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2003 Vol. 29, No. 3

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Longitudinal Shear Stress around Collinear Periodical Rigid Line Inclusions Between Dissimilar Materials
Yang Xiaowei, Jiang Chiping
2003, 29(3): 189-192.
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Longitudinal shear problems of collinear periodical rigid line inclusions at the interface of dissimilar materials were dealt with. By using complex variable method, a closed form solution was derived. On the above basis, stress singularity factor near the rigid line end was derived, stress interaction among rigid lines and the size effect of the rigid line inclusions were also examined. As a special case of the present problem, solutions for an interface rigid line and for collinear periodical rigid lines in a homogeneous material can be obtained.
Engineering Simulation Method for Airfield overComplex Terrain at Minimum Altitude
Liu Gang, Hong Guanxin, Jin Changjiang
2003, 29(3): 193-196.
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To describe the exterior environment where airplanes fly at low altitude, complex landform for minimum altitude flying was formed by planning multiple mountain ranges and many kinds of physiognomies. On the basis of potential flow theory, an engineering numerical simulation model was set up to simulate the complex landform and the airfield over it. The results of a digital simulation example showed that the method is applicable for analyzing the dynamics and track characters of an airplane flying at minimum altitude.
Porting Linux Kernel to New Hardware Platform
Lin Shiding, Ren Aihua, Wang Lei, Zhou Bosheng
2003, 29(3): 197-201.
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As a new VLIW based microprocessor M3270 was manufactured successfully, an operating system was urgently needed to support it. To research the architecture of Linux kernel and analyze the amount of efforts required to port Linux kernel to a new hardware, it will improve OS designing technique and reduce the cost greatly. Based on the research of Linux kernel architecture and M3270 hardware architecture, a methodology of porting Linux kernel to M3270 platform was proposed, which was proved to be practical and successful by the present study.
Experimental Investigation on Aerodynamic Performanceof Serrated Gurney Flap
Shen Xialing, Wan Zhouying, Gao Ge
2003, 29(3): 202-204.
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Force and PIV local flow measurements were conducted in a low speed wind tunnel to study the effectiveness of serrated Gurney flap at different deflections. The results showed that the serrated Gurney flap could significantly increase the lift coefficients and the ratio of lift to drag of the airfoil with high lift coefficients. For a given serrated Gurney flap, there was an optimum deflection, At which, the lift-drag ratio of the airfoil can increased not only at high lift coefficient but also at the low to middle angle of attack. It was also found that near-stream wise vortices shed from the serrated edges can make the flow attach to the upper surface near the trailing edge and can delay flow separation.
Prediction of Turbulent Flow and Heat Transfer Within Rotating Smooth UShaped Passage
Deng Hongwu, Tao Zhi, Xu Guoqiang, Ding Shuiting
2003, 29(3): 205-209.
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A two-equation turbulence model with additional term for Coriolis and buoyancy was used to predict turbulent flow and heat transfer in a rotating smooth serpentine passage. Using pressurized air as the coolant, operating conditions were selected to closely match the real turbine operating parameters. The results indicated that increasing the rotation number tend to increase averaged Nu value and the decrease Eu value, though there are variations in heat transfer on different sides.
GD1 Queuing Simulation with FGN Input
Shen Peng
2003, 29(3): 210-213.
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The traditional queuing theory is not applicable to the self-similar high-speed network traffic. A qualitative analysis of G/D/1 queue with FGN input by computer simulation was presented, and attention was focused on the average delay time and the tail behavior of infinite and finite queues. The effect of Hurst parameter was proven through these experiments that the average delay time rises evidently when Hurst parameter increases, while the input intensity and variance are almost equivalent and the utilization rate is above a certain threshold. Moreover, concerning the tail behavior under same conditions, the simulation results of the G/D/1 model with finite buffer are much more optimistic than the theoretical results of such model with infinite buffer.
Numerical Research on Unsteady Effect of ShockShock Interference Flow
Yan Chao, Tu Zhengguang, Yu Xiaohong, Zhang Zhi
2003, 29(3): 214-217.
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The ASUM+ scheme is applied to numerically simulate the shock-shock interference flow around a semiglobe under steady oncoming flow. The results show that the interference flow is inherently unsteady. The complicated flow structures of an unsteady supersonic jet behind the bow shock are analyzed and a new formation mechanism of the unsteady effect of the shock-shock interference flow is proposed.
Fatigue Life Estimation of Specimen under Spectrum LoadUsing Fuzzy Miners Rule
Jia Xinglan, Liu Wenting
2003, 29(3): 218-220.
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Fatigue damage exhibits some "fuzzy" character when the fatigue stress in load spectrum is lower slightly than fatigue limit. A Miner-s rule considering this "fuzzy" damage character is established by means of membership function of fuzzy mathematics. When a specimen is subjected to programmed spectrum loads, the estimation formula of fatigue life is derived according to regular Miner's rule and fuzzy Miner's rule. Comparing the results of calculations and fatigue experiments, it is shown that the estimation error of fatigue life is decreased by 18.33% with using fuzzy Miner's rule.
Optimization of MPLS Traffic Engineering Architecture
Huang He, Li Weiqin, Sun Guanying, Zhang Hui
2003, 29(3): 221-224.
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Several explicit routing algorithms for Internet traffic engineering were analyzed and compared, in order to put forward the architecture for distributed and on-line implements of MPLS Traffic Engineering. To improve the scalability of MPLS Traffic Engineering through optimizations of the performance of minimal interference routing algorithm, new link state advertisement mechanism was introduced, together with the combination of centralized and distributed computing methods. It was shown that not only the computation efficiency of the minimal interference routing algorithm, but also the scalability of the MPLS traffic engineering system were obviously enhanced through the treatments.
Effect of Atomic Oxygen on Leakage Rate of ORing
Shao Xinjie, Zhang Jianbin, Zhang Yuan
2003, 29(3): 225-228.
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Experiments were conducted with an IFM ground equipment to investigate the effect of atomic oxygen on silicone rubber O-rings. By measuring the pressure between two O-rings, leakage rates between the two O-rings before and after exposure to atomic oxygen were compared. In addition, the surface characteristics of O-ring were analyzed by scanning electron microscope. All experiments provethat atomic oxygen erodes the surface of O-ring seriously, resulting in a weight loss and a weakened sealing capacity of the O-ring. The results show that the surface damage, the weight loss and the leakage rate of an O-ring all increase in proportion to its of the time exposed to atomic oxygen.
Service Life Supervision for Aircraft Structures under
He Xiaofan, Liu Wenting, Jiang Dongbin
2003, 29(3): 229-232.
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A method for supervising the service life of aircraft structures under corrosive environment was developed. Based on the evaluation results of fatigue life at room temperature and in the air and the expected calendar life index, considering the influence of pre-corrosion under ground environment and the corrosion fatigue during flight, an objective function was established to supervise the inspection threshold, overhaul intervals and total life. Fatigue life supervision and calendar life supervision were unified by this function. In addition, significant corrosive environment change was considered. As an example, a practical supervising process was given to demonstrate the application of this method.
Bayes Analysis of Fatigue Strength Distribution Parameters
Chen Bo, Bao Rui, Zhang Jianyu, Fei Binjun
2003, 29(3): 233-236.
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Based on Bayes estimation and Monte Carlo simulation method, a new method of getting distribution of fatigue strength parameters including average and dispersion is presented. With the scanty life date obtained by up and down experimental method, the interval estimation and confidence analysis of the parameters can be carried out, which makes the further study possible. A calculation example is also presented to validate the feasibility of this new method. Through comparison the results, the advantages and disadvantages of the three treatment methods of life date gained by up and down method can be easily seen.
Interchangeable Virtual Instrument Driver Based on COM
Zhang Fengjun, Meng Xiaofeng
2003, 29(3): 237-240.
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A new structure of interchangeable virtual instrument driver was proposed based on COM, a commonly used software component. Analysis was done to explain how the new structured instrument driver implements interchangeability and simulation. At last, some comparisons of performance among VPP driver, IVI driver and IVI-COM driver was listed to illustrate the superiority of IVI-COM structure, such as interchangeability, platform adaptability, remote accessing ability, simulation capability, etc.
Structure and Hardness Changes of Laser Melted TiAl AlloySurface During Continuous Heating
Wu Guoqing, Huang Zheng, Lin Jianguo, Yang Jinhai
2003, 29(3): 241-243.
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Structural transformation and hardness variation in the laser melted TiAl intermetallic alloy surface during continuous heating were studied systemically. The results indicated that, during continuous heating from 50 to 1000℃ with a heating rate of 10℃/min, α2→γ phase transformation in the laser melted TiAl intermetallic alloy surface takes place at about 750℃, and the dendritic structure is transformed into fine-grained structure at about 860℃, correspondingly, variations in the hardness of the laser melted TiAl intermetallic alloy surface were also measured. The fine grain structure was considered to be a good basis of superplastic/diffusion bonding.
Design of SmallSize and HighPressure Centrifugal Fans Used in Helicopters
Li Lin, Yu Jianzu, Xie Yongqi
2003, 29(3): 244-247.
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Based on the characters of high-pressure, high-speed and small-size of centrifugal fans used in helicopters, the basal structure parameters of the fans were analyzed and calculated. Efforts were made to analyze the flowing rules of the gas in the impeller. Influence of distribution of the gas vortex on the across-section was discussed. Restriction requirements of selecting the gas vortex was put forward. The shape of the meridian-section and the across-section was designed. It was proved that the efficiency of the centrifugal fans can be evidently improved by reasonably determining the distribution of the gas vortex.
Modeling of Nonlinear System with Diagonal Recurrent Neural Network
Chen Ping, Qiu Lihua, Wang Zhanlin
2003, 29(3): 248-251.
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Based on an analysis on the modeling principles of nonlinear system, the identification of a nonlinear system was realized with Diagonal Recurrent Neural Networks (DRNN). Serial-parallel identification architecture was applied in the modeling. Time variation was taken into account in the adjustment algorithm of weights. Compared with static neural network, the method based on DRNN displays better ability to deal with a dynamic system, due to its advantages such as without the need of system order number, a smaller neural network structure and a faster convergence. Simulation results testified the feasibility and validity of the proposed method.
Design of Loading Stand for Reverse Operation of Navigating Machine
Cao Tong, Sun Xingchu, Ouyang Qin, Zheng Shijing
2003, 29(3): 252-254.
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Loading test stand for navigating machine is used to simulate dynamical loading from both normal and reverse directions on navigating faces, aimed at conducting performance test for navigating system and control system under reverse operating mode. It uses pneumatic power to realize reverse loading. High loading strength, high symmetry, high Linearity and small loading elements are the basic requirements for the design of this stand. By using the balance technology of robots, we solved the above key technologies,and successfully designes a test stand which is believed to be the first in our country.
PartitionBlock Method of Feature Selection from Information System
Li Guohe, Zhao Qinping
2003, 29(3): 255-259.
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After utilizing the technique of the combination of And/Or Tree with Different Matrix(DM) and Minimum Different List(MDL), this paper presents a method called IBFS to compute a better feature selection from larger Information System(IS).IBFS mainly partitions larger IS into small ones(called identification block, IB) by the identification feature or features, and then computes the feature selections from IBs, finally forming a feature selection for IS. It has the advantage of high efficiency and determinacy.
Precise Forming Simulation of Notched Panels with Double Curvature
Chen Lianfeng, Li Dongsheng, Zhou Xianbin, Chang Hesheng
2003, 29(3): 260-263.
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This paper systemic investigates the fitability of the notched panel with double curvature by FEM method. The FEM simulation model was established for analysing the fitability of the notched panels on discrete nails die. Further more,the effect trend of the notch parameters,such as deep and width,on the precision of the panels was analyzed. The most important factor is the relatively deep of notch. Optimize parameters of notch was found by simulation. It provide the solution for the precise forming of notched panels with double curvature. Both the simulation results and the experimental validation show that the notching technology can achieve the precise forming of doubly-curved reflector panels with continuous surface.
Data Fusion Algorithm for GPS/DR Integrated Vehicle Navigation System
Kou Yanhong, Zhang Qishan, Li Xianliang
2003, 29(3): 264-268.
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An adaptive federated Kalman filter model for GPS/DR integrated vehicle navigation system was established. Attention was focused on the filter algorithm. To improve the precision and reliability, data fusion techniques such as subsystem state evaluation, adaptive information distribution, error compensation, iterative extended Kalman filter, resist outliers, and U-D covariance decompose were used in the algorithm. To solve the problem of filtering divergence, a method to estimate the statistical feature of measurement noise was introduced. Theoretical analysis and semi-physical simulation results demonstrated that the algorithm is efficient in precision, reliability, adaptivity and real-time processing rate.
Modification of Transonic Wing Design Method
Sun Ruozi, Hua Jun
2003, 29(3): 269-272.
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The residual-correction design method for transonic wings with prescribed pressure distribution developed by Takanashi was modified. In order to guarantee the convergence of the design in supersonic flow, Takanashi method could be modified by introducing some upwind based operator to the governing equation in hyperbolic parts. Results of the redesign of a wing indicate that the improved method can overcome the convergence problem of the original method in supersonic region and then is more practical in engineering application.
Integrated Environment Based on HLA for Collaborative
Wang Jiangyun, Wang Xingren
2003, 29(3): 273-277.
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To deal with the simulation problems encountered in the system design for distributed simulations, an integrated environment based on HLA for collaborative simulation run-time management was provided, by integrating all the simulation tools and simulation applications that complied with the well-documented interface standards. The integrated environment supported both the interoperability of different simulations and the integration of simulation tools, as well as provided simulation run-time management, simulation time management and simulation data management. The integrated environment based on HLA was widely used.
Trust Issues in PGP and Solutions
Liu Hailong, Zhang Qishan, Wu Jinpei
2003, 29(3): 278-282.
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As a powerful public key based encryption tool, PGP(Pretty Good Privacy) has been used widely, but wrongful trust assumptions often undermine its security. The PGP's trust model, web of trust, is discussed in detail. The trust architecture and reasoning are presented. Some suggestions are given to solve the vulnerabilities in PGP.

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