority algorithm of AHP net with ultra weight were determined. A simulation credibility evaluation example was given and the numerical evaluation result was obtained. The result proves that, the AHP system with ultra weight can resolve the step problem of credibility evaluation result well.
Detached eddy simulation of homogeneous isotropic turbulence
Wu Jingfeng, Ning Fangfei
2011, 37(5): 589-594.
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Detached eddy simulation was used to simulate decaying homogeneous isotropic turbulence. Simulation results were compared to the experimental data of Comte-Bellot and Corrsin, showing that the detached eddy simulation of homogeneous isotropic turbulence was acceptable. The method proposed by Rogallo was used to construct the initial velocity field and the generated turbulence field fit the Von Karman spectrum. In the choosing of convective flux scheme, second-order centered scheme and fourth-order skew-symmetric scheme and upwind low-diffusion flux-splitting scheme were used respectively to check the numerical dissipation and suitability in the detached eddy simulation of homogeneous isotropic turbulence. Meanwhile, the cutoff wave number was changed with the varying of computational region and turbulence model parameters. In this way, the simulation results shows how energy spectra and energy accumulation for small scales are influenced by the variety of the cutoff wave number.
Design and implementation of man-in-the-loop unmanned airship HIL simulation system
Song Jingjing, Zhu Ming, Wu Zhe, Zhang Lei
2011, 37(5): 595-599,609.
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In order to carry out the unmanned airship system ground integration and flight simulation, the hardware and software of the hardware-in-the-loop(HIL) simulation platform was developed. It was based on real-time operating system(RTOS) VxWorks, Matlab/Simulink and real time workshop(RTW), FUTABA data acquisition system and three-dimensional visual system. The biggest innovation was the usage of the FUTABA remote control (RC) equipments and pulse width modulation(PWM)/RS-422 signal transform module, thus the visual sense and the control output of the pilot could be accessed to the simulation loop. The results show that man-in-the-loop flight simulation tests can verify the function of control mode switching and the effects of attitude and track control. The tests also improve the pilot-s proficiency in controlling this type of the unmanned airship directly to land steady in case of emergency.
Analysis on transmitting characteristics of pressure waves in pipeline
Lin Weiqin, Huang Liang, Cai Maolin
2011, 37(5): 600-604.
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Based on the theory of one-dimensional unsteady flow, a distributed parameter model of gas transmitting in pipeline was given. Then the model was solved with upwind difference formula, numerical simulations of the transmission of pressure waves in the pipe were also performed. Comparing the result of simulation with experiments, it was verified that this model was correct. And then the initial condition, such as the pipe diameter, air velocity, inlet pressure and the space step of simulation, was changed to simulate the different characteristics of the pipeline. Comparative analysis of the simulation results, the characteristics of the pressure waves of different waveforms under different conditions in the pipeline were obtained. The simulation shows that when using pressure wave to gas flow measure, it should use the waveform of half part of sine or square.
DNS of two-dimensional MHD turbulent channel flow under action of streamwise magnetic field
Chen Zhi, Zhang Jinbai, Lee Chun
2011, 37(5): 605-609.
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A direct numerical simulation (DNS) of two dimensional, conducting turbulent channel flow under the action of applied streamwise magnetic fields was performed based on the low magnetic Reynolds number approximation. The numerical results with Re=10 000 under the action of different magnetic interaction numbers ranging from 0.001 to 10 were analyzed. The computed variations of the near-wall velocity distribution, root mean squares (RMS) of the fluctuation velocity, and the Reynolds stresses were presented and compared to the case with neutral fluid. The results show that streamwise magnetic field results in an upward shift of the log layer, the maximum of Reynolds stress varies linearly with interaction number. With the increment of interaction number, the time evolution of average vorticity of the bottom wall shows a growing trend in periodicity and the average vorticity of the bottom wall becomes a constant value finally when relaminarization happens.
Characteristic analysis of flow load around head during vehicles exit of water
You Tianqing, Zhang Jiazhong, Wang Cong, Cao Wei
2011, 37(5): 610-614.
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During water-exit of underwater vehicle, the violent change of flow field is very complex. In order to investigate the variation of hydrodynamic load, the water-exit of underwater vehicles was simulated by a viscous flow solver with homogeneous multiphase flow model and cavitaion model. The effect of different head shape and pitching angle on the water-exit flow field was analyzed by the numerical method. The analysis result indicates that the head shape with stronger cavitation capability, which maintains local cavity, can cause more severe flow field change and produce massive pressure on the hull of vehicle. The result also indicates the flow field of water-exit process with pitching angle is asymmetric which forms the powerful moment applied on the vehicle. And the pitching angle has a great impact on the variation of moment.
Design and realization of the electronic map for UAV GCS
He Jiangyan, Zhao Qi
2011, 37(5): 615-618.
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To meet the real-time monitoring and control requirements to unmanned aerial vehicle (UAV),a navigation electronic map module of ground control system (GCS) was designed under windows platform.This module working with displaying module, mission planning and operating module, and communication module,performed as obtaining the real-time flight information, planning the flight path, showing the real-time flight trace and so on. The function of a navigation electronic map and characteristics of the MapInfo components were introduced and analyzed. The method and process of developing the navigation electronic map for UAV GCS based on MapInfo components in Visual C+ + environment were expounded. A suit of simple and effective method based on MapX control and microsoft foundation classes (MFC) was proposed to achieve the monitoring and control to UAV and the automatic adjustment to range of the navigation electronic map-s longitude and latitude. The main process and part of key code were provided.
Management of quality cost oriented to aerospace product development system
Wang Meiqing, Qin Haiping
2011, 37(5): 619-625.
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The method of quality cost management for the development process of aerospace product was studied. The overall management model of quality cost was proposed, in which the three-layer organizational structure, product development process and the management strategy of quality cost were combined. Furthermore, the method for quality cost management of each layer was presented in which the control granularity, process and object were taken into account. The control process was divided into three stages, control before the event, control during the event and control after the event. The analytic technique, tools and information were integrated, and the closed-loop control policy was applied. Finally, a quality cost management software system based on browser/server architecture was developed, which is called QQ-WebCost, and it has been implemented in an aerospace enterprise.
Lateral flight control synthesis for large transport based on static output feedback
Nie Lu, Xiang Jinwu
2011, 37(5): 626-630.
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Structural flexibility of large transport results unavoidable coupling between control system and structural dynamics due to the application of large amounts of light material. Control system design for such aircraft should consider contribution from structural flexibility, and satisfy the specifications from flying qualities. To consider elastic modes in aircraft control system synthesis process, a novel H∞ loop shaping design procedure was given. Inner loop feedback gain was calculated by rigid flight dynamic model to satisfy specifications from flying qualities requirements and atmospheric turbulence rejection. The initial static output feedback gain obtained by rigid truncated model was used as weight for the high order model. Dynamic controller was consequently given by Glover-McFarlane-s H∞ loop shaping method to keep system stable while elastic modes are involved in the high order model. A typical numerical model and simulation in time domain were given to compare with the original design and better response shape and elastic modes suppression were shown.

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