Abstract:Based on passive theory,a direct adaptive attitude control scheme for spacecraft is proposed,which can estimate unknown inertia matrix and solve the attitude control problem effectively.Theoretical analysis demonstrates that the closed control system is asymptotically stable,and a numerical simulation illustrates the effect of the proposed scheme.

Abstract:Based on the frequency response of the fractional integral operator,this work analyses the limitations of frequency domain approximation algorithm in the calculation of fractional order chaotic systems.The frequency domain approximation algorithm can approach to the original system in desired frequency band,but in the low and high frequency band there are large errors.Therefore,there are some limitations in the calculation of fractional chaotic system.Comparing with the predictor-corrector algorithm,totally different conclusions can be got by the frequency domain approximation algorithm.Taking the fractional Chen system as an example,numerical simulation results verify the effectiveness of our results.

Abstract:To segment moving objects from their shadows in video surveillance systems,a GMM and MRF-based moving cast shadows detection and removing method was proposed.First,the Gaussian mixture model was adopted to build statistical models to describe background,and the foreground pixels were obtained by background subtraction method.Second,the feature information of color,edge,texture and spatiotemporal coherence between the foreground pixel area and the corresponding background area were integrated into Markov random fields’ energy function.Graph Cut algorithm was used to minimize the energy function,and the final segmentation result was got.Finally,the effectiveness of the method on different video sequences of indoor and outdoor scenes was verified.Experiment results demonstrated that,compared with previous methods,the algorithm could detect and remove moving cast shadows more accurately,reliably and robustly.

Abstract:Because the spacecraft moment-of-inertia changes obviously during the on-orbit propellant refueling process,this paper provides a detailed analysis of the change of moment-of-inertia.Based on some reasonable assumptions,the paper proposes an effective algorithm for computing the moment-of-inertia.Including only one variable,the propellant flow velocity,the proposed algorithm can compute the moment-of-inertia on-line.As a natural result,the time-varying attitude dynamic model for the on-orbit refueling spacecraft is established.Finally,the numerical simulation illustrates the algorithm correctness and the effect of the spacecraft related parameters on the moment-of-inertia.This result provides theoretical foundations for attitude control system design of on-orbit refueling spacecrafts.

Abstract:An algorithm of terrain hazard assessment for soft landing based on information fusion is presented.Firstly,two types of terrain features are extracted from the gray images of landing navigation camera and the elevation data of Lidar respectively.Then,fuzzy variables and membership functions on terrain features are presented,and local terrain hazard assessments are realized by fuzzy inference.Finally,the global terrain hazard is assessed based on the decision-class fusion of weighted means,and the safe landing sites are obviously showed.The simulation experiments using 3D digital terrain image have validated the proposed algorithm effectively.

Abstract:A CENS(Credibility Evaluation Net for Simulation) method is proposed in which the net mathematical definition and theory are established,and the net diagram,characteristics,and calculation formulas are presented.To reveal the uncertainty of expert evaluation further,and to evaluate the simulation systems credibility more factually,the fuzzy comprehensive evaluation method is applied to CENS.Based on the introduction of fuzzy comprehensive evaluation theory,the fuzzy CENS system is established,the calculation formulas and procedures of the method are proposed,and an application example of simulation credibility evaluation is given.

Abstract:To solve the problem of low positioning accuracy issue due to trajectory effect of the observer,instable surveillance data receive rate and weak observability during slow moving target tracking by the single-airborne ESM,a course optimizing filtering model under non-equal interval data scenarios based on shifted Rayleigh filter was proposed in this paper,which updated the sampling interval changes in real-time to resolve the problem of instable bearing samplings.It also estimated the optimal movement direction of the observation platform based on the minimum trace of the location covariance matrix,which avoided divergence owing to improper relative position and enhanced positioning accuracy.The simulation results indicate that,in addition to the maintained good tracking stability,the proposed algorithm has fast convergence characteristics,which effectively reduces the positioning error.

Abstract:To research the microstructure change in nanomachining process,a coupling nanofretting nanomachining model of single crystal copper is presented using molecular dynamics methods,and nanocutting processes are simulated.By angle distribution function(ADF) and radial distribution function(RDF),the structure changes of subsurface in material are analyzed,and the results show that there exists an unstable phase transition from the close-packed hexagonal structure to face-centered cubic structure in the subsurface of single crystal copper during coupling nanofretting nanomachining process.

Abstract:To solve the problem of coordinated control for two manipulators with uncertain parameters,the coupled error containing position error and synchronization error is introduced into synchronized control;a new synchronized control strategy with adaptive correct system parameters is proposed;and Lyapunov stability theory is used to prove the global stability of system.The coordination experiment of two 2-DOF manipulators is executed,and the results show the position error of each manipulator and synchronization error of two manipulators convergence to zero simultaneously,which achieves the goal of one manipulator tracking its desired trajectory while ensuring the synchronized motion of two manipulators.The validity and effectiveness of the presented scheme is confirmed by the experiment.

Abstract:To improve prediction accuracy of aviation equipment cost under small sample size,a prediction model named information diffusion support vector machine is proposed after combining the information diffusion method and support vector machine.The topology and modeling process of the model are also described.The model parameters include both continuous parameters and discrete parameters,so that a different update strategy is adopted to each component of the particle position when solving the problem of model parameter selection using the particle swarm optimization.Finally,the information diffusion support vector machine is applied to the production cost prediction of military aircraft avionics equipment.The average absolute relative error of the result is 3.3%,which can satisfy actual requirement.

Abstract:To make up the deficiency of traditional ac electrohydrodynamics in explaining fluid flowing in opposite direction,a 3D point plane electrode system is devised to carry out microfluidic driving experiments,and the influence of electrochemistry and ac electro-thermal on microfluidic driving under low ac frequency has been analyzed.It is found that the flow direction under ac range of 10 Hz～3 MHz in the device is point to plane all the time,which is opposite to the prediction from theory of ac electro-osmotic(ACEO).The experiments verifies the leading role of electrochemical reaction under low ac frequency,and the result indicates that the leading influencing factor of the phenomenon of microfluidic under low ac frequency in point plane electrode system is electrochemistry.

Abstract:To design a high gain concentrator with high efficient,light weight,low aspect ratio and good uniformity of solar cell illumination for a high concentration photovoltaic system,the SMS(simultaneous multiple surfaces) method was used for simultaneous design of total internal reflection optical surfaces and refraction optical surfaces on the basis of conservation of etendue and edge-ray principle.In realizing that,the optical surface profiles of the concentrator was calculated and optimized using numeric method to complete the design of the concentrator including a primary lens and a secondary lens.The optimized concentrator has 1 000 X concentration,an aspect ratio less than 0.4 and acceptance angle of 1.5°.Moreover,the result of ray tracing of the concentrator indicates that high efficient more than 85% and good uniformity of the solar cell illumination can be achieved.Therefore,when the designed concentrator is applied to a high concentration photovoltaic system with a 2-axis tracking system,an easy assembly process and high optical efficient can be realized.

Abstract:To further improve the edge subpixel location accuracy of an image,a algorithm for edge location based on high-order orthogonal Jacobi-Fourier moments(OJFM’s) is proposed.The rotation invariance and special features of Orthogonal Jacobi-Fourier moments are used to fully extract the characteristics of an edge,while the noises in image is efficiently diminished.The edge location is accomplished by analyzing the relationships among three moments of the edge with setting the edge in vertical direction.The effectiveness of the proposed algorithm is verified through experiment,and the location accuracy is up to 0.05 pixels,0.08 pixels and 0.13 pixels for standard line,standard circle image and actual experimental image respectively.

Abstract:To investigate the influence of cellular materials microstructure on it’s properties,numerical simulation is done by closed-cell tetrakaidecahedron model with thick edge.By finite elements method,relative elastic modulus and Poisson’ ratio are calculated.Simulation results show: single-cell wall thickness is the secondary factor of relative density increment,and wall-face connective curvature radius is the primary factor of the increment.The wall thickness and wall-face connective curvature radius can be simplified as two independent factors of relative density.For high porosity cellular materials,the solid of which the surface tension draws to cell-edge has little influence on relative elastic modulus,but for low porosity cellular materials,the influence becomes greater.The dependence of relative density on microstructure,the unitary relation and the influence of microstructure and relative density on relative elastic modulus and Poisson’ ratio are obtained.

Abstract:The session in search engine log denotes a sequential of queries from a user when he is searching for certain information during a period of time.Session analysis is a fundamental work for user behavior analysis.In contrast to current query log analysis focusing on the query modification and the relationship among user,query and clickthrough,this paper presents user behavior analysis based on session,which includes the times of reformulation and the relationship among user,query and click-through.Experimental results show that the way users reformulate queries relates closely to the times they reformulate,while the number of click-through is steady;the last query often gets longer than the first,what is more,the main variation lies in some changed characters;the more often the users use the search engine,the greater the likelihood that they reformulate queries.

Abstract:To solve the problem of limitation of assuming constant market demand scale and not applying to multi-brand enterprises in most measurement models of customer equity(CE),this paper applied markov matrix to simulate the competition between enterprises and the brand switching of customers,and analyzed the influence of mutative demand market scale on CE with the method of trend forecasting,based on full consideration of cross-purchases and propaganda of public praise,which had significant impact on CE measurement but were ignored in most models.Eventually a four-dimensional driven measurement model of CE under the condition of mutative demand market scale was established.In the application study of the model,forecast method,linear regression method,principal component analytical method and logistic regression analysis were used to measure samples’ CE.The results showed that the change of customer quantity had caused remarkable change of CE,and the mutative demand market scale was a key factor to be reckoned with.This model can make more accurate measurement of the CE and is operable,so that it can guide practice more effectively.

Abstract:To deal with the problem that the stable/unstable manifolds of Earth-Moon Lagrange L1 point can not come close to earth,this paper first introduces the trajectory design method based on disturbance manifolds.The parameterized form of disturbance manifolds is constructed,and by searching through four dimensional parameter space,many numerically optimized transfer trajectories are obtained.Then based on the simulation data,a technique of using angular momentum to explain the transfer mechanism is proposed,which suggests that the design of L1-Earth transfer trajectory should aim at reducing angular momentum,and reveals the dynamics behind the transfer trajectories.Finally,an optimized L1-Earth low energy transfer trajectory is presented,that verifies the efficiency of this method.

Abstract:To fair triangular meshes with noise and to approximate the original meshes of the 3D model designed,a smoothing algorithm based local surface approximation is presented.Specific local information of the vertex was acquired and multivariate L1 medians of the neighbor vertexes were used to determine the point set of local second order approximation of surface.The vertex was then projected to the point set along the direction of its normal.The smoothing was finally completed by moving vertex to the position of the projective point.Experiments demonstrates that the algorithm is efficient and robust.

Abstract:To improve processor’s computation capability heavily,one multi-core system with 5 CPUs is designed and H.264 is decoded on it parallely.One CPU is used to lead the other four CPUs.Five CPUs share one 32 KWord SRAM.Any two CPUs can communicate point to point through mailbox,semaphore,hardware lock.When decoding H.264,the leading CPU is used to parse the bit-stream and calculate the intra prediction mode,motion vector,boundary strength.Then,the decoded data is saved to shared SRAM.Other four CPUs fetch and solve one macro-block line each time.The simulation result shows that using the line parallel decoding algorithm,the five-cores system can achieve about 3.6 times acceleration than two-cores system.The line parallel decoding algorithm can also be used on other video protocol and it is universal.

Abstract:To realize adjusting the fire intensity of cooking robot continuously,a numerical calculation and experiments of dual-pressure fire system for blast gas combustor were carried out.Firstly,the basic equations of fluid mechanics,the equations of component transport and the equations of turbulence for the induction tunnel of combustor were established.Secondly,the CFD software FLUENT was utilized to build the two dimensional axisymmetry gas-kinetic model for the induction tunnel,to define the boundary condition,the initial state and the finite-rate chemical reaction model.Thirdly,the control method of dual-pressure fire intensity was obtained.According to the variation curve of pressure value of high-pressure air in the nozzle central axle with the accelerating value of combustible gas and quantity of air imbibed by ejection,the optimal matched pressure value of high-pressure air based on the specific heat load of combustible gas was obtained.The method was used on the cooking robot,which showed that the fire intensity feedback control could be achieved precisely and the power of common pressure(2.0 kPa) combustible gas combustor could be up to 18 kW.

Abstract:To investigate the tribology properties of titanium alloy in static cooling condition,the friction and wear experiments of YG8/Ti6Al4V were carried out on high speed friction and wear test auxiliary device designed by ourselves.The experimental results showed that static cooling technology could effectively decrease the friction coefficient of YG8/Ti6Al4V friction pair,restrain the wear of friction pair,and improve the worn surface quality of Ti6Al4V.SEM observation indicated that in high speed friction,the main wear mechanism was adhesion wear and shedding accompanied with microcracks.Compared with that in dry condition,adhesion wear was less under static cooling condition.The turning test results demonstrated that the anti-friction effect of static cooling technology could effectively restrain tool wear and improve tool life.

Abstract:Spherical helical gears with tooth flank modification were proposed to enhance loaded capacity and improve the sensitivity to assemble errors.The mathematical model of tooth surface was developed by the imagine rack-cutter and gearing theory,and the modification with parabolic curve of rack-cutter was applied to produce a required transmission error curve and improve meshing characteristics.Then,the tooth contact analysis model was established on the conditions of continuous tangency of two contact surface,of which the assemble errors were considered.The simulation results show that the capacity of loaded capacity and tooth contact ratio can be increased by the contact pattern of convex-concave type gears along the helical tooth traces,and the error sensitivity of contact pattern of the convex-convex and convex-helical types of spherical gears can be improved by tooth modification.

Abstract:In the current structure-based image inpainting algorithm,the Fast Marching Method can simply and rapidly repair the damaged region in the digital image.However,the effect is not very good,especially poor to preserve the edge information.By introducing the gradient function and the distance weight function,an improved algorithm has been proposed,which sorts the neighboring points with weight to repair the damaged region and uses the gradient-sorting estimation to preserve the edge.The results of experiments have indicated that the improved one is better.The gradient function and the distance weight function can make results more better.

Abstract:Recognizing special Named Entities from Chinese Web search query logs is very useful for practice.In this paper,a few seed words and feature selection techniques are used to extract features from the query logs first,and then the features are combined into a text classifier for NE recognition.Experiments on a handred milllion queries to mine six types of Special Named Entities show that it is able to find high quality Sepecial Named Entities from Chinese Web search query logs.The average P@500 of the six classes achieves 77%.

Abstract:A modified algorithm was proposed in this paper to deal with the problem that the conventional algorithm of hard decision decoding for Turbo Product Code(TPC) can not correct some detected error symbols.Based on multiple iteration steps of the conventional algorithm of hard decision decoding,the modified algorithm can correct the wrong symbols by detecting them,estimating their total number,constructing their candidate sequences and then selecting the optimum sequence among the candidates.Simulation results show that the modified algorithm can provide a gain of 0.9 dB over the conventional algorithm at BER of 10-5.

Abstract:To select a proper electrical machine and control strategy,based on dynamic parameters predicting model of oil-pumping,the geometry model and movement model are modified and expended.The characteristic of suspension load,driving characteristic of gearbox and coupled torque characteristic of electrical machine are analyzed,as a result,a dynamic coupled model for oil-pumping system is built,and its calculation accuracy is increased by deep analysis of static and dynamic suspension load.Finally,a typical system is selected to be simulated,and the correctness of the model is proved.

Abstract:For the nonlinear coupled system of two-link manipulators,ADRC(auto-disturbance resistant control) controllers are designed for the two joints,in which the ESO of ADRC for linearization via dynamic compensation is used to realize the decoupling control of two joints.Accurate tracking control of manipulator is achieved by selecting the control parameters of ADRC properly.Simulation results show the effectivity and the robustness of ADRC and put forward a new way for the tracking control of manipulator.

Abstract:In this paper,we proposed a novel image hash algorithm based on Zernike moments.We employ Zernike moments to represent the image content for the reason that it is the projection of the image under a group of orthogonal basis.Thus,the discrimination of proposed algorithm is improved.Meanwhile,benefited from the invariance property of Zernike moment under affine transform,our algorithm is robust to rotation attack.In the proposed method,the hash string is generated from the Zernike moments of the normalized input image.Secret key is also introduced to ensure the security of the hash method.In the experiments,the method is tested by 100 sample images.The false accept rate under rotation attack is less than 4%.The error recognizing rate between different images is about 10-9.Experimental results prove that our algorithm has great robustness and discrimination.

Abstract:Aiming at the demands of fatigue driving monitoring,a drowsiness detection system based on High-speed DSP TMS320DM642 from TI Inc was designed.It can determine the driver’s level of attention,and reduce the number of traffic accident.This system uses the machine vision method to get video sequences of a driver from the CCD camera,and than detects the face,eyelid to determine the state of drowsiness by the PERCLOS criterion.The experimental results show that this system has higher accuracy and speed,and can satisfy the demands of non-contact,all illumination condition and real-time monitoring.

Abstract:To improve the precision of initial orbit of spacecraft in launching phase,to execute timely and accurate TT&C in early orbit phase,and to meet the need of the users,this paper puts forward an initial orbit determination method which regards measurement datum and precision of all kinds of redundant and backup equipments as the input parameters of the optimization model and determines the optimized orbit based on Particle Swarm Optimization(PSO) method.The result indicates that it is significant to improve the precision of initial orbit of spacecraft by using a number of measurement data and the precision of different redundant and backup equipments.This algorithm is proved to be accurate and effective,and can be used both in the initial orbit determination and in the spacecraft orbit optimization in operational phase.