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2006 Vol. 32, No. 08

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Fast star tracking technology in star sensor
Jiang Jie, Li Xiao, Zhang Guangjun, Wei Xinguo
2006, 32(08): 877-880.
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Tracking model is one of main models, when star sensor works. Speediness of tracking process affects star sensor′s performance. A fast star tracking algorithm was proposed. Three methods, such as star catalog partition, threshold mapping, sorting and matching, were designed for three time-consuming elements in tracking algorithm, in order to raise the tracking speed. Star catalog partition method divided the celestial sphere into some partitions. It made star mapping search in the partitions near the direction of star sensor′s visual axis not in the whole celestial sphere and reduced the total number of stars searched. Threshold mapping method in required accuracy condition, set a threshold of stars tracked. When the number of stars tracked was less than the threshold, star mapping was performed. It reduced mapping times. Sorting and matching method made sorting based on star′s coordinates in star image, and then matched. It avoided matching between stars which had a long distance. Simulation showed that application of these methods made this tracking algorithm faster, and improved the efficiency of star sensor.
Application of quaternion in ejection seat performance simulation
Feng Wenchun, Lin Guiping
2006, 32(08): 881-884.
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A new method of combined quaternion and Euler angle was proposed to solve the singularity problem of Euler angle velocity equation at large extent attitude movement and all-attitude angles and jumping problems for the limitary of attitude angle using quaternion method in ejection seat performance simulation. Quaternion definition and geometry meaning were described and quaternion movement equation was introduced. Calculation formula of quaternion integral initial values in simulation was put forward through quaternion to Euler angle conversion. The problem of attitude angle jumping and discontinuous in simulation was analyzed. Simulation based on certain seat model was executed. Compared simulation result with experiment data and compared the result with another simulation using single quaternion method, it was shown that this method combined the virtue of quaternion and Euler angle velocity equation could efficiently resolve the singularity of Euler angle velocity equation and could realize all-attitude angle in simulation.
Attitude estimation method for flight vehicles based on computer vision
Zhao Shifeng, Zhang Hai, Fan Yaozu
2006, 32(08): 885-888.
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An attitude estimation method for flight vehicles based on statistic of image was improved. The method improved reduces calculation, and improves the real-time performance for attitude estimation. The bank and the pitch angle can be estimated rapidly with a higher robusticity. Its accuracy satisfies the requirement of attitude estimation to control flight vehicles. Several differentmethods were compared with simulation results, and an application was proposed, which resolved the problem of coupling between the bank and the pitch in the attitude estimation. The method improved is applicable for those which are equipped computer vision systems as navigation systems, especially for MAV(micro air vehicles) equipped only minitype computer vision systems. Range of the attitude angle to be estimated is expanded while computer vision system equipped by the method is adopted with a MIMU(miniature inertial measurement unit) assistant, and the accuracy is higher correspondingly.
Autonomous orbit determination of spacecraft based on UKF using radar altimeter
Liu Jun, Han Chao
2006, 32(08): 889-893.
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The existing problem in using the extended Kalman filter(EKF) to estimate the state of one nonlinear system was discussed. And the unscented Kalman filter(UKF) was introduced, which is widely used today. The radar altimeter as a new measure instrument was introduced in the satellite orbit navigation based on star sensor. A algorithm was presented about the autonomous orbit determination with radar altimeter and star sensor. The complicated sea level model was established, and the influence of the gravity waves caused by wind was considered. Using the measure data recurring to radio altimeter and model of earth′s shape, the direction of earth-satellite vector in satellite orbit frame was calculated. Based on UKF the precision of autonomous navigation was improved obviously. The simulations demonstrate that the precision of the UKF is much higher than the EKF.
Steady state modeling of loop heat pipes and operating characteristics analysis
Bai Lizhan, Lin Guiping, Zhang Hongxing
2006, 32(08): 894-898.
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Based on energy balance, pressure balance, mass conservation and geometric constraint, the steady state model of loop heat pipes was established and solved. The modeling results not only confirms the steady state operating characteristics of loop heat pipes introduced in many literatures, but also brings forward viewpoint to the problems below:the analysis of the heat leak of the evaporator, the reason of the generation of the variable heat conductance zone and the constant heat conductance zone, the variation of the heat conductance in the constant heat conductance zone and the calculation of the mass of the working fluid charged and the volume of the compensation chamber. Results show that the heat leak of the evaporator for heating the liquid through the wick can not be neglected at high heat load;adverse gravity elevation and the heating from environment to the return liquid are the reason of the generation of the variable heat conductance zone;the heat conductance in the constant heat conductance zone decreases as the heat load increases at high heat load, and can reach the critical heat load, which can be avoided by the match of the mass of the working fluid charged and the volume of the compensation chamber.
Reliability analysis on structure with multiple site damage
Wang Chuansheng, Zhang Jianyu, Bao Rui, Fei Binjun
2006, 32(08): 899-902.
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A quantitative analysis method on the occurrence probability of MSD(multiple site damage)was presented based on the theory of statistics in fatigue and fracture mechanics and the existing experimental results. It predigested the calculation for the occurrence probability of MSD and provided reference for the evaluation of fatigue life of aircraft structures. It assumed that the initiating life of single crack follows logarithmic normal distribution or normal distribution according to existing research and experimental results. The assumption was rational and it didn′t affect the foundation of calculation and theory. For the structures with multiple details, MSD in the structure happened when two or more than two details emanated cracks at certain time. According to these, method and formula were proposed. A numerical example and corresponding stress-MSD probability curve were given for the proposed approach. The result indicates that the method is reasonable and can be used in engineering.
Reliability lifetime analysis of the turbine blade of turbofan engine
Wang Dawei, Miao Xuewen, Hong Jie
2006, 32(08): 903-907.
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The loading spectrum is the foundation on which the life analysis of the aeroengine structure is discussed. The life usage consumption of turbine operating blade of some typical missile turbofan engine was predicted by working data processing. The life consumption models was established on which the working data was processed and the loading spectrum of the aeroengine was gained.Distribution of life consumption of the blade was discussed by the Weibull distribution model, and based on which reliability anglicizing models was established. The reliability methods of calculating the usage life by using the middle rank of incomplete life data in the statistical field were introduced. The life of the engine gradually develops with the increases of the reliability growth. Considering the time effect of the sample, the dynamic Weibull distribution model embodies the reliability growth of this engine. The analytical methods were used to estimate the engine′s reliability at research stage.
Chaos-simplex-based hybrid algorithm to collaborative optimization of aircraft design
Zhou Shengqiang, Xiang Jinwu
2006, 32(08): 908-911.
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Corresponding to computational difficulties encountered in the applications of CO(collaborative optimization), existing solutions were concluded. With transformed the system level optimization to unconstrained optimization problem, intelligence optimization algorithms should be chosen, but the computational burden should be controlled. A hybrid search algorithm was composed of chaos optimization and simplex method. Chaos could escape from local minima and approach the global minima, and simplex method was used to perform the local search in the neighborhoods of chaos optimization results. It was studied how to apply the CO to the conceptual design of a trunkliner. The subsystem levels were optimized by SQP(sequential quadratic programming), and the system level by the hybrid search algorithm. The numeric result indicates that the approach is effective.
Improving the atomic oxygen resistance of epoxy resin using organosilicon
Wang Xin, Zhao Xiaohu, Shen Zhigang
2006, 32(08): 912-916.
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To improve the atomic oxygen(AO) erosion resistance of resin matrix materials applied to spacecrafts, γ-Glycidoxypropyltrimethoxy silane was filledin the epoxy resin with a direct-mixing method and then the AO exposure experiments were carried out. After the AO exposure, a three-dimension network structure was formed on the sample surfaces. This network structure protected the underlying materials from the AO erosion and the AO resistance of the polymer was improved remarkably; the mass loss and erosion yield decreased distinctly. It proves that filling the organosilicon in the epoxy resin is an effective method to improve AO resistance of the epoxy resin. After AO exposure for 50 h, the erosion yield of the polymer containing 25.0% organosilicon decreased to 25% of that of the pristine epoxy resin.
Trajectories to the far side of the sun via gravity assists
Ma Wenzhen, Zheng Jianhua, Gao Changsheng
2006, 32(08): 917-921.
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The interplanetary trajectories to the high latitude of the sun via gravity assists of inner planets were analyzed to reduce the energy cost of the space mission. Based on the patched-conic theory, the energy contour maps, which were used to search for the appropriate launch opportunities of multiple spacecraft and celestial body encounters, were plotted by solving the Lambert′s problem. The ratio of orbit periods between the spacecraft and the planet, such as Venus or Earth, was designed as 1∶ 1 or 2∶ 3 to provide repetitious gravity assists. Results show that, if inner planet gravity assists are used, the inclination of the object orbit relative to the ecliptic reaches about 30°at the most following thrice Venus or Earth gravity-assist flybys, and the "Earth-Venus-Mars-Earth-Earth-Earth" flight path which demands lower launch energy and shorter flight time is the optimal trajectory. Launching energy can be much reduced by multiple gravity-assist maneuvers than by single planet maneuver.
Heat transfer measurements on a rotating disk with discrete receiver holes
Luo Xiang, Xu Guoqiang, Tao Zhi, Ding Shuiting
2006, 32(08): 922-925.
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Modern gas turbines are cooled using air diverted from the compressor. In a rotor stator system, the cooling air enters at the center of stator and flows radially outward, then leaves through the discrete receiver holes in the rotor and clearance between rotor and shroud. The rotor with 440mm diameter has 60 blade-cooling holes with 6mm diameter at a radius of 195mm.The temperatures on rotor surface at a number of radial locations were measured by thermocouples. The average Nusselt numbers on the rotating disc Nuav,d and on the surface of receiving holes Nuav,b were determined by experiment results. The magnitude of them was governed by two nondimensional fluid-dynamic parameters: rotational Reynolds number, nondimensional mass flow rate. The experiments reveal that Nuav,d and Nuav,b are increasing as either of them increases. The Nusslet number Nuav,d increases strongly with rotational Reynolds number and weekly with nondimensional mass flow rate compared to the rotating disk without receiver holes.
Computational intelligence technology for optimal design of grid-stiffened composite structure
Rong Xiaomin, Xu Yuanming, Wu Decai
2006, 32(08): 926-929.
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To overcome the difficulties of optimal design for grid-stiffened composite structures, such as multi-variables, multi-constraints, mixed discrete-continuous design variables, highly nonlinear, etc, the application of computational intelligence(CI), namely evolutionary neural networks(ENN) was considered for realizing the global nonlinear mapping between structural design parameters and structural responses. They were aimed to replace the finite element computation during an actual optimization process so as to raise the efficiency of optimization. By using genetic algorithm(GA) as the optimization procedure and the structural buckling constraint as the neural network response surface, the optimal design of grid-stiffened composite panel under axial compressive loads was studied. The results indicate that with very limited FEM sample space, the accuracy of the evolutionary buckling neural network is much higher than that of traditional BP neural network. The resulted ENN-GA algorithm proves that it can offer an efficient approach to the optimization design of large complex composite structures.
Analysis of precision for maximum likelihood estimation in the Weibull distribution
Li Jin, Huang Min
2006, 32(08): 930-932.
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Maximum likelihood estimation(MLE) in the Weibull distribution of parameters is considered an effective method, which is recommended in the case that the number of failure is more than 10 or equal 10. In practice, the number of failure is often less than 10 because of the high reliability or the fewness of sample. It is wanted to be known whether the MLE can be used in the case above; the number of failure, which makes the estimator have a given precision, will be known, sometimes, before the experimentation applying. So a method of analysis and estimation, which resolves that problems, was given with the idea of interval estimation. Then the precision of the estimator of shape parameter was discussed by this way under complete sample. In the practice projects, the precision of maximum likelihood estimation of Weibull shape parameter is quantitatively provided by the conclusion.
Genetic algorithm approach to the jammer′s layout for EW
Gao Bin, Lü Shanwei, Guo Qingfeng, Zhang Na
2006, 32(08): 933-936.
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The assignment problem of jamming resource for electronic warfare(ECM) plays a key role in utilizing jammer sufficiently and obtaining the optimal jamming effect. According to characteristics of modern electronic warfare(EW), the calculation formula of jammer′s avoidance ratio was investigated by use of search theory. The jamming force optimization apportion model was presented, and the limitation for Hungary method in settling this problem was illustrated. So combined with the intelligent optimization algorithm, a jamming force optimization apportion model based on genetic algorithm(GA) was presented. The symbol encoding style what was needed for the optimization apportion model was solved, and selection operator, cross operator and mutation operator were designed concretely. Two application examples were resolved using this model. The results show good practicability of the model, and the GA presented is effective and practical. GA can efficiently help commanders solve the complicate and difficult problem of jammer′s layout.
Infrared image sequence processing based on singular value decomposition
Guo Xingwang, Gao Gongchen
2006, 32(08): 937-940.
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The raw thermal images acquired in infrared thermographic nondestructive testing(IT NDT) usually have low signal-to-noise ratio(SNR) and temperature contrast. In order to restrain the bad effects of noise, singular value decomposition(SVD) technique was used in infrared image sequence processing to yield high defect contrast for digital images reconstructed in IT NDT and to improve the flaw detectivity, and its validity was illustrated by examples. The principle of SVD was introduced. The SVD method was used to process the infrared image sequences obtained in experiments. The image processing effect was quantitatively evaluated by SNR. The research indicates that SVD has the ability of extracting the algebra characteristics which reflect the underlying structural flaw in a sample. It can remove the uneven heating effect and increase the SNR of images, and the defect location in images doesn′t affect the practical efficacy of SVD. Thus SVD is an effective method for IR digital image sequence processing in IT NDT.
Dynamic compensator control strategy of hydraulic parallel manipulator
Yuan Lipeng, Dong Yanliang, Zhao Keding, Xu Hongguang
2006, 32(08): 941-945.
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The prototype of a hydraulic driven 6-DOF parallel manipulator used in fly model simulator was presented. Considering on the mathematical model of the system which has many uncertain effect factors such as disturbed force, friction force and uncertain parameter, the research on the closed loop dynamics model of the system was made. According to the dynamic compensation characteristics of the closed loop model of the system, six-dimension dynamic compensator was adopted. A real time control strategy which is composed by PD controller and wavelet neural network was put forward to make dynamic compensation. Experiment result shows that this method has characteristics of well tracing ability. And it can improve the response time, movement accuracy and resistance to load disturbance of the system. It also can overcome the effects which are produced by the dynamic coupling, real time varied parameters and unknown disturbance. This method presents a brand-new path for high performance of the parallel manipulator mechanism.
TOA data process method for improving the position location accuracy in NLOS environment
Chang Rong, Zhang Jianglin
2006, 32(08): 946-949.
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Based on the statistical property of the non-line of sight(NLOS) propagation in the mobile communication environment, a data process method was presented to improve the position location accuracy of the time-of-arrival(TOA). All of the measured TOA data were analysed, and the data which were apparently non-reasonable and had no use to the location estimation, and even worsen the position location accuracy were eliminated, and the 3 data which had the minimum error were kept. The least-squares(LS) method was applied to evaluate thelocation of mobile station. The simulation results show that this data process method not only can effectively improve the position location accuracy of the TOA method in NLOS environment, but also has little disadvantage to mobile location in line of sight(LOS) environment. It has a good adaptability for the communication environment.
Measurement arithmetic based on linear interpolation and equivalent transducer in aircraft fuel quantity gaging
Ouyang Pingchao, Liu Hongmei, Jiao Zongxia
2006, 32(08): 950-953.
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A measurement arithmetic based on virtual equivalent sensor and linear interpolation was presented, which was applied to aircraft fuel quantity gaging. The aircraft fuel surface which was defined by more than three fuel sensor′s measurement value could be also expressed with one virtual equivalent sensor located in special situation in the fuel tank. In this equivalent principle, fuel quantity could be acquired having three-dimensional linear interpolation through the three-dimensional data stable showing the relation between fuel quantity and the virtual equivalent sensor, aircraft attitude information. Effectiveness and precise of the proposed method were demonstrated by simulation results adopting Solidworks software. The results show that the measurement arithmetic is stable, reliable and effective. Because of the application of the equivalent sensor, data quantity in three-dimensional table is greatly compressed, which makes the interpolation method easy to be realized in actual aircraft fuel quantity gaging system.
Image target distinguish based on Gabor filters
Zeng Shuyan, Zhang Guangjun, Li Xiuzhi
2006, 32(08): 954-957.
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In order to provide useful information for mobile robot, the target distinguish approach based on image matching needs to recognize image pattern. 2D Gabor filters were created by Gabor transform, which had excellent performance and didn′t need to segmente images catched by the single CCD camera. Gabor filters were robust to the various orientations and illumination of target images; They also satisfied the real time image processing. The multi-channel Gabor filters, with multi-frequencies and multi-angles, were used to convolute with images. The corresponding filter results included entirely information of images, from which the feature vectors of the images could be extracted. The method of classifying these feature vectors was SVM (support vector machine). SVM was a new method of machine learning developed by statistical learning theory. It resolved problems such as model select, over learning, non-linear, high dimension, etc. Experiment results indicate that the algorithm can reach up to high recognize rate. The algorithm can be applied in fields such as face recognition, robot vision localization and so on.
Effect caused by coating adhesive on polarization-maintaining fiber coil
Meng Zhaokui, Shao Hongfeng, Xu Hongjie, Zhang Chunxi
2006, 32(08): 958-961.
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The action and effect on the two important performance parameters such as temperature and vibration of the fiber ring and fiber optical gyroscope(FOG) were expatiated. In allusion to the factual conditions of the FOG of some item, all aspects of experiments were done and the experiment results were analyzed. The experiment and analysis results show that the effect caused by coating adhesive to the fiber ring and FOG is brought due to the unsuitable coating adhesive. The amount and uniformity of coating adhesive are the two main facts of the effect. The temperature performance and the state after solidification of the adhesive can bring effect. Conclusions are gained: it is effected greatly by coating adhesive technics and methods or mode; it becomes more clearer with the temperature changing especially; in addition, it is existing after the adhesive curdles.
Moving-mass attitude control system for spinning vehicles based on neural networks
Wang Songyan, Yang Ming, Wang Zicai
2006, 32(08): 962-965.
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The ability of a moving-mass attitude control system to control a spinning vehicle was investigated. The general nonlinear equations of motion with n internal moving elements were provided. The coupling influence to the system caused by the relative movement of the moving masses to the vehicle shell was described. For the self-learning and adaptive capacities of the neural network control system, the attitude control scheme based on the neural networks was produced to improve the dynamic performances, which calculated the desired center position of the system mass. In order to generate the modest attitude corrections of the vehicle, the mass position algorithm was presented by using the optimal principle to get the commanded position of each mass to realize the desired change of the system mass center. A nonlinear simulation of the spinning vehicle with two internal moving mass actuators demonstrated the ability of the controller to effectively control the vehicle attitude.
60Co radiation effects and photobleaching properties of polarization-maintaining fiber in fiber optic gyroscopes
Xiao Wen, Zhang Yuyan, Liu Dewen
2006, 32(08): 966-968.
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For the space application of the interference fiber optic gyroscope(IFOGs), the experiments were made on the PM fiber coil by 60Co radiation source at different dose rate. Radiation effects of it were got from the experiments. And photobleaching experiments were made on the polarization maintain(PM) fiber coil using laser diode(LD). Several conclusions were got form the experiments. First, loss of the PM fiber coil increased in radiation environment. And the bigger the dose rate, the quicker the loss increased. The more the total dose, the bigger the loss. Second, LD photobleaching can meliorate the increased loss of the fiber, and the larger the LD optical power, the better the photobleaching effect. It is concluded that photobleaching can be used in IFOGs as a radiation hardening operation when applied in space.
Suitability of some ductile fracture criteria and yield criteria in forming limit prediction
Chen Jieshi, Zhou Xianbin
2006, 32(08): 969-973.
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Some ductile fracture criteria was applied to predict the forming limit of sheet matels. The numerical simulation for deformation processes with uniaxil tensile, plane strain, equi-biaxial strain and some other strain paths were carried out for HS steel, IF steel and 6111-T4 aluminum alloy sheets. Ductile fracture criteria was combined with the finite element simulation. The constants in the criteria were determined by using the calculated strain path and stress at the element with maximal major strain combined with the critical values of strain obtained in the tests. The effect of yield criteria Hill48,Hill90 and Barlat89 on strain path in numerical simulation was compared and evaluated with the measured strain path near the plane strain. Barlat89 can reasonably well predict the strain paths of three kinds of sheet matels. Further calculations were carried out for the forming limit with several ductile fracture criteria combined with Barlat89. It is shown that Cockcroft-Latham andthe total plastic work criteria give more reasonable prediction and the material constants in the criteria can be calculated easily.
ARL computation and parameters optimization for MEWMA control chart based on the Markov chain
Du Fuzhou, Tang Xiaoqing, Sun Jing
2006, 32(08): 974-978.
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Average run length(ARL) is one of the important indices in performance evaluation on quality control charts, the research on which will set up the foundation of quality control chart parameters optimization, performance evaluation and application. An ARL computation model based on the Markov chain was studied for the multivariate exponentially weighted moving average(MEWMA) control chart, the Matlab program was designed and implemented. The convergence of the algorithm and the performance of the MEWMA control chart in different conditions through the analysis of the computation results were analyzed. A procedure for parameters optimization of MEWMA control chart was proposed. An computation example and some optimization results was presented.
The technique of sub-pixel stripes distinguish on the surface measurement
Chen Shiping, Bi Ya, Li Xiao, Zhou Xianbin
2006, 32(08): 979-982.
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Non-contact measurement of 3-D surface has been extensively applied in industry. The stereo vision is an effective way for 3-D profile measurement.Distinguishing and detecting the high density white-black stripes is one of the key techniques in the 3D-measurement based on the image of grating. Using spatial code technology, the measurement space was divided to several parts, and each part corresponded with a unique binary code. Falling on the space part, there was a unique binary code corresponded with the stripes, thus the stripes could be distinguished accurately. After getting pixel stripes with edge detection algorithm, the high precision strips could be detected by sub-pixel technology. The sub-pixel edge detection algorithm based on gray moment and polynomial fitting was presented. Combining spatial code and sub-pixel technique, it could easily distinguish and detect the sub-pixel stripes. This method can obtain a higher precision comparing with pixel stripes detection and improve the accuracy of measurement system.
Effect of aqueous phase condition on the strength increasing of cement stabilized soil
Ning Jianguo, Huang Xin, Xu Sheng
2006, 32(08): 983-987.
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The strength increment of stabilized soil generated by unit cement content would remarkably increase after cement content reached to a certain amount, and at same cement content there existed obviously strength difference between the stabilized soil samples formated from different soil samples with same physical characteristics. In order to find the reason of these experimental results, concentrations of main ions in the pore solutions squeezed from the stabilized soil samples were measured, and the concentrations of Ca(OH)2 in the pore solutions with many ions were calculated by the thermodynamic method. The result shows that when cement content is not enough to ensure the Ca(OH)2 reach to saturation,the gel generated by unit cement hydration is less, therefore the strength of the stabilized soil is lower; When cement content reaches to a certain amount, the concentration of Ca(OH)2 in the pore solutions reaches to saturation, the gel can be sufficiently generated, therefore the strength increment of stabilized soil generated by unit cement content remarkably increases. At same cement content the concentrations of Ca(OH)2 in the pore solutions are various, so there are strength difference between the stabilized soil samples with same physical characteristics.
Mechanism and forward kinematic analysis for cable-driven humanoid-arm manipulator
Chen Quanzhu, Chen Weihai, Zhang Jianbin
2006, 32(08): 988-991.
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In order to overcome the influence of bad load-bearing capacity and the movement flexibility by the actuators installed on the humanoid-arm, a series-parallel mechanism based on the latest theories of humanoid-arm bionics and research results of the parallel robots was proposed. The shoulder and wristjoints with a cable-driven parallel mechanism were replaced, and the motors were installed on the base. The cable-distribution from the base to the corresponding joint and the coupling instances among 3 joints were discussed. Furthermore, the forward kinematics to deduce the pose and position of the end effector respective to the base coordinate were analyzed. A simulation by means of ADAMS was carried out for two group numerical solutions to verify the effectiveness of proposed algorithm.
Key algorithm in content-based publish/subscribe system based on subscription partitioning
Lu Peng, Liu Xudong, Lin Xuelian, Wang Bin
2006, 32(08): 992-997.
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Partitioning subscriptions interest among multi-brokers acts as an important way to resolve load balancing problem in content-based publish/subscribesystem. A new method of event space-based subscription partition with K-D tree was proposed. With this method, the event space was partitioned into zones with equal load and so the system performance of load balancing was improved. Based on the minimum distance of logical event space, new routing algorithms were proposed for event and subscription routing and another hybrid of unicast and multicast routing policy for notification routing. All these algorithms and policy significantly reduced the event matching cost and promoted the routing efficiency in content-based publish/subscribe system. At the same time, the method of splitting and merging zones of event space was used to realize the self-organizing of the publish/subscribe system. The experiment and related works show that the introduction of partitioning methods and related algorithms can improve the scalability, fault tolerant and load balancing performance of content-based publish/subscribe system.
P2P worm detection based on traffic classification and application identification
Xia Chunhe, Shi Yunping, Li Xiaojian
2006, 32(08): 998-1002.
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P2P worm exploits common vulnerabilities in Peer-to-Peer networks. It is a severe security threat. A P2P worm detection method was presented, which called P2P worm detection(PWD) based on the worm′s propagation characteristics. PWD consists of a preprocess procedure which is based on application identification technology and a P2P worm detection procedure which is based on unknown worm detection technology. Improved heuristics was also advanced to identify and disturbing traffic was eliminated as well as heuristics to detect P2P worm. The selection of detection period was discussed by applying methodologies of game theory. Simulation result and LAN-scope experimental result both indicate that PWD is an effective method to detect and block P2P worm.

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