Advanced Search

2005 Vol. 31, No. 08

  Previous Issue | Next Issue 
Display Method:
Numerical computations of infrared signatures in exhaust flow fields of jet engines
Zhan Guang, Lee Chunhian
2005, 31(08): 829-833.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 957
Abstract:
The thermal radiation field in a high temperature gas flow is coupled with the flow field. However, within the temperature range of the exhaust flow field for a jet engine, the thermal radiation effects can usually be ignored in the computations of the flow field, and the governing equations on the flow field and the radiation field can be decoupled. A decoupling model for computing infrared signatures of the flow fields surrounding the aircraft was proposed. A numerical procedure was constructed by first utilizing TVD(total variation diminishing) scheme to solve the interactive flow field. A finite volume formulation for the spectral intensity was imposed to estimate the total infrared signaturesusing the computed flow field data over the same set of grids. As a test case for validating the proposed numerical procedure, the infrared signatures in an interaction flow field of a uniformed external flow and a frozen exhaust flow with 7 species, N2, O2, CO2, H2O, CO, HCl, and H2, were computed and compared favorably with the available experimental as well as numerical results.
Design of thermal control system for high-altitude and high-speed unmanned vehicle
Liu Yongji, Dong Sujun, Wang Peiguang, Wang Jun
2005, 31(08): 834-838.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 860
Abstract:
According to design of thermal control system for UAV(unmanned aerial vehicles), which is characterized by small flight time-consumption, high speed, and quick change in altitude, thermal analysis and calculation methods which can be applied to practice engineering were put forward. Hot atmosphere, standard atmosphere and cold atmosphere were referred to as design conditions. In virtue of referring temperature, hypersonic engineering prediction or CFD(computational fluid dynamics) numerical simulation, surface temperature of vehicle was attained and taken as outer boundary conditions of thermal analysis mathematics model. Structure thermal capacity's influence of the transitional thermal load was analyzed, and boundary equation was set up and solved by finite difference method. According to flight feature and transitional thermal load value, scheme of temperature adjusting system of electronic equipment cabin was presented.
Extraction of subpixel insect wing features in images
Wang Ying, Zhang Guangjun, Chen Dazhi
2005, 31(08): 839-842.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1193
Abstract:
Wing vein, junction of veins and wing edges are the fundamental image features for wings 3D reconstruction to obtain insect deformations motion parameters. To determine precise position of the wing features in images, gray properties of wing features were analyzed first. For wing vein features, the gray extreme direction was determined by Hessian matrix. The gray variable was fitted by conic curve along the direction of the gray extreme, so the subpixel location of the vein center was obtained by searching the extremum of the curve. For wing edges, image gray gradient was calculated, and then subpixel step edge of wings was determined by searching the gradient extremum along the gradient change direction. Angle constraint in neighbor was used to determine junctions of wing veins based on the change continuity of vein direction. All wing features were determined at subpixel locations. The experiment results show that the extracting method about wing features is effective.
Design and analysis on dropping trajectories of RLV configuration
Yang Fan, Zhang Shuguang
2005, 31(08): 843-847.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 983
Abstract:
The flight trajectories of a RLV(reusable launch vehicles) configuration were designed and the flight dynamics were analyzed along the trajectories. The whole flight process was divided into four phases as the S-turn phase to dissipate extreme energy, the acquisition phase to turn the vehicle for the HAC (heading alignment cylinder), the HAC tracking phase to head the vehicle for the runway and the pre-final approach phase to fit the vehicle to landing. The trajectories were further adjusted at checking windows. The dynamics of the configuration was then analyzed in terms of the sensitivity, control and stability along the trajectories for the navigation and control law design. The results show that the established trajectory design method works well with satisfactory precisions, while the designed trajectories tend to be more sensitive to the lower frequency disturbances than high frequency disturbances.
Improved least-squares scene matching algorithm
Xu Baochang, Chen Zhe, Zhao Long
2005, 31(08): 848-852.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1115
Abstract:
In order to improve the matching speed and the robustness to initial positioning error and noise of the scene matching system, the scene matching model was set by analyzing the relationship of gray level between real-time image and referenced image. An improved least-squares scene matching algorithm was proposed. The generalized cost function in the algorithm was constructed by adding an auxiliary constraint term to the sum of the squared errors. The auxiliary constraint term involved the requirement for the smoothness of measurement input to improve the stability of the algorithm. The recursive equations of the algorithm were derived using Newton iterative algorithm without any simplification. By using the first order and second order derivative information of the generalized cost function, the algorithm had high convergence speed. Simulation results demonstrate the effectiveness of the algorithm.
Path planning for penetrating aircraft to fly at low altitudes based on technology of digital elevation map
Bai Xiaoli, Han Liang
2005, 31(08): 853-857.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 986
Abstract:
Path planning using TF/TA2 (terrain following, terrain avoidance, threat avoidance) technology is the key problem for the research in penetrating aircraft to fly at low altitudes. The terrain information is stored in a real digital map. To make sure the designed path applicable for the aircraft, preliminary treatment for the digital map was researched. A virtual terrain surface was constructed by combining the information of terrain, threat and aircraft performance. The treatment included compressing the original data file, transforming threat information to terrain height information, interpolating data at the point where the original terrain information could not be got, and smoothing the terrain surface. By devising a cost function considering the requirements of TF/TA2, translating its form to the A* algorithm, and using some optimization methods, three-dimensional path generation for the vehicles using TF/TA2 could be realized. The simulation results demonstrate the validity of the algorithm.
Intelligent tactical mission management system for combat aircraft
Zhou Rui, Cheng Xiaojing, Yu Zhouyi, Chen Zongji
2005, 31(08): 858-862.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1028
Abstract:
An intelligent tactical mission management system for modern combat aircraft was proposed based on the cognitive decision process of perception, assessment and decision. As the key subsystems of the mission management system, the situation assessment and mission planning were investigated emphatically. The algorithm of situation assessment based on Bayesian networks and fuzzy logic was established. The model of threat level assessment was developed, based on which, the threat level of threater was assessed using Bayesian networks. The relative importance among the threaters was inferred by fuzzy logic. A novel algorithm of tactical flight path planning in real-time was developed based on dynamic A* algorithm. The two subsystems of situation assessment and flight path planning were integrated based on fuzzy logic to adapt the dynamic situations in battlefield. The simulation results show that the proposed intelligent tactical mission management system can assess the threat situations dynamically and can adapt the changing dynamic situations timely.
Real-time continuous multimedia task model and scheduling algorithm
Ruan Junbo, Li Hongbing, Jin Huihua
2005, 31(08): 863-868.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1014
Abstract:
The oversimplification of traditional periodic task model gives rise to poor flexibility, which can not adapt to multiple forms of real-time media stream applications. User-centered scheduling algorithm for continuous media brings in poor scheduling efficiency, for not considering QoS (quality of service)requirements completely. An improved periodic task model centered on multimedia objects was presented, and the model ould generalize the basic task representative forms of current multimedia applications on the whole. A model called TPP (task presentation path) for continuous media streams was proposed with focus on the whole qualities of presentation for continuous media stream. Considering the overall dead-line, partial periodic dead-line and sequential failure of multimedia stream object in the presentation path, a proportional share CPU scheduling called PSTPP(proportional share based on task presentation path) algorithm was brought forward for continuous multimedia streams. The experimental results show the rationality of models, and the scheduling algorithm can provide better QoS guarantees than the traditional time-sharing and EDF strategies.
Quantitative air combat decision
Yang Youchao, Jiang Yuxian
2005, 31(08): 869-873.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1078
Abstract:
A method to make air combat decision, the quantitative air combat decision, was presented. Based on the launch envelope and the launching condition of air-to-air missile, the air combat situation could be described quantitatively by defining the air combat situation function. Choosing the suitable maneuver according to the values of the air combat situation function and the characteristic of the long-range and the short-range air combat, the relationship between the maneuver strategies of air-combat and the state variables of air-combat situation was built. It was to be made possible to calculate the strategies of air-combat quantitatively from the state variables of air-combat situation, one of which was the effect, the other was the cause of reasoning. The process of analysis, evaluation, decision-making, maneuvering was completed quantitatively. The model of the fighter, target, missile and decision module was built. Giving different initial conditions, the effectiveness of the decision of the long-range air combat and short-range air combat was validated respectively.
Study on sufficiency of sample set in testability demonstration based on information model
Shi Junyou, Kang Rui, Tian Zhong
2005, 31(08): 874-878.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 912
Abstract:
The failure mode information model of the product was created. This information model contained the failure mode data, the structural unit data, the function data, the test data and the mapping relation about them. According to this information model, three types’ failure mode equivalence sets were defined. They were the failure mode unit-equivalence set, the failure mode function-equivalence set and the failure mode test-equivalence set. Based on these failure mode equivalence sets, three types of classical sufficiency measurements and criterions for the sample set in the testability demonstration were defined. They were the unit-coverage sufficiency measurement and criterion, the function-coverage sufficiency measurement and criterion and the test-coverage sufficiency measurement and criterion. The application’s scopes of them were analyzed, and the integrated sufficiency measurements and criterions were established. The integrated sufficiency measurement could be used to evaluate the sufficient degree of the sample set. The integrated sufficiency criterion could be used to determine the required structure of sample set. The application’s method and flow for the integrated adequacy measurement and criterion were established. A case indicates that the method is feasible.
Longitudinal aerodynamic estimation and flight tests for airship
Cui Xiumin, Wang Weijun, Fang Zhenping
2005, 31(08): 879-883.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1007
Abstract:
The longitudinal aerodynamic parameters of an airship were estimated in defect of the data from wind tunnel test, using the form in compilers group of aerodynamic handbooks. The characteristic of the airship was analyzed, using the linear small-disturbance equations, which was acquired from the linear small-disturbance equations of the low-velocity airplane. The PID (proportion, integration and differentiation) control-law was designed and it’s simulation wasdone in the Simulink toolbox of the Matlab software, which was used in the design. The height-holding flight control law was presented, observing the time-response. The auto-long-flight was realized in the actual test. The time of flight was 20min and the ideal fight-altitude was 300 m. The approximation was found, through comparing the actual flight test with the ideal result. It shows that the control law is valid and the aerodynamic estimation method is valuable.
Experimental study on particle concentration in sand and dust equipment
Ma Zhihong, Li Yunze, Zhang Hua, Wang Jun
2005, 31(08): 884-887.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 755
Abstract:
Using the desert wind tunnel Laboratory of Institute of Desert Research in CAREERI of CAS, and applying laser particle imaging technology, the sand particle concentration in the different section from solid-gas nozzle on solid-gas two phase flow was measured and researched and contrasted with the photograph in the equipment. The experimental results indicate that the sand particles can not diffuse the whole section that is about one meter horizontally from the sand orifice and there are all most particles in the tunnel axes, at the same time those greater particles occur below the axes, but they can just diffuse equably the whole space in the section about three meters horizontally form the orifice. The conclusion was reached that the size of supplying was about three meters to accord with our nation military standard and it provided the gist to develop ourselves sand and dust experimental equipment, to confirm the way and the parameter of supplying sand and dust and to design the size of the supplying and the test segment.
Investigation on head of novel chemical thruster for orbit maneuver
Song Yana, Zhang Guozhou, Zhou Wenlu, Huang Xiang
2005, 31(08): 888-892.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 959
Abstract:
To develop light, reliable, sanitary space station maneuverable orbital transfer thruster, the novel gas dynamic resonance ignition method was applied. By means of thruster combustor design combined with coaxial hydrogen/oxygen resonance igniter investigation, method of using fuel-rich resonance ignition torch to further combust with the rest main part of oxygen downwards was adopted for the thruster head scheme. Through investigation on schemes of the thruster head configuration, structural schemes of the main oxygen injector were studied and determined. With respect to the key technique of short ignition response for orbital transfer thruster’s quick starts, several solving approaches were proposed, including: optimization of the resonance device structure, optimization of matches between the resonance dominating parameters, improvement on materials and timing adjustment of the ignition propellants etc. By greatly increasing its heating speed and energy gathering efficiency of the resonance device, the starting delay of the thruster was restricted in 0.2 s.
Numerical simulation of supersonic MHD channel flows
Xu Zhengyu, Lee Chunhian
2005, 31(08): 893-898.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1143
Abstract:
A compressible MHD (magnetohydrodynamic) model composed of MHD N-S (navier-stokes) equations and magnetic induction equations was proposed for analyzing the magnetohydrodynamic characteristics in MHD generator and MHD accelerator channels of MPC (magneto-plasma-chemical) propulsion system. A splitting algorithm based on an alternative iteration was developed for solving the two sets of equations. As a test case, a supersonic MHD flow in a square duct was simulated. The numerical results were compared with the results computed by solving the classical N-S equations for the perfect gas flow, together with the results computed utilizing the degenerate MHD N-S equations for the same channel flow with constant applied magnetic field. The thermo-electro-magnetic performances of the test cases with constant and variable applied fields were then discussed.
Analysis and modification of turntable’s axis calibration
Xu Yongan, Yang Qin, Huai Jinpeng
2005, 31(08): 899-903.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 2067
Abstract:
A new method using the standard ball and geometrical transform technique was proposed to modify the calibration error of the turntable’s axis in three dimensional laser digitizing system. The turntable’s axis was counted by the center of the standard ball at 8 different rotation angles, The center of different positions was revolved to the zero degree position by geometrical transform, the deviations between the center of different positions and the center of the ball at the zero degree position was counted. Through reverse geometrical transform, the modified format of the eccentricity was deduced from the coordinate deviation caused by turning on the eccentricity. The registration accuracy was raised to 0.07mm by self-design three dimensional laser scan measurement platform, the multiple views have been integrated automatically on line. Compared with the previous methods, the new method is simple and efficient, and can be used in other measuring system with a turntable.
Development algorithm of single sampling inspection plan of pass-fail experiment
Li Xiaoyang, Jiang Tongmin, Xiao Lianghua
2005, 31(08): 904-907.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 786
Abstract:
In order to determine sampling test plan of pass-fail product more easily and fast, the integral equations equal to the accumulation ones were put forward. Testing plan can be efficiently solved by using these equations on computer. The equality of these two kinds of equations was proved; The numerical algorithm of the integral equations solution was given. By comparing results, which came from the integral equations under different reliability parameters conditions, with corresponding pass-fail testing plans in national standard, it could be found that national standard neither accounted for actual risks of both customers and manufacturers, nor provided testing plans when risks of both sides were unequal. The determination principles of pass-fail sampling plan was proposed: pay attention to risks of customers and manufacturers and make samples least. An application example showed that this method could make reasonable pass-fail sampling plan with the use of these principles when any reliability parameters were given.
Effects of spraying powder composition and particle size on microstructures of Al-Cu-Fe quasicrystalline coatings
Cai Fei, Zhou Chungen, Gong Shengkai, Xu Huibin
2005, 31(08): 908-912.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 843
Abstract:
Quasicrystals have been widely applied for surface protection coating because of their distinguished properties including low thermal conductivity and coefficient of friction, remarkable oxidation and wear resistances, and high hardness etc. To improve the high temperature oxidation and wear resistance of titanium alloy, the Al-Cu-Fe quasicrystalline coatings were produced on titanium alloy substrates using LPPS (low pressure plasma spraying) method. The effect of the spraying powders on the phase structure and microstructure of as-sprayed coatings was studied by altering the composition and the size of spraying powders. The results of XRD (X-ray diffraction), SEM(scanning electronic microscope)show that the Al-Cu-Fe quasicrystalline coating is dense and uniform, by preparing from Al70Cu20Fe10 powders with particle size of –325 mesh(<44.5μm). After annealing under vacuum condition of 800℃ for 2 hours, it is observed that the icosahedron phase is the major phase together with a few β- Al (Cu, Fe) phase.
Internal resonance property of flexible under-actuated manipulators
He Guangping, Lu Zhen, Wang Fengxiang
2005, 31(08): 913-916.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1029
Abstract:
The dynamic feature of the flexible underactuated manipulator under the state of free-swings or locked of the passive joints was analyzed. Through the nonlinear dynamic analyzing of a planar two-links flexible underactuated manipulator, it can be found that the internal resonance of the multi-modal nonlinear dynamic mechanical system influenced the vibration of the system considerably, An attractive property of the internal resonance of the flexible underactuated manipulator was that it could decrease the vibration of the end of the manipulator effectually with selecting appropriate parameters of the structure. Based on the dynamic analysis results, an open-looped control method, which had some merits in stabilizing the system or realizing by actuator than a closed-loop one for decreasing the structural vibration of the flexible underactuated manipulator, was suggested. A two-links flexible underactuated manipulator was molded mathematically and simulated numerically. The simulation results show some aspects of the research.
Joint power control algorithm for CDMA-TDD system
Zhang Shu, Rong Mongtian
2005, 31(08): 917-920.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 933
Abstract:
A joint power control algorithm based on current link information was proposed to address the shortcoming of the conventional power control algorithms for CDMA (code division multiple access) TDD (time division duplex) system. The joint power control equation was deduced in theory. In the new algorithm, the power adjustment of all UEs (user equipments) was derived jointly from the common network resource. The adjust of transmission power all UEs assigned in the same time slot was based on current information, which took into account the power adjustment of other UEs in next step. The goal is to allow UEs to share network resources equally so as to speed up the convergence of power control. A function model was developed to verify the new algorithm and evaluate its performance. The simulation results indicate that the new algorithm outperforms the conventional algorithms in terms of smaller standard deviation of receiver SIR (signal-to-interference-ratio), lower system interference, higher energy efficiency, and thus better system capacity.
Research of ventilation cooling profile in reliability testing
Wang Xiaohong, Jiang Tongmin
2005, 31(08): 921-924.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 832
Abstract:
The applying of the ventilation stress in the reliability test of the airborne electronic equipment were introduced. Combined with the GJB and the characteristic of the environment control system of airplane, the ventilation and cooling condition of airborne electronic equipments in factual use environment was investigated;Combined with the life profile, task profile and its environment condition, flight altitude, flight mach number, etc, the stress in reliability test and the problems in those standards in use present were investigated. The simulation of the ventilation and cooling conditions of factual environment was introduced. A ventilation and cooling profile with reason in reliability testing (including the conforming method of parameters of ventilate air—such as flux, temperature, humidity and cleanness etc) was established. Through research of a product with these items, the ventilation cooling profile (including the parameters of ventilate air and infliction time )which was compatible with the temperature profile was given.
Investigation of probabilistic safety assessment for in-service mechanical equipment steel structures
Luo Hongyun, Zhong Qunpeng, Zhang Zheng
2005, 31(08): 925-929.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 694
Abstract:
To solve the safety assessment problem of large-scale in-service mechanical equipments’ steel structure , the probabilistic safety assessment method was proposed under the dead load and fatigue conditions with the aid of second level method and Monte Carlo method. Amended equation of it was established according to the three-period corrosion law in consider of corrosion lost under marine environment with which the ship loader bridge and wagon tipper in Qingdao Port were calculated and analyzed. Both definite safety assessment and the probabilistic safety assessment results were obtained. The results from the two assessment methods were generally closed but still there was little difference between them. The primary relation-approximately logarithm relationship,between the definite safety assessment and the probabilistic safety assessment was obtained from the comparative investment between the results of two kinds of assessment methods. The relationship obtained is the key point for the effectively application of the concerned probabilistic safety assessment method to in-service mechanical equipments’ steel structure.
Genetic algorithm with double roulette wheels
Liu Gang, He Linshu
2005, 31(08): 930-933.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 813
Abstract:
Double roulette wheels genetic algorithm was proposed to deal with the inequality constraints directly. Deferent fitness function was built for the feasible and infeasible individual in the population, respectively. The fitness function of the feasible individual reflected the objective function value; the fitness function of the infeasible individual reflected the degree of which the constraints were satisfied. Double roulette wheels was employed to select them respectively. A formula to decide the rotation times of each roulette wheel was given to make the feasible individual has greater probability to be selected than the infeasible ones. During the evolution, the individuals could move to the feasible region automatically. Then the inequality constraints were dealt with in a directive way and all infeasible initial population could be allowed. In addition, an improved real-coding copulation operator was also raised. This operator has more detecting ability than the classical two points inner interpolative operator. Examples show that the algorithm is not only an easy way to give global solution but also a simple and high effective method to deal with the inequality constraints.
Formation mechanism analysis of aviation calamity based on Bayesian network
Luo Fan, Chen Xiaojia, Gu Bichong
2005, 31(08): 934-938.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1525
Abstract:
In order to prevent the emergence of accident-inducing elements and control the further development of them, to improve aviation security management to be scientific and reliable, and decrease the accident rate and aviation calamity loss. It is a key of formation mechanism analysis to probe into interaction of the factors to cause an aviation calamity in accordance with the characteristics. Causality of the factors was analyzed and the interaction law of human, aircraft, environment and management factors is revealed by means of the application of both diagnosis and support inference form based on Bayesian network model. The effects coming from the connotative internal factors of the system were investigated, and the evolution process of the connotative factors from the uncertain state to the certain state and relationships between the external factors and the internal factors were found with formation mechanism analyses of a typical aviation calamity case according to Gauss Bayesian network.

Copyright © Journal of Beijing University of Aeronautics and Astronautics

Address: Editorial Department of Journal of Beijing University of Aeronautics and Astronautics, 37 Xueyuan Road, Haidian District, Beijing Post Code: 100191 Email: jbuaa@buaa.edu.cn

Supported by: Beijing Renhe Information Technology Co., Ltd.