Abstract:The different PID control strategies of waste-gate were used under different transient conditions to establish the transient calculation model of turbocharged gasoline engine. The transient response under constant torque acceleration and deceleration conditions was simulated and compared with the transient response of original engine. The results show that the transient response is improved remarkably when the transient control target value takes the greater boost pressure at each fixed speed. In constant torque deceleration condition, transient response time is shorten when using the strategy that makes the waste-gate fully open in early stage until the speed reaches 1.25 times of the target speed, and then switches the control target to the boost pressure. At the same time, this way not only improves the transient response performance of the engine, but also prevents the turbocharger from surging and overspeeding under transient conditions.

Abstract:To analyze vibration performance of electric vehicle with switched reluctance motor, a filter white noise method was used to describe the road excitations of front wheel and rear wheel based on time correlation between front wheel and rear wheel. A linear model was applied to describe the vertical excitation of switched reluctance motor, and in-wheel motor electric vehicle vibration was determined by a six degree of freedom plane system of vehicle. In the urban driving situation of B grade road and speed range, electric vehicle vibration was studied by simulation analysis under the action of road and switched reluctance motor. The results show that low speed has a big influence on the wheel accelerations and wheel dynamic load, while high speed has a great influence on seat accelerations and suspension dynamic deflections under the presence of the same directional motor eccentricity condition of the front wheel and rear wheel.

Abstract:A novel type of automatic transmission named Overrunning Clutch Shift-assistant Transmission (OCT) was designed in the paper, which realized the shifts by the alternative work of friction clutch and Overrunning Clutch. Dynamic model of a 2-speed OCT was built to discuss the driveline vibration during shifts. Control strategy of the friction clutch and power source was presented in this paper, which was also verified by both simulation and test results. The results also show that the control strategy can make both upshift and downshift smooth, and jerk of the shifts is below 10 m·s-3.

Abstract:To study the vibration of the automobile transmission, the third gear of the automobile transmission was taken as the investigated subject. MASTA was used to carry out the load spectrum analysis. To optimize the module and helical angle of the third gear, the capacity ratio and the size of the gear transmission system of the third gear were improved. The new modulus and helix angle were obtained by the optimum design. Considering the gear meshing stiffness, backlash, bearing clearance and transmission error, a bending-torsion coupled nonlinear vibration model with 6-degree-of-freedom was established by the lumped mass method. The vibration characteristics were analyzed in detail. In order to compare the vibration characteristics before and after optimization intuitively, a method of translating the time-domain signal into the frequency domain signal was proposed by Fast Fourier Transform. The comparison of the frequency spectrum shows that the vibration characteristics are improved obviously. In particular, the reduction of vibration in z axial reaches about 1/4. It provides a theoretical basis for the vibration optimization of the automobile transmission.

Abstract:The vehicle Electronic Stability Program (ESP) can effectively improve the vehicle stability under extreme driving condition. However, traditional Direct Yaw Control (DYC) does not consider the adhesive limitation of tire forces. In order to overcome this shortage, a novel ESP algorithm was proposed based on Tire Dynamic Force Estimation (TDE) in this paper. Combined with Active Front Steering (AFS), this algorithm can make the maximum use of available tire forces. Based on multiple variables regression algorithm and polynomial fitting, a TDE controller was designed to obtain the tire adhesive boundary and the upper limit of optimal dynamic slip ratio. Based on fuzzy logic algorithm, an AFS controller was designed to compensate the insufficient yaw moment caused by adhesive forces limitation. This developed algorithm was verified through simulations, and the results show that the proposed novel ESP can significantly enhance the cornering stability by collaborative control with the AFS. Meanwhile, the proposed algorithm can significantly reduce active braking force of the wheels and alleviate undesired impact on the vehicle longitudinal speed.

Abstract:In order to overcome the difficulty for the parameters identification of occupant restraint system caused by the measured uncertainty, this paper proposed an uncertain identification method for the parameters of occupant restraint system based on Bayesian inference, which combined Markov Chain Monte Carlo (MCMC) sample and surrogate model. This method firstly obtains the prior distributions of identified parameters and measured responses, and then the MCMC sampling is applied to the joint probability density of unknown parameter. Then, the marginal posterior probability distributions of scale factor of webbing and rate of flow can be calculated. Compared with the traditional method of determined identification, the identified results show that the Bayes inference method for uncertain parameter identification not only obtains the probability distributions effectively, but also ensures the global convergence of identified parameter.

Abstract:As for the shortcomings of the existing methods of vehicle instability determination, the study on pattern recognition of vehicle running stability was carried out, and a new method of judging the vehicle lateral stability based on K means clustering algorithm was proposed. The vehicle dynamics model was established by CarSim, and the offline clustering centers and its danger level were obtained by offline clustering analysis of vehicle running state data through K means clustering algorithm. Then, the CarSim and Simulink co-simulation platform was built and Euclidean distance between data points and cluster centroids was also calculated. Vehicle running stability criterion in Simulink was designed, and the vehicle running stability online was identified. This identification method made full use of the comparison of offline data and real time data for data mining of the vehicle running data. The simulation results show that the method can accurately and real-timely quantify the vehicle's lateral stability considering various parameters, which can provide the criterion for intervention timing and degree of control system.

Abstract:Micro-grinding technology is able to achieve high-precision, high-efficiency and low-cost machining of micro-parts on hard and brittle materials. Based on the deeply understanding of micro-grinding mechanism, the cutting models of single abrasive particles including cone, sphere, triangular pyramid and rectangular pyramid were established, which took the radius of edge arc into account. The abrasive particle shape and distribution of the micro-grinding tool with Φ0.5 mm, #600 were observed and counted by ultra depth optical microscope VHX-1000. Then the micro-grinding force models based on single abrasive particle models and comprehensive abrasive particle model were established. The micro-grinding experiment was performed on the ZCuZn38 and the measured micro-grinding force was compared with that obtained from micro-grinding models. The change of micro-grinding force with process parameters was discussed according to the proposed micro-grinding force models. The results show that the micro-grinding force models based on single type of abrasive particles and different types of abrasive particles can predict the micro grinding force under various process parameters. However, the micro-grinding force model based on different types of abrasive particles has minimal error. The normal grinding forces calculated from different single abrasive particle models are close, but the calculated tangential grinding forces are obviously different.

Abstract:By considering the cutting and feed force, tension and band camber, a simplified force analysis mode was set up to investigate the failure pattern of bandsaw blade crooked cutting. The stress distribution and its variation trends of bandsaw blade were obtained through numerical simulation. The result shows that the stress in the tooth side is more likely to be pushed for the situation with larger workpiece, cutting force, insufficient tension and band width. Thus, the bandsaw blade is bent near the teeth tip, and then crooked cutting happens. Under the same failure standard and cutting parameters, when the tension of band increases from 130 MPa to 190 MPa, the cutting pieces were added by 177%. Changing the 27 mm bandsaw blade to 34 mm leads to nearly 50% more cutting pieces, but it is dropped by 83% when increasing the width of the workpiece from 80 mm to 240 mm.

Abstract:To study the cutting performance of disc cutter during breaking rock, the practical process of breaking rock by disc cutter was simplified. The particle discrete element method was employed to build two-dimensional numerical models considering friction when disc cutter broke the jointed rock and intact rock. The variation of cutting force, crack growth and rock breaking format in the simulation were analyzed. Rotation cutting test bench was adopted to conduct rock breaking experiments, the changing and the recorded cutting force of cutter was compared with the simulation force to verify the numerical model. The study can be concluded as follow: For intact rock, the increase of the cutter penetration can increase the main crack depth and rock breaking area, and the increase of the cutting speed can increase the cutter normal force but have little influence on the rolling force. For jointed rock, higher joint strength leads to higher crack depth and cutting efficiency. The joint direction of rock has a certain impact on the specific energy of rock breaking, and the rock breaking efficiency for forward direction jointed rock is about 12% higher than that for the reverse direction jointed rock. Lower joint angle leads to bigger specific energy difference between forward and reverse direction. Reasonable selection of the cutter head rotating direction can improve rock breaking efficiency.

Abstract:To solve the phenomenon of load sickness in which the transfer path of the weak load disappears by using the traditional topology optimization method, a simple and effective strategy of sensitivity hierarchical filtering was proposed. The loads were stratified by magnitude, and the strain energy corresponding to the structure was calculated. On this basis, two coefficients were introduced, which were used for comparison and amplifying the influence of strain energy. Then, the sensitivities were stratified on the basis of degree, and the sensitivity of different stratification was filtered by different filters to obtain the optimal material layout under multi-load. The strategy was proposed in the framework of SIMP and solved by OC method. Both two-dimensional and three-dimensional numerical examples were presented to show the effectiveness of the proposed strategy, demonstrating that the strategy can effectively overcome the phenomenon of load sickness, and provide important guidance for the completed structural force distribution of the structure.

Abstract:In order to solve the unstability of the core-annular flow in the transport of high viscous oil, this paper proposed a new core-annular flow generator, and explored the stability characteristics and optimization research of generator transmission characteristics. To simulate the core-annular flow under the condition of different thickness and to improve the stability characteristics by using spiral blade, the VOF model was used to simulate the flow. A numerical model of core-annular flow according to the principle of core-annular flow forming was established, and the correctness of the numerical model was verified by comparing the experimental results. The results show that the formation and stability of core-annular flow is not conductive when the thickness of the gap is too large or too small, and when the flow rate is 1 m/s, the core-annular flow generated by the generator gap of 1.4 mm in the pipe with the diameter of 19 mm is more stable, which means that when the ratio of the gap thickness to the diameter of the main pipe is 3∶20, the most effective result is observed. The use of helical blades can increase the stable length of the core-annular flow from 150 mm to 500 mm with an increase of 2.3 times.

Abstract:To identify the vulnerabilities of Cyber Physical Power System (CPPS) and formulate the corresponding prevention and control strategy, the models of two kinds of CPPS interdependent networks with different subnetworks were presented, in which IEEE 118 bus system was chosen as Power Grid and cyber networks adopted two typical structures: double-star and mesh, respectively. An index of comprehensive importance on interdependent pairs of nodes was proposed, and it was used to identify the key pairs of interdependent nodes causing large influence on CPPS structural vulnerabilities, which overcomed the limitations of single-layer network indicators. Based on the model of cascading failures in interdependent network, CPPS structural vulnerabilities were analyzed by using two extreme attack strategy: randomly attack and deliberately attack. The effect on CPPS structural vulnerabilities of Key Node Protection Strategy was considered. Simulation results indicate that, compared with double-star cyber network CPPS, the structure of mesh cyber network CPPS is more vulnerable under randomly attack. Under deliberately attack strategy, prior attacking pairs of interdependent nodes can cause more damage to network connectivity. CPPS structural vulnerabilities can be improved with selecting proper nodes of Key Node Protection Strategy.

Abstract:In this work, the dielectric functionally graded material (ε-FGM) was initially employed to improve the electric field distribution along spacer surface. Taking the permittivity distribution as the object, a global optimization algorithm was proposed in this paper, which usesd the maximum electric stress as a feedback to update the permittivity distribution. Using the APDL language incorporated in ANSYS combined with MATLAB, the influences of step length and layer number on the field were studied. The results show that the electric stress along spacer surface becomes smoother with the decrease of step length and the increase of iteration number. Correspondingly, the permittivity range is significantly enlarged. The high electric field area of spacer is shifted from the electrode and triple junction to the middle part, and the utilization ratio along the lower and upper surface reaches 0.75. The results provide useful references for spacer design.

Abstract:This paper constructed a model of VRB (all-vanadium redox flow battery),which is suitable for grid simulation.The external characteristics of VRB energy storage system were researched.Then an equivalent model of VRB energy storage system was proposed from the principle of external characteristic equivalent fitting and ignoring the reactive power of the VRB system.This equivalent model has a simple structure, less parameters,and can be identified easily.It can fit the external characteristics of VRB energy storage systems effectively in the case of large disturbance and continuous small disturbance of power system． The advantage is that it can simulate the output limit of the battery energy storage.A GSLM (Generalized Synthesis Load Model) was established in which the proposed VRB equivalent model is connected in parallel with the traditional load model considering distribution network parameters and reactive power compensation, the generalized synthesis load model multiplied with equivalent model is used to fitting the characteristics of power synthesis load containing the VRB energy storage systems.The examples show that, compared with the traditional integrated load model,the GSLM can precisely describe the integrated load characteristics of the distribution network with energy storage system,the greater the proportion of VRB in the synthesis load,the more obvious this advantage,and the parameter identification results of the model have good stability and comprehensive description ability.

Abstract:This paper presented an embedded system based on dual-core architecture to solve the contradiction between high performance and low power consumption of today fingerprint lock. TI's AM437x high-performance processor was used to transplant identification algorithm, with AVR microcontroller MEGA8 microcontroller of ultra-low power as a master chip to control non-contact start, infrared light, motor drive and other peripherals to ensure that the system has a lower standby power consumption. By setting the ultra-low power sleep mode of the master chip, the system is in a low power state for most of the time, and the non-contact start-up module controls the high power consumption identification module to power up only when it is needed, thus greatly reducing the power consumption. Comprehensive test shows that the static operating current is as low as 1.51 μA when the system is in sleep mode, while the wake-up current is optimized to 3.3 mA. The maximum system life of six dry cells is 638 days. Compared with the existing design methods, the system has both lower power consumption and higher performance.

Abstract:For the problem of image restoration of observed images corrupted by impulse noise, the widely used TVL1 model may deviate from both the data acquisition model and prior model, especially for high noise levels. To overcome this problem, based on MCP function, a new model called TV-MCP and its approximation method were proposed. It is proved that the approximation method converges globally to a stationary point of TV-MCP model. Alternating direction method of multipliers was applied to solve the approximation sub-problem. In the numerical experiments, TVL1 and TV-MCP were applied to the problem of image de-noising and de-blurring in the presence of impulse noise, which verifies the effectiveness of the proposed model and method. The results show that TV-MCP outperforms TVL1, especially for the high noise level image de-noising. The maximum SNR value of TV-MCP image restoration can reach 2 times that of TVL1 method.

Abstract:In view of the improvement requirements for accuracy and real-time performance of traffic sign recognition in natural scenes, an improved traffic sign recognition algorithm was proposed based on a multi-scale Convolutional Neural Network (CNN). At first, the comparison experiments on image enhancement methods was carried out, and contrast limited adaptive histogram equalization method was chosen as the preprocessing method to improve the image quality. Then, one kind of multi-scale CNN model was proposed to extract global and local features of the traffic sign images. Finally, the traffic signs were recognized after the combined multi-scale features were put into a fully connected SoftMax classifier. The effectiveness of the proposed algorithm was examined on the benchmark dataset---the German Traffic Sign Recognition Benchmark (GTSRB). The examination results show that the proposed algorithm can achieve 98.82% recognition accuracy and real-time processing with 0.1 ms per image on GTSRB dataset, which verified its superiority to some extent.

Abstract:It is difficult to detect the foreground targets accurately in the sequence images in the situation of moving background. According to the characteristics of the targets in moving backgrounds, a fast visual saliency-aided ViBe method was proposed. The “memory window” random sample consensus algorithm was first proposed to estimate the background motion model. Then, the compensated frames were delivered into the detection algorithm with adaptive background updating factor determined by the two-dimensional entropy and saliency of the image. The saliency was also used to suppress the “ghost” effect. Experimental results show that, in the absence of prior knowledge of the moving foreground targets, the proposed method can effectively detect targets in the situation of moving background, and it also has good robustness and high efficiency.

Abstract:In-network caching scheme is one of the key technologies of Content Centric Networking (CCN). In some existing CCN caching schemes, the dynamic information of cache state and load condition are not fully considered so that the differences of cache state between nodes cannot be reflected accurately, which affects the reasonability of caching decision. In this paper, a Cache Pressure Based Selective Caching Scheme (CPBSC) was proposed. In this scheme, the cache occupancy rate and cache replacement rate were used to estimate the cache pressure of node. According to the cache pressure and content popularity, the caching nodes were rationally selected. Meanwhile, the content replacement is implemented based on the cache value of content which is evaluated by the content request rate and the residual time to live of Interest packet. Simulation results show that CPBSC effectively increases the resource utilization and improves the whole cache performance.