Abstract:Several remote control modes and a layered architecture for teleoperation of space robot(LATSR) are designed aiming at the characteristic of space robot.A teleoperation system for space robot is developed,which is comprised of five subsystems:the task planning subsystem,the master-slave control subsystem,the predictive simulation subsystem,the information processing subsystem and the ground-based validation subsystem.Experimental results verify the functionality and performance of the system and its subsystems.The flexible operation interface of the system provides simple user interface for general users,and the low-level control capability for roboticists.

Abstract:To predict the performance of bubbly water ramjet propulsion,the physical processes occurring in the diffuser,mixing chamber and nozzle were analyzed.The mathematical models were obtained separately under the restrictions of certain simplifying assumptions.The bubbly nozzle flow was calculated with two-fluid model and variable step-size Runge-Kutta scheme.The influence of area ratios(mixing chamber to inlet area,Am/Ai) ,inlet area A i,air mass flow rate,vessel speed,initial bubble radii and half nozzle converging angle on the thrust and efficiency was investigated by comparing the simulation results.It is indicated that bubbly water ramjet propulsion is more effective for bigger area ratios Am/Ai and bigger inlet area Ai.With the increasing air mass flow rate and vessel speed,the thrust increases,but the efficiency decreases.The increase in half nozzle converging angle and initial bubble radii reduces the ramjet thrust and propulsion efficiency.The results are useful for further investigation of bubbly water ramjet engine.

Abstract:In order to research the character signal of high load rotating bending fatigue before the fracture of specimens,the theoretical study was conducted based on magnetomechanical effect and magnetic field superposition,and the high load rotating bending fatigue experiment was carried out on 45#steel specimens with annular notch.The distribution variation of normal magnetic signals was analyzed.Theoretical analysis indicates that the magnetic signal distribution near the fatigue crack changes as the crack propagates.Experimental results show that,before and after the rapid crack propagation,the size order of signal near the crack changes. The detection effect is impacted by nominal stress,stress concentration factor,environmental magnetic field and sensor liftoff,then the corresponding strategies are put forward.So it is feasible to detect high load rotating bending fatigue damage using metal magnetic memory technique.

Abstract:This paper addresses the fuel-optimal control problem of satellite relative orbit transfer on an arbitrary elliptical orbit based on Legendre pseudospectral method.Firstly,the relative motion equations are formulated with the true anomaly as the independent variable,which are much simple.To ensure the consistency with the dynamic equations,a special cost function is proposed.Next,the optimal control problem is transformed to a parameter optimization problem using Legendre pseudospectral method.Based on the state translation matrix,a control law is obtained under the constraint of the start and final state.Then,to the linear model,another control law based on the whole state equation is presented.Unlike the methods in the literature,the above control laws are both analytical,and no computer soft is needed.Finally,the numerical results show that the control laws work well for the fuel-optimal relative orbit transfer.

Abstract:To realized the robust control of underactuated autonomous underwater vehicle with uncertainties of time-delay,un-modeled dynamics and time-varying hydrodynamic parameters,a fuzzy sliding mode controller is proposed,with switching function of variable structure control and its derivative as fuzzy control inputs,and derivative of the variable structure control law as fuzzy control output.The design method of the controller offers a systematical means of constructing a set of shrinking-span and dilating-span membership functions for the controller.A technique to adaptively tune scaling factors of fuzzy controller is presented for better performance of eliminating chattering.The contrast simulation results indicate that the proposed adaptive fuzzy sliding mode controller has better performance.And then the controller is applied to the dive plane control of AUV with parameter uncertainties,un-modeled dynamics and control input time delay.The results demonstrate the effectiveness and robustness of the controller with low control effort.

Abstract:To study the electrode second order effects(ESOE) at high frequency,a two-dimensional periodic finite element model of SAW sensor IDT was developed.Taking a YX128°-LiNbO3 high frequency SAW sensor as the simulation object,the ESOE with different electrode design parameters were quantitatively analyzed. The relationship between the electrical admittance of sensor IDT and the center frequency was analyzed via the harmonic response analysis,and the resonance and anti-resonance frequencies of the IDT were extracted.Results indicate that the modal frequency and the velocity of surface wave decrease as the metallization ratio(MR) or the electrode height(EH) increases.At the same EH,stopband gets wider and reflection ration of electrode increases with the increasing MR.The resonance frequency and the anti-resonance frequency extracted from the simulation are 973 MHz and 1 002 MHz respectively.

Abstract:In order to improve the precision of inertial navigation system during long time operation,the autocompensation technology was employed to suppress the divergence of errors.The auto-compensation principle of the rotated strapdown inertial navigation system(SINS) was introduced,and the effect of the optical gyro’ s scale-factor error,fixing error,bias and random drift error on the rotated compensation system was investigated.Different errors of single-and dual-axis rotation have been analyzed.The effect of the rotating auto-compensation system was analyzed by simulation.The study results offer an academic basis for optimization and design of the optical gyro rotating strapdown inertial navigation system.

Abstract:In order to research the vibration control of weak coupling antenna structures in satellite,a dynamics model of this kind of structure is established through the finite element method,by which the dynamic characteristics of the disordered and perfect structures are investigated respectively.Active vibration control of the structure is studied by applying neural networks predictive(NNP) control method and linear quadratic regulator(LQR) control method respectively.Simulation results show that little disorder of the weak coupling antenna structure can induce remarkable mode localization of vibration.The vibration control effects of NNP method are superior to those of LQR method,and NNP method has good performance on the occurrence of model mismatch induced by the structure disorder.The disorder must be considered seriously in active vibration control of weak coupling antenna structures.

Abstract:In this paper,the delay-range-dependent exponential stability problems for Ito^ stochastic Markovian jump linear systems with interval time-varying delays satisfying h1≤d(t) ≤h 2 are investigated.In terms of linear matrix inequalities,the criteria of less conservative delay-range-dependent stability for Ito^ stochastic Markovian jump systems are proposed by constructing a different Lyapunov-Krasovskii function and introducing some improved integral-equalities.Numerical examples are provided to demonstrate the efficiency and reduced conservatism of the results in this paper.

Abstract:Concurrent design of component synthesis active vibration suppression(CSVS) method and closedloop feedback control is presented in order to remarkably enhance the insensitivity to external disturbances for CSVS method.The attitude dynamics and vibration equations of rotary motion for the system consisted of central rigid body with flexible appendages are obtained.By using series of unconstrained modal functions,the decoupled motion expressions for both of the central rigid body and flexible appendages are derived.Through choosing appropriate controlled variable,the flexible appendages vibration and CSVS are added to the constraint equations in designing parameters of closed-loop feedback control and the best performance solution are obtained.Numerical simulation on a flexible single beam model shows that the proposed method can suppress not only the inherent flexible harmonics in the system,but also the additional vibrations introduced by the feedback loop.Meanwhile,the settle time is shorter than that of normal control method.

Abstract:To use the commonly finite element software to conveniently realize the calculation of homogenization method,the paper proposes two realization methods of homogenization using ABAQUS software:thermal stress method and boundary force method.The control equation of homogenization method is converted to the form which can be solved with commonly finite element software.ABAQUS user subroutine and ABAQUS scripting are programed in this article to calculate the homogenization equations.Then the homogenized coefficient is calculated by the two proposed methods for unidirectional composite material,the results show that the two methods agree well with theoretical results.

Abstract:The present paper is concerned with the evaluation of ablative performance of 3D carbon/carbon composites.The morphology and microstructure of ablative samples are investigated by on-line real-time monitoring system and SEM techniques.The results show that the ablation of 3D C/C composites is as a result of integration of thermo-chemical ablation and mechanical denudation.Mechanical denudation is dominant at the edge of sample surface,and while thermo-chemical ablation and mechanical denudation are coupled in the center region of sample surface.It has obvious discrepancy for ablative performance between carbon matrix and carbon fiber.The ablation resistance of carbon fiber is much better than the carbon matrix’s.The ablative performance of 3D C/C composites displays clear anisotropy.It is better in the longitudinal direction of 3D C/Cs because the fiber bundle can resist the ablation until it loses the support of the surrounding matrix.On the contrary,the ablation resistance is poor in the radial direction of 3D C/Cs because the surface delamination is dominant in the course of ablation.

Abstract:In this paper,the technology of large size sapphire grown by SAPMAC method is elaborated and the quality of the obtained crystal has been inspected and analyzed.Results indicate that the crystal structure is complete and the FHWM value is only 11 arcsec.The defect concentration is in the 10 2 /cm 2 level,the purity is higher than 99.995%,and the transmission in 3-5μm band is greater than 85%.Ultrasonic vibration machining is used to process the large size sapphire and a special grinding composite cutting tool is designed to improve its efficiency.

Abstract:In this paper,we combine the computational fluid dynamics method based on RANS equations and finite element method in the design of composite marine propeller.The primary design is completed through computing the hydrodynamic performance,conducting the finite element model,designing stacking sequence,transferring the load,calculating the mechanic performance of structure,and checking in the convergence in turn.A predeformation method is presented for improving the combination performance of composite propeller. The results show that the designed propeller can meet the hydrodynamic demand of the propeller made of metal,at the same time,reduce the weight by 30%and improve the efficiency.

Abstract:Aiming at the time-varying contact stiffness in haptic force/position control,an adaptive force/position control algorithm with closed loop of velocity is presented.Based on the definition of the specific scalar function of the system,the proper adaptive update law can be fixed.With the control law and update law,it can be proved that the error of tracking force is finite limit and its derivative function is square integrable. Then with Barbalat lemma the whole control algorithm is proved to be globally asymptotically stable.The architecture of hardware of the whole control system is given.The result of experiments of sinus force tracking shows that the tracking error of this algorithm is less than that of the normal impendence control algorithm at the same signal frequency.The whole control system is stable and has an excellent control quality.Effects of key parameters of the control law are also presented by analyzing the experimental results.

Abstract:To analyze the stability of beam structures accurately and reduce the order of the system stiffness matrix,a model reduction technique based on transfer matrix method and exact finite element method is presented.The noncollinear branch chain substructure with elastic supports is modeled as a super element.In combination of exact stiffness matrix of beams,the force-displacement relation between both ends is developed by the transfer matrix method.The symmetrical stiffness matrix of the super element in the global coordinate system is derived,which has the same order as the classic beam element and can be assembled into the system stiffness matrix directly.The Euler critical force of the structure can be obtained from the determination of the reduced system stiffness matrix.The internal DOFs of the substructure are not used in the model,so the order of the model is greatly reduced and the accuracy of the computation is guaranteed.The validity and efficiency of the proposed method are shown by solving various numerical examples found in the literature.

Abstract:To investigate the treatment effect of different algorithms on network planning problem,the coefficients of network complexity(CNC) and network evaluation indices are proposed,taking the topological structure,interchangeability of resource and due date of the network into consideration.And then the relationship between the effects of different algorithms and the characteristics of network is analyzed based on multiple regression technology.The experimental results show that the proposed coefficients of network complexity are reasonable and the regression equations can accurately estimate the results of the algorithms,so that useful information can be provided to select a proper algorithm based on the characteristics of network planning problem.

Abstract:In order to study the quantum effects in the liquid helium,we use path integral Monte Carlo(PIMC) method to simulate the liquid helium system.We calculate the number of atoms which permute with others,the pair-correlation function,the structure factor and the superfluid fraction on the platform of pimc++.Comparison between experiments and the results of pair-correlation and structure factor computed by PIMC manifests the precision of this method and the strength of this approach in simulating the microscopic arrangement of atoms in liquid helium.Below 4K,the number of atoms which permute with others increases as the temperature goes down,the quantum effects become more and more apparent.At about 2.17 K,the system will undergo a phase transition and turn into superfluid.The superfluid fraction will increase as the temperature goes down,and eventually equals to 1.Path integral Monte Carlo can simulate the structure of liquid helium with high precision and reflect the quantum effects of particle permutation and transition to the superfluid state.

Abstract:Aiming at the high computational complexity of particle filters,in order to reduce the number of samples,this paper proposes an improved particle filter based on subtractive clustering.Cluster vectors,composed of particles and their corresponding weights,are classified at a given radius through the improved subcluster algorithm presented by this paper,and then all the cluster vectors are replaced by the central vectors obtained from the classifying processing.Finally the central vectors are decomposed and the new particles and their weights are restructured.The simulation results show that the proposed algorithm maintains the performance of the general particle filters,and meanwhile keeps less number of samples and higher computational efficiency.

Abstract:To solve the problems of low acceptance rate,too much resource capacity debris,serious waste of storage space caused by directly applying binary resource capacity reservation strategy to storage resource capacity reservation(SRCR) in data grid,by analyzing the characteristics of SRCR for data grid application,a four-tuple reservation strategy(FTRS) is proposed.The traditional time slot algorithm for binary strategy can not be applied to FTRS,so the basic trapezoidal algorithm and threshold trapezoidal algorithm(TTA) are put forward.The experimental results show that,compared with binary strategy,FTRS achieves higher resource utilization and acceptance rate,meanwhile,TTA can adapt to network speed jitter.

Abstract:The numerical simulation on spray characteristic of pressure swirl nozzle was carried out,and the main factors effecting the atomizing performance of the nozzle were studied.The distributions of velocity and diameter of droplets were obtained at different special sections.Simulation results were compared with the experimental results.The simulation results indicate that the droplet size is proportional to pressure and nozzle diameter,and inversely proportional to viscosity and surface tension of liquid.Along the spray axis,droplet velocity decreases acutely,and keeps steady at the downstream of 200 mm.Along the radial direction,the axial velocity of droplet in the center is lower than that on the edge,where the droplet size is maximum.Due to droplet collision and breakup,the droplet size decreases first,and then slowly increases.The simulation results are in good agreement with experimental results.

Abstract:In order to get the details of flow in the cooling fan of a turbo generator and propose a reasonable scheme to optimize the fan,numerical simulation was carried out on an original model of the fan under the condition of 25 m 3 /s.The relationship between the efficiency and the setting angle or the twist angle of the vane was detected by changing the setting angle and the twist angle of the vane.The result indicates that there exists a parabolic relationship between efficiency of the fan and the setting angle or the twist angle of the vane in a certain range.The fan has the highest efficiency at a certain setting angle and a twist angle of the vane. The efficiency of the fan is improved by 15.8%after optimization.

Abstract:In this paper,high-level Rossler chaotic oscillator and proportional differential control are used together to detect the frequency of weak signal.Rossler system is controlled to critical state from periodic state to chaotic state.Then the unknown signal is put into the Rossler system.Proportional differential control is used to regulate the system to periodic state and the method of spectrum analysis is employed to detect the frequency the unknown signal.The presented method exhibits higher detection precision and is simpler than Duffing equation which needs many chaotic oscillators.Numerical simulation verifies that the presented method is feasible.

Abstract:In order to solve the problem of losing solution,a lot of multiplications of inverse matrices and a lot of solutions in the solution process of inverse kinematics of robot,a new inferential method for inverse kinematics of MOTOMAN manipulators is presented.The dual variable tangent function is used to avoid losing solutions in the process of deduction.The method avoids a lot of multiplications of inverse matrices,simplifies the solving process and reduces the computations.Additionally,the shortest distance rule is presented to choose a solution closest to the current manipulator for a number of inverse kinematics solutions.The research resuts have been applied successfully in a 6-DOF robot,which proves that the presented method is correct.

Abstract:A 5-axis parallel-serial machine tool is introduced,which consists of a 3-DOF parallel mechanism and a 2-DOF serial mechanism.The size of transform matrix is decreased by adopting unit matrix and the problem of parameter coupling is resolved by adopting vector method.The relationship between the velocity,acceleration of movable platform and those input parameters of the parallel mechanism is established in detail.These algorithms are verified through ADAMS and can provide references for kinematics analysis,dynamics analysis,motion control of parallel or parallel-serial machine tools,which have coupling kinematic parameters.

Abstract:In order to track and estimate 3D head-shoulder poses in monocular videos,we propose a new 3D head-shoulder model based particle filter.Edge cue and chamfer distance are used to build the likelihood function of the proposed particle filter.In each time step,the proposed algorithm generates a discretized grid state space and takes a subspace of it as the searching space of particles.Therefore,the number of particles is well limited and the performance of the particle filter is improved.The experimental results prove that our method is effective and robust for the tracking and estimation of 3D head-shoulder poses.The study provides a new basis for the human pose analysis and behavior understanding.

Abstract:In order to improve competitive power of construction enterprises the method of multi-level fuzzy comprehensive evaluation is adopted to build a fuzzy comprehensive assessment model,the model of value chain management and its optimization are investigated.Then all elements of value chain core competencies have been separated to build the assessment system to evaluate the value chain core competencies of construction enterprises.Results of the research indicate that the intensity of value chain core competencies and the influence of all elements can be calculated by the assessment model.

Abstract:A three-dimensional,two-phase transient model was developed to analyze the transient characteristics of proton exchange membrane(PEM) fuel cells with parallel and interdigitated flow fields.The effects of voltage load changes and channel to rib width ratios on the transient response were examined for both flow fields.The predictions show that the current overshoot and undershoot are mainly resulted from deviations of the oxygen concentration on the cathode diffusion layer-catalyst layer interface from steady-state distributions. The time for the water content in the membrane to reach a steady-state distribution determines the transient response time.As the voltage decrease rate is reduced,the overshoot peak is weakened and the response time is shortened.Since the interdigitated flow field has higher oxygen concentrations on the cathode diffusion layercatalyst layer interface due to forced convection,the overshoot peaks and the undershoot valleys are all higher than those in the parallel flow field.Larger channel to rib width ratio causes longer response time and more overshoot for both flow fields,with less undershoot for the parallel flow field and more undershoot for the interdigitated flow field.

Abstract:In order to eliminate the narrowband interference,a new recurrent neural network predictor(RNNP) based on the adaptive Kalman filter(AKF) was proposed in the spread spectrum system in this paper. The adaptive Kalman filter was used to modify the weights of the RNNP and precisely estimate the interference,with the virtue of rapid convergence rate,high prediction precision and perfect numerical robustness. Simulation results show that the RNNP based on AKF learning algorithm has improvement to different extent on interference elimination capability compared with the adaptive linear least mean square(LMS) interference predictor,the adaptive approximate conditional mean(ACM) interference predictor and the RNNP based on the real-time recurrent learning(RTRL) arithmetic.

Abstract:Based upon the exponential matrix and exponential products of modern screw theory for the description of rigid body transformation,the pose error of kinematic pair axis is treated as the result of equivalent screw motion,and an error model of robot is built by using the products of exponentials formula.Meanwhile,the position and orientation errors of tool tip are represented as prismatic and revolute pair’s screw motions respectivly,and the calculation formulas are presented.Using SCARA robot as an example,the simulation experiment is done with Matlab and Adams,and the results show that the presented modeling method is intuitive and correct.

Abstract:For a better understanding of the essential characteristics of passive robot,making the research of model be a better guide to the design of actual prototype,methods of numerical simulation and verification of Adams were employed to research a two-dimensional pure passive walking model with round feet.Characteristics of the passive model were analyzed and the dynamic equations were derived with Lagrange Equation. Based on the phenomenon of dynamics of symmetric gait of the robot appearing to be a limit cycle in the phase space,a complete process of the simulation of steady-walking of this model was given with Matlab tool and the initial conditions of the steady-walking model were achieved.The dynamics and characteristics in each stage of the biped locomotion cycle were discussed.Adams was used to verify the simulation.This study will be the basis of stability analysis of the robot and a guide to the design of a passive robot prototype.

Abstract:Mixed modeling method with underwater electric potential as a clue is put forward in order to research the distribution characteristics of corrosion related static electric and magnetic fields of a ship,that is to regard a ship as a combination of horizontal current line and several discrete dipoles.The unknown parameters of the mixed model can be found out by fitting the measuring data of the underwater electric potential in a plane under the ship.Then the characteristics of corrosion related static electric and magnetic fields underwater can be studied based on the mixed model.The ocean environment has been simulated in laboratory,then the method of mixed modeling has been validated by experiments using a 1∶100 physical scale model of a ship,then the distribution of corrosion related static electric and magnetic fields of the ship model has been calculated based on the built mixed model.The experimental results show that the mixed modeling has advantages of less unknown parameters,easier actual measurement,less calculation and more stabilization.

Abstract:Classic rough set theory solves problems by means of indiscernibility relation,but it is powerless to resolve the sequencing classification problems in which qualitative attributes,quantitative attributes and criteria exist at the same time.In view of this situation,classic rough set theory is extended,and then a decision analysis method based on the extended rough set theory is proposed.This method replaces the indiscernibility relation in original rough set theory with the indiscernibility-similarity-dominance relation and achieves rough approximation of knowledge.An example study shows that the method can effecively resolve the above mentioned problems and can deal with inconsistence in decision table.