Advanced Search

2002 Vol. 28, No. 6

  Previous Issue | Next Issue 
Display Method:
Series-Mixed-Cell Computational Model of Molecular Sieve Oxygen Concentrator
YANG Feng, LIN Gui-ping, YUAN Xiu-gan
2002, 28(6): 609-612.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 876
Abstract:
A series-mixed-cell model was proposed to describe the adsorption beds in order to transform the control equations of molecular sieve beds from partial equations to normal equations. Considered pressure variation in the column and Henry coefficient variation due to adsorption heat, a nonisothermal adsorption mathematical model was established, which could simulate molecular sieve oxygen concentrator. Based on several working conditions, the adsorption processes of molecular sieve oxygen concentrator were simulated using the above model. The results agree with those reported in the references.
Kinematics Analysis and Simulation of Free-Floating Space Robot
REN Jing-yi, SUN Han-xu
2002, 28(6): 613-616.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1061
Abstract:
The movement of the end-effector of free-floating space robot is related to not only the movement of each joint, but also the trajectory and the mass distribution of each link. This is the most distinct difference between free-floating space robot and terrestrial robot. Thus, the kinematics of free-floating space robot is closely connected with its dynamics. Screw theory and linear and angular momentum conservation were used to analyze free-floating space robot system. A general jacobian was derived, which includes the system's mass. On the above basis, a movement simulation of free-floating space robot was given.
Study on Theory and Arithmetic of Stationary Alignment for PINS
LIU Zhun, CHEN Zhe
2002, 28(6): 617-620.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 929
Abstract:
The observability of stationary alignment for PINS was analyzed systemically, and condition number of observable matrix was adopted to compute quantificationally the observability of stationary alignment for PINS. Three unobservable states with the least condition mumber were chosen in this condition, then both adaptive Kalman filter and general Kalman filter was employed to compare for simplified model. Simulation results showed the former was faster than later. Furthermore, a alignment method based on Elman neural network was proposed.
Ground-Speed/Air-Speed Control of Airplane During Penetration of Windshear
CHEN Yong, JIN Chang-jiang
2002, 28(6): 621-624.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 914
Abstract:
To design the control logic during the penetration of windshear, Non-linear Inverse Dynamics (NID for short) method has been employed to achieve the decoupling of the non-linear flight control system and the implementation of the real-time/on-line control for the flight trajetory. Two independent control laws were developed: climb rate/airspeed control mode in the wind-coordinate systemand climb rate/ground speed control mode in the ground-coordinate system. On the basis of analysis of the two modes, they were integrated to form a new and more feasible penetration-trajectory control law: ground speed/airspeed control law. The simulative calculation results indicated that the NID method works effectively in the trajectory control of airplane during the penetration of windshear.
Interference-Free Cutter Location Data Computation for Flat-Endmill in 4-Axis NC Machining
WU Li-ping, SHI Fa-zhong, CHEN Wei-dong
2002, 28(6): 625-628.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 885
Abstract:
An analytical method based on discrete model was presented to detect and avoid interference for flat-endmill in 4-axis NC machining. Based on the analyses conducted, an algorithm of interference-free cutter location data computation for flat-endmill in 4-axis NC machining was developed. Calculation examples showed that the algorithm could handle the interference problem in 4-axis NC machining with improved computation efficiency and stability.
Optimization Design of Connecting Power Cable in Induction Heating
ZHAO Jing, QI Bo-jin, CHEN Jing-wu, NI Qian
2002, 28(6): 629-632.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 928
Abstract:
In some induction heating process, induction coil is connected with power source through connecting power cable. In order to solve the problem of lower heating efficiency brought by connecting power cable, the power loss and the energy stored in inductance during induction heating were calculated. The analysis and the experiments carried out three kinds of cables, including parallel solid cables, hollow cables with same axis, and the cables made by lots of electrically insulated slimlines. It shows that the cables made by lots of electrically insulated slimlines have the lowest power loss and the hollow cables with same axis have the lowest inductance. So a kind of advantageous cable structure was put forward, which is arrayed around same axis by lots of electrically insulated slimlines for both inside conductor, and outside conductor and the middle of inside conductor is hollow.
Quick Construction of Radar Blind Space for Stealthy Penetration
WU Qiang, JIN Chang-jiang
2002, 28(6): 633-635.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1364
Abstract:
Before planning stealthy penetration flight route, the Threat States Space (TSS) and the Radar Blind Space (RBS) should be constructed firstly, which represent the defense strength of the enemy. On analysing the factors of generating RBS, a quick algorithm of constructing RBS for planning stealthy penetration flight route was presented, together with an orientation treatment scheme for RBS to be practical. An example of building a 50km×50km RBS within 8s was given, which shows the feasibility of the proposed method.
Dynamic Stability Analysis and Control Law Design of Stability Augmentation System for Helicopter
SU Yuan, CAO Yi-hua
2002, 28(6): 636-639.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1181
Abstract:
Dynamic stability and control laws of a hingeless rotor helicopter were studied. Based on dynamic stability analysis of the helicopter, the unstable mode and the necessity of installation of Stability Augmentation System (SAS) were cognized. The control laws of SAS for helicopter pitching, rolling and yawing motions were presented. Following establishing helicopter flight control state equations, the calculations of effective derivatives, the performance analysis and step response simulation for helicopter SAS were carried out. Through the design of SAS, the helicopter dynamic stability can be improved, the stability augmentation performance can meet the requirements of the first level qualities of the design specifications.
Method of Testing and Calculating for Frequency Characteristics of Digital Closed-Loop FOG
MA Ying-jian, WANG Zheng, ZHANG Wei-xu, WANG Yan
2002, 28(6): 640-642.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 941
Abstract:
A mathematical model for digital closed-loop FOG(fiber-optics gyroscropes) was established to get the difference equation of the model. Also, the differential equation and transfer function corresponding to the model were deduced. Frequency characteristics calculation of the digital closed-loop FOG was conducted based on error analysis between the transfer function and the model. A method found for testing frequency characteristics of the digital closed-loop FOG on common speed platform was established. The validity and veracity of the methods were verified by comparing the testing and calculation data.
Precise Imaging Processing for Spaceborne Spotlight SAR
WANG Guo-dong, ZHOU Yin-qing, LI Chun-sheng
2002, 28(6): 643-647.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1593
Abstract:
Signal properties of spaceborne spotlight SAR were discussed. The relationships of centroid Doppler, Doppler bandwidth and PRF(Pluse Repetition Frequency) with squint angle were analyzed. Based on a modified Chirp Scaling algorithm, a subaperture method was used in this algorithm. With the subaperture method, data rate and radar transmit peak power can be effectively reduced, the time-variant of Doppler center frequency can be resolved. In addition, the necessities of yaw steering were analyzed, a yaw steering rule was given. It was proved that yaw steering can be used to decrease range migration and to reduce imaging difficulties. The validity of the processing method was tested by computer simulation.
Image Processing Method to Detect Seam Track of Thin Sheets
WU Xin, QI Bo-jin, WU Hong-jie
2002, 28(6): 648-651.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1252
Abstract:
Aiming at automatic welding of butt and lap joints of the seam track of the key components of aviation engine by means of CCD camera direct shooting to obtain seam track, a relatively universal algorithm and thought was put forward including detecting edge points and obtaining edge line. Several key steps were improved. The experiments shows that the algorithm and thought possesses have better adaptability and can give some technical reference to solve the key technique of obtaining seam track in the field of welding automation and intelligence of welding robot.
Numerical Simulation of 3D Viscous Flow in Exhaust Casing of a Low-Pressure Steam Turbine
XU Xu, KANG Shun, JIANG Hong
2002, 28(6): 652-655.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 974
Abstract:
Numerical results of a 3D viscous flow in an exhaust casing of a low-pressure steam turbine were obtained with the 3D Navier-Stokes solver Fine/Turbo. Good agreements with the available experimental data in velocity, static and total pressure coefficients were exhibited. The computational results revealed a complex vortex system within the casing model, including a passage vortex, a separation vortex and an endwall vortex. Of all the vortices, most portion of energy losses within the casing is contributed by the passage vortex. The calculated overall mass averaged total pressure loss in the casing is nearly 47.8%, very close to the experimental value of 40.9%.
Optimization Selection in Conceptual Design of Advanced Trainer Aircraft
HUANG Jun, HUAI Jin-peng, WU Zhe
2002, 28(6): 656-659.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1020
Abstract:
Improved cost-efficiency ratio is a major factor considered in the development of trainer aircraft. Operational analysis was introduced as a method for evaluating training effectiveness of trainer aircraft. Approaches to the engineering estimation of aerodynamic characteristics for aircraft with double-delta wings configuration were studied and the procedures for determining aircraft performance indices were formulated. Then, taking training effectiveness as an objective function, through numerical method for multivariate optimization, the conceptual design optimization selection of a certain advanced trainer aircraft with double-delta wings configuration was accomplished under the constrains of tactical and technical requirements and interrelated geometry. Agreement of a calculation example with engineering practice indicates that the optimal design has higher training effectiveness than the baseline design, in addition to improve structural force-bearing conditions.
Modeling of Selective Laser Sintering for PC Powder
PC Powder, ZHAO Bao-jun
2002, 28(6): 660-663.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 964
Abstract:
Numerical computation model for the thermal process of selective laser sintering of powders were presented to predict the sintered depth in selective laser sintering．The factors of the material thermal physical properties varing with the temperature and the un-uniformed distribution of laser intensity across the beam diameter had been taken into account in the computation model．The problem was formulated by a three-dimensional transient heat transmission model and solved by the finite differential method．The results show that the predicted sintered depth accord with the measured value and the model can be used to estimate the sintered depth in selective laser sintering．
Carrier Tracking Technology of High Dynamics Spread Spectrum Signal Based on Software
REN Jun-tao, SHAO Ding-rong, LI Shu-jian
2002, 28(6): 664-667.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1043
Abstract:
In high dynamics environment, the movement of object changes sharply, so the transmitted signal has some special characters: larger Doppler frequency shift, the first order derivative and the second order derivative. It is difficult to demodulate correctly. A method of compound software loop of tracking the carrier was presented. The receiver is realized on DSP, and the result of the experiment approves that the project is feasible.
Experimental Investigations of Atomic Oxygen Effects on a Carbon Fiber/Epoxy Resin Composite Material
ZHAO Xiao, SHEN Zhi, XING Yu, MA Shu
2002, 28(6): 668-670.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 892
Abstract:
When used in spacecrafts, carbon fiber/epoxy resin is affected severely by many factors of space environment, especially the atomic oxygen effect. Experiments were constructed to investigate the atomic oxygen erosion effect of this material with a ground-based simulation facility, and as a function of temperature change. Masses and surface morphologies of the sample material before and after the experiments were compared. The reaction characteristics of the material in the facility and the impact of temperature change on atomic oxygen effect were acquired. In addition, the effect of ionic oxygen on the mass loss of the sample was qualitatively studied.
Simulation Study on the Thermodynamics System of Aircraft Avionics Pod
DONG Su-jun, LIU Meng, WANG Jun
2002, 28(6): 671-674.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 843
Abstract:
Simulation model of the thermodynamics system of aircraft avionics pod was established and its dynamic characteristics of thermal load and main temperature parameters during the whole flying were obtained, which assisted in the selection and verification of the refrigeration system. In addition, a valid proposal about the optimization of the hull framework was offered. The study proved that dynamic simulation is an advanced calculation and analysis method for the design and model selection of the refrigeration system.
Computation of Transonic Turbulent Flow Around a Blunt Nosed Short Body at Large Angle of Attack
WU Zong-cheng, ZHU Zi-qiang, LI Jin, CHEN Ze-min
2002, 28(6): 675-678.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 981
Abstract:
The transonic turbulent flow around a blunt nosed and short body at large angle of attack was calculated and analysed by using numerical simulation method to solve the full N-S equations. In the computation, Van Leer's scheme was used to discretize the inviscid flux terms and a new limiter function was constructed to realize TVD character. The viscous flux terms were discretized by using a central difference scheme. The Baldwin-Lomax turbulent model was used in the viscous terms. Numerical results qualitatively show that the separated flow has an unsteady quasi-periodic character.
Robust Fault-Tolerant Control Design for a Class of Sensor Failures
YAN Xi-jun, GAO Jin-yuan
2002, 28(6): 679-681.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 842
Abstract:
Considering the uncertainty of a linear system and a class of sensor failures including the reduction of sensors gains, the switching-on-off of sensor channels, and the switching-off of sensor channels, a method of robust fault-tolerant using LQR theory was studied. The resulting design guaranteed closed-loop stability and robust performance not only when all sensors are operational, but also in case of some sensors outages. Conclusion and proof were given which ensured that the controller is insensitive to the class of failures. Simulation results identified the validity of the method.
Experimental Study on Fuzzy Control of Transient Aerodynamic Heat Flow of Missile
WU Da-fang, GAO Zhen-tong, WANG Yong-hai
2002, 28(6): 682-684.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 967
Abstract:
The characteristics of transient heating control process of aerodynamic simulation experiments are complicated, transient, high non linearity and strong coupling, which make it difficult or impossible to get a mathematical model. By using fuzzy control method,many good qualities (such as robust, high adaptability on changing parameters and short transition process time) can be obtained. Based on the fuzzy control method, a transient aerodynamic heating simulation control system for missiles was established. It was demonstrated that quick dynamic control of aerodynamic simulation heating process according to the transient and continual change of heat flow on the surface of a flying missile body can be completed by using this control system.
Method of Short Interleaver Design for Turbo Codes
REN Jun-tao, SHAO Ding-rong, QI Feng, ZHANG Bo
2002, 28(6): 685-687.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1146
Abstract:
The interleaver structure plays a very important role to the bit error rate performance of Turbo code. The periodic character of the feedback minimum polynomial and the divisibility character of the input information sequences were analyzed. Some interleavers were found that can change the divisible input sequences into indivisible ones, and the high Hamming weight codes can be obtained. A designing method for the short interleaver based on periodic character of the input information sequences is presented. It is proved to be an effective way by the simulation.
Research of Notchback Automobile Wake Structure
ZHANG Qun-feng, Lü Zhi-yong, QIN Yan-hua
2002, 28(6): 688-691.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 975
Abstract:
The aerodynamical drag of a automobile directly influences its fuel comsumption. For a notchback automobile, its aerodynamical drag relateded with the rear shape amounts to nearly 50 percent of the total aerodynamical drag. Therefore, it is important to make the wake structure clear for designing automobile with good aerodynamic characteristics. The wake structure of notchback automobile and the influence of the rear shape on the structure were analyzed. The result is quite striking for designing new type notchback automobile with good aerodynamic characteristics.
Neural Network Data Fusion for Maneuvering Targets Tracking
BI Jing, WANG Qing, SHI Xiao-rong
2002, 28(6): 692-694.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 2259
Abstract:
A neural network data fusion approach for radar/infrared dual mode guidance was presented.By taking a neural network consisting of one neuron for each component of the measurement vector as the fusion center, the infrared measurements were fused first to keep synchronous with the radar measurements processed by Kalman filter. The processed data were then transmitted to the central neural network where a fused estimation of target was formed. The goal of this pager was to propose a method for computing the fused estimation in the absence of covariance information. Simulation result was demonstrated the effectiveness of this method.
Optimum Search in Terminal of Midcourse Guidance
JIANG Yu-xian, ZHANG Hua-ming
2002, 28(6): 695-698.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1487
Abstract:
The optimum searching problem, in which beyond-line-of-sight missile flying in the terminal of midcourse guidance searches the moving target automatically to maximize the probability of acquisition by use of the residual propellent was studied. The position-probability distribution of moving target was provided. The project of searching course-line based on the position-probability distribution was proposed. The composition schema of the searching system was drawn up and the system was designed. At last, the system was simulated and the probability of acquisition of moving target was proved.
GPS/DRS/DMAP Vehicles Navigation and Location System
GAO Peng, FU Li, FAN Yue-zu
2002, 28(6): 699-702.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 650
Abstract:
A dead reckoning system (DRS) based on MCU was expatiated, which was composed of compass, rate gyroscope and odometer and its essential theory. On the above basis, a novel multilevel filtering GPS/DRS vehicles navigation and location system was designed. Positioning accuracy was further improved by using map matching. Data of positioning were communicated through GSM. Trial run experiments indicated that the system possesses higher positioning accuracy and higher reliability.
Eye-Moment Analysis of Simulating Airplane Landing Course
LIU Zhong-qi, YUAN Xiu-gan, LIU Wei, WANG Rui
2002, 28(6): 703-706.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 2409
Abstract:
The distribution of subject's attention was studied by analyzing his eye movement principle. Through simulating the airplane's landing course, eye's fixation point and velocity data were collected by using EMMS. Analysis was made to the shift of the subject's vision and the primary processing and cognizing of information. The conclusion is that the top-down mechanism is the main way to drive eye movement and the good SA has important meaning to the pilot.
Optimizing Dispatching of Public Traffic Vehicles in Intelligent Transport Systems
ZHANG Fei-zhou, YAN Lei, FAN Yue-zu, SUN Xian-fang
2002, 28(6): 707-710.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1923
Abstract:
The basic principles of Genetic Algorithm (GA) and Tabu Search(TS) were expatiated on. Both of optimizing algorithms were availably integrated into Hybrid Genetic Algorithm (HGA). With regard to actual status and operation environment of Public Traffic Vehicles (PTV), intelligent dispatching of PTV was studied with HGA. The simulation results were demonstrated that intelligent dispatching of PTV could be realized to decision-making, and the shortcoming could be effectively overcome based on GA-TS Hybrid Genetic Algorithm. As a conclusion, the efficiency is 15% higher and traffic operation cycle 5% shorter than those of common PTV. In the way operation efficiency, traveling safety and service level of PTV were enhanced, the reasonable and viable means were provided for intelligent dispatching of urban PTV.
Mechanism and Effect of Vibration Suspression Using Two Squeeze Film Dampers
LI Lin, WANG Bao-feng
2002, 28(6): 711-714.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 983
Abstract:
For researching the function of two Squeeze Film Dampers on steady unbalance and transient vibration of rotor system, a single-disk flexible rotor model was developed and analyzed with transfer coefficent method. It could be seen that the mechanism and effect of vibration suspression are different for the two motion.
Grinding of Ballend Cutter on Virtual Axis Machine Tool
LI Wei, FAN Rui, CHEN Wu-yi, CHEN Ding-chang
2002, 28(6): 715-718.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 866
Abstract:
Working principle of a virtual axis machine tool was analyzed. Curve equation of ballend cutter blade was established. Using moving frame methods, a mathematical model of rake face and flank face was inferred. According to the mathematical model of ballend cutter tool and inverse solution model of the virtual axis machine tool, generalized cutter location contrail of the rotating cutter tool was deduced, and converted into the length of the pole under pole coordinates. Cutting action can be conducted through controlling the length of pole, and dissertate the advantages of virtual axis machine tool in cutting tool's machining.

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.