Abstract:In view of the phenomenon that the large vibration of the car body floor leads to uncomfortable riding under the original hanging stiffness of a certain type of EMU, the optimal design of the hanging stiffness of traction transformer of the EMU was carried out. In the process of optimization design, the Latin hypercube design (LHD) method was used to sample. According to the sample data obtained, the adaptive response surface method (ARSM) was introduced to optimize the design of the suspension stiffness of transformer, which avoided the problem that the traditional response surface method was completely dependent on the original sample points. After the design optimization, the hanging stiffness of traction transformer was verified, and it was found that the vertical vibration acceleration of the car body floor was greatly reduced. The hoisting frequency was 9.0 Hz, which was much lower than the first vertical bending frequency of the rigid hanging car body. After modal analysis, the first vertical bending frequency was kept above 10 Hz, which conformed to the requirements of the modal matching for EMU.

Abstract:By designing the stiffness of elastic suspension for the transformer under an intercity train, the natural frequency range of the transformer system (suspension frequency) based on the vibration isolation theory was determined during the design process. Then, the design scope of suspension stiffness was obtained according to the suspension frequency range and different suspension stiffness was established. The frequency response characteristics of bodywork floor under transformer excitation and the running comfort of the vehicle under air spring excitation were analyzed and compared. According to the results of comparative analysis, the optimal suspension frequency of the suspension system was 5 Hz. By comparing the vehicle using this elastic suspension with the vehicle using rigid suspension, the vertical vibration acceleration of the bodywork floor was greatly attenuated and the running comfort of the vehicle was obviously improved, which indicated that the design method adopted was correct.

Abstract:In this paper, an adjustable rail of small radius curve with serious wear on the LonghaiLine is selected as the research object to conduct personalized grinding scheme design. The geometrical contact state of wheelrail is analyzed, and the dynamic simulation of vehicle-track multi-body system is established. The results show that: the rail surface of the adjustable rail, the rail surface light belt, rail wear rate and the track quality index TQI are significantly improved after grinding. Through the geometric analysis of wheel-rail contact, the equivalent taper and wheel-rail contact point are optimized after grinding, and the train operation stability and wheelrail contact state are improved. Through the dynamic simulation of vehicle-track multi-body system, the maximum wear power, the maximum wheel weight reduction rate and transverse acceleration of the vehicle body are reduced, and the wheel-rail wear characteristics, train operation safety and stability are improved.

Abstract:When the train passes the curve, the excessive swing angle of the coupler will seriously threaten the safety of the train. Therefore, the coupler angle must be checked when the train passes through curves. In this paper, the attitude position of the front and rear vehicles was given by analytical method, and the swing angle of the coupler was solved according to the relative position of the coupler. Finally, according to the algorithm, the swing angle of the coupler was calculated when the train passed through the horizontal curve and the vertical curve. It showed that under different working conditions, the maximum swing angle of the coupler appeared when the front and rear center pins of the two cars were in different directions. Under the curve-line working condi tion, the maximum swing angle of the coupler appeared when the two trains just entered the curve; under the Scurve condition, the maximum swing angle of the coupler appeared after the first position train completely entered rear curve and the center pin of the second position train was located in the line; under the condition of the vertical curve, the maximum swing angle of the coupler appeared at the slope point.

Abstract:On the linear section of the Hangzhou -Shenzhen passenger rail line, there exists alternating side grinding on the linear rails. When the EMU passes through the grinding section, the truck will be swayed in an unstable state. This paper studies this problem from the perspective of wheel-rail dynamics of long trains, and gives some harnessing measures about the alternating side grinding. By building a simulation model of trains based on MATLAB/SIMULINK software, the operation of the EMU through the existence of pure rolling line offset straight rail is carried out. It is found that the formation of alternate side grinding of the rail is affected by the wheel-to-pure rolling line offset. When the rail is unevenly worn due to factors such as asymmetric grinding, the pure rolling line of the wheel pair on the rail will be offset, which will cause the periodic polarization phenomenon of the train wheel pair, thus eventually leading to the overall lateral low-frequency shaking of the long trains.

Abstract:While air transport provides travelers with efficient and convenient flight services, the air pollution caused by carbon emissions from air transport has become a problem for worldwide attention, which also brings great pressure on China's civil aviation transport industry to reduce emissions. Effectively identifying the driving factors of carbon emission and analyzing the influence degree of each factor are the key to realizing emission reduction. Based on the calculation of the carbon emissions of China's air transport from 2000 to 2017 and the analysis of its evolution characteristics, the paper conducts an empirical analysis of the driving factors affecting the carbon emission of China's air transport through the deformation of Kaya identity and the use of logarithmic average index decomposition (LMDI). The result shows that the scale of economic development, industrial scale and population play a positive role in driving carbon emissions, while energy intensity and transport intensity play a negative role in restraining carbon emissions.

Abstract:To solve the problem of logistics UAV transportation path planning in low-altitude environment, considering the internal and external constraints of low-altitude planning airspace and physical performance, an improved A* algorithm is designed to plan the path quickly. To apply the method to the transportation for logistics UAV, the algorithm uses the grid method to model the environment. It also introduces grid’s danger rate and the cost of flight time and energy consumption in the cost function. At the same time, the dynamic weighting method is applied to estimate the function. The simulation results show that the algorithm can plan the obstacle-avoidance transportation paths with low risk and low energy consumption quickly under the constraints of the assumed environment and UAV performances. Also, its performance is superior to the original algorithm and ant colony algorithm. Meanwhile, the corresponding grid length and weight value of the optimized path are obtained, and the effectiveness of the algorithm is verified.

Abstract:In the process of airport operation research, non-expected output factors are often neglected. Meanwhile, the effective DMU can not be ranked further in researching the efficiency of airport operation. Therefore, this paper established Super-SBM model and selected 30 major airports in east China in 2017 as samples. This paper also divided the airport operation into two stages of airport service and passenger service. Then, it evaluated the airport operation efficiency and gave the ranking of the airports. Simultaneously, the necessity of introducing non-expected output and the advantage of Super-SBM model in solving the efficiency of airport operation was proved by the comparison and verification of calculation examples. It is found that the DEA-efficient airports were further differentiated. After introducing non-expected output, most of the airport operation efficiency of the sample airports has increased. Five airports have changed from DEA-inefficiency to DEA-efficiency and the operational efficiency of small airports has been significantly improved. Based on the Super-SBM model, this paper, researching airport operation efficiency from different stages, can provide guidance and help for airport operation.

Abstract:This paper investigates the impact of product differentiation and competition on the airlines entry decisions into international air market where the nonstop and transfer product coexist. Using the liberalizing transatlantic market as an empirical study, this paper establishes a Probit model. The results show that: 1) The product differentiation degree significantly influences airlines entry decisions; 2) When the market share of an airline preexisting one-stop product is larger, the probability that the airline opens new nonstop intercontinental routes is larger; 3)In a liberalizing market environment, airline alliances are also one of the significant factors influencing airlines entry into the transatlantic market. The results can provide theoretical fundamentals and decision support for carriers to open new international routes.

Abstract:The impact factor of airport passenger throughput usually has a lag period. After selecting the influencing factors, the paper determines the lag period of each factor by the random forest importance index. Then, a stepwise regression model for throughput prediction is established using the data of Nanjing Lukou International Airport from 1987 to 2018. Finally, the model effect is evaluated and the throughput of Nanjing Lukou International Airport in 2019 and 2020 is predicted based on the established model. The results show that the influence of impact factors on passenger throughput has a lag period ranging from 1 to 9 years. By comparing with the model without considering the lag period, it is found that the model fitting effect considering the lag period is better and the reduction is significant. Therefore, it is necessary to introduce the lag period into the airport passenger throughput forecast.

Abstract:With the rapid growth of China's electrified railway mileage, the safe and stable operation of catenary is facing tremendous pressure, so it is of great significance to monitor. In this paper, the avian hazards affecting the normal operation of the catenary of electrified railway were studied. Through the analysis and comparison of different depth learning models, DSSD model was selected to automatically identify the catenary of high-speed railway. At the same time, this paper used transfer learning method and Caffe platform to improve the generalization and stability of bird's nest recognition training network by fine-tuning the trained DSSD network under the condition of insufficient data set. The trained model has faster recognition speed and better robustness, which has important reference significance for the safe and stable operation of OCS.

Abstract:Aiming at the difficulty of accessing vehicles in underground garages for large buildings such as shopping malls, a guidance system for vehicle entry and exit is proposed in this paper by improved ant colony algorithm based on angle migration function and distance function. According to the actual demand, the system takes the free parking spaces, elevator positions and the number of curves of the guiding route as the optimization target, and plans the parking path closest to the elevator opening and the least number of turns under the premise of the shortest distance. Compared with the traditional shortest distance path planning algorithms, it has the characteristics of simplified path and higher efficiency, which is more in line with the actual needs of garage management.

Abstract:Aiming at the problem of complex mechanical structure and low digital level in the traditional driver controllers, a digital driver controller based on MCU was proposed and the corresponding prototype was developed. Non -contact absolute value photoelectric encoder was adopted to detect the position of traction/braking operation handle, and the software control mode was used to replace the traditional cam group control switch mode. At the same time, the RS-485 communication interface was introduced and the touch screen was used as the human-computer interaction interface to facilitate the driver's control. The results showed that the design can simplify the mechanical structure of driver controller and improve its digital level.

Abstract:In order to study the effects of Nano -cellulose on the high temperature properties and rheological properties of modified asphalt, the conventional technical indices of three different types for Nano -cellulose modified asphalt were compared. Then, the dynamic shear rheological test (DSR) was applied to analyze the rheological property of modified asphalt. The results indicat that Nano-cellulose can effectively improve the hightemperature stability, anti-rutting and anti-deformation performance of modified asphalt; the higher the Nanocellulose content is, the higher the performance of modified asphalt will be; TEMPO-oxidized wood cellulose has the best effect on improving the road performance of modified asphalt.

Abstract:Numerical simulations for the excavation of asymmetrical foundation pit is formed on both sides of soil mass near the subway station with the finite element software of MIDAS/GTS. In this paper, the deformation characteristics of the foundation pit of the semi-infinite soil body on one side and the semi-infinite soil body on the other side were analyzed in details. The comparative analysis was conducted with field monitoring data. It was found that under the typical stratum condition in Xiamen, the deformation of finite soil side of foundation pit was obviously less than the infinite soil side, and the influence range of the width of soil on finite soil side of the foundation pit was about 1.5 times of the excavation depth. Specifically, with the increase of the width of soil on the finite soil side of foundation pit, the heave values increased while the surface settlement and the horizontal displacement of pile on the infinite soil side of foundation pit decreased. The surface settlement and the horizontal displacement of pile on the finite soil side of foundation pit increased and the deformation of foundation pit gradually changed to the deformation when both sides of foundation pit were infinite soil sides.

Abstract:In order to study the transverse distribution change of hollow core slab bridge after reinforcement by transversal steel plate, a simply supported hollow core slab bridge was employed as an example. The field load test data of the bridge before and after reinforcement were compared with the theoretical results by hinged-joint slab method and modified rigid-joint slab method. It is found that the phenomenon of ‘single plate load effect’ can be clearly displayed by comparing the measured and calculated values of the transverse distribution ratios. As the trend line formed by the measured data was not smooth, the relative transverse distribution growth value was introduced in the paper. Although the cast-in-situ deck and transverse steel plate reinforcement enhanced the transverse stiffness, the measured transverse distribution ratios were in good agreement with the calculated values according to the hinge-jointed slab method. The results show that the theory of hinge-jointed slab method can meet the transverse distribution calculation before and after the strengthening of such bridges.

Abstract:Aiming at the disadvantages of low detection accuracy and collision efficiency of the traditional hybrid hierarchical bounding box, the concept of centroid in material mechanics was introduced. The location of centroid was used to determine the center of parent node bounding box. Then the tree structure of hierarchical bounding box was improved. AABB bounding box was used in the upper structure to ensure the renewal efficiency, and OBB bounding box was used in the lower structure to ensure the detection efficiency. Finally, the improved hybrid hierarchical bounding box collision algorithm was obtained. The simulation results show that the improved algorithm has a certain improvement in accuracy and efficiency, which may provide a the oretical basis for future research on collision detection.

Abstract:Aiming at the problem of information security interaction in the transmission of remote control for CNC machine tool, a secure interaction protocol for remote control of CNC machine tool based on signcryption is designed. By embedding the signcryption algorithm between client and CNC machine tool, the verifiability of information source can be realized, which can prevent information leakage and ensure the safe transmission. The experimental simulation proves that the protocol has high feasibility.

Abstract:In order to give full play to the scale benefits of clean energy, combine heat and power generation, electric heating energy storage system and controllable load, and to realize the coordination and complementarity of multiple energy sources, this paper establishes the model of combined optimal dispatch of heat and power in the integrated energy system. Based on the idea of bi-level parallelization and the principle of intermolecular interaction potential, a parallel molecular differential evolution algorithm is proposed, which can effectively balance depth and speed of optimization. Thus, the integrated energy system scheduling model can be solved quickly and accurately. Finally, the validity and superiority of the proposed method are verified by the calculation of the integrated energy system scheduling model.