Abstract:An nm-level positioning precision and high-speed are required by using macro movement of long stroke linear motor and high-precision micro movement of planar motor in the wafer stage of lithography. In order to reduce the movement scope and acceleration of planar motor, the tracking precision of linear motor must be improved, so this paper presents a combined control strategy based on the combination of zero phase error tracking controller with feed forward (ZPETC-FF) and the disturbance observer (DOB). ZPETC-FF is feed forward controller, which improves the system bandwidth and tracking performance effectively, and reduces the system′s dynamic tracking error, while DOB reduces the influences of the uncertainties, such as external load disturbances, unmodeled dynamics and system parameter perturbation. The experiments show that compared with traditional control method, the proposed control method not only achieves more rapid and accurate tracking of the system, but also has stronger anti-interference ability.

Abstract:Velocity-attitude matrix” matching method is proposed as a new approach to transfer alignment, in allusion to the disadvantages of “velocity-attitude” method which has a huge computation and low robustness, and “angular rate-acceleration” method which has a difficulty to compensate the lever-arm effect, and then an alignment model is deduced. Simulation results show that this method can complete a high precision alignment process and achieve a high precision, even if carrier aircraft do simple Angle maneuver. With the development tendency of SINS(strap-down inertial navigation system) as both master INS and slave INS, the characteristics of mathematics platform in SINS will make “velocity-attitude matrix” method used more and more widely.

Abstract:In this paper, an analytical method is presented to calculate the dynamic responses of a harmonic forced oscillator with dry friction. The friction of the oscillator is modeled by an Iwan model with finite Jenkins elements. As the force-displacement relationship of the oscillator is piecewise linear, the motion of the oscillator is analyzed interval by interval. The vibration equation in each linear interval is given and the corresponding analytical solution is derived by use of variable substitution. The initial values of each interval are obtained by the continuity condition of the displacement and velocity of the oscillator. Combining the dynamic responses of these intervals in sequence forms the dynamic responses of the model in the whole time history. The simulation results show that as the excitation amplitude level increases, slipping occurs in the contact surface which makes the contact stiffness decreased, thus results in obviously left shifted of the peak amplitude of the frequency response function curves. It is also found that the equivalent viscous damping first increases then decreases with the excitation amplitude level.

Abstract:An adaptive compensation control scheme is presented to address the problems of actuator misalignments and external disturbances for over-actuated spacecraft. It is proven by Lyapunov stability theory that the desired attitude trajectories are followed in finite-time. The attitude tracking error is almost globally asymptotically stable. Taking torque position and speed constraint of actuators into consideration, a dynamic control allocation strategy is designed to ensure the energy optimization and stationarity of control torque. With application of the proposed approach to attitude tracking maneuver of a spacecraft, simulation results verifies that good robustness to uncertain inertia parameters is ensured, external disturbances and actuator misalignments are successfully compensated, and the proposed methodology is able to achieve energy optimization.

Abstract:The traditional power control problems of cognitive radio are based on the situation that the position of cognitive user is unchanged. This paper has done a lot of work on the power control problems of mobile CR users. First of all, we analyze various communication situation and sort with normalization, establish general communication model which highly simplifies the interference estimation and power control algorithm; Secondly, according to the mobility of the CR users, the function expression of the interference of PR user, moving distance and the vector direction of CR user which realized the real-time prediction of interference from CR to PR users is deduced. Finally the power control of the cognitive users is realized according to the prediction result by minimum transmission power norm. The simulation result shows that the algorithm can control the transmitting power of CR users timely and efficiently which can save 20% for the power consumption compared with the fixed step power control algorithm.

Abstract:According to the information redundancy caused by high classification feature space dimension, we have proposed a method of cloud detection based on linear dimension compression for feature space. First, the classification feature parameters were extracted and the feature space was established. According to the different distribution structures of cloud and underlying surface samples, based on the completeness of classified information in compressed subspace, the sample’s probability distribution model is established. Then the model parameters are solved by using the maximum likelihood estimation method and the optimum transformation matrix is estimated, which is used for features compression and decorrelation. At last, a classifier is introduced for cloud detection in the compressed subspace. Experimental results have shown that the proposed method can effectively remove the classification features redundancy of the clouds and underlying surfaces, and achieve effective separation of clouds and underlying surfaces in compressed subspace. The cloud detection probability in optical remote sensing images is up to 98％ or more.

Abstract:There are great differences in action potentials between the Purkinje fiber cell and ventricular muscle cell. In many conditions, Purkinje-ventricular junction is considered as the source of serious ventricular arrhythmia. An idealized 2D computational model of ventricular electrical conduction is established to simulate the coupling junction of Purkinje fiber and ventricular tissues as well as the excitation conduction in the cardiac tissue. Simulation results show that the Purkinje fiber cells can generate the conduction of electric excitation in tachycardia and also can suppress excitations in extremely slow or fast rhythm. The Purkinje fiber plays an important protective role to keep ventricular tissues in normal rhythm. This model provides a new method to research the mechanism of arrhythmia and also can be used to study arrhythmia induced by congenital gene mutations and effects of antiarrhythmic drugs.

Abstract:In order to improve the transmission stiffness of harmonic gear drive with short flexspline, a design of harmonic drive with new teeth profile is proposed. The teeth profiles of flexspline and circular spline are designed as double arc profile and its conjugate profile with certain axial inclination angle, respectively, so that the contact area between meshing teeth is improved. The WEDM-LS processes for teeth of short flexspline and circular spline are presented, and 50 prototype harmonic gear drives with tilt tooth circular spline and 1/4 and 1/2 length-diameter ratio are developed, respectively. The results of transmission stiffness experiments show that the transmission stiffness of the new designed harmonic gear driver is increased by 39% compared to that of the previous designed harmonic gear driver without tilt tooth.

Abstract:To research the influence of technological parameters, such as mold temperature, melt temperature and compression force, on mechanical property of injection-compression Polycarbonate plate, the injection-compression experiments and tensile experiments of PC plates were conducted by adopting single factor method on the basis of optimized process parameter combinations. The results show that the yield strength of PC specimen decreases with the increasing of mold temperature, but increases with the increasing of melt temperature, compression force and compression speed. The total elongation decreases with the increasing of mold temperature, compression force and compression speed, but increases with the increasing of melt temperature.

Abstract:Optimizing and improving the ability of emergency material collection is a main purpose for evaluating the adaptation of emergency material collection network. Based on evaluation indexes of emergency material collection network(EMCN), the intelligent evaluation system of improved compensatory fuzzy neural network (CFNN) is introduced to evaluate the adaptation of emergency material collection network, and to solve problems of the fuzzy and non-linear from emergency cost, emergency time and stability of emergency material collection network. Simulation experiments show that the improved CFNN is an effective mean to evaluate the suitability of emergency material collection network with a fast convergence, a high fault tolerance and an adaptive ability.

Abstract:In view of the limitation of the range factor on analyzing low probability of intercept (LPI) performance of MIMO radar systems, a performance parameter is derived and applied for quantifying the LPI performance of distributed MIMO radar systems. A series of contour charts have been given with different values of geometrical parameter. By plotting and analyzing these charts, the LPI performance can be obtained intuitively. Simulation results show that LPI performance of distributed MIMO radar systems depends on both radar parameter and system geometry. It is shown that the spatial diversity gain plays an important role in designing a distributed MIMO radar system with robust LPI performance.

Abstract:To evaluate the influence of reservoir dick engineering on agricultural production and agricultural scale economy, this paper constructs a fixed effect model at first, in which Cobb-Douglas production function is chosen as the agricultural production function according to the real situation in China, and the influences of reservoir and embankment engineering, consumption of agricultural resources, scientific and technical level of agriculture and breeding, and the agricultural performance of reservoir and embankment engineering in different regions on agricultural output are measured effectively. Then, this paper employs the theory of scale economy to study the relationship between reservoir or embankment engineering and agricultural scale economy. The results show that the reservoir and embankment engineering have important effect on the growth of agricultural economy. In general, the contribution of embankment engineering to the growth of agricultural economy is more than that of reservoir engineering. With the improvement of reservoir and embankment engineering, the population benefited will increase gradually, as well as the total benefit and the benefit per capita, where the acceleration of benefit per capita is greater than that of the population benefited, which indicates that reservoir and embankment engineering are able to realize agricultural scale economy.

Abstract:The two-dimensional entropy image segmentation algorithm has a huge amount of computation problems. Based on immune adjustment mechanism, a new image segmentation algorithm is designed to solve the problem in this paper. In this method, vaccine theory is combined with entropy theory to propose the entropy vaccine operator. Entropy vaccine operator is selected as an antibody vaccine. Extract updated vaccine bank by using entropy calculation. In this way can make the formation of optimal segmentation threshold and the update of vaccine library with adaptive, and the select of vaccine more accuracy and more effective. The simulation results indicate that the searching speed of algorithm is accelerated and the adaptability is increased due to entropy genetic operator. The algorithm is approved to have good segmentation effect and strong real-time processing capability.

Abstract:To understand the characteristics of fire whirls in a vertical shaft with corner gaps, experiments of fire whirls induced by n-heptanes and numerical modeling for liquid fuel which is based on large-eddy simulation were performed in a vertical shaft with the height of 200 cm. Model validation was verified. Absolute values of tangential velocity at typical height are around 100 cm/s on the edge of shaft. When the height is 60 cm, from the fire to the walls of the shaft, firstly, the tangential velocity immediately increases to the maximum value, and then, decreases to 100 cm/s. However, once the height is greater than 120 cm, the tangential velocity increases only. From the fire to the walls of the shaft, the ratio of Coriolis force and buoyancy is almost symmetrical. The ratio first increases, then decreases and the position where the ratio of Coriolis force and buoyancy achieves its maximum value is outside the fire. In contrast with buoyancy effect, the Coriolis force has great effect on lower part of the shaft, and the effect drops as the altitude rises. The maximal axial velocity is almost two times of the maximal tangential velocity for the thermal flow field of fire whirls in a vertical shaft.

Abstract:To improve the production efficiency of multi-cluster tools, modeling and scheduling problems of dual-blade multi-cluster tools with residency constraints and multi-type wafers were researched. Firstly, based on the proposed conception of virtual buffer modules, time interval sets were introduced to characterize the running states of the system. Then a non-linear mathematical model of the problems was formulated, and a scheduling algorithm was presented based on the conception of virtual buffer modules and the swap scheduling strategy. Finally, experiments were carried out to evaluate the proposed algorithm. Results indicated that, when scheduling a lot wafers, the running time of the constructed algorithm is only about 0.5 seconds, and the response time of the algorithm is also quick. Comparing a lower bound of the research problem domain, solutions are close to the lower bound. When the device factor is greater than 5, the cycle elongation R is less than 0.05. The algorithm achieves good results.

Abstract:To minimize the straightness error of deflected Longitudinally Submerged Arc Welding (LSAW) pipes, a quantitative control strategy of pressure straightening process with multi-step three-point bending is studied. Based on the springback equation of small curvature plane bending and the equivalent principle for over-bend straightening, this paper proposes a theoretical straightening moment which corresponds with the initial deflection distribution of pipes. The principle of the multi-step pressure straightening process is revealed, and the parameters in three-point bending process for each step can be obtained only by measuring the initial deflection distribution once. To improve the straightening efficiency and ensure the straightening accuracy, the concept of load correction coefficient is firstly proposed. Experimental results show that when the number of straightening step is fixed, the residual deflection of the pipe is reduced with the growth of load correction coefficient. Meanwhile, as the number of straightening step increases, the load correction coefficient decreases. The feasibility and the reliability of the control strategy are verified by the physical simulation experiments of small pipes.

Abstract:Numerical fluid dynamics model of a liquid-drop micro-manipulator was built to investigate its control mechanism. Computational simulation was conducted to analyze the relationship between the shape of the liquid-drop adhered to the end of the micro-manipulator and the end shape of the micro-manipulator. The factors affecting the performance of the micro-manipulator were discussed. Experiments were carried out to verify the correctness of numerical simulation model and feasibility of the micro-manipulation method as well as the implementation of the micro-manipulator. Both the experiment results and simulation results indicate that this micro-manipulator can adjust the shape of liquid drop sticking to its end by changing the boundary surface between the liquid and needles with different combinations of six tungsten needles motion. The orientation of a tiny object attached to the liquid-drop by surface tension force can be adjusted subsequently as it alters with the shape of liquid drop. The liquid-drop micro-manipulator can be used in operating different targets in micro devices assembly by changing the parameters of the micro-manipulator, such as the size, number or displacement of the tungsten needles, as well as liquid properties.

Abstract:Inspired by the body character of jellyfish and the swimming mode of caudal fin, a new-style efficient autonomous underwater vehicle tends to be developed. A kind of smart material-shape memory alloy wire is adopted as the actuator to imitate the muscle of jellyfish. Based on rebuilding the configuration of jellyfish and analyzing the swimming strategy, a bionic jellyfish robot prototype propelled by 6 bionic tentacle propulsors is developed. The robot is 230 mm in length, 110 mm in diameter, 590 g in weigh and contains power supply. The robot can reach 110 mm/s straight speed and 18°/s turning speed in wireless control. The swimming experiment demonstrates that the bionic swimmer has the merits of simple structure, easy to seal, good maneuverability, silent propulsion and biology friendly. The feasibility of taking shape memory alloy wires as bionic muscle material is verified.

Abstract:New diffuser profiles designed by constant rate of velocity or pressure change method (CRVC／CRPC) were adopted to improve the jet pump performance. The orthogonal design was used to arrange the structure combinations of jet pump. The throat length, diffuser angle and profile were chosen and each factor had three levels. Considering the interactions between factors, 27 combinations were obtained and simulated to gain their performance. The effect of structure parameters on the flow details was studied. The results from the variance analysis show that all the factors and interactions have great influence on the pump performance. The interactions among the geometric parameters should be considered during jet pump optimization. The CRVC or CRPC diffuser produces a smoother and more uniform velocity and pressure gradient along the axis than the conical diffuser. Combining with appropriate throat length, the CRVC or CRPC diffuser could improve the pump performance and shorten the total pump length considerably. The most desirable combination consists of a throat with its length 6 times of its diameter and a conical diffuser with angle of 8°

Abstract:In order to obtain the friction mechanism of friction element in engagement with the changes of speed and pressure boundary condition, a newer speed control test method for friction characteristic of friction element with different grooves is proposed. The effect of mixed, boundary and adhesion friction can be well embodied in friction and lock-up experimental process of the friction element. The grooves can impact the trends of the friction coefficient curves with the increase of speed. The static friction coefficient declines with the increase of load and tends to be stable in the end. The friction coefficient sensitivity to speed is different. It is verified that Cu-based sintered friction material can work in heavy duty condition and the one with double arc grooves can engage more smoothly by the fiction static and dynamic ratio investigation.

Abstract:A manipulation assignment strategy of full-mode flight based on unmanned tilt-rotor aircraft flight dynamics model trim and small perturbation linearization processing results was presented, and its manipulation efficiency was analyzed for different flight mode. The control efficiency matrix coefficients were solved with an objective optimization function specification of multi-object nonlinear control method. A difficult problem that was the manipulate redundancy as the flight mode changes in the process of flight control was overcome. A unified flight controller was designed with the help of manipulation allocation strategy, without having to design a controller for different flight mode. The design difficulty of the flight controller is effectively reduced. A full-mode of flight simulation is given out, in which a stable flight control is achieved with a linear PID controller. Simulation results demonstrate the credibility of the tilt-rotor aircraft flight dynamics model and the effectiveness of the manipulation assignment strategy.