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2009 Vol. 35, No. 1

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Mixed-mode TRL algorithm based on symmetrical reflection standard
Wan Liang, Wu Jianhua, Miao Jungang, He Guoyu
2009, 35(1): 1-4.
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A mixed-mode through-reflect-line(TRL) calibration algorithm based on symmetrical reflection standard was proposed to accurately characterize coupled differential devices using scattering parameters. Using the transition structure’s generalized reciprocity and the phase relationship between its scattering matrix entries, the sign ambiguity was removed and the transition structure’s mixed mode wave transfer matrix was obtained. The calibration standards of the proposed algorithm are similar to the requirement of traditional single-mode TRL algorithm, and unsymmetrical structured reflection standard is not necessary to yield mode conversion. To verify the proposed algorithm, the single-mode scattering matrix of calibration standards and device-under-test(DUT), both of which are embedded with the transition structures, were calculated from full-wave electromagnetic simulation, and the proposed algorithm was used to process the simulation data to calculate the DUT’s mixed-mode scattering matrix. The calibration results were compared with that from full-wave simulation, and the agreement of the data obtained through both approaches indicates that the proposed algorithm is valid to calibrate linear differential devices.
Low complexity sequence detection algorithm for time-frequency overlapped multiplexing system
Mo Yong, Wang Jing, Liu Dong, Li Daoben
2009, 35(1): 5-8.
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Overlapped hybrid-division multiplexing(OVHDM) can achieve high spectrum efficiency, and the performance is superior to multi-level modulation. The system model and the optimum detection were studied. The joint soft interference cancellation and sequence estimation algorithm, SIC-SE, was proposed to reduce the detection complexity. The sub carrier data stream of OVHDM signals was first separated by soft interference cancellation, then filtered by finite impulse response (FIR) filter based on fast matrix inversion, and finally detected with sequence estimation. The complexity of proposed algorithm is much lower than maximum likelihood (ML) detection, while the performance is better than conventional SIC algorithm. Simulation results show that the performance of coded OVHDM system is better than the same coded QAM-OFDM system.
Processing system reliability model based on products reliability
Fu Guicui, Shangguan Yun, Shi Xingkuan, Liang Peidong
2009, 35(1): 9-12.
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In order to improve the product reliability, the relationships of processing system, process product deferent parameters, product performance and product reliability were analyzed. Then a reliability model named "reliability model of basic influence relationship in processing system" based on product reliability was presented, and the modeling method was introduced. The model considered the interaction of each working procedure, and represented the relationships between processing system and product reliability. Finally, quantitative calculation method of reliability degree of processing system and working procedure were discussed which has provided theoretical basis for locating processing system-s weak parts, making processing optimization and product reliability advancement.
Key technology of deep web search
Chen Peng, Liu Liehong
2009, 35(1): 13-17.
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Deep web is web database accessed by the web search, it is different from surface web, so technology of traditional search engines is not applied to deep web research very well. Some key technology of deep web search was researched, including automatic discovery of deep web resource and ontology-based information extraction of deep web. Effectiveness of these technologies and relevant algorithms were verified through experiments. Based on these technologies and relevant algorithms, a deep web search system was implemented, it could access deep web resource and extract structured data for various applications. The system has been applied to national important project "national portal of science and technology infrastructure" and has achieved obvious effect.
Numerical investigation of heat transfer and flow resistance in U-shaped variable cross-section channels with different rib heights
Zhu Jianqin, Xu Guoqiang, Tao Zhi, Ding Shuiting
2009, 35(1): 18-22.
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The flow and temperature distribution in U-shaped variable cross-section channels with different rib heights was investigated numerically by a new developed three-dimensional Navier-Stokes code with low Reynolds number k-ε turbulence model. The rib pitch is 25 mm and the rib heights are 1 mm,1.5 mm,2 mm respectively. The Reynolds number Re based on the inlet velocity of the cooling air and hydraulic diameter are 7 500,12 500,18 500,25 000. Numerical results reveal that the average Nusselt number of the channel increases with the increase of Reynolds number. The enhanced heat transfer was achieved with the higher rib height e when Re is equal to 7 500 and 12 500. The higher heat transfer characteristics can be reached for the case of e =1.5 mm when Re is equal to 18 500 and 25 000. The effects of rib heights on local heat transfer show different behavior due to the different local Reynolds numbers and centrifugal force. The higher rib height e enhanced the heat transfer of inflow passage. In outflow passage, the higher the rib height, the better heat transfer behavior is produced for Re =7 500 and 12 500, while for Re =18 500 and 25 000 the optimum rib height is 1.5 mm.
Filtering algorithm used for high dynamic GPS frequency estimation
Zhu Yunlong, Yang Dongkai, Liu Zhongkan
2009, 35(1): 23-27.
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Aiming at the drawbacks of the extended Kalman filter (EKF) which is the widely used GPS frequency estimation algorithm in high dynamic circumstance, a novel filtering algorithm called simplified unscented Gaussian particle filter (SUGPF) was proposed. The SUGPF is the combination of Kalman filter (KF), unscented Kalman filter (UKF) and Gaussian particle filter (GPF). In time update step, KF methodology was used to update the predictive distributions. In measurement update step, the UKF methodology was used to obtain the important sampling function, and the posterior distributions were updated by using the methodology of GPF. The simulation results indicate that the SUGPF has improved performance and versatility over the EKF and UKF, under both Gaussian and non-Gaussian observation noise condition, SUGPF can achieve good performance which is similar as that of the GPF, and the computational complexity of the SUGPF is lower than that of the GPF.
Nonlinearity of temperature and scale factor modeling and compensating of FOG
Wang Xinlong, Ma Shan
2009, 35(1): 28-31.
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The error composite modeling and compensating of temperature effect and scale factor nonlinearity of fiber optic gyroscope(FOG) was studied. The mechanism of thermal affect arising from nonreciprocity of optic-loop was analyzed. Based on the severe nonlinearity drift error induced by temperature change and scale factor nonlinearity, an practical and precise composite model was proposed to compensate the error caused by temperature and scale factor-s nonlinearity. The test experiment and data processing were carried out at full temperatures and full rotate rates of FOG-VG951 and indicate, utilizing piece-wise modeling and compensating the FOG, its drift error can be minished from 4.4 (°)/s to 0.1 (°)/s , which is much better than the conventional modeling and compensating means, and the experimental results indicate that the method is useful and feasible.
Design of trusted Java card code loading mechanism
Xu Yixi, Zhang Qishan, Liu Jianwei
2009, 35(1): 32-35.
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Based on the requirements of the trusted computing platform (TCP) program code management, a trusted code management framework was proposed. The Java card technique was the core of the framework. The code signature technique was adopted for the program loading authentication while the on-card security domains were created as the off-card software authorities- security policies executors. The novel mechanism supported the installation and hot update of the device issuer software, promoted the installation and update procedure of the application provider software, and expanded the code-loading command data structure. The framework implemented the un-manual code broadcast distribution with the limitation of mutual independency of all software authorities under the hostile environment. This advanced Java card software loading mode improves the system-s security, and enables the trusted computing on the Java card platform.
Tensile and compressive mechanical properties of polyurethane foam plastics reinforced by glass fiber bundles
Lu Zixing, Zou Bo, Li Zhongming, Lu Ai
2009, 35(1): 36-39.
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The quasi-static tensile and compressive experiments were performed in order to investigate the mechanical properties of conventional polyurethane foam plastics and reinforced ones by glass fiber bundles. The influence of material density and mass content of glass fiber bundles on mechanical properties was analyzed. It is observed from tests that the tensile samples happen to fracture suddenly along perpendicular direction with loading, which appears to be a brittle break. And the compressive rupture samples exist obliquely chapped block on the surface of cylinder. The experimental results show that the stress-strain curves of reinforced foams plastics are same with those of conventional foams. The young-s modulus and strength of the material can be improved by glass fiber bundles. If the density of the material is larger, and the volume fraction of the resin matrix as well as the glass fiber bundles is higher, the reinforced effect on the resin matrix by glass fiber bundles will be better.
New method of modeling stealth aircraft-s signal based on emulator
Li Ying, Huang Peiling, Wu Zhe
2009, 35(1): 40-43.
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There are great differences among the target-s radar cross section(RCS) in its different detect angle territory. Five different models about the partition of important radar detect territories were presented. In the computer simulation platform, it adopted the five different models to part the important detect territories according to the characteristics of scattering around the target. Calculating the detect probabilities according to the average RCS from the different five models. The average tolerance of detect probabilities between the results of five models and exact detect probabilities are 13.66%, 12.35%, 6.6%, 5.07% and 2.4%.The differences between the tolerances indicate the detect probabilities from the last two models about the detect territory partition are more accurate. They can reflect the real changes of detect probabilities in the dynamic process of the radar detects the target. The last two models about the partition of important radar detect territories in the computer simulation platform can save the computer storage by using five or eight RCS to instead of lots of RCS. It can increase the computer speed.
Fuzzy logic control based on genetic algorithm to integrated flight control for hypersonic vehicles
Li Huifeng, Wang Jian
2009, 35(1): 44-47.
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An integrated flight control system was designed according to the six DOF nonlinear general model of pitching channel of hypersonic vehicle. The system has an integrated flight control loop, which is composed of one fuzzy controller and two PD controllers. Based on genetic algorithm, the optimization process of fuzzy control rules and PD feedback parameters was carried out automatically, which means experts- knowledge and training data were not necessary in advance, so the problem of obtaining fuzzy logic control rules was solved. Nonlinear dynamics, parameter uncertainties and constraints were concerned in the research on the control of trajectory, attitude and thrust. Simulations show that the method is able to satisfy both the robustness of flight control system and the convergence of optimization process on request, especially obtaining superior robustness compared to conventional double loop flight control system, which is based on the same basic control strategies and optimization tool.
Direct kinematics of Stewart mechanism robot
Zhuang Yufeng, Huang Xiguang, Liao Qizheng
2009, 35(1): 48-51.
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The Groebner-Sylevester hybrid approach was presented to obtain the closed-form solutions of the direct kinematics of the Stewart mechanism robot. The reduced Groebner basis under degree lexicographic ordering for the closed-form equations was presented based on computer algebra method. And 20 Groebner basis were picked out from the 51 Groebner basis. Then a 20×20 dimensional Sylvester-s matrix was constructed, which is relatively small in size. And a 40th degree univariate equation was presented from the determinate of the matrix by analyzing the numbers of the variables in the equations. To verify the proposed algorithm, a same numerical example was calculated based on the continuation method as well as the the proposed algorithm. It shows that the proposed algorithm calculates simply and rapidly to lead to the univariate equation. The results both by using the continuation method and based on the proposed algorithm are same. Then a novel and practical algorithm to solve the direct kinematics of the parallel mechanism robot was presented.
Fuzzy reliability of repairable consecutive- k -out-of- n system
Wu Yueqin, Zhou Hong
2009, 35(1): 52-55.
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Under the condition that a key component will have a higher priority of repair, a repairable consecutive-k-out-of-n:G system with one repairman was studied. The probability of states was derived by using Markov process. The membership functions of the states to success and failure were defined and the reliability indices of repairable systems were analyzed utilizing reliability theory incorporating fuzzy states. The difference between fuzzy reliability and conventional reliability was compared. When the system was in the working state, the reliability of the system was intuitively characterized by the number of working components. The fuzzy reliability can fully describe the action of system. In the end, an example was given to illustrate the method.
Node selection in simulation grid
Song Changfeng, Li Bohu, Chai Xudong
2009, 35(1): 56-60.
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Simulation grid is a networked simulation platform by combining modeling and simulation (M&S) technology and grid technology. Node selection is an important method to increase the performance of simulation execution in simulation grid. Based on the feature of resource heterogeneousness in simulation grid, a formula appraising criterion for node selection was proposed, a mathematic model for node selection was built on the appraising criterion, and finally a node selection algorithm was designed. Experiment result shows that the algorithm puts emphasis on selecting nodes with good computation capacity, communication performance among nodes is considered at the same time, and the situation where good communication performance overlaps poor communication performance is avoided in this algorithm. So the node selection method is able to achieve the purpose of raising simulation execution efficiency.
Ultrasonic frequency pulse tungsten inert gas welding power source topology and welding applicability
Qi Bojin, Xu Haiying, Huang Songtao, Zhang Wei
2009, 35(1): 61-64.
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An ultrasonic frequency pulse tungsten inert gas welding power source was developed. The power source topology and work principle were introduced. By contrast with current waves output from conventional tungsten inert gas welding power source, faster rising and falling pulse current edges were output from this power source at every ultrasonic pulse frequency. The pulse current change rate was up to 50A per microsecond. The power source was suited for welding not only sheet metal, but also medium and thick metal for base current, peak current, duty, pulse current frequency and other weld technology parameters expediently adjusted. By comparing with 1Cr18Ni9Ti austenitic stainless steel joints welded by conventional tungsten inert gas welding, these joints welded by the ultrasonic frequency pulse tungsten inert gas welding were shown grain refinement and narrow coarse grain zone in weld beads. The experiment results show that the ultrasonic frequency pulse tungsten inert gas welding power source is applicable to arc welding.
Flexible assembly technique for aircraft parts joining based on laser tracking and positioning
Mei Zhongyi, Fan Yuqing
2009, 35(1): 65-69.
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The technique of digital flexible assembly is one of the research directions in the field of aircraft manufacture in recent years. Aiming at aircraft parts positioning and joining, the technique and theory of digital flexible assembly based on laser tracking and positioning were studied. The laser tracking measurement system was developed through using the developing software package of the laser tracker. The frame and theory of mechanism motion and position device and servo control system were discussed. The servo control system of mechanism motion was carried out which could be used to control aircraft position. The integrating system of digital flexible assembly for aircraft parts joining was developed by using one graphics software package. Real-time simulation of aircraft parts joining based on laser tracking measurement was also achieved on the integrating system. This research work can be used for reference to the researching on the technique of digital flexible assembly in recent time.
Numerical calculation and experimental verification of stress at joint between two pipes of thermal shrouds
Pang Hewei, Meng Xianhong, Zhang Xing
2009, 35(1): 70-73.
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The large special environmental equipment KM6 is subjected to repetitive stress. In order to assure the safely of space laboratories, two kinds types of thermal shroud structures with T and L shape were chosen and the stress analysis was carried out by use of PATRAN & NASTRAN software under stress and temperature spectrums. The stress of critical part was determined. After that, the stress of the same parts was also obtained from experiments, and the results obtained by theoretical calculations and experiments were compared. The results obtained by the finite element method are approximately accordant to that obtained by experiment, and thus the work stress considering the effect of temperature can be determined by numerical method and then the safety of the thermal shroud structures can be predicted accordingly.
Analysis for determining trim, stability and controllability of tandem helicopter
Li Guozhi, Cao Yihua, Yang Qian
2009, 35(1): 74-77.
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Two nonlinear tandem helicopter dynamic models (i.e. the vortex theory model and the momentum theory model) were built separately to trim the helicopter at the hover in the forward and backward flight. A computational method for the stability and controllability derivatives was proposed based on the linear perturbation theory and five-point central difference algorithm. The stability roots of the tandem helicopter in the uncoupled mode were computed using the dynamic equations in the state-space form. Based on the momentum theory model, the stability and controllability of the tandem helicopter were analyzed through using the MATLAB software as the computational platform. The agreement between the computational results and the referenced data indicates that the models are feasible and effective, and they can lay the foundation of the research about the tandem helicopter-s flying qualities.
Optimization of resolution on Java card
Zhang Dawei, Ding Wenrui
2009, 35(1): 78-81.
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The pre-resolution was proposed based on the process of Applets deployment in order to optimize the resolution on Java card. At first, The optimized structure of import, constant pool and export component in CAP(converted Applet file)and package registration table were given. The fixed length structure instead of variable length structure in optimized components was used so as to speed up the search of resolution objects. Furthermore, the index of export component was designed to improve the resolution of classes in external packages. Secondly, the fast runtime resolution algorithms of static fields, static methods and classes were designed based on this optimized structure. The time complexity of those algorithms is O(1). Thirdly, the optimized component structures were generated by pre-resolution during Applet download. The fast resolution of static fields, static methods and classes was implemented with runtime resolution based on those optimized structures. Test results show that this optimization algorithm reduces the times of memory access, speeds up the execution of resolution and improves the runtime performance of Applets on Java card.
Air-combat ability and sensitivity analysis of modern fighter aircraft
Jin Lei, Zhang Shuguang, Sun Jinbiao
2009, 35(1): 82-86.
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With the characteristics of the 4th generation fighters and modern air-combat included, an improved hierarchical architecture model of the air-combat capability was put forward, and combined with the analytic hierarchy process and fuzzy membership function technique for the static evaluation of the air-combat effectiveness. Moreover, the sensitivity of the air-combat effectiveness to each single item at the lowest level and all the items at the same level was defined and formulated. Two typical fighter examples, denoting for the 3rd and 4th generation fighters respectively, were used to demonstrate the rationality of the model, and the sensitivity analysis shows to be able to provide guidance to fighter upgrade and aircraft combat operation.
Noise suppression of fiber optic current transformer system based on robust control
Li Hui, Zhang Chunxi, Zhang Xi, Zhang Chaoyang
2009, 35(1): 87-90.
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The fiber optic current transformer is a system that comprises parameter uncertainty and noise signals. For improving precision of the system, the design of robust H -infinite controller was discussed. The fiber optic current transformer based on closed-loop detection was analyzed, and the model of the system was built. The design problem of the fiber optic current transformer controller was considered which guaranteed that the closed loop system was asymptotically stable and the noise suppression of the system was improved. The controller was proved that the control system meets the design target. Then the problem of the design of the robust controller can be solved on the basis of linear matrix inequality technique. The result was provided to show the effectiveness and feasibility of the robust controller by the computer-s simulation and experimental test.
Fast and precise initial alignment of strapdown inertial navigation system on rolling base
Wang Xinlong, Ma Shan, Wang Haiyong
2009, 35(1): 91-95.
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The rolling base and the lever arm error are major factors affecting the performance of carrier weapons. Based on the initial alignment characteristic of strapdown inertial navigation system (SINS) on carrier weapons, the mechanism and compensatory method of the lever arm were analyzed. The feasibility of replacing the Kalman filtering by parameter identification to align a strapdown inertial naviagtion system SINS on a rolling base was thoroughly investigated. Taking into account instances of the real engineering applications, an improved parameter identification method to align a SINS was proposed. Furthermore, the improved parameter identification method to align strapdown inertial navigation system on a rolling base was studied via simulations. The precision of initial alignment can be improved, as well as speediness. The investigative results would offer the principle foundation for design and choice of the alignment schemes of SINS for carrier weapons.
Engineering analysis method in fluid-structure interaction problem of hemispherical parachute
Song Qianfu, Cao Yihua, Jiang Chongwen
2009, 35(1): 96-99.
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To carry out fluid-structure interaction (FSI) parachute simulation is difficult, but some engineering design work demands that the operation completes quickly and efficiently. Therefore, to meet this requirement, an engineering fluid-structure interaction simulation method was established to simulate the stage of hemispherical parachute stable descent. Supposing the initial canopy shape is axis-symmetric, the canopy-s pressure coefficient needed by structural simulation was computed from flow field simulation, and the new canopy shape was obtained from the structural simulation. This recycle procedure was repeated until the canopy gore centerline shape and parachute line shape were stable. The results show that the canopy shape can be quickly converged, and the method satisfies the engineering demands.
Hierarchical Markov decision processes based path planning for UAV in three-dimensional environment
Hong Ye, Fang Jiancheng
2009, 35(1): 100-103.
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The ability of path planning is an important ensure for unmanned aerial vehicle (UAV) in autonomous flight. A path planning model was based on Markov decision processes (MDP), in which the problem of path planning was regarded as looking for the best tactic through the model of environment and the principle of rewards and punishment. To solve the problem such as huge space-time spending and changing course at high frequency, the hierarchical Markov decision processes (HMDP) were introduced based on the method of clustering states. The arithmetic was also used for path planning in three-dimensional environment. The results of simulation show the HMDP model can be used to path planning for UAV in three-dimensional environment. It lays the foundation for local path planning in real flight.
Error modeling and calibration method of AMR compass
Sun Hongwei, Fang Jiancheng
2009, 35(1): 104-107.
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During the hard magnetism calibration process of compass by traditional methods, the compass was always disturbed and the calibration parameters were relative values. Considering these problems, the errors of anisotropic magneto resistance (AMR) compass were analyzed, the error model of compass was established and a method called scalar calibration was used to calibrate the compass. Compared with the traditional calibration methods of compass, the scalar calibration method didn-t need the reference of head direction. During the calibration of the compass by this method, a great volume test data of any different positions was used to estimate the optimal parameters by iteration. So this method could reduce magnetism disturbance influences through exerting the restraint and the calibration value is the absolute vectors. By the hard magnetism calibration, the precision of compass was improved by 7 times. The experimental result proves the validity and usability of this method.
Novel adaptive denoising method for extreme noise based on PCNN
Liu Yuanmin, Qin Shiyin
2009, 35(1): 108-112.
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To implement the removal of salt and pepper noise effectively and the conservation of image details and textures, a novel adaptive denoising method for extreme noise based-on pulse coupled neural network(ADEN-PCNN)was proposed. A kind of detection mechanism was applied to discriminate whether a given pixel was corrupted or not, and only the corrupted pixels must be denoised so that the original image information could not be damaged and the details as well as the textures of the images clould be conserved effectively. To improve the image quality, the self-organization mechanism was introduced into PCNN array framework, thus the neighboring connection modes of neurons in the PCNN could switch automatically. Furthermore, an adaptive mechanism was used to automatically select the optimal filtering times based on the estimated noise intensity to enhance adaptability of algortihm. Experiment results indicate that this method presented is more preponderant than the conventional methods and other congeneric methods in removing noise and conserving image details.
Light-stripes matching method for raster binocular stereo vision sensor
Xie Guanghui, Wei Zhenzhong, Liu Zhen, Zhang Guangjun
2009, 35(1): 113-116.
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Light-stripe matching is one of the difficulties of raster binocular vision sensor. Usually, matching methods based light-stripe coding require projecting multi-images or viewing minimum stripes in one image. Additionally, when the depth of the measured object has a relatively large range of variety, mismatching will frequently occur. To solve this problem, a new method was presented as follows: The raster binocular stereo vision sensor was regarded as two raster structured-light vision sensors which had been calibrated under the same measurement coordinate system. The 3D coordinates of the light-stripe center points was measured by the two rater structured-light vision sensors respectively. The distances between the light-stripe center point sets were calculated and the ones which had the minimum distance and the same model number were the matching light-stripes. The experiment results indicate the validity of the presented method for light-stripes matching.
Testing control flow of composite service
Yu Ying, Jin Maozhong, Huang Ning
2009, 35(1): 117-121.
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OWL-S (Web ontology language for services) and linear temporal logic were used to investigate formal method of describing composite service flow for testing and analyzing dynamic testing information. OWL-S was used as requirements reference model of composite service. Combination of composite service standard and formal method was adopted. Linear temporal logic was used to describe dynamic semantics of control constructs in OWL-S. Accordingly control flow requirements of composite service was described by a set of linear temporal logic formulae. Besides the existing advantage of OWL-S, the describing method can explicitly express atomic services interaction pattern and the describing result can be used as reference model of testing composite service implementation. Based on the explicit expression and semantic model of linear temporal logic on finite execution traces, dynamic testing information captured during composiste service execution was analyzed to test the correspondence between composite service execution and composite service control flow requirements.
Novel structure of NC program processor for CNC system
Wang Qikui, Li Wei, Chen Youdong, Wang Tianmiao
2009, 35(1): 122-125.
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A novel structure of the interpreter for the special vendors using different standards was presented. A new structure was proposed for the purpose of reducing the time while developing a new interpreter for computer numerical control (CNC) system. The interpreter was divided into three sub-modules called input data, internal data interface and functions. Numerical control codes were formally expressed in internal data interface so as to separate the other two sub-modules. The computation in the interpreter could be independent of the input data format because of this internal interface. Relationship between the numerical control codes and features was studied. Numerical control codes were sorted based feature. And gathering concept was introduced in functions sub-module to export data by means of this classification. This method facilitates functions independence. The results show that sub-modules could be reused with this structure. The development efficiency of the interpreter could be rapidly improved for different NC program formats.

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