Abstract:To resolve the problem about the redundant in thrust allocation,an cost function was proposed in this paper.In the function,not only the net force error between the desired force vector and net force generated by thrusters into account was taken,but also the consumption of jet.And then,according to symmetry principle of the force vector generated by the thrusters,the search range is reduced from 256 to 11,and the computation is largely reduced;Finally,mathematical simulation results show that the approach is reasonable and effective,and it provides theoretical basis for hardware-in-loop simulation.

Abstract:To solve the coupling problem from driving electrode to sensing electrode of micro-mechanical angular rate sensor,a closed-loop driving approach of electrostatic force based on voltage frequency modulation is proposed,which separates the mechanical resonance frequency from voltage drive frequency without changing the phase and frequency of electrostatic force.Automatic gain control circuits are adopted to get 0.01% amplitude instability of closed-loop drive,and integrated transimpedance amplifier on chip has capacitive resolution of 1 aF/sqrt(Hz).The chip is fabricated in the 2 μm two-metal and two-poly n-well CMOS process with an area of 18.9 mm2.The complete module operates from ±9 V supply and has a measured sensitivity of 10 mV/(°)/s with bias instability is 190(°)/h.Test results show that the proposed approach can be applied to closed-loop drive of micro-mechanical angular rate sensor without adjusting circuits phase in atmospheric package(Q is 80).

Abstract:A closed-form pulse train control algorithm is presented for vibration suppression of flexible spacecraft during large angle maneuver.Based on attitude angle and angular velocity,the control algorithm uses thrusters for coarse attitude control and reaction wheels for high precision attitude control at the final stage of operations.The input shaping is introduced to modulate thruster pulses with a set of properly timed impulses to suppress vibrations introduced by on-off control.Physical experiment results demonstrate that the proposed approach can significantly reduce the vibration of flexible appendages during fast large angle maneuver,and the presented control algorithm has the advantages of less fuel consumption,as well as simplicity and efficiency for practical on-board computer operation.

Abstract:To study the vibration characteristics of supercavitating projectiles under tail-slapping conditions,the fundamental frequency and the first principal mode shape of the transverse vibration of projectiles were presented,based on the dynamics of coupling system for rigid and elastic motions.By simulations,the influences of rotational speed,slenderness ratio and material characteristics on frequency and the mode shape of vibration were investigated.The results show that the frequency and the mode shape vary with the rotational speed,and the increase of the slenderness ratio and the material characteristic parameter could accelerate these variations.For the small slenderness ratio or the rotational speed is less than 50 rad/s,the influence of coupled motions can be disregarded and the natural frequency can be used as the frequency of vibration,and the natural mode shape also can be used when the rotational speed is less than 100 rad/s.

Abstract:Considering the problem of trajectory planning for Free-Floating Space Robot(FFSR),a particle swarm optimization(PSO) based on minimum torque trajectory planning scheme is presented.By analyzing the dynamic equation of system,an optimal control algorithm is applied to FFSR trajectory planning,in which the driving torque of manipulator joint angles is considered as the objective function.Moreover,the high order polynomial is used to approach the trajectories of the joint angles.To achieve the optimal trajectory,the PSO algorithm is implemented so that the planned joint angle trajectories are smooth and continuous.Numerical simulation results show that the proposed methodology is effective and available for solving FFSR trajectory planning problem.With accomplishing the space robot attitude adjusting mission,the driving torque is reduced to the least. free-floating;space robot;dynamic equation;particle swarm optimization;minimizing torque

Abstract:Aiming at features of dual-frequency HFGWR data fusion,this paper proposes a detection area zoning hybrid fusion tracking method.In this method,the detection area is separated into two subareas,one is far subarea and another is close subarea,and there exists an acrossing belt within these two sbuareas.Measurements fusion is executed in the far subarea,single frequency tracking is executed in the close area,and the output tracks of these two subareas are then fused to form system tracks.The zoning hybrid fusion tracking method adapts well to the characteristics of HFGWR and gives full play to the advantages of measurements fusion and track fusion.Simulation results and measured data both demonstrate that the presented method can greatly improve the whole tracking performance.

Abstract:Based on head pursuit consideration,a novel adaptive sliding-mode guidance law is presented for high-speed target interception.By adjusting the trajectory continuously,the interceptor is positioned ahead of the faster target to satisfy a specific geometry relation between the interceptor lead angle and the target flight direction relative to the line of sight(LoS).In this guidance law,the maneuvering dynamics of interceptor and target,and their model errors are considered.The boundary values of target acceleration and model errors are not required by use of adaptive sliding-mode design method.A realistic interceptor model is used in simulation and the results show that this guidance law can realize the head pursuit of high-speed targets and is feasibility.

Abstract:This paper constructs a continuous and smooth extended state observer and disturbance rejection cascade decoupling control technology,which is aimed at the nonlinear attitude model with strong coupling,aerodynamic parameter perturbations and uncertainties in the process of hypersonic vehicle without power re-entry.An ADRC attitude controller is presented for hypersonic vehicle in convenient to the practical application of engineering,and a continuous and smooth extended state observer is designed by constructing qin function to avoid high-frequency chatter during ADRC application process,which solves the problem of ignoring the coupling impact on outer loop that is caused by inner loop in the inner and outer loop controller,and also solves the problems of charged aircraft model,aerodynamic parameters and perturbation boundaries which are difficult to obtain accurately and precisely.Simulation results show the effectiveness of the method.

Abstract:In order to obtain the analytical expression between objective functions and design variables for space deployable truss antenna during the structure optimization,prediction model of optimal parameters was built based on BP neural network.According to the truss structure and training principle of neural network,network model was established.Optimal parameters were calculated by using the finite element software ANSYS,and the training samples were obtained by orthogonal design.Adjusting the transfer function,the number of hidden nodes and training algorithm,prediction model was constructed,which satisfied the error requirement.Generalization capacity of neural network was tested by means of testing samples.The results show that predictive values of neural network agree well with finite element calculation results,which the relative error is within 10%.Moreover,the run time of model is shorter than that of ANSYS,which only needs 0.13 s.This model can predict optimal parameters more accurately and provide a theoretical reference for the structure optimization.

Abstract:To carry out the analysis and calculation of the transmission efficiency of tri-axial differential mechanism better,the theory of bond graph is applied to the analysis of power flow of the tri-axial differential mechanism utilizing the characteristic of power fluxion of bond graph.According to the transmission relationship and method of absolute speed,the bond graph model of the mechanism restricted by speed is established.The status of the internal power flow of the tri-axial differential mechanism,as well as the power flow of the conversion mechanism of the differentials,is got by simulation.The result of the simulation shows that the tri-axial differential mechanism belongs to the power conflux mechanism,and there is no circulated power and no possibility of self-locking.Based on the result of power flow,the transmission torque is analyzed,and the efficiency can be computed easily.This method is more systematic than the traditional method,and is convenient to be solved by computer.

Abstract:Considering the turning in place motion as an independent motion which can enhance the mobility of spherical robot,a turning in place motion control method of two pendulums driven spherical robot is studied.First,the mechanism characteristics of two pendulums driven spherical robot are introduced,and then the force condition of turning in place motion is analyzed based on D’alembert’s principle and the motion principle of turning in place motion of two pendulums driven spherical robot is discussed,finally,the dynamic model of turning in place motion is constructed.The whole process of turning in place motion is divided into three stages which are startup stage,stick stage and slip stage respectively,and a stick-slip principle for turning in place motion control is proposed.The effectiveness of the control method is validated by both simulation and prototype experiment.

Abstract:To minish the pulsation coefficient of flow rate of a gear pump,a multi-compound gear pump is studied.By the analysis method of displacement of mesh point,the flow charateristic of multi-compound gear pump is analyzed,and that expression of transient flow rate and general formula of pulsation coefficient of flow rate are deduced.The analysis result shows that the pulsation coefficient of flow rate is minimal and the flow charateristic is the best when z1=kN+1(k is an odd number).Taking an example from three-compound gear pump,its transient flow rate is simulated,which shows that the general formula of pulsation coefficient of flow rate is right.

Abstract:To meet the needs of real-time characteristics as well as to overcome the time overhead caused by memory copying operations during the process of semispace collection,an improved method was proposed which was based on partial copying mechanism.Based on the fact that the large objects are always long-lived objects as well as distributed continuously in memory space,the lived large objects will only be marked without being moved during the collection phase of semispcae GC.The marked objects remain in the original space,and a compaction phase is added to maintain a low degree of memory fragmentation.SPECjvm2008 and Dacapo test suites are used to demonstrate the effectiveness of the proposed algorithm.Comparison experiments shows that proposed method can efficiently reduce the average pause time of the collection and ensure the realtimeness for semispace garbage collection.

Abstract:To investigate the factors that affect incentive mechanism of BitTorrent system,this paper makes a modeling analysis.Because there are random selections,we use Markov process to model the incentive mechanism.We first get the transition probability matrix and then calculate the limit of the transition probability matrix.Theoretical analysis and experiment results show that peers with same upload bandwidth cluster,and adjusting randomly selected nodes can affect the speed of clustering.The model is consistent with the incentive mechanism,and by adjusting parameters we can improve the performance of the system.

Abstract:The mechanical eccentricity makes much more influence on precision of one pair pole reluctance resolver.One pair pole axial flux reluctance resolver with new magnetic structure is put forward,which has compensating character inside its two side air gap.The prototype has both exciting windings and signal windings in its stator,which are vertical to each other.There is no winding in its rotor and one inclined ring is set in it.By using analytical method,the conclusion is got that the resistance of the reluctance resolver is varied by changing its electro-magnetic coupling area.At the same time,by selecting appropriate shape of the inclined ring of rotor,the output sine and cosine signal of the EMF is optimized.To analyze the axial flux through the stator and the rotor,3D transient FEM is used.The character of the EMF in signal windings is got at the same time.The FEM result agrees well with the analytical result,this will offer us the basic parameters for the further analysis in the future.

Abstract:The effects of different kinds of concentration of sizing agent on the performances of carbon fibre and interface of its composites were studied by atomic force microscopy(AFM),and the surface energy along with contact angles was determined by dynamic contact angle analysis test(DCAT) with three different polar liquid.The interfacial shear strengths and hygrothermal ageing of carbon fibres micro-composites was also studied.It was found that the grooves on the 2% sized carbon fiber were disappeared.A significant change in the surface energy of these materials was displayed with the decreased γd and increased γp.The results indicate that the concentration has great effect on the micro-composites interface and ageing properties.The 1.5% sized carbon fibre shows better interfacial adhesion and ageing property than others.

Abstract:To enhance the efficiency of a new seawater desalination technique based on rotating coupling electromagnetic theory,and to optimize its parameters and to select the proper electronic and reverse osmosis membranes,we investigate the effects of seawater concentration on the seawater’s microstructure and dynamics by molecular dynamics(MD) simulations in details.The results indicate that with the increment of ion concentration,the ion-ion interaction strengthens,while the ion-water and water-water interactions weaken,resulting in reducing seawater short-range order.The number of the contact ion pairs as well as the solvent separated ones increases.The hydrogen bond network is gradually indistinct,and the self-diffusion coefficient of water molecule decreases.Therefore,the increment of ion concentration is disadvantageous to seawater desalination.

Abstract:As the TOA ranging error was always corrupted by the direct path blockage and excess delay in complicated indoor environments,the NLOS ranging error due to IR-UWB through wall propagation was modeled by dividing it into two parts: the geometrical error caused by the pulse transmitted through wall,and the peak biased error caused by the pulse waveform distortion due to frequency dependence of huge bandwidth.The theoretical geometrical error bound was derived from transceiver distance,wall thickness and materials.The IR-UWB through wall propagation was modeled using sub-band method,and the peak biased errors were investigated through the waveform distortion of IR-UWB signal propagated in different wall structures.The simulation results show that the geometrical error was mainly determined by the obstacles parameters and the peak biased errors caused by IR-UWB waveform distortions were within the distance resolution of IR-UWB signal.

Abstract:We analyzed the contents and structure of current electronics medical records,and proposed a definition of Five-Tuples pattern and another more fine-grained definition of two-turples pattern and semantic classes.On this foundation,we proposed a series of algorithms including patterns generalization,patterns automatic extraction and medical information extraction.The experiments with 312 actual medical records show that the system performs well both in the precision and recall.And because of the functionality of self-learning,the system will be more outstanding with an increase in the training corpus.

Abstract:To study the variation of cutting temperature in high-speed milling of titanium alloy with polycrystalline diamond,factorials design and uniform design were applied to the cutting temperature experiments.The main effects and interaction effect which have significant influence on cutting temperature were found out by factorials design.By using uniform design,the influence law of main effects and interaction effects on cutting temperature were investigated.Nonlinear mathematical model on the relationship between cutting parameters and cutting temperature was established.The results show that under high speed milling,the interaction effect between cutting speed and width of the uncut chip is significant.The relationship between cutting temperature and cutting parameters is nonlinear,and the effect of one cutting speed on cutting temperature changes with width of the uncut chip.

Abstract:To evaluate the suspension kinematics characteristics,by using roll center model and pitch center model,the unified formula between suspension deformation and acceleration were established,and by using g-g map,the suspension characteristics with longitudinal and lateral acceleration acting on vehicle were expressed.The toe angle,camber,as well as kingpin trailers were proposed to describe the suspension that affects vehicle dynamics.The suspension kinematics characteristics can be evaluated by g-g method not only from suspension view,but from whole car view.At last,by the suspension K & C data of an A-class car,the suspension kinematics in 3D field map was calculated by this method.

Abstract:Based on calorimetric method,a method to measure the thermal power of chips when cutting nickel-based superalloy at high speed was introduced and the cutting power and the cutting heat in the chips was calculated by measuring cutting force.The effect of cutting parameters on chip power and cutting power,and the distribution of cutting heat were studied too.The simulation results of the cutting heat by Deform-2D agree well with the experimental results.The experimental and calculation results indicate that as cutting speed increases,the chip power and cutting power increase almost linearly;the ratio of cutting heat taken away by chips increases with the increase of cutting speed,but it is much smaller than the ratio in carbon steel cutting;the feed per tooth has a relatively small influence on the distribution of cutting heat.

Abstract:To calculate the volume fraction of interfacial transition zone(ITZ) in cement-based composite materials,two quantitative expressions combining with actual sieve curve were put forward based on the most nearest surface distribution function and an approximate way of surface area of aggregates.The results show that the error of the ITZ fraction was about 10 percent,when the volume fraction of aggregate and the ITZ thickness per unit volume concrete is less than 0.5,50 μm,respectively,and the smaller the ITZ thickness,the smaller the calculated difference between two methods.

Abstract:To study the technology of marine energy-saving and emission reduction,an optimal control strategy of induction motor is described for marine main engine waste heat utilizing system.The energy-saving system utilizing waste heat,which consists of turbocharger and induction motor,is analyzed;LQG optimal controller which employed dynamic model of exhaust gas turbocharger-induction motor is designed,and the energy feedback control of induction motor is realized.Mathematical simulation and hardware-in-the-loop experimental results show that reversible induction motor can enhance the dynamic performance of turbocharger.The proposed control scheme effectively harmonizes the relationship between rotor speed and the instability in main engine exhaust gas,and improves the dynamic response,stability and waste heat utilizing efficiency of exhaust turbocharger system.

Abstract:In order to recover original shape of the holes in triangular meshes,a hole-repairing algorithm based on surface feature was proposed.First,the hole triangulation and subdivision were performed as coarse filling.Then,gauss ball was used to determine the hole neighbors and their surface types.Quadric surface equations were fixed by non linear least square.The hole neighbors of freeform were fitted by B spline surfaces.Finally,accurate positions of vertexes were acquired according to surface equations of the hole neighbors and the hole-repairing was completed.The experimental results show that the presented hole repairing algorithm can not only fill the holes but also recover surface feature in the hole regions.

Abstract:Aiming at the current failure in accurate grain purchase data collection and the demand for the guarantee of the national macroeconomic control of grain,this paper studies a management mode for grain purchase data collection based on RFID technology,and establishes a farmer card management system.The systematic structure,functional structure and information flow of the farmer card management system are designed.Oriented to farmers,driven by financial subsidies,tied by farmer card and supported by the operation platform,this system realizes the integrated management of grain circulation information collection,purchase loan supervision,purchase invoice audit,subsidies supervision,quick and safe balance and grain security tracing.

Abstract:Based on the combination of blind source separation(BSS) and time-frequency spectrum analysis,a multi-component linear frequency modulation(LFM) signal detection method is proposed,and by adopting the concept of time-domain separation and time-frequency analysis,the method effectively suppresses the cross-term interference problem based on WVD detection method and prominently reduces the impacts of strong noise interference source on the traditional time-frequency analysis and detection method.The computer simulation results demonstrate that the proposed method for the multi-component LFM signal separation and feature extraction exceeds the traditional method of time-frequency analysis.

Abstract:The dynamic model of flexible multi-body spacecraft with topological tree configuration has been established based on the Lagrange’s equations in terms of quasi-coordinates.The kinematics of the spacecraft is described by Modified Rodrigues Parameters(MRPs).For this time-varing uncertainty flexible multi-body spacecraft dynamic system,a modified fractal controller via variable universe of discourse was designed and the numerical simulation was done.The results show that this control scheme avoids the flaw caused by real-time calculating of shrinkable factors,realizes the effective control of flexible multi-body spacecraft for large angle attitude maneuver,and assures the vibration suppression of the spacecraft flexible appendages at the same time.

Abstract:Based on combination weight method in extenics evaluation model,this paper proposed a new geological disaster evaluation method.According to the monitoring data of geological disasters in Jilin Province,and by using matter-element theory,extension set theory and its associated functins,the geological disasters in the field of classical field and the sectin was determined.To determine the weight,we created a geological disaster extenics comprehensive evaluation model by the fuzzy analytic hierarchy process(FAHP) and the combination entropy weighting method,and finally go to the realistic district level.

Abstract:To delete spams from User data stream,an adaptive self-learning spam filtering system has been studied and presented.On the basis of cost analysis mistakenly classified of normal and spam e-mail,a filter to meet the requirements of filtering tasks with learning methods of probabilistic is created,and the use of mail domain name characteristic variables for a particular e-mail filtering is studied.Finally,experiments verify the reliability of the algorithm.