Abstract:The fast calculation of stiffness chain model by directly using the parameters of real main section is the key problem which should be solved in the design of vehicle-body stiffness chain. Taking the control and engineering on the parameters of stiffness chain nodes as the target, this paper evaluated the relationship between the parameters of stiffness chain nodes and the parameters of main section property. Furthermore, the parameterized method of controlling the real shape of the main section was studied by using the polar coordinate method and computing method of complex section properties that considers single variable control theory based on an established and improved computing model for static stiffness chain of vehicle body. It achieves the targets of parameterized calculation for the stiffness chain nodes and the engineering for the parameters in stiffness chain model, which provides a foundation for the investigation on the optimal distribution of static stiffness based on real main section structure and shape. Finally, the proposed method was verified by a numerical example of a light-weight of vehicle body.

Abstract:In order to satisfy the requirements of design and performance of an internal combustion engine, all kinds of existing variable valve actuation systems were compared by analyzing their advantages and disadvantages, and a novel electro-hydraulic variable valve actuation system was then developed. Afterwards, a simulation model based on the mathematical and physical equations was developed through MATLAB/Simulink softwares, and the developed model was verified by experimental results. Furthermore, the effects of controllable parameters such as the phase angle difference between high and low pressure rotary valve, accumulator pressure and engine speed on maximum lift, valve open duration, and valve velocity and acceleration were investigated. The results showed that phase angle difference had limited influence on valve trajectory at the beginning section of lift, but changed the valve closing by altering valve open duration. The pressure of accumulator did not change the valve timing and its duration， but influenced significantly on the maximum valve lift. The maximum valve lift and valve closing were affected by the engine speed variance. Sectional area of valve lift decreased and valve closing delayed with the increasing engine speed.

Abstract:To investigate the influence of the parameters of the hydraulically interconnected suspension on the responses of a vehicle, a 7-DOFs (degrees of freedom) frequency domain model of the vehicle coupling with hydraulically interconnected suspension was established, and the frequency response function of roll angle acceleration, pitch angle acceleration, vertical acceleration on the center of mass, and vertical force on left-rear tire were then deduced. The parametric effects of the hydraulically interconnected suspension including the system oil pressure, volume of the accumulators, the differences and ratios between the areas of the two chambers of the cylinders on the dynamic response characteristics of the vehicle were evaluated. The results show that the system oil pressure has the adverse correlation with the volume of the accumulators on the frequency domain responses, the differences between the cylinder areas play a significant role on the responses, and the ratios between the cylinder areas have a certain effect on the responses of the roll angle acceleration and the tire forces but limited effect on the others. The performance test of the vehicle was taken to verify the simulation model, which shows that the influences of the key parameters on the frequency response characteristics of the vehicle are in a good accordance.

Abstract:In order to solve the battery charge problem under low temperature, liquid cooling battery system was analyzed and studied, and thermal management with heating and preservation was designed. According to the battery low temperature test data and the requirement of battery heating and preservation, battery heating calculation model was proposed on the basis of the theory formula. The performance of battery heating system was studied by the proposed model. Optimization design of the liquid cooling control system was also investigated according to the analysis results. The results show that the liquid cooling battery management system exhibits excellent performance of low temperature heating and preservation.

Abstract:A simulation model of a certain diesel engine was built by ABAQUS to solve the engine cracking problem. The temperature boundary of the model was calibrated based on experimental temperature data. The temperature and stress/deformation distributions of the diesel engine were analyzed based on the thermosetting coupling theory. Three kinds of cylinder center surfaces including convex, flat, and concave surfaces were put forward due to the thermal stress concentration in the bridge of nose area. Simulations were carried out to verify these three projects. It showed that the stress of the concave surface was smaller than others. Reduction of the wall thickness of the center area decreased the maximum stress of the bridge of nose area. The temperature distribution of the analysis model was found to be consistent with the experimental results. The experimental results also verified the accuracy of the thermosetting coupling numerical simulation. In a whole, the investigation in this paper provides the theoretical basis for the optimization design of the cylinder head.

Abstract:For a metal gear pair in the core parts of planetary reducer with few teeth difference, the problems of poor deformation compensation can be solved by designing a metal rubber complex gear pair, which reduces the vibration and achieves deformation compensation. The simulation analysis with rigid flexible coupling multi-body dynamics was used to verify the vibration of the metal rubber complex gear and metal gear pair. The vibration characteristics of these two gear pairs under different operating conditions were also studied by the experimental method. The results of simulation and experiment show that the vibration characteristics of the complex gear pair are improved by the addition of the metal rubber material, and the complex gear pair is obviously superior to the metal gear pair in meshing force, angular acceleration, transmission efficiency and vibration acceleration. The transmission stability of the complex gear pair is also greatly improved. Moreover, the simulation results are consistent with the experimental ones.

Abstract:Taking the hydraulic hoist cylinder in water projects as an example, the maximum axial load of super-long large scale hydraulic cylinder was calculated and analyzed. The effects of the friction between earring and bearing shaft pin and the fit clearance between cylinder and piston rod on the axial bearing capacity were studied. The nonlinear buckling analysis of the hydraulic cylinder was carried out by ANSYS software. The maximum axial load of the prototype is 580 kN and about 6% different from that calculated by theoretical model, which verifies the rationality of the theoretical analysis. The results show that the limit load determined by strength condition is less than the critical load determined by stability condition. The maximum allowable axial load of hydraulic cylinder is determined by the limit load. The axial bearing capacity of hydraulic cylinder increases with the increase of the friction coefficient or the decrease of the fit clearance. When the friction coefficient increases from 0 to 0.3, the maximum allowable axial load increases by about 5%.

Abstract:The model reduction technique was applied to solve the dynamic response. In order to make the system show the actual responses of the expected signals, the iteration procedure was then used to modify the load signals based on Tikhonov regularization load identification. Furthermore, the accuracy of the load signals was identified. The comparison of the proposed method with the traditional Tikhonov method shows that the proposed method can retain a good anti-noise characteristic, and improve the precision of load identification. The accuracy of the load identification by the proposed method is much higher than that of the traditional method.

Abstract:In order to improve the performance and reduce mass of an ossicular silencer, the average transmission losses (TL) in the low frequency range and the broadband were chosen as optimization goals, several structural parameters (width of the main duct，depth of the enclosed cavity, and length of the enclosed cavity) were chosen as optimization variables, and the mass of the silencer was taken as the constrain condition. The finite element model was also established for the silencer, sample points were obtained by central composite design (CCD)，the quadratic polynomial model was constructed based on response surface methodology (RSM)，and the fitting accuracy was tested. Response surface methodology combined with genetic algorithm II (NSGA-II) was applied to optimize the structural parameters of the silencer. The optimized ossicular silencer shows better performance and lighter weight. The optimization results indicate that the structural parameters of the silencer are optimized by combining the response surface methodology with genetic algorithm.

Abstract:For sharing modules selection in the modular platform design, an algorithm based on constraints was proposed, which was inspired by Collaborative Optimization using the constraints to coordinate the System Level Optimization and Sub-system Level Optimization. In this algorithm, NSGA-Ⅱ was used in the System level to solve the Multidisciplinary Design Optimization problem, and a Pareto set was gotten. By using the fuzzy set theory to evaluate each equation in the Pareto set, the optimum solution was easily picked out, and the sharing modules selection was realized in this way. At last, this method was verified by using an application example constituted by involving a SUV, a hatchback, and a sedan.

Abstract:Load identification based on acceleration frequency response matrix is an ill-conditioned problem. The identification accuracy can obviously be affected by small perturbations of the response data. Based on Tikhonov regularization method, a new approach is proposed in which both the response data at measured points and the loads to be identified are normalized, the transformed frequency response matrix and regularization function are introduced, and the corresponding problem of functional minimum is solved to obtain the loads. The optimal regularization parameters are determined by generalized cross validation criterion. The identification of four transverse dynamic loads on a rectangular thin plate with simply supported edges is performed. Four numerical examples are designed to have different application locations of loads and measured points as well as different magnitude ratio of dynamic loads in frequency domain. The results show that the new approach of dynamic load identification in frequency domain is effective to improve the identification accuracy and the noise resistance. Particularly, the errors of the identification can be significantly reduced in the cases where the large difference between the magnitudes of dynamic loads in frequency domain exists, or when excitation positions are close to structural boundaries.

Abstract:Nearest level modulation is a common modulation method for Modular Multilevel Converters (MMC). As the number of modules is few or the modulation voltage is low, the output current is distorted. Firstly, this paper theoretically analyzes the reason why the harmonic of output current is distorted in MMC, and then proposes a control method to suppress the harmonics. The method extracts the harmonics of output current, and through a proportional integral regulator, the negative harmonic voltages is obtained. Lastly, the harmonic voltages are added to the modulation reference voltage. The purpose of this method is to obtain the total reference voltage. The proposed method is simple, feasible, and easy to implement. The simulation and experimental results show that the distortion of the output current of MMC is suppressed by the proposed method.

Abstract:In order to improve the power quality of 220 kV transformer substation, a four winding transformer based on inductive filtering technology was proposed. Compared with the traditional three winding transformer, the four winding transformer has an additional filter winding with the characteristics of zero impedance design.The additional filter winding connecting to the set of filter compensation devices can efficiently restrain the harmonic from the 35 kV and 110 kV load sides, and reduce the harmonic currents of 220 kV side. Comparative analysis of several commonly reactive compensation was studied, and match coefficient distribution method was adopted to design transformer matching filter compensation devices in order to realize the purpose of the minimum inductance, which can guarantee the efficiency of filter compensation devices. Finally, through the software of PSCAD/EMTDC, the modules of the four-winding transformer and filters are modeled, and a total simulation goes on with all modules. The results show that the induction filtering four winding transformer and its filter are much better than the traditional three winding transformer, which is applicable to practical engineering.

Abstract:This paper presented a control strategy of indirect position estimation for switched reluctance motor (SRM) based on the single threshold of pulse injection in order to reduce the application scope of the limitation due to the position sensors. Considering the case of the bus voltage change, through injecting voltage pulse into one idle phase of 6/4 motor, the pulse peak current is detected by the mean sampling method proposed in this paper. The results are then used to predict the position by means of comparing the current preset threshold. After acquiring the time interval between adjacent threshold, it is convenient to calculate the speed and to confirm other position at every time. The deviation between estimated position and actual position was also analyzed. The proposed method not only reduces the negative torque influence brought by injection pulse but also flexibly implements the angle control that optimizes the motor running state. The SRM sensorless speed control system is built in Simulink, and the DSP experiment results verify the present method.

Abstract:A Lyapunov-function-based control strategy for NPC-SAPF was proposed. The mathematical model of NPC-APF was built, and Lyapunov energy function including the tracking error of compensation currents and DC voltage was also constructed. Characteristic equation including control permanents was derived and plotted. Linear range of control permanents were also obtained after the overall consideration of system globally asymptotically stable conditions and pole location. Error feedback control technique was then utilized to keep neutral point potential balanced. In order to verify the compensation performance of the proposed current control scheme, nonlinear loads including diode bridge rectifier with an inductive load and a capacitive load was simulated and tested. Simulation and experimental results show that the proposed control strategy is effective in the nonlinear loads of both current-source type and voltage-source type.

Abstract:As influenced by the improved requirement of electric meters operation and maintenance task (EM-OMT), the traditional mode is not applicable to the new management needs any more. In terms of the existing problems in the traditional operation mode, for instance, the unscientific allocation of tasks, the unreasonable planning of path and no response to the dynamic requirements in time, a novel dynamic optimization model and algorithm was proposed. The quantity of tasks, real time traffic condition, attribute and quantity of workers, and preference of the decision maker as well as some other outside conditions can be responded dynamically by the proposed model, which satisfies the daily requirement of power grid enterprise effectively. Furthermore, considering the characteristics of the model, a novel PSO with Solution Space Decomposition(PSO-SSD) algorithm was also proposed and applied to the path optimization. Simulation result shows that the proposed dynamic optimization model and PSO-SSD algorithm can obtain a good performance on different scale of problems, and provide the dynamic optimization of electric meters operation and maintenance task, which significantly improves the management efficiency of power grid enterprise.

Abstract:By improving the circuit structure and adopting the CMOS cross-coupled structure to provide negative resistance, a 20 MHz integrated quartz crystal oscillator was proposed. In this oscillator, the common-mode feedback was adopted to achieve stable DC output, and the RC high filter circuit and the pre-rejection circuit were designed to reduce the phase noise. With NUVOTON 0.35 μm CMOS process, the circuit was designed and simulated by the Spectre in Cadence. Under the supply voltage of 3.3 V and the bias current of 400 μA, the results indicated that start-up time of the oscillator was about 1.5 ms, the peak value of the output waveform was 1.08 V, the DC output was about 801.6 mV, the frequency of output was 20 MHz, and the phase noise reaches -155 dBc/Hz@1 kHz and -164 dBc/Hz@10 kHz, respectively.

Abstract:Base station is a major node for communication network's energy consumption. The accurate calculation of the energy-saving amount for the base station under EPC model is a technology bottleneck in this field. This paper proposed a modeling method of energy consumption of the base station based on particle swarm optimization (PSO) and least squares support vector machine (LSSVM) of sliding window, oriented at three kinds of typical scenarios base station. In this approach, a sliding window was established by selecting configuration parameters of base station and real-time data for pretreatment, and then the dynamic energy consumption model was obtained for the base station, which varied in accordance with that of the sliding window by means of the parameters for PSO training model and LSSVM regression training model. Compared with the simulation and test results from the sample base station, the proposed energy consumption model shows high prediction accuracy and generalization ability, and is applicable for the evaluation of energy-saving engineering of the base station.

Abstract:The basic principle of Compressed Sensing (CS) theory is that if a signal is sparse, CS promises to deliver a full recovery of this signal with high probability from far fewer measurements than the original signal. Unfortunately, image signals usually are not sparse, and thus it is difficult to obtain high compression performance for image compressed sensing.This paper proposed a simple and efficient zerotree compressed sensing method for images. In the proposed scheme, the classical zerotree coding is integrated into the process of measure to encode the precise locations of significant elements, which is used to restore the original image by the proposed pursuit reconstruction algorithm to improve the quality of the reconstructed image. The experimental results show that, compared with the existing matching pursuit algorithms and Embedded Zerotree Wavelet (EZW) coding algorithm, the proposed algorithm achieves much higher compression ratio and better image quality.

Abstract:In order to balance the utilization of multi-dimensional physical host resources and reduce usage number, a virtual machine allocation energy saving algorithm was proposed based on hierarchical topology tree (HTES) in the environments of distributed data center, which enhances allocation efficiency of the virtual machines. Laplacian matrix was then used to split large-scale network topology and to build hierarchical topology tree model. Furthermore, according to the distance between request IP address and the data center, HTES divided the virtual machines into groups, and searched the appropriate physical host region from hierarchical topology tree for allocation, which is based on the match degree between virtual machine requests and physical hosts. Simulation experiments were performed on HTES algorithms and other three algorithms, considering the virtual machine allocation time, resource balancing rate, energy consumption and physical host usage, and other aspects. The results shows that the HTES is able to balance multi-dimensional resources physical hosts, reduce physical host usage, and save energy consumption.

Abstract:For the simplification for the original trajectory sequence of the moving object collected from the mobile devices, this paper defined a kind of backtracking based simplification framework, which used the linear prediction and length of simplification queue to dominate the time of simplification, and simplified the original trajectory sequence between the present moment and starting time of a retrospective historical trajectory adopting the method of temporal distance as the error metric. In the backtracking based simplification framework, this paper first utilized the new reduced points to construct several vectors and predicted the velocity, which could narrow the gap between the prediction and actual velocity in the future. This paper then utilized the point sets to store the edges in the directed acyclic graph needed in the access to reduce time complexity of the algorithm. The first experiment shows that the reduction rate using the optimal velocity prediction is greater than that of the original velocity prediction with the high fluctuant trajectory data. It suggests that the predicted velocity is closer to the actual velocity in the future moving direction than that in the tangent direction. The second experiment shows that the time performances of the optimized simplification algorithm are improved. This study shows that the reduction of the visits of the edges can decrease the time overhead of the algorithm.