Abstract:This article describes gyro fault diagnosis architecture in satellite attitude control systems and designs two H∞ optimal fault observers by dint of Takagi-Sugeno(TS) fuzzy model in the case that the premise variables are known or not.Sufficient conditions for the existence of the two H∞ optimal fault observers are derived respectively.Mathematical simulation is carried out to validate the effectiveness of the fault diagnosis method.Performance and practicability properties of the H∞ fault observers are analyzed synthetically.

Abstract:In order to explore dynamics modeling and control of supercavitating vehicles,memory effect of the cavity and its influence on the shape of cavity were researched based on the principle of cavity expansion independence.The cavitator orientation effect and cavity flotation were taken into account in computing the hydrodynamic forces of all parts of the supercavitating vehicle.Efficiency of the fin with the change of the fin immersion depth while the vehicle was traveling underwater was researched.A more precise nonlinear dynamics model of supercavitating vehicle was established.Robust pole placement controller was designed after exact input-output linearization.This controller has good control performance in depth tracking.Its shortcomings are input saturation and adverse effects of planing force.Model predictive control controller was designed to solve the problem of input saturation by restricting the distance between tail part of vehicle and the cavity wall,so that the planing force was avoided,the friction drag was reduced and the motion stability of the vehicle was improved.

Abstract:Aimed at the problems of ensuring the approaching safety of net-based space robotic system and reducing fuel consumption by trajectories plannings during proximity maneuver to the target,according to the passive safety concept,the multi-pulses flying-by approaching trajectory is designed for thruster with the consideration of collision avoidance under relative measurement failures,and the trajectory enables the robotic system to perform the capture operation when passing by the target.Based on the relative dynamics of the spacecrafts,the flying-by approaching trajectory planning model is established with safety inequality constraints,and the solution is achieved by applying linear programming method with velocity increment optimization.Finally,the rationality and trajectory safety are verified by a series of simulations.

Abstract:Based on two-fluid model,the gas-droplet flows in nozzle were studied numerically using variable step Runge-Kutta scheme.Heat interaction between the two phases was introduced in the model.The characters of subsonic and supersonic flows were analyzed,and the impacts of droplet size and initial void fraction on the flow field were investigated.Simulation results show that the liquid velocity increases more slowly compared with the gas velocity.With the decreasing droplet size,the exit liquid velocity increases,but the gas velocity decreases.Both gas and liquid velocities increase with the increasing initial void fraction.For the supersonic flow,the Mach number at the throat is less than 1,and the throat area decreases with the increasing initial void fraction and droplet size.The results are useful for the investigation on the performance of mist jet propulsion system.

Abstract:To solve the problem that tensile instability may occur in adopting Smoothed Particle Hydrodynamics(SPH) in the cases involved in material strength,an artificial stress of continuum type was presented to improve the tensile instability.The condition of application of the artificial stress was given and the tensor form of the stress was set up.The unification form of artificial stress was established through combining the artificial viscosity stress that eliminates compressive instability and the artificial stress that resists tensile instability.Two examples were calculated and the results were compared.It is indicated that better results can be obtained by using the artificial stress presented than those of other forms.The results have less vibration and approach those of Finite Element Method,which proves that the artificial stress presented can improve the tensile instability in SPH.

Abstract:Attitude control problem of staring mode spacecraft in Low Earth Orbits(LEO) is studied in this paper.The staring mode of LEO spacecraft and its merits for observation are initially presented,and then the dynamic equation and kinematic equation are obtained on the basis of deriving the expected attitude quaternion and angular velocities.In order to improve the observation precision and prolong the observation time,a variable structure controller and a disturbance observer are proposed to reduce inherent chattering.Simulation results show that the controller has quick response and good robustness to the inertia parameters uncertainty and the external disturbance,and the chattering of variable structure control is effectively weakened.

Abstract:We propose an efficient bit-loading algorithm to minimize the total power to transmit a target rate of a single user in OFDM communication systems.Considering the digital modulations exploited by 802.11a,which are BPSK,QPSK,16QAM and 64QAM(constellation using Gray code and each sub-carrier carrying a maximum of 6 bits),?RT /6」subcarriers which have litter power addition are allocated with 2 bits each time.The proposed bit loading algorithm is optimal and has the same performance as Hughes-Hartogs algorithm,but greatly reduces the computational complexity.Simulation results show that the proposed bit loading algorithm has the same bit allocation results as Hughes-Hartogs algorithm,but the computational complexity is less than 50% compared with that of Hughes-Hartogs algorithm.The computational complexity will be further reduced when the transmission rate or subcarriers number increases.

Abstract:In this paper,the existing linear forwarding time delay allocation methods are analyzed,and then a non-linear forwarding time delay allocation method is proposed for cooperative ultra-wideband system.Theoretical analysis verifies that the minimum conflict probability can be obtained using the proposed method with equal probability.Numerical results show that compared with traditional linear time delay allocation methods,the proposed method can reduce the conflict probability of forwarding signals efficiently,and the performance gain of the cooperative ultra-wideband systems can be obtained.

Abstract:Aimed at the difficult problems in emotion modelling,methods of artificial emotion modelling including OCC model,agent model,fuzzy logic model and so on and their application were analyzed.Then an emotion model based on EFSM was proposed,in which the variable set V was defined to offer the data for the behavior of robot.The EFSM emotion model can obtain emotional information accurately,realize the description,parametric modeling,and theoretical calculation of the emotion with multi-feature fusion.The experimental study verifies the effectiveness of the model.

Abstract:The in-plane and out-of-plane global stability of tower crane’s tapered luffing jib was analyzed,which consists of tapered and uniform segments.From the governing differential equation for buckling of a multi-step column,the formula for solving the exact Euler critical force of global stability was obtained with the transfer matrix method.The tapered column was simulated by multi-step columns,and then the non-uniform structure with tapered and uniform segments was generalized into multi-step columns for buckling analysis.The results in the present paper are compared with some classical and ANSYS results.It shows that the proposed method provides higher computation accuracy.When using the multi-step column of 6 sections with the same length to simulate the tapered column,the error of Euler critical force is less than 0.5% .

Abstract:Using Lagrange equation and other mechanics methods,this paper analyzes the motion characteristics of rolling and turning of a micro-spherical robot,and achieves the conditions of jumping.A general dynamics model is built based on the analysis of characteristics of precession,which can make the robot roll along any curve.A virtual prototype of the spherical robot is developed,and the motion simulation is conducted.The result verifies the correctness of above analysis.The work in this paper establishes the foundation for further research on nonlinear control of spherical robot.

Abstract:To make the prosthetic hand move faster with less vibration and smaller than adult thumb,a prosthetic thumb has been designed on the basis of underacutuated mechanism.To make the hand more intelligentized,torque and position perception devices have been integrated.The thumb consists of three joints and is actuated by one motor.And the motor,gearhead and bevel device are all embedded in palm.Planar four-bar linkage and spatial four-bar linkage are adopted between metacarpal and proximal phalanx to make the appearance and track more humanoid.It is verified from experiment that the thumb has faster grasping speed without vibration at the beginning and end of grasping.It is more humanoid when grasping and can accomplish the prehension by subterminal opposition,tridigital grip,cylindrical palmar prehension.and can meet the basic life needs of the handicapped.

Abstract:To achieve the rapid and optimal solution of the inverse kinematics of hyper-redundant robot,an inverse kinematics analysis method based on joints equivalent and partial optimization is proposed for a hyper-redundant omni-directional mobile manipulator with 9 degrees of freedom.According to the features of system structure,degrees of freedom are divided reasonably on the basis of separating position and posture.The position of wrist is obtained from the posture of end-effector and the minimal movement of the joints is taken as objective function,then the two-joint optimization problem which determines the height of wrist is converted to the problem of conditional extreme for 2-variable function.By this way,the redundancy of the system is effectively used while solving the problem quickly and precisely.The simulation shows that this method can satisfy the requirements of real time,accuracy and optimization.

Abstract:In order to solve the problem that no functional type of prosthetic finger is suitable for handicapped person with only truncated base knuckle,a novel partial finger was designed in this paper.First,the characteristic of truncated base knuckle was analyzed.Based on the passive drive principle,mechanical structure of the partial finger was designed.Then,research on the motion law of the knuckles was carried out based on personification ideas,and parameters of the bars were determined to realize the approximate equal ratio transmission.Finally the kinematics analysis as well as the performance experiment was done.The partial finger with its size smaller than the little finger of an adult is driven by truncated base knuckle and has two degrees of freedom,moreover,each joint approximately moves with stable drive ratio.Experimental results indicate that the disassembly and installation of partial finger can be accomplished only by one hand,the maximum force output by fingertip is 10.7 N,the shape and motion of partial finger are similar as the human finger,and no problem appears after 50 thousand of fatigue tests.The partial finger can accomplish 95 percent of the hand function with the cooperation of other fingers.

Abstract:An algorithm for converting the three-dimensional(3D) electromagnetic(EM) data calculated on finite element(FEM) nodes into a finite difference(FDM) format was proposed in order to perform efficient FEM/FDM-coupled computations for solidification transport phenomena(STP) under various EM fields.The present method is available for arbitrary spatial relationships between the irregular FEM and FDM mesh patterns based on the interpolation principle of FEM.The corresponding programs for the data conversion and post-processing for 3D-displays were developed using Fortran-95 language and the QuickWin module on a Visual-Fortran-6.6A platform.The sample calculations and displays for the system of a cold-crucible EM directional solidification show that the proposed FEM-FDM data conversion algorithm is successful and effective.The present work will provide reliable EM field data and an efficacious 3D graphic analysis tool for the subsequent EM-STP-coupled computations with an FDM-based numerical method.

Abstract:To reduce the impact of noises and other factors in traditional feature extraction of breast ultrasound based on gray level images,we propose a novel computer aided diagnosis system for breast cancer.Mathematical model was established using both texture features and color Doppler features to distinguish the benign and malignant tumors.The accuracy,sensitivity specificity,false positive rate and false negative rate of the proposed system are 92.30%,91.42%,93.33%,94.11% and 90.32%,respectively.Experimental results show that the proposed system is valuable for radiologists to improve the accuracy of the diagnosis of breast cancer.

Abstract:Though Dijkstra algorithm is the best known algorithm to solve the shortest path problem with nonnegative weight,it can only get one path from the source vertex to a designated vertex.In order to present all shortest paths from the source vertex to a designated vertex,the revised Dijkstra algorithm is obtained by improving the temporary label updating process.As a result,the revised algorithm gives the shortest path graph other than the shortest path tree.Compared with Dijkstra algorithm,the revised algorithm is simple,and all shortest paths can be given according to the number of edge by applying Yen algorithm.

Abstract:As an important process in knowledge management in the knowledge economy era,knowledge innovation is an effective method to improve organizational competitive capability.Based on analysis of existing researches,this paper establishes a research model,defines knowledge innovation capability and its four elements for construction project,and makes corresponding hypothesis.Survey questionnaire is carried out to get data.Then reliability and validity analysis are used to test the measures of each element and make corresponding revision.Structural equation modeling is employed to test the research model and identify the influence of each element on knowledge innovation capability.

Abstract:In order to study the correlations between different pozzolanic activity evaluation methods of calcined coal gangue,NMR,XPS,ICP,XRD techniques are employed.The pozzolanic activity of coal gangue calcined at different temperatures is evaluated by strength method,polymerization degree method,chemical method and XPS method.The correlations of these results obtained from different methods are analyzed.It is found that these evaluation methods can reflect the changes of pozzolanic activities,among which strength method and polymerization degree method are more sensitive to pozzolanic activity of calcined gangue than chemical method and XPS method.For calcined coal gangue,strength method and polymerization degree method are more appropriate for pozzolanic activity evaluation.There is an obvious correlation between strength method and polymerization degree method.

Abstract:Aimed at the problem that some visual perceptual degradation and distortion are usually generated during 3D mesh simplification process,we take the salient information as the property of the vertex and partition the bounding box of the mesh into some 3D local window.Then the mean perceptual structural degradation(MPSD) metric based on salient information and information theory is presented and used as a quantitative and objective metric to evaluate the visual perceptual degradation.Both analytical and experimental results show that the MPSD metric can effectively evaluate the visual perceptual structural degradation induced by mesh simplification operations and provide the functionality of multi-scale visual perceptual degradation.

Abstract:To improve the fuel economy of parallel hydraulic hybrid vehicles(PHHV) by operating the engine in the optimum efficiency range and making use of regenerative braking during deceleration,the design criteria of important components for PHHV were researched.Based on the analysis of braking characteristics of PHHV in the city drive cycle and the high power density of hydraulic transmission,a new regenerative braking strategy tailored specially for PHHV was proposed.Based on the Matlab/ Simulink software platform,the performance simulation was accomplished under a selected driving cycle.Results show that the parameters of propulsion system are reasonably matched;the proposed hydraulic regenerative braking strategy can reasonably distribute the hydraulic regenerative braking torque and traditional friction braking torque,which effectively regenerates braking energy of the vehicle under the premise of safe braking and improves the braking performance.

Abstract:A method based on Stirling’s polynomial interpolation to approximate the nonlinear process and using landmark’s statistical information to adjust the state vector and state vector’s covariance is proposed to resolve the simultaneous localization and mapping(SLAM) speed and consistency in dense landmark environment.By using Stirling’s polynomial interpolation,the nonlinearity can be approximated to the second or even higher Taylor series and the state vector and its covariance’s size can be limited to fixed size by the dynamic method based on the weight value of each landmark.It can be seen from experiment that not only in sparse landmark environment but also in dense landmark environment,the SLAM memory,speed and consistency of the proposed method are all superior to those of FASTSLAM.

Abstract:A new method for design of yaw and roll motion controller is proposed in order to improve the performance of roll control.Variable structure control is applied,which is based on the nonlinear model of submarine motion and the principle of rudder roll damping.Sliding surface of variable structure controllers is founded with corresponding error and error derivative of heading angle and roll angle.Exponential approach law is used to derive the control algorithm for yaw and roll accordingly.Then the total control law for rudder steering is obtained with weighting method.Two adaptive neurons are used for online adjusting of approaching speed,so chattering of variable structure control is restrained.Simulation results show better horizontal maneuvering performance of submarine navigation near free-surface by using the modified variable structure control.

Abstract:To increase the computation efficiency of multi-scale retinex method(MSR) in image enhancement,in which the Gaussian convolution has to be used for several times,especially when large scale Gaussian convolution template is used to get the low-frequency information of image,the convolution template is simplified as mean template because the Gaussian template of large scale Gaussian convolution has the property of mean template.Furthermore,a filter window irrelevant mean filtering algorithm is proposed to fulfill and speed up the filtering process.It employs an array s to storage each column pixel value of current filtering rows and consequently reduces the redundant calculation.Taking the 640 × 640 color image as an example,the processing time is only 0.0867 s and it is 723 times faster than original MSR method.It can be seen from the analysis of experiment that the new proposed method can greatly improve the computing efficiency and fulfill the image enhancement remarkably.

Abstract:The simulation of a high-order modulation LDPC code is carried out in the field of underwater acoustic channel for improving the spectral efficiency.The computation complexity can be reduced by using the simplification algorithm of soft information of the high-order modulation.Effects of the code length,times of iterations and other related factors on the performance of LDPC codes are analyzed and simulated.The results show that the high-order modulation LDPC codes can significantly improve the transmission performance.

Abstract:In order to improve the applicability of overall performance of thermal imager and reduce the uncertainty introduced by human observation,TOD test method and its machine vision implementation were studied.As for the limitation of MRTD method for overall performance of staring array thermal imager,the adaptability of TOD method was analyzed under dynamic scene,dynamic non-uniformity correction and so on.By using human visual transfer function and psychological model to replace subjective observing procedure,using blur function and down sampling to simulate the signal transfer procedure,using geometric template matching to replace human perceptive processes,the objective measurement of TOD method was achieved.The measurement uncertainty of overall performance for staring array imager using TOD can be improved from ± 20% to 8%,which can be improved further by using the geometric template matching in machine interpretation procedure.The applicability and consistency of the overall performance of thermal imager can be improved effectively with the TOD method and its machine vision implementation.

Abstract:To explore the applicability of single-negative materials pair(SNGP) in microwave devices,we established an equivalent transmission line model of reflection-typed band-stop filters based on SNGP.Its working principles and the design method were studied,and then the simulation on its performances was carried out.Results show that the filters perform well in a certain frequency range,which verifies that the method is feasible.

Abstract:To realize the stable walking cycle of passive biped robot,this paper presents a method to find the fixed point and a detailed analysis on the effect of the change of mechanical parameters of the passive walking model and slope gradient on the existence of stable fixed point is carried out.The effect for each parameter at the given initial conditions on the speed of converging to the stable cycle walking and the effect of changing status of stable fixed point from the change of the parameters are investigated.It is concluded that the smaller mass for legs,a higher location for the center of mass,the right radius of foot,the larger moment of inertia as well as the right slope gradient are beneficial for improving the local stability of the passive robot.

Abstract:Based on discrete element method(DEM),the segregation of granular flow on an inclined plane was numerically investigated in order to investigate its mechanism.The flows with the granular mixture with the same density and different sizes and the mixture with the same size and different densities were simulated respectively on an inclined plane with different roughness.Numerical results show that the granular flow with the same density and different sizes segregates obviously and it gets more obviously when the roughness of the plane is larger.However,the flow with the same size but different densities mixes well in the current study.

Abstract:To reduce the development time and cost,an automatic sensory feature selection method is proposed for the systematic design of condition monitoring systems for machining operations.Force,acceleration,sound and acoustic emission sensors were used in high-speed milling operations.The time domain,frequency domain and wavelet analysis technique were employed to process the signals.Gradual tool wear was used for evaluating the proposed self-learning automated sensory feature selection approach.The experimental results show that the suggested algorithm can be applied in an automated,self-learning monitoring system for the selection of the most sensitive sensors.

Abstract:To solve the problem of partner selection in establishing dynamic alliance in agile manufacturing,a genetic algorithm based on the analysis to the limitation of traditional selection method was designed and the corresponding algorithm model was constructed.The method for individual coding and initial population generating,the selection method for combining probability elimination with roulette and the design method for mutation operator about coding cycle value were discussed.Example analysis verified the stability,reliability and high convergence speed of the algorithm.It is concluded that the algorithm is beneficial for solving the partner selection problem in dynamic alliance.

Abstract:Aimed at the nonlinear friction,disturbance torque and load variation in typical mechanical-electrical servo systems,by considering discrete-time output signals of angular position sensor as the observer input,the design of an angular acceleration boundary observer design is presented using sliding-mode control method.Based on the analysis of the structure of the boundary observer,we propose a method to determine the control input by designing the sliding mode.Furthermore,the key performance parameters and the design principle are provided.For a practical mechanics system,the designed angular acceleration observer exhibits the excellent dynamical performance under the nonlinear disturbance.

Abstract:We theoretically analyze the effective electronic and magnetic responses of a 3-dimensional nonlinear composite consisting of periodical arrays of wires and split-ring resonators(SRRs) embedded into a nonlinear dielectric.We calculate the dependences of the real parts and imaginary parts of the effective permittivity and permeability of the structure on the varying external magnetic field strength.We demonstrate that both the real parts of the effective permittivity and permeability have hysteresis structures.We also discuss the switching of the composite among right-handed materials,epsilon-negative materials,and mu-negative materials under different conditions,which can be controlled by a proper choice of the external magnetic field strength(intensity of incident electromagnetic waves) in a certain frequency range.