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2010 Vol. 36, No. 3

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Numerical analysis on traction performance of trapezia lugged wheel by distinct element method
Cui Yi, Li Wen, Wang Jun, Sun Peng
2010, 36(3): 253-256.
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The soft-terrain trafficability of trapezia-lugged wheel on lunar surface was analyzed by distinct element method (DEM). The modeling technology of DEM was presented to produce irregular-shaped particulate system. The mesoscopic formula of traction performance for wheel was built. Based on simple shear test data, the optimal parameters of lunar simulant particles were obtained by repeated debugging. It is shown from analyzing wheel-soil interaction that there is relationship between traction performance and slip ratio as well as lug configuration. The higher drawbar pull can be obtained as increasing slip ratio, however the driven torque will be enhanced simutanously. Furthermore, bigger lug height produces higher soil thrust, but the motion resistance increases together. The influence of lug-s number on wheel-s traction performance is negligible, whereas it influences on smooth-running of wheel.
Effects of pressure on the coking characteristic of jet fuel RP-3
Ju Yinchao, Xu Guoqiang, Guo Jun, Wang Yingjie
2010, 36(3): 257-260.
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The influences of pressure on the surface coke deposition of RP-3 were studied by experiments. The flowing RP-3 is heated up to supercritical state in a 2m long single-pass stainless steel tube( Ф 2.2×0.2, 1Cr18Ni9Ti) with constant heat flux. The mass flow is 4g/s. The mount of surface coke deposition was obtained by weighting method. The influences of pressure on RP-3 surface coke deposition rate were investigated by changing the pressure. The result shows that the greater pressure can suppress coke deposition to a certain extent; the location of coking peak value tends to move backwards along the experimental segment; the shapes of surface coke deposition distribution curve under different pressure are the same.
Fault diagnosis for piston head looseness of aero hydraulic pump
Zhao Sijun, Wang Shaoping, Shang Yaoxing
2010, 36(3): 261-264.
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Piston head looseness is a typical progressive failure of aero hydraulic pump. It is difficult to make precise fault diagnose because the fault feature is misty, the fault samples are insufficient and the measurable signals are full of structure coupling and noise besides failure feature. In order to solve above problems, a fault diagnosis method based on contracted support vector machine(SVM) was proposed. In the new method, rough set was utilized to reduce the fault characteristic value and eliminate redundancy in order to find the minimal attribute describing system fault characters on the premise of unchanged classification quality. The sample data disposed by rough set were used to train SVM to realize fault diagnosis. The experiment result of the trained contracted SVM shows that this diagnosis method is suitable for the high-precision fault diagnosis of the aero hydraulic pump.
Approach to choose integration testing combination for foundational software platform
Gao Jing, Lan Yuqing, Jin Maozhong
2010, 36(3): 265-269.
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Concerning the problem of combination explosion which was caused by the combinations of all kinds of foundation software, the methods of combinatorial design were studied, and an approach based on combinatorial design was proposed to choose integration testing combinations that cover the interaction between foundation software. Foundational software platform was composed of many types of foundational software, and each type of foundational software had different brands and different versions. Each type of foundational software was expressed as a variable factor, and software products of different brands were viewed as variable values, then foundational software platform could be regarded as a multifactor system. The corresponding orthogonal array or the covering array based on orthogonal array was constructed. Integration testing combinations were chosen with the help of orthogonal array and the covering array. The results of the cases indicate that the number of the testing combination can be effectively decreased, and the pairwise test coverage is ensured.
Improvement method for testability modeling with multiple faults
Shi Junyou, Gong Jingjing, Xu Qingbo
2010, 36(3): 270-273.
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The existing methods for testability modeling were analyzed,and their shortcomings in project application were given. An improvement method for testability modeling was proposed, based on the signal flow graph method. It supports to set multiple faults for units, and can distinguish between global fault and local fault, while the global fault can be set to propagate along special signal flow of units. The graph definition, the hide attributions definition, the dependency matrix definition of the testability model and the corresponding testability inference method were provided. An improvement algorithm to generate the dependency matrix was presented, based on the high order dependency analysis. An inertial navigation system was taken as an example for modeling. The system testability graph model was built. The improving dependency matrix was generated, and compared with the dependence matrix built with the exiting method. The result shows the feasibility and validity of the improvement method for testability modeling.
Air-SeaSim CGF model system based on factory mechanism
Zhang Yuan, Zhang Limin, Zhang Lin
2010, 36(3): 274-278.
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Aiming at simultion model reusability deficiency problem, based on the tactical background of a sea-air combat, the Air-SeaSim CGF(computer generated forces) simulation model system based on the factory mechanism was designed. Following the "bottom-up" development principle, the system software architecture consisted of model layer, object layer, service layer and application layer was constructed. Based on the entity model factory mechanism design, the system decomposed the CGF entity appropriately and abstracted some models meeting with simulation demands, which was in form of the component description. Also, the system realized the model rapid re-composition and its function expansion through defining component interfaces. The application results show that the Air-SeaSim CGF entity model based on the factory mechanism can integrate different particle simulation model, realize entity model behavior component sharing and combination during creating different entity modeling. Also, it can simplify the user definition to make for a unified model of development.
Fast slicing algorithm for triangular mesh model
Sun Dianzhu, Zhu Changzhi, Li Yanrui
2010, 36(3): 279-282.
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A fast slicing algorithm for triangular mesh model was proposed. The node splitting algorithm and the clustering algorithm of R*-tree were improved and the spacial index structure of triangular mesh model was established based on the improved R*-tree. The position of slice planes was computed according to data nodes- distributing of the spacial index structure, thus the distribution of slice planes was intensive in the cragged region of triangular mesh, and the distribution of slice planes was sparse in the smooth region of triangular mesh. The intersection triangular facets with slice plane were obtained with depth-first traversal algorithm of R*-tree. The intersection line segments between slice plane and interection triangular facets were computed and they were sorted end to end, then the orderly section contour lines were obtained. It was proved that this algorithm can obtain section contour line accurately, effectively and has strong adaptability of triangular mesh model.
Design of novel planar shorting structure broadband monopole antenna
Chen Aixin, Wei Wenxuan, Jiang Tiehua, Zhang Yanjun
2010, 36(3): 283-286.
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An improved novel planar shorting structure broadband monopole antenna was presented. In the light of planar structure easily conformal to substrate, the special shape structure and the technique of load-adding, this kind of antenna realizes the miniaturization and has a better bandwidth and radiation compared with the conventional monopole antenna. The theoretical parameters analysis of the main structure and simulation results with high frequency structure simulator(HFSS) show that the antenna satisfies the conditions of voltage standing wave ratio(VSWR) less than 3, vertical polarization, horizontal omni-directional radiation, radiation gain no less than -10dB and radiation smoothness below 2dB, on the work frequency band ranged from 30~88MHz. The antenna has a wide application in vere high freqwency(VHF)communication system. The calculational results derived agree well with the experimental results.
Fault diagnosis approach for bearing based on EMD and slice bi-spectrum
Zhang Lin, Huang Min
2010, 36(3): 287-290.
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A new approach based on the empirical mode decomposition (EMD) and slice bi-spectrum was presented for fault diagnosis on roller bearings. Original signals were decomposed into a series of intrinsic mode functions (IMFs) of different scales. Envelopes of the IMFs were extracted and a diagonal slice bi-spectrum for the envelopes was computed to extract the non-linear feature deriving from the quadratic phase coupling, as well as the fault characteristic frequencies. An analysis on simulation signals shows that the drawback that traditional envelope spectrum methods based on EMD cannot inhibit the noise can be overcome by this approach. Meanwhile, its computation load is less than traditional high-order spectrum methods. A diagnosis instance of the bearing 6205-2RS JEM SKF was presented to show the feasibility of this approach.
Optimal design of clutch in automatic transmission
Tang Pengxiang, Liu Yanfang, Wang Shuhan, Xu Xiangyang
2010, 36(3): 291-294.
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For commonly used wet multi-plate clutch in automatic transmission(AT), completed the optimized design of the clutch using fuzzy theory and main objective method with optimization toolbox of MATLAB. According to clutch design formula, the optimal design mathematic model was set choosing average energy loss in sliding friction surface at the end time of bonding and the max power loss per area as the optimized object and turning clutch torque capacity calculated as a whole into a constraint condition. Also the dynamics implementation simulation model with multi-disciplinary dynamic simulation software platform Simulation X was set. Through the model, the change of the relative thermal index after optimized could be truly reflected,and the operation characters of clutch are heightened.
New algorithm for inverse kinematics of 6R serial robot mechanism
Huang Xiguang, Liao Qizheng
2010, 36(3): 295-298.
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The theory of double quaternions and its application in the inverse kinematics of serial mechanisms was introduced. A new algorithm for the inverse kinematics of 6R mechanisms was presented based on the complex exponent form of double quaternions. Based on double quaternions, a mathematical model of 6R mechanisms was created. Then, a 6×6 resultant matrix was obtained directly by using linear elimination and Dixon resultant method, without factoring out or deriving the greatest common divisor, due to the proposed algorithm used the complex exponent form of double quaternions. A 16th degree univariate equation was achieved from the determinant of the matrix and all 16 closed-form solutions were also obtained. The proposed algorithm is comparably easy and simple to program. It was verified by a numerical example that the obtained roots satisfy the original equations. The research result provides a new method for the inverse kinematics of serial mechanisms.
Fault tree analysis of corrosion failure for aircraft structures and improvements
Pan Bo, Huang Lingcai, Jiang Tongmin, Hou Weiguo
2010, 36(3): 299-302.
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To analyze corrosion failure of aluminum alloy structures on export airplane used in marine environment, the fault tree analysis was proposed to analyze the erosion factors of aircraft structures. Through investigating and analyzing on failure processes and failure mechanism of structural components of aluminum alloy on airplane, factors which brought on erosion of structural parts were found. Fault tree of corrosion failure was set up and the minimal cut-sets were obtained by Boolean operation, and the top-event occurrence rate was calculated. The probability importance and relative probability importance of bottom events were analyzed and arranged, and then the important bottom events which caused corrosion of aluminum alloy structures were found. Results show that the main factors which caused corrosion of aircraft structures are ocean environment, anodic oxidation and select material. Some improvements with respect to the main factors had been proposed.
Vertical cantilever rotor machines vibration self-recovery regulation system with continuously dripping liquid-injection automatic balance device
Li Yan, Wang Weimin, Li Shuangxi, Gao Jinji
2010, 36(3): 303-306.
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To improve the disadvantage of normal injection balance device, the continuously dripping liquid-injection automatic balance device was developed. The balance device can change the mass distribution of rotor with injecting liquid to right chamber, and it-s balance capability can-t be reduced by dripping. If this balance device applied in equipments which the vibration phase varying, it has two advantages to normal injection balance head, that are fast response to varying vibration and the balance ability not lost. A vibration self-recovery system was constructed using the device. The system can analyze the vibration signal on real time and output the amplitude and phase, make sure the balance device-s installation position, to balance the unbalance directly by inject liquid, so the rotor vibration will fall in a short time. The balance device was installed on a high gravity machine which is a typical vertical cantilever rotor machine. The experiment results show that the continuously dripping liquid-injection balance device can decrease the vibration effectively, and response to the phase shift in a short time, satisfy the safe long ruing of equipment.
Flow separation and side-load in nozzle
Lin Zhen, Wang Changhui, Liu Yu, Xu Xiaoyong
2010, 36(3): 307-310.
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A three-dimensional numerical simulation about the separation flow in the high-altitude nozzle of a liquid rocket engine on ground was conducted. It obtaines the flow field parameters and the side-loads under work conditions from 8MPa inlet total pressure to 1MPa inlet total pressure. The results indicate that, with the reduction of inlet total pressure, the nozzle flow field will sequentially experience free shock separation mode and restricted shock separation mode. In restricted shock separation mode, the wall pressure has great fluctuation, and is even beyond the ambient pressure in reattachment point. In separated flow fields, side-loads will occur, the directions of side-loads are random. The calculation obtaines the biggest side-load under 4MPa inlet total pressure. It can be predicted that the side-load peak will appear with the exchange between free shock separation mode and restricted shock separation mode.
Modeling and performance analysis of IEEE-1394 asynchronous transfer mechanism
Yang Yusheng, Zhang Chunxi, Li Lijing
2010, 36(3): 311-314.
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High speed data bus technology is one of the core techniques in avionics. IEEE-1394 is a serial high speed data bus, and has been applied in avionics successfully. Its asynchronous transfer mechanism guarantees the reliability of data transferred and is widely used to transfer command and status data. To solve the problems of transmission delay, throughput and bus utilization in IEEE-1394 bus asynchronous transfer, IEEE-1394 asynchronous transfer model was developed based on deterministic and stochastic Petri nets (DSPN). Furthermore, the asynchronous transfer performance was simulated by means of the established model. Through simulation research, the relationship between IEEE-1394 asynchronous transfer system-s throughputs, average waiting time and packet size, packet arrival rate was obtained. The computation method for the limitation of IEEE-1394 asynchronous transfer packet arrival rate also was given.
Stress-strain incremental law in asymptotic state for soils
Luo Ting, Tian Xinguo
2010, 36(3): 315-318.
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Based on the classical elasto-plastic theory, the transformed stress space deduced from the spatially mobilized plane(SMP) criterion and a new concept of similar elastic volume modulus, the stress-strain incremental equations of soils for the asymptotic state constitutive model were established. A simple stress-strain incremental matrix under triaxial compression condition was formulated, in which the modified Cam-clay model was a special case. The stress-strain incremental equations were then proposed to simulate the stress-strain relationships in some triaxial stress path tests as the triaxial compression, the consolidated undrained and the strain incremental ratio controlled. The proposed equations were used to simulate and compare the triaxial test results. They show that the equations proposed can be used easily and the asymptote state model can describe the stress-strain and strength behaviors of soils reasonably.
Building and simulating associated multi station aeronautical search models composed of active and passive sonars
Wu Fang, Yang Rijie, Gao Qingwei
2010, 36(3): 319-323.
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In the background of aeronautical anti-submarine, the search range models of multistatic sonar, aircraft associated search models of dipping sonar and buoys, submarine moving models were built. Based on those models, the influence of the varieties of submarine initialization courses, sea environment noises, search manners in the experimentation was simulated and analyzed. The results show that it can save search time and improve search probability using multistatic aeronautical sonars composed of dipping sonar and buoys. And the factor of submarine initialization course had a litter effect on the aircraft associated search of dipping sonar and buoys, the factor of sea environment noises had a great effect on it.
Constellation design method of space cooperation detection system
Yu Ze, Zhou Yinqing, Chen Jie, Li Chunsheng
2010, 36(3): 324-327.
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The working mode of the space cooperation detection system composed of several synthetic aperture radar (SAR) satellites and one optical satellite was studied. After investigating the properties of the sun-synchronous orbit and the frozen orbit, the orbital semimajor axis, the eccentricity, the inclination angle and the argument of perigee were selected to satisfy the application requirement of the near-earth-orbit remote sensing satellite. Considering that the effect of yaw steering on the coverage performance, the expression of the intersection of the observed direction and the ground was derived in the fixed geocentric coordinate system. And the algorithm of determining the longitude ascending node and the perihelion passage time was proposed. A design result of the system including two SAR satellites and one optical satellite was demonstrated, which was validated by the international recognized software Satellite ToolKit. It shows that this method is right.
Micro-material-test mechanism oriented precision technique
Lu Zhen, Chen Xuedong, He Guangping
2010, 36(3): 328-332.
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Micro electromechanical systems(MEMS) have vast vistas of application in the aeronautics, astronautics, automobile, bioengineering, environmental management, military, etc. However, the material tests are the bottleneck of the property test for MEMS. That is concerned with subtle motion, precision location, and the measurement of tiny load/displacement. Traditional mechanical manufacture is helpless for the mission duo to friction, clearance, crawl, and error-accumulation of multi-transmission. For this reason, a new type of the redundantly actuated compliant parallel mechanism with piezoelectric actuators was proposed. Based on the inverse kinematics of the redundantly actuated compliant parallel mechanism, and by means of optimum topology, kinematical analysis, and dynamical optimization, the key dimensions of the mechanism were determined. The experiment demonstrates the mechanism is capable in the subtle motion, precision location, and the measurement of tiny load/displacement for the MEMS material test.
Adaptive CMAC hybrid control for rudder electric loading systems
Yang Bo, Wang Zhe
2010, 36(3): 333-337.
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Aiming at the nonlinearity and the surplus torque in rudder electric loading systems of unmanned aerial vehicle(UAV), a self-adaptive cerebellar model articulation controller (CMAC) was proposed, which was parallel to an adaptive neuron controller. This hybrid control strategy adopted the desired value and the actual output as the incentive signals of CMAC, and put the current system error as the training signal of CMAC. The method was proposed by using the error to adjust the learning rate on line, which eliminated the excess self-learning phenomena. The mathematical model of rudder electric loading systems for UAV was established and the detailed control structure was put forward. Simulation results show that the proposed hybrid controller can effectively eliminate the surplus torque, enhance the control stability of the systems and fairly improve the dynamic loading performances of the systems, which is highly suitable for real-time control of nonlinear systems.
Design of flight control and navigation systems based on two ARM for unmanned helicopter
He Tianpeng, Wang Jidong, Hu Jizhong, Wang Son
2010, 36(3): 338-341.
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Central processing unit(CPU) of embeded flight control and navigation systems was designed in a certain type of coaxial unmanned helicopter by two microcontrollers based on advanced RISC machine(ARM), together with power source and servo signal processing module, signal processing and interface module, to form a highly integrated embedded flight control and navigation computer. It was provided by 8-way asynchronous serial communications interfaces, 8 digital signal ports, connected with integrated navigation equipment, signal conditioning device, radio receiver and transmitter, attitude stabilization system with the steering gear, and other peripheral devices, to constitute a complete set of embeded flight control and navigation systems of coaxial unmanned helicopter, and configure another 16MB flash eeprom(FLASH) for mission and flight data storage, the flight control and autonomous navigation software of system was developed based on ARM developer suite(ADS) integrated development environment .It is proved that running state of system is good by testing and debugging in ground.
Modeling of VCM-DDV and control simulation
Wu Shuai, Kang Rongjie, Yu Juntao, Jiao Zongxia
2010, 36(3): 342-345.
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The characteristic of a new type voice coil motor-direct drive valve(VCM-DDV) was investigated based on the co-simulation environment of AMESim and Simulink. By using AMESim the VCM-DDV nonlinear model and hydraulic environment have been set up. By using Simulink the digital controller mode has been set up. A strategy of divide the VCM-DDV model into linear part and nonlinear part was proposed. Regards the nonlinear part as a disturbance factor when derive the linear state space model, the disturbance as one of states in space state vector has been set up. A full state observer was designed to estimate the spool position, velocity and the disturbance. Then a linear quadratic regulator(LQR) state feedback control algorithm with a nonlinear compensator was applied. The simulation result demonstrates this control algorithm improve steady precision and dynamic performances both.
General test platform for data manager system of spacecraft
Yin Jia, Wang Zulin, Feng Wenquan, Zhao Qi
2010, 36(3): 346-349.
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In order to accelerate the data manager system testing rate of progress, the general test platform for data manager system of spacecraft was designed and structured. The standardization of the testing method and system framework was realized by the platform to study the testing objects. General availability of software and hardware of the system was fully considered, and a development environment that based on the LUA with good portability was introduced, so the reconfigurable test platform which fits in many types of the dms can be build quickly. A number of model tests show that general test platform for data manager system of spacecraft can significantly reduce the test cycle and the development costs, the operation is stable and reliable, and has achieved the desired purpose.
Formal definition and characteristic analysis of UML sequence diagram
Li Xiaoli, Long Xiang, Bao Xiaolu, Li Hu
2010, 36(3): 350-352.
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A formal method of software specification and a set of mathematics models were put forward based on UML(unified modeling language) sequence diagram. UML sequence diagrams reflect the interaction and sequence of message among the concurrent objects in the system, and hold the important position in software modeling. A formal description of UML sequence diagram and compound sequence diagram was dealt based on UML criterion. The send character and receive character of the message, as well as message consistency in message-sending and message-receiving were analyzed in detail. UML sequence diagram character was proved by example. A formal description and analysis of UML sequence diagram character was proposed, which provided a prior condition for model transforming and model validation, and provided the foundation for automated software test case on UML sequence diagram. The formal definition of UML sequence diagram was used in the construction of a software comprehension and modeling tool.
DSMC numerical simulation of Taylor-Couette flows
He Xiaoying, He Bijiao, Cai Guobiao
2010, 36(3): 353-356.
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Taylor vortices in Taylor-Couette flow between two coaxial cylinders were simulated numerically using 3D direct simulation Monte Carlo(DSMC) model with grids in cylindrical coordinates. The axial vortices structure in stable flow was investigated for different computation domains under different boundary conditions. Axisymmetric DSMC model was also used to simulate the Taylor vortices with the same grid and the same flow field parameters. The results accord well with the 3D results, validating that it-s feasible to simulate micro-scale and low-speed rarefied gas flows by 3D DSMC method. The 3D results show that Taylor vortices rotate around the axis in a great circumferential speed, which could not be acquired in axisymmetric results. The critical value of rotational speed of inner cylinder at which Taylor vortices could be generated was figured out by several simulations.
Control strategy for single-phase Z-source inverter
Zhang Jin, Qi Bojin, Zhang Shaoru
2010, 36(3): 357-362.
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The control strategy for single-phase Z-source inverter, which consisted of Z-source network voltage feedback, ac-side instantaneous feedback and voltage ripple feed-forward loop, was presented. Due to the non-minimum-phase effect of Z-source network, an ac-side instantaneous controller was incorporated based on the Z-source network voltage feedback loop to guarantee fast dynamic response. The Z-source network has voltage ripple during operating with the heavy load, which decreases the performance of the output voltage. The proposed voltage ripple feed-forward controller could modify the modulation index, thus the effects were prevented from propagating into the ac-side and hence the quality of the output ac voltage waveform was improved. Both computer simulation and experimental results verify the effectiveness of the proposed strategy.
Polarization restraint based fast motion estimation approach to stereoscopic video coding
Ai Mingjing, Zhao Lili, Zhao Qinping
2010, 36(3): 363-367.
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An efficient polarization restraint based fast motion estimation algorithm for stereoscopic video coding was proposed after analyzing polarization restraint principle in a parallel binocular-camera system. The left- and right-view images were compressed as the base and enhancement layer respectively in the proposed scheme. An optimal motion vector predictor for the right channel was attained after combining disparity estimation and motion estimation(ME), and a final motion vector was got by using different motion searching method. If the final motion vector predictor was got by referring to that of left channel, then ME searching only in horizontal direction within a small range was sufficient according to polarization restraint, and thus the ME complexity in the right view channel could be greatly reduced. Experimental results show that the ME time of proposed algorithm is just 0.27, 0.58 and 0.67 times of that of full search block matching algorithm, diamond search and three step search respectively, accelerating coding speed greatly.
Integer algorithm of lapped biorthogonal transform compression method with GPU
Yu Zhuo, Liang Xiaohui, Ma Shang, Shen Xukun
2010, 36(3): 368-372.
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Compression/Decompression of huge terrain data is an important component of GC(Geometry Clipmap) method which has significant impact on rendering speed. Integral lapped biorthogonal transform(binLBT) method was used to reduce the complexity of computation by converting float point operations which spent lots of time in LBT method to integer operations and shift operations. In order to avoid the condition the data bigger than memory in graphic card, the method divided the data into some pitches which fit the memory and load one pitch each time, and then used CUDA(compute unified device architecture) to accomplish binLBT step which supports the parallel features of GPGPU(general purpose computing on graphics processing units). Experiment results show that this method based on binLBT by GPU can improve the efficiency of compression/decompression of huge terrain data and accelerate the rendering speed of GC.
Optimal deployment in sensor networks based on hybrid artificial fish school algorithm
Liao Canxing, Zhang Ping, Li Xingshan, Zhang Yan
2010, 36(3): 373-377.
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A hybrid artificial fish school algorithm was presented for optimal nodes deployment of sensor networks. The hybrid artificial fish school algorithm included two phases. In speed priority phase, a suboptimal solution in the neighborhood of optimum solution was found rapidly by using the artificial fish school algorithm. In accuracy priority phase, taking the suboptimal solution as its initial solution and by using its monotonic convergence of the pattern search method, the solution to global extremum was led to. The merits of global search and rapid optimization of the artificial fish school algorithm were retained, and the search accuracy was improved. Node locations were optimized by artificial fish school algorithm, hybrid artificial fish school algorithm and particle swarm optimization in computer simulation for area coverage problem using the probabilistic detection model. Simulation results show that hybrid artificial fish school algorithm can effectively optimize the nodes deployment of sensor networks to improve coverage.

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