Abstract:To solve the problems of collision between neighboring agents, a formation control algorithm is presented for multi-agent systems integrating virtual leaders into artificial potentials to keep and adjust formation. Firstly, the interaction forces and expectation distances between neighboring agents are determined by artificial potentials. Then, the formation and the motion direction of the group are controlled in the artificial potentials proposed by means of the amount and distribution locations of virtual leaders. Finally, the approach provides a construction for a Lyapunov function to prove stability of the formation systems using the system kinetic energy and the artificial potential energy. Simulation results show that the controller is effective and can keep or change formation configuration rapidly, stably and exactly with no collision.

Abstract:Focusing on the completely inspection and salvage of target spacecraft, this paper presents an algorithm to enable the on-orbit-servicing spacecraft to circumnavigate a target spacecraft in any plane based on the impulse transfer method. By dividing the specified period into N parts, the impulse transfer method is applied during every part between two specified points until the circumnavigation is accomplished. With the error analysis of algorithm, a method is presented to solve the least pulse number N in the tolerant guidance error. Finally, a simulation is carried out and the results indicate that the guidance algorithm consumes less energy than others and can accomplish the flyaround in any plane efficiently.

Abstract:To enhance the vibration control bandwidth of active-passive hybrid piezoelectric network (APPN), a kind of piezoelectric hybrid constrained layer damping (PHCLD), which combined the advantages of the APPN and passive constrained layer damping, was presented to control the vibrations of cantilever beams. Complex shear modulus was used to characterize the dynamic behavior of viscoelastic material, and Hamilton′s principle with Raleigh-Ritz method was employed to establish the dynamic model of the cantilever beams with PHCLD treatments. On this basis, the velocity feedback control strategy was used to design the active controller, and numerical simulations were performed to analyze the open-loop and closed-loop characteristics of the beam/PHCLD system. Analysis results indicate that the PHCLD has better vibration control performance and wider vibration control bandwidth as compared with the APPN. Furthermore, this PHCLD treatment could be easily extended to control the vibrations of other kinds of structures.

Abstract:To improve the transmission efficiency of resonant wireless power transfer system in high frequency condition, the class E power amplifier is used as a driving source based on the traditional structure of wireless power transfer system. An adjustment method of load network for class E power amplifier in wireless power transmission system is proposed to further reduce the system losses, and then, the optimal matching parameters of load network in soft switching condition are calculated. The effect of load network changes on the system efficiency and the state of soft switching by adjusting the duty cycle of the switch are verified. Result shows that the system output power can get 78 W at 1 MHz frequency, and the system power efficiency is up to 76.5％.

Abstract:Planar core is added to the magnetic resonant wireless power transmission system to increase the self-inductance and the coupling coefficient between the primary coil and secondary coil, and to enhance the transfer power and efficiency. Based on the equivalent circuit analysis, mathematical expression of system parameters are given by the circuit differential equations. Furthermore, a prototype of wireless power transmission system is built, and experiments including coupling coefficient, operating frequency, misalignment, and power transfer characteristic of the system are conducted. The system realizes 1.85 kW power transmission with 10 cm air gap and 80％ efficiency. By using the planar core, the coupling mechanism can achieve stable and effective transmission in 25％ misalignment, and its volume is smaller.

Abstract:Domestic and foreign research status and progress in the field of ultra-precision machine tool is reviewed, and the development tread is given. Based on the analysis of the main issues and the gap between foreign country and our country in the field of ultra-precision machine tool, the development strategies and countermeasures in the basic research, technology and industry are put forward.

Abstract:To give full play to the mechanical potentiality of the pin-loaded composite laminate, the macro-mesoscopic multi-scale numerical method is developed to predict accurately the failure load of the structure, to simulate partial damage initiation, expansion and to guide the structure design. The improved unit cell model(GMC) is implanted to the numerical model by the user subroutines (USDFLD) provided by ABAQUS. The macro-micro multi-scale numerical model considering the damage／failure of micro-constituent materials is created for the pin-loaded composite laminate based on the general finite element software ABAQUS. The failure modes and the extruding strength of the pin-loaded laminate structure under the double-shear loading are simulated and predicted. By comparing the simulated failure modes with the test results in the literature, and compare the limited load with the experimental results, the feasibility of model is verified. The effect of specimen geometry dimension on the failure mode and the limited extruding strength of pin-loaded laminate structure are analyzed. The change of the width-diameter ratio will affect the failure mode, the extruding strength of the pin-loaded composite laminate and especially for the extruding strength.

Abstract:An innovative fabrication method of integrated manufacturing composite truss is developed to improve the geometric accuracy and rods connecting efficiency. Unlike previous research, the rods are connected by bonding composite shell, winding fiber tow and wrapping fabric together with the designed rod fixture. Fabrication process demonstrates good operability and stability of truss manufacture and advanced geometry accuracy of fabrication. Three-point bending test on bending bearing capacity of the truss suggests a high specific bending stiffness with rods connection of high efficiency. In addition, consistent results from a finite element simulation based on a simplified model show its potential in high computational efficiency to evaluate the bending stiffness of the truss.

Abstract:To reveal systematically the state of art of relevant sub-processes related to reliability in software test, management of test resource and cost, optimal release are studied in this article. Firstly, research contents are divided into four parts. Secondly, test resource allocation and control, cost model, optimal release, and relation of four parts are discussed, and then the formulations are also described. Thirdly, the related developing technologies are classified and summarized in accordance with software architecture modeling, test process modeling and nonlinear optimum or simulation solving. Furthermore, research contents are unified from five aspects and the latest models are classified and summarized respectively. Finally, future research directions are put forward.

Abstract:To circumvent the problem in GPS／INS integrated navigation for data infusion that Kalman filter degrades severely since the statistics of the noise might be time-variant, an adaptive Kalman filtering algorithm based on variational Bayesian learning is suggested and used in the integrated navigation system model in which both the moment of noise and the states are considered as stochastic parameters and estimated together. Using a probabilistic approach, a concrete derivation is given to represent how variational Bayesian learning works in a recursive way to approximate the true posterior of the noise together with the states. Experimental results demonstrate that the proposed filter is adaptive and performs well in tracking variances of the noise and estimating the states including position and velocity in GPS／INS integrated navigation system.

Abstract:To the navigation of Unmanned Aerial Vehicle(UAV) in the complex unknown environment, an algorithm of position and attitude estimation based on the binocular stereo vision is described in this paper. Stereo vision pairs are taken by the binocular camera. The feature points are detected with the Harris algorism after the stereo vision pairs are rectified and the feature points are matched with NCC algorithm. Then the 3D stereo information of the feature points can be calculated in the camera coordinate system and the position and attitude of UAV are estimated with RANSAC algorithm and L-M iteration algorithm. The result of the experiment shows that the position and attitude estimation algorithm based on binocular stereo vision has strong adaptability of the unknown environment. Compared to the real position and attitude, there is a small error. The algorithm can meet the requirements of UAV navigation. A new way can be provided for the UAV navigation.

Abstract:Based on 3-RSR parallel mechanism, a triangular bipyramid rolling mechanism with two modes is proposed by using parallelogram mechanism folding technique. The mechanism has folding mode and mobile mode in normal position and singular position respectively. In folding mode, it gains the ability of folding by single degree of freedom, and the ability of folding makes the mechanism decreasing the storage space and acquiring the concealed ability. In mobile mode, the mechanism has three degrees of freedom which makes it rolling by deforming. The structure and the reason of freedom changing are analyzed. A prototype is manufactured to testify the feasibility of deforming method and rolling function.

Abstract:A no-reference video quality assessment method is proposed for H.264／AVC network videos. The affection of packet loss on video qualities is first analyzed. Then, the video qualities are assessed by analyzing the spatial-temporal error propagation and error concealment which is induced by the new coding features of H.264／AVC. The complexity of the proposed quality assessment method is low, and it is suitable for assessing qualities of real time videos. Experimental results demonstrate that the MSE(mean square error) of the assessed video qualities is consistent with that obtained by full reference quality assessment. The correlation coefficient is greater than 0.85.

Abstract:To solve the problem of the balance between performance and energy efficiency on real-time control and industry-oriented wireless sensor networks, we propose a quantitative evaluation and optimal design scheme of energy efficiency model. Firstly, by introducing the feedback control theory, we construct an evaluation method of energy efficiency model under the QoS constraint using an analytic hierarchy process and compute service usability using comprehensive quantitative metric weights based on weighted sum. Then, based on this, we provide an optimization model based on a utility function and design a multi-metric optimization algorithm. The simulation results show that this method can adjust and optimize the network protocol, satisfy QoS constraint under the condition of limited energy, ensure reliable data transmission, reduce energy consumption and prolong network life-time.

Abstract:To reduce the loss of people′s property caused by traffic accidents because of driver fatigue, a new driver fatigue monitoring method based on non-contact is proposed. First, a camera gets driver's facial image, and then by using online method of identifying to identify the driver's facial features after pre-processing, the fatigue state of the driver can be acquired. Hardware system including TMS320DM642 as the core processor will alarm when driver is fatigue. Experimental results show that the use of pulse coupled neural network method to enhance and identify image, can determine the area of face and eye effectively, the master chip TMS320DM642 meets the requirement of detection distance between 30 cm and 150 cm when camera focal length is 8 mm. Coupled pulse neural network method has high reliability in driver fatigue detection, and choosing the right hardware platform and installation position have important influences on the detection results.

Abstract:In order to maximum the effectiveness of the limited resources, it is crucial to find out the bottleneck of the resilience and determine optimal path in the supply chain resilience optimization process. Combining the barrel theory and the utility valence theory, this paper puts forward an integrated method for the path selection of supply chain resilience optimazation problem. The results show that the optimal path selection method considers both the preferences of the decision-makers and the interaction among the various indicators. The example shows that the optimal path selected by the proposed method is in line with reality, and it is feasible. This provides a reference for the path selection of supply chain resilience optimization problem.

Abstract:Based on virtual equivalent system (VES) theory, this paper presents the viewpoint that the structure information of plant to be controlled and the convergence of parameter estimates are both unnecessary for the stability and convergence of various types of self-tuning control (STC) systems. A general self-tuning control system comprised of arbitrary control strategy, arbitrary parameter estimation algorithm, and arbitrary plant (deterministic or stochastic, minimum or non-minimum phase), is stable and convergent if only the control strategy stabilizes the parameter-known model; the parameter estimates are bounded and slow time varying with relative infinitesimal estimation error.

Abstract:According to the feature that the measurements of the same target at the same time have spherical shape, an algorithm of track initiation based on adaptive K-means clustering and modified logic-based approach is proposed in this paper. The improved K-means clustering algorithm can determine the cluster number and the initial cluster centers adaptively. Then the center of each cluster is found and taken as the measurement of the targets at this moment. By doing so, the track initiation process is simplified. According to the target’s movement characteristic, a modified logic-based method is used to initiate the target track. Simulation results show that the improved K-means clustering algorithm can recognize the number of targets correctly and the recognized targets are close to the true targets; the modified logic-based approach can effectively suppresses clutter and reduces the probability of false alarm.

Abstract:To research the problem of flight delays occurring in rush hour of busy airport which make airport’s operation lower efficiency, the effect of congestion pricing being aimed at rush hour on slot demand is analyzed. A bi-level programming model of airport slot management for multi-user is established to determine the congestion pricing rate and corresponding flight flow, which considers the characteristic of direct flight and connecting flight. The case analysis shows that the volatility of flight volume and average delay time in different time are decreased. The model is an effective method of reducing flight delays and improving operation efficiency of busy airport.

Abstract:To explore the reasonable mechanisms of resources property rights and the complusory system, taking the radio spectrum as an example and in acorrding to the first order sealed auction principle, this paper establishes an incomplete information bidding model during the radio spectrum auction process to analyze the impacts on operators optimal of factors such as the number of operators bidding, bidding probability of success and so on, and the effects on operators expected profit function of the number of successful bidders, and draw the general expression of operators quote by solving model.Analysis showed that the application of auction mechanism in the radio spectrum resource allocation not only fully reflected the economic value of spectrum resources, but also conducive to the efficient allocation of spectrum resources, and was the ptimizing decisions as well under the premise that the profits of operators was maximized.