Abstract:Under the background of tethered deorbit system and considering the mass and flexible factor of the tether,a deployment dynamic model for flexible tethered-assisted deorbit system was given based on the micro-element method.For the complicated nonlinear and strongly coupled dynamic equations,the dynamic model was discredited to obtain numerical solution by Galerkin method.Then a mathematic simulation was conducted to validate and analyze the dynamic characteristics of the system.The results showed that the Longitudinal and Transverse vibrations and the frequency increased with the deployment of the system,but the amplitude decreased,and the amplitude of the vibrations of the in-plane angle and tension also decreased.So the vibrations induced by the flexibility of the tether damped and tended to a quasi-stationary configuration with the increase of the deployed tether.

Abstract:A input shaping control algorithm is provided for vibration suppression of rigid-flexible coupling systems with large overall motion.For the sake of describing actual dynamics of those rigid-flexible coupling systems,a first-order approximation dynamic model was presented.The second-order coupling terms was included in the longitudinal deformation.The modal characteristics of the flexible beam in rigid-flexible coupling system was different from that of the beams in structural dynamics in large overall motion.Considering the differences,a robust multiple-mode input shaper was designed.Simulation results show that the presented control strategy suppresses the beam’s vibration successfully during attitude maneuver.

Abstract:A post-processing method for SPH was presented based on Delaunay triangulation.However for non-convex domain occupied by SPH particles(nodes),Delaunay triangulation results in some empty elements which contains no mass.Thus an "element mass weighing" method should be proposed to identify and delete those empty elements from the element collection.The reasonability of the algorithm is that each empty element has a very much less SPH-weighted-approximation than the average quality of the particles on it.With the SPH data and the kept elements being exported into the universal post-processing software Tecplot,the values at any point in the computational domain could be obtained.The feasibility of the algorithm was tested in a series of numerical cases including a case with heterogeneous particle distribution and material splashing.

Abstract:To solve the problem of robust fault diagnosis in satellite attitude control system,based on UIO,a nonlinear UIO(NUIO) is proposed to dealt with actuator and sensor faults.Considering the external disturbance and uncertainty of the nonlinear attitude control system,a new model for the system is established.By using H-infinity control and linear matrix inequality(LMI) approach,the NUIO matrix is obtained.At last,the diagnosis simulation of satellite attitude control system with actuator and sensor faults validates the feasibility of the proposed method.

Abstract:To solve the problem that in the traditional satellite attitude determination system,the changes of conditions are unconsidered,viz.the traditional method lacks of module to eliminate the polluted data and applies a fixed method to process the data,an intelligent fusion scheme selection method is proposed based on NFE model.This method can eliminate the polluted data with wave gate,and compute the confidence of the attitude determination system by NFE model,and then select the matching fusion scheme according to actual situation to suit the practical attitude determination condition,which are verified by the computer stimulation results.So that it can be realized to get higher precision satellite attitude determination by using the fault avoidance module and the intelligent selection module.

Abstract:Partition-and-Shift codes have been paid much attention in the area of error correction in telecommunication system,because of its ideal girth and min-distance property.An Improved algorithm for constructing PS-LDPC codes is presented to improve constructing efficiency,by employing a precise criterion for choosing the shift parameters in shift matrix and a perspicuous and reasonable method to search for closed paths simply.Finally,the improved PS-LDPC codes are simulated over AWGN channel and a better BER performance is obtained.

Abstract:To improve the reliability of drive system of space robot joint,modular joints with a variety of sensors are developed,and the fault-detection algorithm and fault-tolerance strategy for the joints are established.The experimental results show that by using this algorithm,the dependence of fault detection strategy on model can be overcome,and the joint failure can be quickly detected in the low and high-speed range,which ensures the security and stability of the joint operation.

Abstract:To built pilot tracking control strategy model,the combination of sliding model control characteristic and optimal control characteristic is adopted to propose a sliding optimal control method,and the time-varying sliding surfaces are designed so that the system state is on the sliding surface from the beginning of the motion without reaching phase.The system is robust and stable.A parameter selected method of weighting matrix on H∞ control is improved,by which the weighting matrix of linear quadratic optimal control is calculated.To drive the system state variables to the acquisition control switching surface in minimum time,the acquisition control strategy is builed by sliding model control.The main error is regared as a judgement from acquisition control strategy to tracking control strategy.The simulation results show that the pilot variable stategy control is suitable to the real pilot control characteristic.

Abstract:To achieve quick and exact segmentations for intensity inhomogeneous images with complicated structures,we propose a novel level set method based on local region energy and gradient sensitivity,and initialize the level set automatically using the global intensity information.It is an improvement of minimization of region-scalable fitting energy with the introduction of two gradient sensitive energy functions.In this model,the local region energy based on the gray fitting functions acts as an external drive,which has an advantage in segmenting intensity inhomogeneous images.Gradient sensitive items can determine their drive directions of level sets adaptively according to image features.The external one draws zero level sets to the object boundaries,while the internal one pushes zero level sets out of intensity homogenous regions.Thereby,our method not only speeds up the convergence and improves robustness of level sets,but also copes with weak boundaries as the gradient sensitivity could be adjusted to respond to different gradient intensities.Meanwhile,interactive initialization is unnecessary.Experiment results demonstrate that our method has faster convergence,better robustness and good performance in segmenting intensity inhomogeneous images.

Abstract:Since the bidirectional reflectance distribution function(BRDF) could show well the infrared reflecting and scattering characteristics of exterior surface of buildings,three typical materials,granite,aluminum sheet and coated glass,which are often used on the exterior finishing surface of high-rise buildings,were chosen to be investigated.The BRDF distributions of these surfaces were measured by laser waves of 0.632 8 μm,1.340 0 μm and 3.390 0 μm respectively at different incidence angles,using the white standard plate(approximate Lambert Body)as a single sample,and the reflecting and scattering characteristics of these surfaces were analyzed.When the length of laser wave is 3.390 0 μm,there is a phenomenon of more peaks on the reflecting of coated glass’s surface and the values of these peaks are higher than that of 0.632 8 μm and 1.340 0 μm at the same time.It is shown that there is large diversity in the reflecting of coated glass’s surface with different incidence waves.

Abstract:To improve the accuracy of defect detection in bank note sorting and decrease the effects of cracks and scratches of bank note on detecting,a new algorithm based on wavelet decomposition is proposed,in which affine transform and wavelet transform are applied to bank note image registration and the edge information is extracted by Kirsch operator,while the defect feature is extracted from edge intensity differential.The bank note image is divided into several fixed size subzones,in each of which the defect feature is calculated to judge the degree of contamination.The experimental results reveal that the proposed feature extraction method is robust to the gray intensity change in each subbone,and obtains high recognition rate and high stability.This method has already been used in practical bank note sorting system.

Abstract:Based on the anatomically detailed geometry of human heart,an integrated human ventricle model is proposed to simulate the reentrant wave propagation for studying the generation mechanism of arrhythmia caused by myocardial ischemia.To deal with the no-flux boundary conditions,the phase-field method is adopted to automatically handle the complicated boundary conditions.Through increasing the concentration of extracellular K+ in the ischemic region,reentrant spiral wave dynamics under different ischemic conditions is simulated.Experimental results show that the degree of myocardial ischemia would have an important influence on the behavior of wave propagation.With the increasing of myocardial ischemia,the reentrant wave would become more and more instable,which eventually leads to breakup.Although the reentrant wave can pass through the ischemic region,the behavior of action potentials of myocardial cells in the ischemic region would be different from the normal behavior,and the inconsistency of action potentials in space is the intrinsic reason for the emergence of arrhythmia.

Abstract:There are many requirements for the multilanguage static information retrieval,and it is wasteful and complex to build specific front end for each language.So to meet the need and conquer the weakness we present a method based on GCC source code change to provide a uniform interface for retrieval.According to the static information type and the GCC inside mechanism,this method integrates the specific hook point with the GCC’s internal functions to gather the needed.The details to be collected include: the type and function declaration,the statements traverse and the uniform multilanguage middle-representation.The reusability of this method reduces the duplicated cost of the construction for each language.The comparison experiments shows that this method can efficiently and robustly parse multilanguage and be directly applied to large-scale open source code to retrieve the static information.

Abstract:To improve the solving efficiency and performance,a new Discrete Particle Swarm Optimization(DPSO) algorithm for the problem of weapon-target assignment(WTA) was presented,in which the velocity and position in the original PSO formulas were redefined to solve a discrete combination optimization such as WTA.The greedy heuristic policies were exploited to adjust the solutions generated during the execution of the algorithm to find optimal or suboptimal solution rapidly.The experiments show that the new algorithm can get the optimal or suboptimal solution quickly,and the result is satisfying.

Abstract:To obtain good fusion and precision of drops during drop deposition increasing material manufacturing,the drop deformation and solidification after impinging on the substrate was simulated.Two phase flow model,combining with free surface tracking algorithm and solidification interface tracking algorithm,was adapted to built up the coupled calculating models for drop deformation and solidification.The results show that the temperature transformation of the drop agrees well with the shape deformation,and the part contacting with the substrate solidifies instantaneously as the drop impinges on the substrate.The solidification layer radius equals to the drop radius,and the effect of the impinging velocity on solidification is more than that of the temperature.A concept of semi-solidification was proposed,and the time,radius and thickness of frozen layer for semi-solidification drop were calcutlated.The fusion was in the good conditon when the former drop was in semi-solidification state.

Abstract:Archard’s wear law and the contact mechanics method are used to evaluate the evolution of contact characteristics including contact pressure,contact width,gap and slip functions under conditions of different tangential force within slip zones of curvic attachments of a gas turbine with wedge-side surface in fretting.It can be concluded that the repeated slip occurring near the edges of contact generates wear that changes the contact geometry and contact stresses.Thus,the change of contact geometry and redistribution of the contact pressure in turn influences the wear rate in the slip zones.All functions in the wear contact problem are time-dependent and inter-connected.The results,compared to the experimental ones,show that the present model is valid and reasonable.

Abstract:To realize automatic analysis and prediction large-scale failure data for high-performance computer systems,an information-theoretic Co-clustering method for large scale nonlinearly correlated failure data was proposed.The failure data were sorted according to the nonlinear correlation of failure features and the failure feature signatures were defined.Then a nonlinearly correlated failure data Co-clustering algorithm was proposed and measured using mutual information entropy.Moreover,the convergence and local optimality of Co-clustering algorithm were proved theoretically.Experimental results on labeled failure data showed that the Co-clustering analysis algorithm outperformed other clustering analysis algorithms and the proposed Co-clustering analysis method had the features of rationality and effectiveness for discovering the nonlinearly correlated failure patterns and could help to predict underlying failures.

Abstract:To evaluate the reliability of NC machine tools,based on AIC and BIC information criteria,a method of model selection and parameter estimation for time-between-failures of multiple NC machine tools with time truncation is proposed.The confidence intervals of model parameters,the reliability given MTBF(mean time between failures) and the warranty time with 90% reliability are all given by Fisher Information Matrix method.At last,Monte Carlo simulation method is used to enlarge sample size of small-sample data to improve the precision of interval estimation.The results show that the interval length of reliability given MTBF and warranty time with 90% reliability are both reduce by 95% and 93% respectively.

Abstract:To improve the computational efficiency of the kernel minimum squared error(KMSE) algorithm,we propose a fast KMSE by using the uncorrelated sample vectors,known as basic samples,in the feature space.And we describe the theoretical relationship between the linear correlation of sample vectors in the feature space and the determinant of the kernel matrix.The kernel functions between a sample and the basic samples were used to extract the features from the sample.The whole basic samples is only a small portion of the training set.The experiments on the intrusion detection dataset KDDCUP1999 and other benchmark datasets show that the fast KMSE is computationally efficient and can achieve high classification accuracy.

Abstract:In this paper,solar-sail attitude control system which employed moving masses for pitch/yaw trim control and roll stabilizer bars for roll control was studied.Physical model of solar-sail attitude control system had been analyzed,and the dynamical model was established using Euler’s attitude dynamical equations.According to the model,a nonlinear PID controller was found to control the three-axis attitudes.Finally,a series of simulations,including the Solar Polar Orbit Radio Telescope misson’s trajectory transfer,were run to determine the effectiveness of the attitude controller and characterize the behavior of attitude control method using moving masses and RSB.

Abstract:To construct more almost perfect binary array pairs and almost perfect punctured binary array pairs,and to expand their scope of application,the complex product,two-dimensional cycle of product and folding transform method were adoped,and by using the known perfect discrete signal,large amounts of optimum signal of almost perfect binary array pairs and almost optimal shielding binary array with new and good characteristics related circulation could be constructed.The two kinds of optimum discrete signal gets rid of the limitation of volume 4t2,so that more examples of the optimum signal can be found.

Abstract:To study the non-linear bifurcation characteristics of face-gear transmission system,a nonlinear dynamic model is presented.This model includes bearings,backlash,time-varying meshing stiffness,general transmission error,meshing damping,and external load,etc.The PNF(Poincaré-Newton-Floquet) method is used to solve the dynamic differential equations.The calculation results show: when the amplitude coefficient of time-varying meshing stiffness increases from 0.4 to 0.5,the system will go into chaos through period-doubling bifurcation;when the meshing damping ratio decreases from 0.061 000 0 to 0.060 000 0,the system will enter chaos through quasi-periodicity bifurcation;when non-dimension amplitude of general transmission error decreases from 0.120 to 0.112,the system will appear boundary cataclysm.

Abstract:A vibration analysis modeling method was presented to analyze the vibration of multi-rotor system geared by angular spiral bevel gear pairs.The vibration equations of a single-rotor system were obtained using the vibration equations formula of each node with six degrees of freedom.The global vibration equations of the entire geared multi-rotor system are established through the whole coupled matrixes of the angular spiral bevel gear pairs.The nature frequencies,critical speeds,amplitude-frequency diagram and whirling orbit etc,were obtained by analyzing the global vibration equations of multi-rotor system.The numerical analysis showed that the system produced some new modes and the exciting forces on a rotor of the system would evoke considerable responses of the other rotors for the gears mesh.The numerical example indicated that the whirling orbits of each node varied with the shaft angle of the spiral bevel gear pairs.The effect of the shaft angle must be taken into account when analyzing the vibration behavior of the geared multi-rotor system.The feasibility and the reliability of the method proposed for vibration analysis of geared multi-rotor system are proved by the numerical example.

Abstract:This study used two kinds of proton exchange membranes Gore 5621 and Gore 57 to fabricate 16 cm×16 cm proton exchange membrane fuel cell with serpentine flow field.The performances of both cells were tested experimentally at various operating conditions.The cell performance was found to be closely relative to the membrane hydration,cathode flooding and a proper combination of cell temperature and humidification temperature.At a specified cell temperature and humidification temperature,Gore 57 had better performance than Gore 5621,since thinner membrane Gore 57 can maintain very good hydration with a small amount of water,which made the cell operate at a higher cell temperature and lower humidification temperature.At the lower cell temperature the performance of Gore 57 cell was better with dry air or dry hydrogen than humidified air or humidified hydrogen,while at the higher cell temperature the cell performance was worse with dry air or dry hydrogen.The performance of Gore 5621 cell was worse with dry air or dry hydrogen than humidified air or humidified hydrogen for all cell temperatures,which indicates that for thicker membrane Gore 5621,cathode humidification and anode humidification are all important to improve cell performance.

Abstract:A kind of real-time communication protocol named Message-Stream Test Protocol(MSTP) and based on reflective memory network,is designed for the Simulation Testing Environment of Avionic Software to solve the common communication problem of periodic and asynchronous communications.The MSTP is designed on SCRRAMNet;the layout of memory is introduced;and the sending and receiving process are described.The testing result demonstrates that the design is feasible.At last,a more precise model of system cost is presented.

Abstract:In order to improve the precision of machining and efficiency of cathode movement planning,the shaping law of tool-cathode for precision electrochemical contour evolution machining of integral impeller has been studied,and the mathematical model was established,the offset curves along the normal direction of vane transversal in fitting surface of impeller blade profile has been used to design the movement trajectory of contour evolution,cathode velocity along the trajectory have been designed according to the mathematical model.Then,the thickness of electrochemical solution could be controlled.The results of experiment shows that using the mathematical model and the designing method of movement planning can improve the productivity of movement planning in electrochemical contour evolution machining integral impeller.

Abstract:To solve the problems of large calculation and narrow application scope of present feature selection algorithms which do not take the correlation among sample features and that between sample features and classification labels into account,a feature selection algorithm combining within-class variance with correlation measure was proposed based on the principle of the minimum mean square error for classifier and the idea of linear discrimination analysis,then the algorithm was expanded to solve nonlinear feature selection problems by using kernel technology.The proposed algorithm can not only consider both the correlation among the features and that between the features and classification labels,but also minimize the within-class variance,effectively improving the generalization performance of classifier.The experimental results show that the proposed algorithm can be used to select important features from these data sets with numbers of correlation characteristics,and effectively improves the classification accuracy.

Abstract:To solve the problem that the random optimization method costs huge calculation and the best response method tends to get a weak local optimization,an effective optimization algorithm is built in this paper,which use best expected improvement(EI) strategy to balance response value and response precision.Tests of airfoil shape optimization indicate that the drag coefficient is reduced by 22% and the calculation time is reduced by 68% comparing with that of the particle swarm optimization,which shows that this effective optimization algorithm is realizable and effective.

Abstract:To study the effects of wave on exceeding water process of underwater vehicle,the wave surface velocity of the second-order Stokes wave was coupled into the incident boundary condition,thus the unsteady numerical wave was obtained,which agreed well with the theoretical value and had high accuracy.The effects of wave on the flow field and dynamic characteristic of the underwater vehicle model when it was launched vertically under the water were investigated under fifth wave level.The results show that when the vehicle approaches the water surface,due to the induced effects of the vortices caused by the wave,the position and the size of the attached vortices at two sides of the vehicle vary significantly.The vehicle body deflects in the left under the effect of the moment rotated around the z axis in the anti-clockwise direction,so that the offset of the vehicle afterbody is about one meter when the vehicle exceeds from the water completely.

Abstract:For studying the effects of technological parameters on sapphire crystal growth and quality of the sapphire,several modifications of technological parameters were made on self-developed Kyropoulos furnace during crystallization,including the adjustment of flow rate and temperature of cooling water in thermal exchanger,and the descending rate of maintain power.It was found that the cooling intensity of thermal exchanger influences the crystal growth obviously in the stage of seeding and shoulder-expanding and the influence weakens gradually,while the descending rate of maintain power during the stage of iso-diametric growth has a great effect on the crystallization rate and the quality of the sapphire.Too fast decreasing of maintain power will cause the failure of mono-crystal growth,so that the proper adjustment of cooling intensity of thermal exchanger and the careful control of maintain power during crystal growth are the two important factors for successfully producing sapphire mono-crystal.