Abstract:In this paper, in order to eliminate the effect of STATCOM dead-time effect on the voltage and current, a new dead-time compensation method was proposed. According to the principle of discrete-time disturbance observer, corresponding observer was designed. The D-value of STATCOM output voltage and reference voltage caused by dead-time effect can be real-time observed on line. The D-value as a compensation value feeds back to the dead-beat control system to realize the self-adaption dead-time compensation. Simulation and experimental results show that it can effectively improve the effect of dead-time compensation, eliminate the phenomenon of the zero current clamping, and reduce current harmonic content of STATCOM.

Abstract:In order to improve the speed of machine tool spindle and overcome the rapidly wearing off of the conventional electric brush in the rotary ultrasonic machining, research on non-contact power transmission system which based on the principle of electromagnetic induction has been conducted. Through the mutual inductance coupling theory and the simulation on Maxwell electromagnetic simulation software, the non-contact rotary electromagnetic coupling mechanism is established and the influence factor on the transfer efficiency of the rotary mutual inductance, such as rotation speed, inter-stage magnetic gap, matching compensation and the ultrasound frequency has been explored. It demonstrates that transfer efficiency of the energy from the primary to secondary forward load can achieve 80% with proper selection of matching parameter and magnetic gap at a high rotary speed. The electricity intensity in the coil and the magnetic flux shows no significant difference with the acceleration of the rotary speed, while the efficiency decreased with the magnetic gap. Furthermore, it shows that the coupling has an optimal frequency within the input frequency range of the ultrasonic excitation, where the transfer efficiency goes up initially and then turns backward as frequency increased. The research provides a reference for the optimal design of the ultrasonic spindle.

Abstract:In order to improve the accuracy of the measurement algorithm for traffic matrix, a novel traffic matrix measurement algorithm with compressive sensing is proposed. This algorithm gets the judge gate by the principal components analysis and normalization of singular value. To reduce the measurement error created by approximation of sparse express and inaccurate choice of sparsity, we use L2 formulation of residual error to match the sparsity in the process of reconstitution of the traffic matrix on each time of measurement. Simulation results show that, this algorithm can obtain less spatial relative error and temporal relative error compared with the existing algorithm. With the help of adaptive selection for initial value of sparsity, this algorithm can obtain a higher accuracy.

Abstract:To avoid the halo artifact in the traditional filters, a new edge-preserving filter based on local average saliency gradient was proposed. The criterion to determine whether or not a region should be smoothed is difficult to give, hence it will introduce the “halo” artifact along the edges by unwanted smoothing in an image. Our idea is motivate by the feature of saliency map that enhances the salient edges in an image. Using the feature, we simplify the work to determine whether or not a region should be smoothed, and smooth the image adaptively according to local average saliency gradient. We retain the region with high average saliency gradient, and smooth the region with low average saliency gradient. Experiments show that our method performs better than traditional edge-preserving filters in smoothing, multi-enhancement, and HDR while avoiding “halo”.

Abstract:In this paper, a robust model prediction controller with state-feedback structure is constructed for a class of uncertain discrete nonlinear systems with multiple states time-delay, inputs time-delay and nonlinear perturbation. Firstly, an improved quadratic Lyapunov-Krasovskii functional is constructed by making full use of the upper and lower bounds of the time-delay information, and then the difficulty of solving min-max optimization problem is transformed into convex optimization problem with linear matrix inequality (LMI) constraints by utilizing LMI technique. Simultaneously, the sufficient conditions for the existence of robust predictive controller and the expression of the controller are given. Theoretically, it is proved that the designed controller can guarantee the closed-loop system is asymptotically stable. Finally, simulation results demonstrate the feasibility of the proposed scheme.

Abstract:In order to expand the application range of the virtual chamber measurement system, improve the measurement precision in actual measurement, a mathematical method of adaptive filtering and wiener filtering is used to analyze the inherent defects of the measurement system based on traditional ANS (automatic noise suppression), and point out the main factor restricted the application range and measurement precision is the existence of source signal component which is detected in the reference channel. According to the analysis result, the measurement system is rebuilt, coming up an ANS based on spectral estimation. Analyzing the mixed signal detected in the main channel, the remodeled system can get the PSD (power spectrum density) of radiation signal and noise signal .According to the frequency of the peak point in the PSD, notch filter has been designed to filter the radiation signal component captured by reference channel, then the system meets its expectation. The simulation and experiment results show that this method shows good performance in the high SNR (signal noise ratio) measurement circumstance as well as low SNR, which means that extracting the radiation signal of equipment under test exactly, high noise suppression ability and environmental adaptability of virtual chamber.

Abstract:Considering the energy harvesting properties of solar-driven wireless sensor network node, an optimal transmission power scheduling policy was proposed aiming at maximizing data bits delivered by a deadline. Assuming data bits have arrived, the proposed forward-backward searching (FBS) transmission power policy established an optimal transmission power series. According to the average harvested energy estimate during the harvesting decreasing period, the method can provide a global optimal transmitting series. Simulation was made based on the solar radiation data of Los Angeles(N33°,W118°), America in 1990. The results show that FBS performs better than the energy used up(EUP) policy. The longer sensor node harvestes energy , the better FBS performs.

Abstract:To meet the requirements of military development, firstly, the framework of the fire control simulation system (FCSS) is designed; then establishes every mathematical model of the fire control system, including the test management subsystem model, the weapon management subsystem model, the flight control subsystem model, the sensor management subsystem model and the fire control task machine subsystem model; secondly, based on the embedded real-time operating system VxWorks, this paper realizes the functional modules of each subsystem, and on this basis realizes the communication among them; finally, two sets of simulation results are analyzed in air-attack. Simulation results show that: to ensure the stability and smoothness of the attack route, PL-8 is better in the air to air missile fire control attack, PL-12 is more suitable in the long-distance combat.

Abstract:To improve the super maneuver flight control performance with model uncertainty, a super maneuver flight control law design method based on auto disturbance rejection backstepping control is approved in this paper. The high angle of attack six-DOF nonlinear airplane model is established. Based on the backsteppint design method, the steady flight control ability for nonlinear airplane model is realized. For model uncertainty, the extend state observer of the auto disturbance rejection control is used to observe the modeling error and online compensate. The super maneuver flight digital simulation results show that the controller has high angle of attack control ability with 40% model error. The auto disturbance rejection backstepping nonlinear control method has good super maneuver fight control performance.

Abstract:In order to improve the ability of complex power quality disturbances recognition, a new type of complex disturbances recognition approach based on Multiresolution Generalized S-transform (MGST) is proposed. Firstly, the spectrum of original signals is segmented into 3 frequency areas including low frequency area, medium frequency area and high frequency area. The width factor of window function in S-transform is defined respectively in different frequency areas. MGST has different time-frequency resolution in each frequency area in order to satisfy the recognition requirements of different disturbances in each frequency area. Otherwise, the width factor of window function in the high frequency area is adaptively adjusted according to the value of Fourier spectrum of the fundamental frequency. On this basis, the decision tree based on 6 features is constructed to recognize disturbance signals. Finally, the minimum classification faults rule is designed to get the optimum threshold of each node. The simulation and real signals experiments show that 13 types of disturbances including 5 types of complex disturbances are recognized accurately by the new approach. The new approach has better classification accuracy and noise immunity than other methods such as S-transform , generalized S-transform and Hyperbolic S-transform.

Abstract:In order to make the process of generating small traffic zones into middle traffic zones more reasonable and taking the similarity and the positional relation of small traffic zones into consideration, two-dimensional graphic theory-clustering method on the mergence of small traffic zone is applied. Given conditions that satisfied the adjacent small traffic zones, the positional relation of small traffic zones by the adjacent matrix is re-formulated. After the undirected weighted graph construction, the minimum spanning tree (MST) was solved. Choose the threshold according to the MST for the small traffic zones mergence. Finally the F-test is used to determine the optimal mergence in theory which is the reference of the selection of the small traffic zone mergence. The result of example analysis shows that the clustering number reduces along with the increase of the threshold value, and only the similar and adjacent small traffic zones can be merged during the mergence. In addition, the F-test is adopted to determine the exclusive optimal scheme of mergence for reference, which proved that the division result was feasible.

Abstract:In order to provide decision for drivers at urban road crosswalk, experiment of driver’s decision and risk perception was conducted. And driver’s perceptional risk and decision were analyzed. Changing rule of driver perceptional risk with speed variation was given, and driver’s decision loss function was put forward. Collision risk probability model was established based on probability theory. Loss for delay and collision risk was calibrated respectively. The redult is that driver should keep uniform speed or accelerate at low speed, and deceleration will increase loss; at medium speed, there is no evident difference for driver among acceleration, deceleration and keeping uniform speed, but keeping uniform speed is better; at high speed, the best solution is keeping uniform speed.

Abstract:In order to study the fluid flow and heat transfer process of paramagnetic medium in the high temperature environment, in this paper, the radiation effect on the thermo-magnetic convection in participating paramagnetic medium under gravity condition is studied numerically. The external magnetic field with non-uniform magnetic gradient is imposed. For a paramagnetic fluid, the magnetic force is proportional to the product of magnetic susceptibility and the gradient of the square of the magnetic induction, and acts on fluid particles cooperatively with gravity. The magnetic susceptibility is related to absolute temperature according to Curie′s law. The thermo-magnetic convection is carried out in high temperature environment and the paramagnetic fluid is a semitransparent gray medium which absorbs and emits energy. In the present study, the distribution characteristics and the regularities of fluid flow, temperature field and average Nusselt number are investigated under different magnetic Rayleigh number and optical thickness. The research results show that the magnetic field and radiation could enhance the convection, but have suppression effect with the increasement of optical thickness.

Abstract:In simulation of long-span bridge and airfoil flutter, a large-amplitude motion-induced force model is required. However, existing time-domain motion-induced force models cannot simulate memory effects and amplitude dependency simultaneously. This paper proposes a new time-domain non-linear motion-induced force model, which employs a set of nonlinear differential equations and augmented aerodynamic degrees of freedoms to simulate memory effects and amplitude dependency. Motion-induced forces under different deck motion amplitudes, different reduced wind velocities and non-sinusoidal motions can be simulated using a single set of model parameters. A fitting algorithm for the new model is also proposed and the model parameters of a bridge deck are fitted using results obtained by CFD simulations. Numerical example shows that the new model can reproduce variation of aerodynamic damping characteristics with reduced wind velocity and amplitude. A model fitted using single-frequency forced vibration tests can reproduce forces generated by multi-frequency vibrations.

Abstract:A new two-stage thermoelectric couple (TE couple) is proposed in this paper. In order to overcome the disadvantages of 1-D heat transfer model mentioned in the previous research, 3-D finite element models are established based on the conventional thermoelectric couple and the two-stage thermoelectric couple separately, the temperature, convention and electric potential boundaries are defined and reasonable boundary conditions are set to simulate the models in ANSYS Workbench environment. Controlling variable method is used to study the influences of different input variables on the output performance of thermoelectric couples. Simulation results show that the load resistance influence the output voltage and current. The two-stage TE couple are better than the conventional one when load resistance is smaller than one critical value, but the maximum output power of the two-stage TE couple is always larger than the conventional TE couple.

Abstract:This paper presents an approach of freeway traffic state estimation based on speed gradient model. Under the sensitivity analysis of model parameters, it is found that error of model estimation is sensitive to the free flow speed and jam propagation speed, which are recommended to be calibrated online. Moreover, the extended Kalman filter and the unscented Kalman filter methods are introduced combined with the speed Gradient model to solve traffic state estimation problems. The real traffic data were used to evaluate the methods. The results indicate that the accuracies of both extended Kalman filter and the unscented Kalman filter are around 85%, while the latter has a slight vantage in estimation accuracy and disadvantage in computing efficiency. The speed gradient model based traffic state estimation method can estimate and track the traffic dynamics effectively, with less model parameters when compared with similar methods.

Abstract:The characteristics of traffic accidents is analysed in order to determine the mainline alignment index in the diamond interchange diverging areas. The recognition sight distance of the diamond interchange diverging areas by combining the automobile theory, traffic psychology and ergonomics,and simultaneously are acquired. Based on the VB software and the setting conditions of the lateral clear distance of the expressway, the relation model between the indicators of the mainline plane and vertical section and the recognition sight distance in the diamond interchange diverging areas is set up. The values of the circular curve radius and the convex vertical curve radius of the mainline which meets the requirements of the recognition sight distance in the diamond interchange diverging areas is obtained. The analysis results show that it is necessary to analysis to the recognition sight distance of the diamond interchange diverging areas to be constructed and check the alignment index of the mainline with the recognition sight distance, for the constructed diamond interchange diverging areas, it is necessary to strengthen the safety precautions so as to guarantee the traffic safety of vehicles driving on the mainline and off the mainline.

Abstract:In order to study the strain compatibility of the nickel powder-filled cement based sensors and their surrounding concrete, the models of the sensors and concrete were set up by finite element software ANSYS. The stress and strain of the sensors and their surrounding concrete were calculated based on different embedded locations and angle deflections of the sensors, strength grades of concrete, and magnitudes and types of load. The strain compatibility of the sensors and their surrounding concrete were analyzed through the relative difference of strain. The results show that the sensors should be embedded in the internal homogeneous strain area of concrete members, rather than being embedded in the superficial area. The small angle deflection has little effect on the monitoring accuracy. As the sensors are used for health monitoring of concrete structures, the effect of strength grade of concrete and magnitudes and types of load should be systematically considered. The degree of strain compatibility of the sensors and their surrounding concrete can be better reflected by relative difference of strain.

Abstract:To solve the problem that the optimal average station spacing guidance does not play a significant role in the actual layout of the stations, the model and algorithm optimization of the site distribution of urban rail transit station is proposed. Firstly the city radius is defined, and the city was divided into three types, and rail transit lines was divided into two types, the rail transportation average station distance model was established and solved based on the city scale, respectively. The line was divided into obstacles, connected region and the feasible region, according to the area line through is constructly or not. And then the stations was divided into three grades according to the station passenger flow and the functional layout of the area line through. Station location model was established and optimized. Finally, the optimal average station spacing and each site layout position can be solved by proposed model, in the case of Changchun light rail line 4. Light rail line 4 peak hour capacity was increased by 6%, site distribution of the model compared with the existing site.

Abstract:The traffic state would become congested at the bottleneck region during peak period, which increase travel time, and decrease efficiency. From time-space traffic characteristics on freeway mainline, macroscopic traffic flow model METANET is modified to describe the traffic flow with VSL control. Furthermore, based on the modified traffic flow models, establish the VSL models at bottleneck region, with the objective of improving traffic efficiency and decreasing travel time. As part of the VSL control algorithm, the proposed VSL control model is implemented at VISSIM simulation platform, the results reveal that the given VSL values according to real time traffic flow conditions can control the vehicles arriving effectively. Therefore, the implement of VSL control can improve traffic efficiency and decrease travel time effectively.

Abstract:To improve the operation efficiency of automatic storage and retrieval system (AS/RS) at air freight station in term of job scheduling, on the basis of analyzing the effect of double unit load device (ULD) transport combination and anti-collision avoidance to the completion time of command sequences, a scheduling optimization model of AS/RS whose objective was to minimize the completion time of command sequences was established, and an improved ant colony algorithm was given to solve this model. To avoid trapping in local optimum in the search process, weight pheromone and random perturbation strategy were introduced. Besides, a state transfer parameter with a mutation probability was proposed to decide the moving direction of ants in the optimization process. Simulation results indicate that comparing with basic ant colony algorithm and genetic algorithm, the improved algorithm has better global search ability and solution precision. In comparison with the first-come-first-served scheduling strategy, the completion time of command sequences obtained by the scheduling optimization method proposed in this paper is improved by 37% at least.

Abstract:To reduce the risk of lane changing behaviors, based upon drivers’ visual characteristics and vehicle motion states, a method for lane change prediction is proposed. By using visual tracking system, millimeter-wave radar and so on, the research group conducts experiments under real road environment. Based on drivers’ fixation characteristics of the rearview mirrors before lane change occurs, lane changing intent time window is determined as 5 s, the characteristic index for predict lane changing behavior is further built. By designing BP neural network, the lane change prediction model is constructed. Results show that the model may predict drivers’ lane changing behavior for at least 1.5 s in advance, and the prediction accuracy can reach 95.58%. As compared to predict lane change behavior via turn signals, the prediction accuracy and time series characteristics are both improved remarkably, thus verifying the effectiveness of the predictive index and method.

Abstract:To study different influences of original water tables on the roadbed moisture field infiltrated by rainfall, five scale-down laboratory roadbed physical models with different original water tables were tested base on saturated-unsaturated soil seepage theory. The roadbed moisture field change rules were examined and its mechanism was explained through analyzing infiltration test results of two different rainfall intensities. The results show that the water tables rise significantly with the increase of rainfall strength, and the influences of original levels on moisture fields get more significant along with the increase of roadbed depths. With decrease of original levels the amplifications of roadbed moisture range increase quadratically to a steady value and the extended distances of moisture disturbed zone decrease quadratically to a steady value. A balanced original water table should exist according to a given field situation. The influences of groundwater on moisture fields are very slight while the original levels are deeper than the balanced one, otherwise, with increase of original levels the amplifications of roadbed moisture increase logarithmically and the influence is very significantly when the water table is higher than the balanced one.