Abstract:This paper deals with the trajectory tracking for a flexible spacecraft subjected to bounded control input under parameter uncertainties and external disturbances.A simplified adaptive sliding mode control system is designed for the attitude tracking control and vibration suppression of flexible spacecraft,with the degree of sharpness of the control permitted to vary with time according to a set of user-defined parameters.The associated stability proof is constructive and accomplished by the development of a Lyapunov function candidate.It is shown that global stability of the overall system is guaranteed with explicitly accounting for the bounded control input and even in the presence of bounded disturbances and parametric uncertainty.Although control smoothness is preserved at all times,it is important to note that the results of this paper that are derived with respect to bounded control input place no additional restrictions on the body inertias and make no other small-angle assumptions.The closed-loop performance of the new control solution derived here is evaluated extensively through numerical simulations,in which the flexible dynamics is treated as additional disturbance acting on the rigid structure.

Abstract:Aimed at the less robustness of conventional path planning method,an adaptive ant colony algorithm is presented to realize the path planning of space robot.The ant colony algorithm modifies the updating method of pheromone based on the distance between the learning times and the closest obstacle to reduce the stagnation behavior of the conventional ant colony algorithm in the initial calculation.Simulation results show that the proposed algorithm can obtain better path with less ants than the conventional ant colony system.

Abstract:To meet the demand of quick maneuver at large angle and high precision stability during the process of maneuver for an agile small satellite,a control allocation strategy is proposed in this paper to control the maneuvering process with configuration of redundant thrusters and reaction wheels.The control allocation algorithm distributes the control requirement among mixed redundant actuators dynamically and changes the weights of control parameters presented in the optimized objective function to choose suitable actuators actuated.The normalized linear programming model is used to obtain the solution.The results of simulation on Microsim platform which is equipped with redundant thrusters and reaction wheels demonstrate the effectiveness of the proposed strategy.

Abstract:A high performance controller was designed based on variable structure control(VSC) theory in this paper.The control plant is the typical structure of two axes and four frames,and the controller is sliding mode controller based on Kalman filtering.Comparisons between the controller with filter and the controller without filter were made through tracking different signals when process noise and sensor noise were obvious.The results show that the tracking performance is improved by variable structure control scheme based on Kalman filter,and the accuracy of tracking is enhanced.

Abstract:A relative navigation method based on INS/Vision is presented with the consideration of the measurement of vision navigation equipment with time delay,and the relative inertial equation between the leader and the follower is derived.The line of sight measurement is acquired by observing the beacons on the follower using the vision navigation equipment on the leader.The extended Kalman filter is used to estimate the relative attitude,relative velocity and relative position by fusing the inertial navigation information and the line of sight measurement.For the time delay problem of vision navigation equipment,a method of fusing the inertial navi gation information and the measurement with time delay is provided.Simulation results verify the effectiveness of the relative navigation method.

Abstract:To study the real-time estimation method on tether parameters for orbital motion of tethered satellite system,after analyzing the main problems in current estimation methods,the measurement information of a three-axis tether tensiometer and the extended Kalman filter were introduced,then a real-time estimation method was developed for large-angle change on tether swaying angle.This estimation method was deduced and demonstrated in detail.Finally,the validity of the estimation method was verified by simulation results and a preferable estimation precision was obtained.

Abstract:In order to dispose some faults of screw pump wells widely applied in the oil field exploitation and improve the veracity of fault diagnosis and the capablility of multi-fault diagnosis,an intelligent integrated fault diagnosis expert system based on the fuzzy neural network was established,and the construction of the system was given.The construction and function of fuzzy neural network were introduced,and the structure and performance of the integrated repository were analyzed,then the fault diagnosis processing of the system was designed.The running application of the system on the practical field screw pump achieves the expected diagnosis effect.

Abstract:To deal with the vibration and turbulence due to the long optical paths in extra-large concave aspheric mirrors testing,the dynamic interferometer associated with compensators is advanced.The difficulties in large concave aspheric mirrors testing are studied in this paper.Dynamic interferometer is employed to deal with vibration and air turbulence.Using the optical design software Zemax,compensators with 3.5 m aperture are designed as an example for concave aspheric mirror testing.Tolerance analysis indicates that the precision of this testing method is better than λ/90.

Abstract:Through analyzing the whitening and separation process of signal based on natural gradient,a blind source separation algorithm with natural gradient based on whitening process is proposed.The algorithm colligates the whitening and separation of signal,and need not whiten the signal individually.By the application of natural gradient,the performance of algorithm is improved.Deduction proves that the algorithm satisfies the separation,equal variety and nonsingularity of separation matrix.Simulation shows that the algorithm can separate and reconstruct source signal effectively.Compared with the random gradient algorithm without signal’s whitening and the conventional FastICA algorithm,it exhibits faster convergence as well as better separation effect and is more favorable for blind source separation.

Abstract:In this paper,a logic algebraic algorithm in computing entire routes among the nodes of a communication network is improved,and a new algorithm of detecting cycles in bipartite graphs of LDPC codes is proposed.The algorithm obeys the logic algebraic calculation rules.Through integrating and deleting rows of relative matrix and correcting some elements of the matrix,the new algorithm can detect all the cycles in the bipartite graphs of LDPC codes.When the code length is n and information bits number is k,the integrating and deleting algorithm needs(n-1)×k times and the correcting algorithm needs k times.The validity and rationality of the algorithm are demonstrated in detail.The calculation course of the algorithm is shown by an example and the correctness is validated.

Abstract:At present most of the aircraft recognitions rely on sample database,which leads to poor accuracy for aircraft outside the database.The problems of feature selection and extraction for aircraft in optical image were studied through analyzing the principle of the methods commonly used in pattern recognition.Extracting method for five recognition features based on human way of thinking and the characteristic of aircraft in optical image was proposed.Fuzzy pattern recognition was applied in the aircraft recognition.Experimental results show that the method can accomplish aircraft recognition with high accuracy.

Abstract:Controlling a multi-DOF prosthetic hand by EMG signals demands for effective pattern recognition methods that can be easily embedded in the controller of the hand.In this paper,methods of K-nearest neighbor and support vector machine(SVM) were used to identify different modes of myoelectric signals,which were obtained in several on-line experiments.Both methods were performed on different training sample sets,called threshold set and steady-state set,and in the case of abundance and relative insufficiency of samples.Experimental results show that the SVM method is superior to K-nearest neighbor,and the real-time recognition results are better when using threshold dataset as training samples than using steady-state dataset.The proposed method,which is based on SVM and embedded in DSP,can discriminate 10 hand gesture EMG modes with a prediction accuracy of above 95% and a decision frequency of about 30 Hz.

Abstract:The hydraulically driven 6-DOF parallel Gough-Stewart mechanism was used as a motion simulator to simulate the real motions of carrier for testing firing control systems in laboratory.The bidirectional force/torque versus velocity interactions between mechanical dynamics system and its hydraulic driving system was explored to establish an integrated dynamic model.Then the couplings of pose outputs were presented and experimental results show that the couplings between these outputs will become more intense with the increase of motion frequency within natural frequency of the Gough-Stewart mechanism.Moreover,for the safety of the motion simulator,a simple criterion which only uses the lengths of legs instead of complicated and time-consuming method of condition number of Jacobian is proposed to distinguish singular area from the workspace.Amplitude and Phase Control(APC) and random wave duplication techniques were employed to greatly improve the simulation fidelity not only for sine waveform but for random waveform as well.

Abstract:Aimed at the parameter uncertainties and extra torque in passive force control system,an adaptive backstepping controller is proposed based on the established nonlinear model of the system.The stability of the controller is testified by the Lyapunov stability theory,in which the parameter uncertainties and extra torque are considered.The nonlinear model of the system is established to construct several new virtual subsystems,then the backstepping thought is introduced to the design of the dummy controllers for each dummy subsystem.By backstepping recurrence,the nonlinear controller with parameter uncertainties and disturbance of load bearing system is obtained.The result of simulation shows that the designed controller can eliminate extra torque better compared with traditional controller,which proves the effectiveness of the proposed approach.

Abstract:In order to get a better convergence and transition for passive bipedal robot research,this article analyzed the initial model of passive biped robot,i.e.the two-dimensional rimless-wheel model.Its dynamic model was constructed and its motion characteristic was analyzed with Adams.The effect of initial velocity,quality,foot radius,the number of spokes,the length of spoke,moment of inertia and slope gradient on the movement of rimless-wheel was analyzed.Results show that a right initial velocity and slope gradient,larger quality and foot radius,more and shorter spokes,as well as larger moment of inertia can lead to a fast and smooth cycle motion for rimless-wheel.

Abstract:In order to reduce the hoop count and increase search efficiency,the notion of pointer table is introduced into CAN.In a scale of 2L identifier space,coordinates in each dimension are divided with binary search.The nodes corresponding to the divided coordinates compose the next hoop set as a pointer table,which cuts down the search scope from the whole CAN to a local CAN area.Simulation results show that the distribution of nodes’coordinates generated by improved CAN search algorithm is more uniform than that of the original CAN model.In the scale of 26 CAN and the scale of 27 CAN,90% and 70% searches cut their hoop figures,and the rates of decrease are 53.2% and 31.5% respectively.The distribution rates of search length reduction in the scales of 25,25 and 27 CANs are given after the sample space is extended.The experiment demonstrates that the improved algorithm based on CAN has less search hoop count than the original one.

Abstract:In order to decrease the forging temperature and improve the microstructure and properties of titanium alloy blade,based on the theory of hydrogen-induced plasticity enhancement at elevated temperature,thermohydrogen treatment technology was used in the forging process of titanium alloy blade in this paper.Microstructures of hydrogenated TC4 titanium alloy blade and TC4 titanium alloy blade without hydrogen forged at different conditions were investigated.The microstructures of hydrogenated TC4 alloy and TC4 alloy without hydrogen after dehydrogenation treatment in vacuum and common heat treatment processes were compared.Results show that hydrogenation can decrease the forging load of TC4 titanium alloy blade.The microstructure is improved after heat treatment and the bimodal microstructure with fine equiaxed α phase is obtained.The reasonable heat treatment parameters of TC4 titanium alloy blade with 0.25wt.% hydrogen are dehydrogenation treatment in vacuum at 750℃ for 5 h after forging,then 900℃ anneal treatment for 1 h and 450 ℃ ag-ing treatment for 4 h in conventional furnace.

Abstract:The evaporation and deposition process of Ti-Al thin sheet under actual experiment conditions was analyzed to obtain proper processing parameters of Ti-Al thin sheet prepared by EB-PVD technology.By using thermotics theory with experimental analysis and according to the trait of EB-PVD technology,the transfer of evaporating particles,the effect of saturated vapor pressure on different atoms and the re-evaporation of Al were studied.The results indicate that the optimal source-substrate distance is about 280 mm,and the cross section of deposit presents natural lamination due to the deviation of saturated vapor pressure between Ti and Al element.The addition of Nb tablet on target can reduce component deviation between deposit and target resulted from the diversity of evaporating rate of component.Besides,the effect on deposit by re-evaporation of Al can be neglected.The depositing rate can be increased and the effect of deviation of saturated vapor pressure on the component deviation can be reduced by the proper design for processing parameters and the introduction of Nb into molten pool.

Abstract:In this paper,means and method used for characterizing the interface behavior of single fiber composite are elaborated comprehensively from three aspects:mesoscopic-mechanical test,mesoscopic-mechanical models and numerical simulation.Mesoscopic-mechanical test establishes the basis for mesoscopic-mechanical models and numerical simulation.The relationship between them should be fully utilized to establish a sound system of interface performance characterization to accurately forecast the mechanical properties of composite materials and meet the requirements of various industries.

Abstract:In order to correctly analyze the control dependence and data dependence relations of C program,and then carry out the program slicing,code redundancy and code duplication detection,a method to extract the static information of C program from GCC AST text was put forward.Firstly,the GCC AST text was standardized and the nodes unrelated to control dependence and data dependence analysis were eliminated.Secondly,control dependence subgraph was constructed.If data flow analysis was necessary,control flow graph was constructed based on control dependence subgraph and data dependence subgraph was constructed based on control flow graph.At last,by the introduction of inter-process analysis,system dependence graph was improved.It is indicated that the research can correctly analyze the control dependence and data dependence relations.

Abstract:For simulating non-Newtonian fluid motion,in this paper a particle-based method is proposed in this paper.Through adding the stress tensor terms into the Navier-Stokes equations and using the essential method of smoothed particle hydrodynamics,a unified model for simulating non-Newtonian fluid is established.The experimental results show that the elasticity and plasticity of the fluid will change with the values of model parameters k and μ.The fluid exhibits more obvious plastic flow and weaker elasticity when k is increased and μ is decreased,conversely,the fluid exhibits stronger elasticity and weaker plasticity when μ is increased and k is decreased.By extending the Navier-Stokes equations,non-Newtonian fluid with various elastic and plastic characteristics can be simulated realistically by using this model.

Abstract:Flow properties in a liquid-solid fluidized bed were simulated by means of an Euler-Euler two-fluid model.A k -ε turbulent model was used to simulate the flow behavior of liquid by considering the couplings between liquid and solid phases.The effect of liquid properties of density and viscosity upon flow properties was studied in the liquid-solid fluidized bed.Results show that the mixing of liquid and particles is uniform in the liquid-solid fluidized bed,and it exhibits a homogenous fluidization.The axial velocities of particles increase with the increase of liquid density and viscosity,and they both have the same trends in the bed.The simulation result of bed’s expanding heights is in an agreement with the calculation results of Babu et al..

Abstract:To dynamically retrieve reusable business components that can satisfy the service request of user tier from component library,a service-oriented business component model based on service specification matching is proposed to solve the problems of semantic deficiency and weak interface.In this model,the behavior semantic of business component interfaces is described as finite state machine,and business data type is represented as sign data type based on XML.Based on this model,three semantic matching relationships are proposed.Refering to database query language,business component query language is proposed to provide the automatic retrieval of business components.The proposed method can provide effective technology support for large scale business component development and reuse.A business component library management tool is developed to verify the feasibility and effectiveness of this method.

Abstract:In order to improve the process of non-traditional micro machining,a composite technology with solid tool was proposed.Several non-traditional micro-machining processes were analyzed and their common features were found out.The micro electro-discharge machining(EDM),micro ultrasonic machining(USM) and micro electrochemical machining(ECM) were combined in the same system.The module design was used for this system.The basic module was developed,and a video microscopic subsystem was equipped in the system.Then,Ф5 μm micro rods,Ф6 μm micro holes,and microstructures with complicated profile were machined by micro EDM;the micro holes with aspect ratio larger than 25 were machined by EDM with USM in inversion installing;Ф13 μm micro holes were drilled by micro USM;and Ф100 μm micro holes were machined with micro ECM.This kind of combination expands the range of non-traditional micro machining and improves the processing efficiency.

Abstract:The authors brought forward composite fluidization structure against the problems in the CFB-FGD.Axial swirl vanes,which formed the composite fluidization of swirl-once through flow,were installed in the venturi.The characteristics of gas-solid flow at cold state were discussed through experiment and simulation.The comparison between the composite fluidization and the once-through fluidization was carried out.As a result,the composite fluidization mode is nonuniform air distribution mode.Its tangent velocity is larger than that of the once-through fluidization,which results in the longer particles residence time,higher particles concentration,stronger fluctuation,and better capability of diffusion and mixture.The uniformity is improved and can be achieved more quickly,which improves the flow field in the composite fluidization.

Abstract:To realize the interopration and integration in CNC,a CNC programming model is illustrated.According to CNC function,CNC system data structures are studied and fuction models based on XML Schema are established.The CNC network programming technology is studied,and the CNC software system includes three layers:Web Services requester,Web Services provider and Web Services monitor,thus a CNC programming model based on XML Web Services is established.Web Services in CNC application and equipments are studied.By experiments,the programming model based on XML Web Services is proved to be effective in trans-platform and trans-regional seamless integration and collaborative operation of numerical control equipments.

Abstract:Three-dimensional numerical simulation on the double-velocity stage of a steam turbine adopting the design idea of the Curtis stage was carried out.The whole circle flow fields of the two stages were computed and the flow features of the Curtis stage under designed operation were analyzed.Results show that the scattering effect of each nozzle group is not intense after the flow flows out of the Curtis stage nozzle,which only affects one blade passage near the boundary.The main direction of the flow is in the axial direction.When the pressure ratio is relatively larger and the flow velocity becomes supersonic,the circumferencial non-uniform at the outlet of each nozzle group is very serious,the wake aera with low speed and the mainstream area with low pressure appears by turns,so the aerodynamic loads on the rotor blades located at different positions in the nozzle region change greatly.An over-expanded low pressure area occurs in the supersonic nozzle,and the pressure is the lowest in the whole stage,which will strengthen the unsteady effects in the rotor blade passages.

Abstract:Based on the modified conflict coefficient which takes the consideration of classical conflict coefficient and evidence distance compressively,a new model to dynamically determine the sensor credibility through data collected in multisensor systems was constructed in this paper.A numerical example in target recognition was used to illustrate the efficiency of the method.It is shown that correct results can be obtained when the evidences conflict with each other even in a high degree.

Abstract:In order to research the bionic mechanics in unsteady flow,a two-degree of freedom(DoF) motion model was established for a rigid pectoral fin,and the experimental device named imitating pectoral fin system for the propulsive system was developed.This fin propulsive system consists of two servomotors and can realize various demanded feathering lead-lag coupling motions within the system limitation.During the experiment,the effects of phase difference,oscillating frequency,oscillating amplitudes and angular bias on the hydrodynamic performances were studied.The hydrodynamic coefficients against time in a cycle were obtained and analyzed.The study provides a foundation for the development of small underwater bio-robot.

Abstract:In order to reflect the effect of viscousness and vortex on added mass of submerged vehicles,especially these with complex shape in low Reynolds flow and strong vortex,the measurement on added mass of vehicles with sphere,ellipsoid and complex shapes was carried out by numerical simulation and model test.Programs in numerical simulation include viscous and non-viscous fluent CFD solvers and potential Hess-Smith procedure.After simulation a series of experiments was carried out in towing tank.By comparing the results from simulation and experiments,it is found that for simple shape bodies,the viscousness and vortex have little effects on added mass,and each numerical simulation program does the work even based on potential flow.While for vehicles with complex shape,their effects are large and up to 9%,only viscous solver results are relative to model test results.These conclusions are useful in hydrodynamic design of submerged vehicles.

Abstract:A new detection scheme for range-spread broadband radar target using high-resolution range profiles(HRRP) is proposed.The location of the target and the noise power were estimated in a window function,and a fuzzy threshold map was used to refine the target data,then envelope alignment was carried out through the target moving with a constant velocity.Finally,the detector of fuzzy threshold map dependent generalized likelihood rate test(FTMD-GLRT) was derived based on the estimation of signal steering vector.Remarkably,the detection scheme ensures the constant false alarm rate(CFAR) property with respect to the unknown noise power.Experimental results of the measured data of three kinds of planes show that the proposed scheme achieves a visible performance improvement compared with the scatter density dependent generalized likelihood rate test(SDD-GLRT).

Abstract:The high level synthesis approach based on PSA is proposed.The datapath represented by PSA was constructed with the library elements firstly,then the basis of polynomial representation datapath was computed.Some operations were implemented using basis,such as multivariate polynomial decomposition,the grea test common divisor extraction,library mapping and so on,thus the optimization of datapath with these operations was achieved.The complexity analysis of algorithm was carried out.The experiment was implemented on the SUN station with Maple10.The results show the efficiency our method.

Abstract:To avoid the pre-designed " teaching" or " training" phase for the condition monitoring system at present,an intelligent monitoring system for high-speed milling process is proposed based on the analysis of the tool wear rule and different tool wear stages.Self-learning was introduced to the system to automatically identify different tool wear states and estimate the wear value,which is independent of the pre-designed " teaching" or " training" phase.Three-direction components of the cutting force signals generated in high-speed milling process were processed using discrete wavelet decomposition technology.Features in different time and frequency domains were extracted and selected through correlation analysis method.The real-time intelligent monitoring system was built on the cycle process of linear fitting and Mahalanobis distance(MD) calculation.A series of experiments on a CNC vertical milling machine tool shows that the proposed method is accurate for feature extraction and efficient for condition monitoring of cutting tools.

Abstract:To design an effective automatic control system of planing craft,a prediction model should be built to realize the real-time and precise prediction of its motion attitude.The applicability of using MGM(1,N) model to predict the planing motion attitude was analyzed.According to the characteristics of planing craft motion attitude data and real-time request of prediction,the recurrence formula was proposed to calculate MGM(1,N) model’s parameter matrix after a batch of data was acquired.Using this formula,the prediction accuracy can be greatly improved and the predicting time can be prolonged without the significant increase of computational complexity.The result of numerical simulation shows that it is feasible to use recursive batch MGM(1,N) model to predict the motion attitude of planing craft and the prediction accuracy is very high.

Abstract:For estimating the effect of the medium pressure rotor cooling system in ultra-supercritical turbine on the main steam flow and cooling efficiency,the steam-thermo coupled numerical simulation method was used to study the medium pressure rotor steam cooling system,with the 600 MW ultra-supercritical turbine medium pressure casing as the computational model.The computational results show that the maximum and minimum temperatures of the blade root are decreased by 19 K and 95 K respectively,and the medium pressure rotor is cooled at the present cooling structure and initial parameters of the cool steam.The nonuniformity of temperature distribution of the rotation blade is increased by the cool steam,so the thermal stress is enhanced.Thus the important problem for the rotation blade to be cooled is the thermal stress verification.

Abstract:In order to efficiently monitor the selfish behavior in networks,form reliable relations and solve problems such as the single point of failure or bottleneck effect in traditional client-server environments,we adopt a novel P2P trust arithmetic named P-Trust based on the social people trust relation mechanism and the idea of IT governance,in which the direct trust arithmetic and the recommend trust arithmetic are modified.The P-Trust integrates the direct trust value and the recommended trust value to create the final trust value.Simulations prove that the P-Trust arithmetic can tackle the P2P trust problem in a simple and efficient way.