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2009 Vol. 35, No. 4

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Acquisition method of frame head PN mode in DTMB system based on FFT
Li Chunyu, Zhang Xiaolin, Zhang Zhan
2009, 35(4): 393-397.
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An acquisition method of frame head pseudorandom noise(PN) mode in digital terrestrial television multimedia broadcast(DTMB) system based on fast fourier transforms(FFT) was proposed according as the analysis of the character of frame head PN in Chinese national standard on DTMB. In this method, firstly, three kinds of local sequence are chosen based on the frame head-s character and the difficulty in hardware design to correlate with signal frame received, in which FFT correlation method was used. Then, correlation peak of each channel was compared with the relevant threshold to judge whether the acquisition succeed in a certain channel or not. At last, frame head mode corresponding to the channel which has acquired PN successfully was chosen as the final frame head PN mode for the output. Compared with the acquisition method based on time-domain correlation, the proposed method needs less computation overhead and acquisition time. Simulation results show that the method can acquire and identify all kinds of frame head PN mode accurately and the feasibility of the method is validated.
Numerical simulation of film cooling effectiveness on rotating curvature models
Yang Bin, Xu Guoqiang, Meng Henghui, Wu Hong
2009, 35(4): 398-402.
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Computations were performed to investigate the adiabatic effectiveness η distributions on the curvature turbine blade models under rotating conditions. In the present study, the Reynolds number Re based on mainstream velocity and film hole diameter varies from 3 198.4 to 6 716.6, the blowing ratio M ranges of 0.2 to 1.2, and the rotation number Rt alters from 0 to 0.015 9. Both κ-ω and the shear-stress transport(SST) models were chosen for turbulence closure. Results show that the increase of Rt leads to decreased η values in the centerline region downstream the film hole, but can improve the integrated effectiveness properly on the pressure surface. The augmentation of M also results in the decreased adiabatic effectiveness, while the variation of Re has little influence on the comprehensive cooling effect. In addition, the values of η on the suction surface are much greater than that on the pressure surface under the same operating conditions.
Virtual multipath routing for reliable data delivery in wireless sensor networks
Zhang Xia, Zhou Gang, Yu Hongyi
2009, 35(4): 403-406.
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Aiming at reliable data delivery in wireless sensor networks, VMR(virtual multipath routing) protocol was proposed. It integrated path optimization into data transmission so that data delivery quality was guaranteed at very little control overhead. In this protocol, paths were constructed on demand, and data was delivered along multiple paths. Meanwhile ATT(accumulated transmission times) of each packet from source to sink along a path were collected. Path quality information was fed back to source where low quality paths were identified and filtered out via interval estimation on the expectation of ATT. Route optimization was achieved step by step in this way. Simulation in NS2 platform showed path selection converges to optimal or suboptimal solution fast. VMR is competent to deal with adverse, dynamic, bandwidth constrained WSN network and outperformed typical reliable routing protocol AODV_ETX in both energy efficiency and reliability.
Failure rate model of components under random repeated load
Wang Zheng, Kang Rui, Xie Liyang
2009, 35(4): 407-410.
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The models for calculating the reliability and failure rate of components were developed with the order statistic theory and load-stress interference model when the life of components was measured by the times of random load action. The failure mechanism of components when random load acts for multiple times was analyzed and from the statistic meaning of random load action, the reliability model of components under random repeated load was built with the order statistic. Further, the model for calculating the failure rate of a component was derived, and the relationship between reliability and times of load action and that between failure rate and times of load action were studied. The model proposed can be applied to direct ESS (environmental stress screening test) and other reliability experiments for products.
Theoretical analysis and experimental validation on gas jet blowing-off process of submarine emergency
Yang Sheng, Yu Jianzu, Cheng Dong, Gong Shaofeng
2009, 35(4): 411-416.
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By thermodynamics analyzing on the process of gas jet blow-off in the ballast tank, a series of energy equation, quality equation and state equation of the process were established, in considering the evaporation of water circumstances. Therefore the mathematical-and-physical model of the process was deduced. Principle tests of emergency gas jet blowing-off process, which is the small-scale-model of emergency blowing system with gas generator for submerged vehicle, were carried out, which simulated the drainage regularity and the major performance parameters of emergency gas jet blowing-off process while at 100m depth underwater, and the influential factors which impact on the efficiency were investigated. The simulation results of the model was compared with the experimental results, and it was suggested that the model of the process which developed by thermodynamics methods for engineering calculating is accord with the factual experiments situation and can provides significant basis for the designing and applying of the emergency blowing system with gas generator for submerged vehicles.
Trajectory planning and control for high-dynamic unmanned aerial vehicles
Zhang Qingzhen, Gao Chen, Shi Bobo, Ma Wentao
2009, 35(4): 417-420.
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According to the strict aerodynamic heating and force environment, which had the characters of strong uncertainty of flight parameters and structure, the planning and optimization of multi-constraints trajectory were studied for high-dynamic unmanned aerial vehicle (UAV). The attack angle and the bank angle were the control parameters of high-dynamic UAV and the bank angle was taken as the main control parameter in the proposed method. Hence the optimization of trajectory was cast as the optimal control problem. The aims of the optimal control problem were to be achieving the minimum accumulated heat load of high-dynamic UAV and satisfying the flight bounds and terminal constraints. Maximum theory and amelioration adjacent extremism approach were adopted to solve the optimal control issue. At last, the effectiveness of the method was demonstrated by simulating on an example of high-dynamic UAV.
Transient heat transfer model of proton exchange membrane fuel cell stack with internal humidification
Huang Min, Li Xinghu
2009, 35(4): 421-424.
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A transient heat transfer model of proton exchange membrane fuel cell (PEMFC) stack with internal humidification,based on mass transportation phenomena in cathode,was developed. Factors affecting the stack temperature were considered. Equations were solved with Runge-Kutta-Felhberg method. Results indicate that the stack temperature can-t be maintained below 80℃ itself when current exceed 25A. Influence of current,pressure,stoichiometric ration and water flow rate on stack temperature were researched as well. Heat management tests were carried out on a 5kW PEMFC stack,and a good agreement was found between tests and model prediction.
Mechatronics systems multidisciplinary design heterogeneous information integration
Bi Luyan, Jiao Zongxia, Fan Shengtao
2009, 35(4): 425-428.
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To implement the heterogeneous information integration of mechatroncis systems multidisciplinary design, a novel information integration framework of mechatronics systems multidisciplinary design was proposed. Furthermore, mechatronics system common information model and generic data access interfaces were presented. To verify the feasibility and validity of the mechatronics system multidisciplinary design information integration framework, a case study of multidisciplinary design system for missile launcher was presented. The results indicate that mechatronic system common information model can provide the multidisciplinary engineers with an integrated logic view of the mechatronic system information and generic data access interfaces provides an unified data access facility for the integration of multidisciplinary applications. Furthermore, the information exchange and interoperability among the multidisciplinary application are implemented .
Take-off and landing features of flying-wing configuration fighter
Ma Chao, Wang Lixin
2009, 35(4): 429-433.
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Innovative control surfaces are implemented on the flying-wing configuration combat aircraft, and the flaps of traditional aircraft which are used for lift increasing during take-off and landing are canceled. The control principles during take-off and landing were summarized. A flying-wing configuration aircraft was chosen for instant, so the low-speed aerodynamic characteristics of the typical flying-wing configuration aircraft were compared with conventional aircraft based on results of tunnel tests. Then the performances of take-off and landing were calculated and compared with typical traditional fighter F-16. The results prove that, the inherent feature of all-wing design brings low wing-load, which makes take-off and landing performances of flying-wing configuration fighter easy to satisfy. The valuable references were provided for estimating the battle effectiveness and designing of flying-wing configuration fighter.
Registration method based on ICP algorithm for 3D surgical navigation
Wang Junchen, Wang Tianmiao, Xu Yuan, Fang Liming
2009, 35(4): 434-438.
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Registration between medical images and physical space is an important procedure in 3D surgical navigation systems. A registration method based on ICP (iterative closest point) algorithm was presented. Two point sets, one of which is acquired from physical space by the optical localizer and the other is from a 3D model reconstructed by the marching cube method, were used to calculate the transformation matrix between preoperative CT image space and intraoperative fiducial marker space. The registration procedure was divided into the following two phases. PCA(principal component analysis) was used to calculate the eigenvectors of the two point sets respectively to achieve initial registration. ICP method was used to make the initial transformation matrix to converge into the best solution, in which the k-d tree structure was used to accelerate the procedure. A spine model experiment was carried out and a virtual 3D measurement environment was set up to evaluate the accuracy of the registration method. Error analysis was conducted by adding Gaussian noise to the point sets. The result shows that under this condition the final average registration accuracy is less than 1mm.
Frequency characteristics of breakdown vortices over delta wings with small amplitude oscillation at the high angle of attack
Zhang Minglu, Liu Shaohui, Lü Zhiyong
2009, 35(4): 439-443.
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Experiments of dynamic unsteady pressure measurement and hot film velocity measurement with the small amplitude oscillation delta wings were carried out in a water channel and a wind tunnel respectively in order to investigate the influence of the nondimensional oscillation frequency n on the frequency characteristics of leading-edge vortices over delta wings. Power spectral analysis of pressure signal measured in the wind tunnel shows that at n =0.018~0.036, which is close to the oscillation frequency of vortex breakdown point, resonant phenomenon will happen and oscillatory energy will be largely enhanced. Power spectral analysis of velocity signal measured in the water channel shows that at n =0.8~1.38, which is close to the propagation frequency of spiral wave, the vortex breakdown point moves towards trailing edge, and therefore breakdown of vortices will be delayed and the dominant frequency will be increased.
Robust adaptive control scheme for uncertain switched systems
Hou Yanze, Dong Chaoyang, Wang Qing, Deng Wuyan
2009, 35(4): 444-448.
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For a class of uncertain switched linear systems, based on multiple Lyapunov functions method and model reference adaptive control theory, a robust adaptive switching control scheme with controller having nonlinear deadzone character was proposed, on which the switching law evolves according to the independent decision variables. Firstly, the closed-loop switched system was constructed by reference switched system and adaptive control laws. Afterwards, using Lure-Postnikov Lyapunov function, a sufficient condition via linear matrix inequations was deduced, which guaranteed closed-loop switched system was bounded model reference adaptive control system. Finally, five operating points of HiMAT(highly maneuverable aircraft technology)vehicle within the operating envelope were selected, and the five linear decoupled models corresponding to short period dynamics of the longitudinal motion composed the switched system, and then finite robust adaptive controllers with nonlinear deadzone character were designed. Simulation shows the effectiveness of proposed method, the system trajectory well tracks desired trajectory under fast and consecutive switchings.
Packet scheduling for AFDX switch under hard time constraints
Zhou Qiang, Xiong Huagang, Zhang Xiaolin, Zhang Yanzhong
2009, 35(4): 449-452.
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AFDX(avionics full duplex switched Ethernet) is a switched interconnection designed to meet requirements related to the ever increasing demand for civil aircraft such as A380. A packet scheduling scheme on hard real-time performance in AFDX switch was studied. Based on the dual-priority-message scheduling principle of AFDX protocol, an analytical expression of its key parameter was derived, and a new packet scheduling scheme(DP-LM, dual priority-load match) under hard real time constraints was proposed. The different factors such as scheduling progress, key parameter and load-match method between dual-priority-message scheduling and single-priority-message one were deeply compared, and example resultants indicate that low priority message can impact on real time transmission for high priority one.
Electromagnetic occultation algorithm based on facets grouping and optimization
Ji Jinzu, Liu Zhanhe
2009, 35(4): 453-456.
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When calculating complex target-s radar cross section(RCS) with physical optics(PO) method, the facets shadowing relationship was judged through overlapping and depth-of-view of facets along the incident wave direction. The facets were projected on the plane that was perpendicular with the incident wave direction and then grouped to several groups to make sure that the distance of facets in the same group were close. Only the facets in the same group needed to be judged whether they are shadowed or not instead of making the judgement between all of the facets thus the calculating time was saved. The grouping size was optimized to make the the calculating time be the least. The calculating examples showed that this method is feasible and can make the calculating more efficient.
Different kinematics modeling method and analyzing of new lunar rover with eight wheels
Yu Xinyi, Gao Haibo, Deng Zongquan
2009, 35(4): 457-463.
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In order to improve lunar rover-s autonomous navigation, path planning and simulation of trafficability in rough terrain, different kinematics models should be made. A new type of lunar rover was presented and three different kinematics models were made based on rover-s mechanical characterization and contact situation between terrain and rover. Using D-H transform modeling method of joint robot, plane geometry kinematics relation and 3D geometry kinematics relation, three types of kinematics models of eight-wheel torsion bar rocker-bogie lunar rover were deduced. Then the comparative analysis on three different kinematics models was produced with their respective application conditions and scope. The new lunar rover-s kinematics model can be as model of multi-wheels coordinated motion control and kinematics solver of rover in simulation environment.
Failure risk analysis for fracture critical aero-engine components
Du Shaohui, Hong jie, Xie Liyang
2009, 35(4): 464-467.
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Accroding to the newly certification specifications and standard for engines, safety analysis for aero-engine critical parts such as disks must be done. The ultimate objective of a safety analysis is to ensure that the risk to the aircraft from all engine failure conditions is acceptably low. The failure risk for fracture critical aero-engine components was discussed first. The fracture risk of a disc was analyzed based on risk assessment method. The result shows that hazardous engine effects are predicted to occur at a rate not in excess of that defined as extremely remote (probability less than 10-7 per engine flight hour).
Rapid wing structure design and automated scheme adjustment for civil aircraft
Luo Mingqiang, Feng Haocheng, Liu Hu, Wu Zhe
2009, 35(4): 468-471.
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In order to improve the quality and efficiency of civil aircraft conceptual/preliminary design, the implementation of wing structure and associated fuel tank design in a computer aided aircraft conceptual/preliminary design system were studied. The coordinate of wing-like components was defined. The parametric modes of wing, spar, stringer, rib and skin were represented. A prototype system for wing structure and associated fuel tank design were constructed, the characteristics such as weight, center of gravity, inertia were estimated too. The automatic adjustment and estimation of geometrical properties for wing structure and fuel tank were implemented, which were the base of multidisciplinary design optimization that took into account weight, aerodynamic and structure. At last, an instance was given to illustrate that the methods of wing structure design and automated adjustment are effective.
Diagnostic Bayesian networks modeling based on multi-signal flow graphs
Dai Jing, Yu Jinsong, Zhang Ping, Li Xingshan
2009, 35(4): 472-475.
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The similarities and differences between multi-signal flow graphs and Bayesian networks were analysed, which show that the conversion of multi-signal flow graphs to Bayesian networks is feasible. A diagnostic Bayesian networks modeling method was proposed based on multi-signal flow graphs in order to reduce the diagnostic Bayesian network models development cost. The method includes the conversion of the structure of multi-signal flow graphs to the structure of Bayesian networks and the conversion of information of multi-signal flow graphs to the conditional probabilities table of Bayesian networks. The diagnostic Bayesian network model is good at dealing with uncertainty and conflicting evidence in complex systems fault diagnosis. The experiment results show that the diagnosis accuracy of diagnostic Bayesian network models is the same with multi-signal flow graph models.
Time-optimal fuel-fixed orbital rendezvous with multiple impulses
Liu Tao, Zhao Yushan
2009, 35(4): 476-479.
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Minimum-time, impulsive, fuel-fixed orbital rendezvous problem with path constraints was modeled and saluted with genetic algorithms. For several initial phase angles of the target relative to the vehicle, optimal solutions were obtained for a range of fixed-fuel consumptions and terminal radius, besides the influences of path constraints on the solutions were also considered. Finally, the rules how optimal numbers of impulses changing with these factors were determined. The results obtained can be used in missions with fuel and path constraints, such as space rescue operations and avoidance maneuvers.
Ultra-low voltage ultra-low power NMOS bulk-biased mixer
Song Dan, Zhang Xiaolin
2009, 35(4): 480-484.
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By using two pairs of NMOSs and the bulk-biased technology, an ultra-low voltage ultra-low power NMOS bulk-biased mixer (NBBM), applied to some satellite navigation dual-system compatible receiver, was implemented in SMIC 0.18 μm CMOS process. The GPS system was included: the frequency of the radio frequency (RF) signal, local oscillator (LO) signal and the intermediate frequency (IF) signal is 1575.42MHz, 1570MHz and 5.42MHz, respectively. Measurement results show that the circuit with the resistive 1000Ω termination consumes approximate 1.37mA under the supply voltage of 1V, the conversion gain ( GC ) is higher than 2.11dB, and the input 1dB compression point ( P in-1dB) is about -13dBm. For the mixer including operational amplifiers GC can rise to more than 14dB, which comes along with the worse linearity, more power consumption and larger area.
Design of power/ground distribution network for transmitter of digital terrestrial television multimedia broadcast
Zhang Shuai, Zhang Xiaolin, Zhang Zhan, Su Linlin
2009, 35(4): 485-488.
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The influencing factors and the reason of IR-drop and electromigration were analysed. Taking the design of power/ground distribution network for transmitter of digital terrestrial television multimedia broadcast for an example, power/ground distribution network which ensured the normal operation in maximum IR-drop area was built around standard cells. Maximum IR-drop estimation was made by treating standard cell area as power/ground and resistor network. Finally, macro area was converted to standard cell area to build another power/ground network considering the difference between core ring and macro ring. The networks in standard cells area and in macro area formed a integrated network. The method was used in the floorplan phase of the actual design, which shows its efficiency and reliability of power distribution. The successes of IC tape-out and function accuracy prove the practicality and efficiency of the method.
Service-oriented integration of coordination logic in air combat simulation
Yan Bin, Zhang Shuguang, Sun Jinbiao
2009, 35(4): 489-492.
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The importance of system agility in simulation has been widely realized and understood. However, the current architecture of coordination logic in aerial warfare simulation is central "single layered", while it has total control over coordination process, but solidifies the coordination logic in the simulation system too. A service-oriented integration for coordination logic in the air combat simulation(ACS)was proposed. Based on the principle of separation of concerns, the solution provides mechanisms for factoring out coordination logic in the ACS, and then distributes them to a series of flexible coordinator proxy which extends passive component model into self-coordinating service. A service is autonomous and is contractually defined in a description. According to the specific simulation task, coordination logics are dynamic bind by interconnecting related services at run time, therefore promoting system agility in ACS.
Virtual modeling and rendering technologies of high-seas environment
Yang Xinying, Gong Guanghong, Zhang Bo, Huang Zhanpeng
2009, 35(4): 493-496.
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A real-time linear accumulation ocean wave spectrum algorithm was adjusted by disturbing weighted phasic and amplitude factors which meliorated the defective smooth figure of billows and stormy waves. Base on the synthetic natural environment (SNE) information such as stormy level, wind level, equalized wave amplitude, and average cycle, advanced real-time combining environmental influence algorithm was presented. Based on the psychoacoustics and musical acoustics, advanced storm wave parameter adjusting method was proposed, and then real-time sound implementation node was realized using audio equalizer. Runtime shading method for flowing texture was proposed, background texture was appended to original one after mirror-image generation and Gauss blur distortion. Texture graphical quality was modified and image noise was also reduced after this underline processing. A harmonic visual and audio virtual system combing SNE information was realized which testified the feasibility of the advanced storm wave spectrum.
Design method of soil stabilizer produced with industrial waste
Li Zhanguo, Zhao Yongsheng, Huang Xin
2009, 35(4): 497-500.
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Such problems were discussed as the influence of chemical factors in soil on hydrates growing in stabilized soil and the countermeasure to eliminate the influence, the system character of hydrates to form optimal stabilized soil structure, the concordance of growing process between cementitious hydrates and expansible hydrates and control method to the concordance. On this basis, according to the technical advantages of industrial wastes in prepare stabilizer the design thought and method for the soft soil stabilizer prepared with industrial wastes was proposed and an example was presented. Experimental results show that according to this design method, the 28d unconfined compressive strength of stabilized soil stabilized by the stabilizer prepared with industrial wastes is 1.5~2.75 times higher than that of stabilized soil by cement.
Numerical analysis on travelability of lunar soil simulant by means of distinct element method
Gao Feng, Li Wen, Sun Gang, Sun Peng
2009, 35(4): 501-504.
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The geometric model of lunar simulant particles was built based on its scanning electron microscopic-photograph(SEM), and a producing strategy for irregular-shape particle assembly was presented. A simplified contact reaction model of lunar particles was created. The relationship between soil macro-mechanical property and its meso-parameters was obtained by means of dimensional analysis and biaxial test simulation by distinct element method (DEM). According to the relationship and triaxial test data of lunar simulant, the model parameters were determined numerically. Wheel-lunar simulant interaction was simulated by DEM under moon gravity, and the soil thrust expression in granular-scale was derived. The dynamic behavior of soil particles was quantitatively analyzed at different slip ratio, and lunar simulant-s travelability was qualitatively estimated. Results show that soil thrust increases with higher slip ratio; there are transient period and steady-stage period when wheel travels at high slip ratio, and soil thrust value is bigger in transient period than that in steady-stage period.
Dynamic properties of noise barrier structure subjected to train-induced impulsive wind pressure
Zhao Libin, Long Liping, Cai Qingyun
2009, 35(4): 505-508.
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According to noise barrier design scheme of special railways for passenger transportation from Beijing to Tianjin, the finite element model of noise barrier was established based on the general software ANSYS. The natural frequency of noise barrier structure was detailedly researched and a practical calculation model was presented. The dynamic environment around the noise barrier,which includes the natural wind pressure and the air turbulent force induced by the high speed train, was considered to simulate the transient dynamic response of the noise barrier structure. The laws of each component-s vibration of the noise barrier structure were obtained. In addition, items needed be paid attention to was put forward.
Activity-centered equipment support system analysis method
Guo Linhan, Kang Rui, Zhang Zhenying
2009, 35(4): 509-513.
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Equipment logistics support activities analysis mythology was presented according to operation and maintenance tasks analysis (O&MTA) output outcomes and process model describing equipment logistics support system implementing mechanisms. Equipment logistics support activities frequency and executing time two basic properties were abstracted focused on operational support activities and maintenance support activities. The parameters calculation methods were also given. Finally, the analytic function of logistics support activities frequency and equipments operation mission rates were constructed. Equipment logistics support system support time parameters and support resources employment time parameters were acquired through executing synthesis calculation via to the relations among different support activities locating on different equipment logistics support system levels. So support resources number can be predicted and equipment systems readiness characters can be evaluated. It is proved that the presented model and analysis mythology is effective infrastructure theory support for equipment logistics support development department to design, analysis, and construct support concept.
Nonliearity compensation for pseudolite/INS integrated navigation
Wang Wei, Liu Zongyu
2009, 35(4): 514-518.
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Pseudolite-based positioning systems have a bright outlook in providing users higher precision navigation information due to the stronger anti-jamming capability and flexibility compared with orbiting satellites. A nonliearity compensation algorithm was studied for the pseudolite/inertial navigation system(INS) integrated navigation. The influence of pseudolite measurement nonlinearity is more severe than that of satellites since the distances between pseudolites and users are much closer. By utilizing the second-order items correction, the algorithm to a certain extent overcame the problems of large modeling errors and bad filtering performance or even divergence when using conventional linear algorithm. And a two-stage cascaded estimation method was employed to avoid the difficulty of solving nonlinear equations, which greatly decreased the computational complexity of the compensation algorithm. The simulation results indicate that the algorithm can greatly enhance the precision and reliability of the pseudolite/ INS integrated system, hence is of great value in practice.

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