Abstract:Turnout of Beijing-Shanghai high-speed rail was selected as the research object of turnout rail disease grinding.This paper analyzed the geometric relationship of grinding wheels/rails, and the dynamic characteristics of high speed train before and after grinding. The results show that the working edge of turnout rail appears to be angular, and double light band appears on the rail surface. The conicity of wheel/rail equivalent is not within the ideal range. When the train passes through the middle region of the turnout, the dynamic characteristics of the high-speed train are better improved, but when the train passes the front and the back regions of turnout, the dynamic characteristics of the high-speed train are not as good as that before being polished. It is suggested that the wheel/rail relationship should be fully taken into account in the grinding of high-speed turnout in addition to the rail surface diseases grinding.

Abstract:Taking K6 wheelset of railway freight car bogie as the main research object, the Simpack multi-body dynamics model was established. By setting the corresponding wheel diameter difference, the change of wheel/rail vertical force, transverse force and lateral displacement with the change of wheel diameter difference was emphatically analyzed, and the corresponding relationship of wheel/rail force corresponding to different wheel diameter difference was analyzed. Analysis results show when the wheel diameter difference appears, wheel vertical force and lateral force on the contact surfaces have the corresponding difference, and the difference increases with the increase of wheel radius. The lateral displacement of the wheelset with wheel diameter difference also increases with the increase of wheel diameter difference, and within a certain range, the variation difference is basically linear with the wheel diameter difference.

Abstract:The large -diameter shield tunnel is usually designed to be many segment blocks and the ratio of thickness to diameter is smaller. A similar model test is conducted to study the influence of segment thickness on the force and deformation of a large-diameter shield tunnel. The results show that, increasing the thickness of segments can effectively reduce the convergent deformation of the tunnel under overload condition, whilesuch ef- fect will gradually decline with the increaseof segment thickness. The increase of segment thickness can alleviate the problem of concrete cracking at the arch roof and bottom, but the stress state of tunnel section will be changed into large eccentric from small eccentric. And too large segment thickness is not conductive to bearing capacity for the tunnel structure. The growth of the segment thickness has the most obvious effect on the internal force of the arch waists, followed by the arch roof and arch bottom of the tunnel, and there is no significant in- fluence of internal force on other parts of the tunnel.

Abstract:Before accurately evaluating the current situation of a regional road network's guide sign system, the current situation should firstly be investigated and relevant data should be collected. Then, aiming at the existing problems, an evaluation structure model was constructed. The criterion layer of the model consisted of three main factors, such as correct selection of information, no interference and continuous information, while the scheme layer of the model was made up of ten small indicators. Then, the method of AHP was used to match the corre- sponding weights of each index, and the score of the road network-level guide sign system could be calculated with its current situation evaluated. Based on the evaluation results, the paper further evaluated the strength of the revamping. Indicator sign system of single road can also be evaluated with the same method, and evaluation results of road level may guide its construction and transformation. The reliability and applicability of the evalu- ation index system were verified by the case study of Huangpu District, which proved that the evaluation system could make a scientific and reasonable evaluation. AHP method is widely used in engineering, industry, manage- ment, commerce and other industries, but there are not many studies on the evaluation of guiding sign system, so the study has a certain foresight and reference.

Abstract:Reasonable method of replacing bearings can ensure bridges with obvious bearings diseases to be safely used after maintenance. If the bearings can be replaced under traffic in short time，the influence of con- struction on the traffic can be reduced. In this paper，a method of single-pier jacking-up for replacing bearings is studied，and 27 bridges in a highway in Guangxi Province are taken as examples. The bridge's service condi- tion such as the existing stress at the control section of beam is obtained by finite element analysis and the in- spection and investigation of the bridge construction and maintenance history. Then the stress caused by the dif- ferent height of single -pier jacking -up under different traffic conditions is analyzed. The paper optimizes the method by comparing the result of the present stress in key control section. Finally，it draws a conclusion that if the existing stress of the bridge is appropriate，the method of single-pier jacking-up with reasonable traffic con- trol can replace bearings with no harm to the beam and less influence on the traffic.

Abstract:Based on complex network theory, the route networks of the three major airline alliances (Star Al- liance, SkyTeam, Oneworld) are taken as the research objects. The topological characteristics and robustness of the three alliance networks are compared and analyzed. The results include the following points: the route net- work of Star Alliance radiates the largest number of airport nodes with the largest average degree；the three major alliance networks all have scale-free features and small-world network effects；the robustness of the three al- liance networks is better under random attacks, and weaker under deliberate attacks；no matter underdeliberate or random attacks, the robustness of Star Alliance network is better than that of Sky Team and Oneworld. This study may provide a theoretical basis for the optimization design of alliance route network.

Abstract:The competition between parallel flights is becoming increasingly fierce. In this study, to improve the airline’s revenue, the flights and the passengers were separately modeled in the ticket sale system. The problem of dynamic pricing of flights was modeled as Markov game, and the Logit choice model was used to model for the mixed-type passengers. The multi-agent reinforcement learning was adopted to solve the problem in reality. The results indicated that the number of convergence for WoLF-PHC algorithm was more than that of the Nash-Q, but the WoLF-PHC algorithm had higher convergence frequency with strong adaptability. In addition, the pricing strategy of flight ticket sale process was different from that of other perishable products, which generally reflected an upward trend. The pricing strategy would also be adjusted with the modification of environment parameters of passengers. The pricing policy obtained by WoLF-PHC algorithm has positive effects on improving revenue.

Abstract:In view of the problem of reasonable transportation planning in the passenger transportation channel, the sharing rate of passenger transportation modes in the Nanchang-Jiujiang transportation corridor is studied in this paper. Firstly, according to the Delphi method, the main factors affecting the mode of travel are determined and the utility function and nested logit model are established. Secondly, the parameters of the model are cali- brated by TransCAD, and the contents and statistical results of the questionnaire are analyzed by SPSS software. Finally, based on the combination of the survey results and the sharing rate model, the sharing rate of the four modes of transportation in the Changjiu passenger transport channel is calculated. The calculation results are ba- sically consistent with the survey results, which proves the applicability of the model, and provides suggestions for the development of the transportation industry by analyzing the preferences of passenger travel choices in the future passenger transport corridor.

Abstract:Under the context of alliances, airline products have complex attributes and high risk of cooperation compared to individual flights. Differences in product attributes lead to different market share. Airline alliance partner selection and collaborative value calculation are based on accurate forecasting of airline market share. Therefore, based on the QSI (Quality of Service Index) indicators of Delta Airline, this paper made full use of the alliance transportation data and added indicators such as route competition degree and alliance cooperation rela- tionship to establish market share forecasting for international alliance route products. When fitting the nonlinear relationship between the eight factors and QSI value, considering that the parameter method needs to determine the form in advance, it introduced BP neural network to fit the nonlinear relationship between market share and factors. In order to solve the problem that the BP neural network falls into the local minimum value, the particle swarm optimization algorithm was introduced to determine the initial weight of the neural network and finally the QSI model of the PSO-BP algorithm was established. The results show that the QSI model based on PSO-BP al- gorithm can better predict the market share of international routes and the absolute error is below 1%.

Abstract:In order to ensure the safety of vehicle driving，an active obstacle avoidance system for intelligent ve- hicles was built in this study，which included four parts：environmental perception，dangerous situation assess- ment，path decision-making and control execution. Based on the improved artificial potential field model，a path planning module was constructed which consisted of the road boundary repulsion potential field，dynamic obsta- cle repulsion potential field and gravitational potential field. At the same time，the front wheel declination was used as the control variable to establish the vehicle dynamics model，and the model prediction algorithm was used to track the planning path. The results of the joint simulation of CarSim/Simulink show that the established model predictive control is better than the driver's preview control，which has better tracking effect on the path and improves the tracking accuracy，and finally realizes the active obstacle avoidance of the automobile.

Abstract:Taking the cascaded H-bridge rectifier (CHBR) of power electronic transformer (PET) in the traction drive system of the new electric locomotive without power frequency transformer as the research object, the CHBR mathematical model of power electronic transformer is established. Based on the theory of instantaneous power, a new type of power electronic transformer CHBR DC capacitor voltage balance control strategy is pro- posed. At the same time, the unit power factor of the system under non-ideal traction network voltage is realized. Finally, the computer simulation software is simulated by Matlab / Simulink, and the simulation results show the effectiveness and superiority of the proposed control strategy.

Abstract:Due to the high frequency change of the membership relationship of the substation-line-transformer, the relationship of the substation-line-transformer is complex. This paper designs a method based on FM-EEMD signal decomposition to identify the line-dependent relationship. The method makes use of the characteristics of the carrier signal, such as small shunt ratio at the low-voltage side load and other branches, and large shunt ra- tio at the medium-voltage side of the transformer of the correct branch. By injecting a carrier signal of a certain frequency into the 0.4KV side, the strength of the carrier signal at medium-voltage side is detected to identify the substation-line-transformer relationship. In this paper, the signal of the medium voltage side is decomposed by the FM-EEMD method and the line change relationship is identified by analyzing the carrier signal which is obtained by FM-EEMD. Simulation and experiments show that this method can extract carrier signals effectively.

Abstract:Water is an indispensable resource for all living things on earth and plays a vital role in the process of human development. The configuration and design of nanoconfined water channels is one of the most critical steps in the molecular dynamics study of nanoconfined water. The flow of confined water in micro-channels often presents a different form from traditional macroscopic fluid mechanics. This paper focuses on the configuration and design of nanoconfined water channels based on carbon-based materials. A systematic summary is conduct- ed based on the recent important research achievements in related fields at home and abroad. Then the applica- tion of nanoconfined water in fields of seawater desalination, medicine and energy is mainly introduced. Finally, the development prospect of nanoconfined water is discussed.

Abstract:Intelligent AC power electronic switch has a great advantage compared with traditional mechanical switch. There are high scientific researching and commercial values for developing a remote-controllable and re- liable and low-cost intelligent AC power electronic switch. Based on silicon-controlled rectifier (SCR), the intel- ligent AC power electronic switch is researched by internet and infrared control technology through mobile phone with excellent safety and humanization. The computer simulations and experimental tests are completed. The re- sults show that the design of the intelligent AC switch is feasible. Due to its safety and convenience, intelligent AC power electronic switch can replace the traditional mechanical switch and can be applied to smart home with the remote control of mobile phones. The circuit system is simple, reliable and easy to install with low cost and mass production.

Abstract:To solve the problem of identity authentication in microgrid system, a microgrid security login system based on SM2 smart card is designed. Firstly, with SM2 smart card as the core, the process of user identity au- thentication is described. Then the security of the scheme is analyzed. The scheme is characterized by anti-counterfeiting, anti-tampering and anti-replay. Finally, the system is implemented on the embedded development platform. The experimental results show that the system has a certain stability and efficiency, which has certain significance for the safe and stable operation of microgrid system.

Abstract:Aiming at the problem of lack of authentication between the public key and public key holder in the traditional certificateless signature scheme, a certificateless signature scheme based on key binding is proposed. And the security of the scheme is ensured by the random oracle model and the assumption of Inv-CDH difficul- ty. At the same time, efficiency comparison with other certificateless signature schemes is carried out. The results show that the scheme has certain advantages in computational efficiency which is suitable for applications of In- ternet of Things with limited computational power.

Abstract:Red clay is a typical special soil, and its characteristics of swelling in water and shrinkage in water loss will have a great impact on the stability of red clay foundation and subgrade. In order to further understand the physical and mechanical characteristics of red clay, the relationship between shear strength and water con- tent of remolded red clay in Jiangxi province is studied experimentally in this study. The indoor direct shear test results show that with the increase of water content, the shear strength and cohesion of red clay decrease, the variation curve of cohesion and water content is similar to " S" type, while the internal friction angle fluctuates within a certain range, and the influence mechanism is more complex. According to the analysis of X-ray diffraction test, the mineral composition of Jiangxi red clay mainly includes Shi Ying, mica, potash feldspar and a small amount of iron oxide as cementing material. Through scanning the soil sample with electron microscope, it is found that the microstructure characteristics of red clay have changed greatly after shear failure, which indi- cates that the change of microstructure of red clay after shear makes the soil deformed or even destroyed.

Abstract:Screw-driving dispensing system is widely applied with the advantages of high precision and extensive use of fluid. Based on the flow rate dynamics model of screw-driving dispensing system，the influences of operat- ing setting time，bulk elastic modulus of fluid and index of non -newtonian fluid on the dynamics of flow rate were analyzed. It is proved that the longer the system operating time is，the more stable the system is；the stronger bulk elastic modulus and index of non-newtonian，the slower the velocity transient response. Comparing simulation results with experiment results，it is revealed that integration of the flow rate can be used to predict the volume of fluid dispensed with the error less than 5%.

Abstract:Considering the traffic flow characteristics near the on-line bus stop, a three-lane cellular automaton vehicle lane-changing model is established by optimizing car-following rules and lane-changing rules. The mod- el is based on the STCA model and emphasizes the bus priority. Using the established model, the road traffic operation of dedicated bus lane (DBL) and intermittent bus lane (IBL) is partially simulated. In light of the lane change frequency of vehicle and the departure frequency of buses, this paper makes a comparative analysis of the fundamental diagrams, time-space evolvement, average speed and speed stability, and further explores the applicable traffic conditions of IBL strategy. The results show that when the vehicle density is greater than 20 veh/km and the departure frequency of buses is less than 200 veh/h, IBL strategy is better than DBL strategy. At this time, some social vehicles are allowed to enter and leave the bus lane. Although the lane change frequency of vehicle is higher, it has no negative impact on the traffic flow of the section. Instead, it can improve the traffic efficiency and the utilization of road resources, and ease the traffic congestion.