Abstract:The smart manufacturing CPS throughout the world, being it the I4.0, China 2025, or, FoF drive, is so much focusing on the ability to reconfigure the system smartly and seamlessly via OTA (over the air). The legacy connections equipped in machines, factory systems, manufacturing execution systems, to even the resource plan- ning system have to be transformed towards a universal dimension in order to be really able to achieve ultimate benefits for each subsystem being designed for its purpose. Data is the common language among them. The data platform realizes seamless and robust interconnection between the CPS IoT and cloud data platform by use of wireless sensor and its network. Distributed wireless sensors have been widely used for sensing and monitoring in space, human, environment, automation, military, structure and building applications. With the advancement of technology, such devices have become even smaller and cheaper, making them even more attractive to use. How- ever, the operational sustainability is a major concern for such batteries powered devices, requiring regular changing of fresh batteries.

Abstract:The prediction method for the coexistence of the rail rolling contact fatigue (RCF) crack initiation and wear growth was applied to analyze the influence of axle load on RCF crack initiation and wear growth. The high rail with a small radius of 800 m and a material of U75V heat treatment was taken as the research object. This study found that as the axle load of the vehicle increased from 23 t to 30 t, the average wear rate of the rail in- creased from 3.813 2 μm/104 to 4.208 3 μm/104 cycles. The average cumulative fatigue rate was from 0.019 5/ 104 cycles to 0.028 8/104 cycles and the initiation life of crack reduced from 3.18×105 cycles to 2.31×105 cycles. For each additional ton in axle load, the average rate of wear increases by 1.48%, the average cumulative fatigue rate increases by 6.81%, and the initiation life of crack decreased by 3.93%.

Abstract:OGFC slabs with the same mixture design were treated by SHRP aging, water damage, and self-de- veloped aging+water damage coupling environment simulator. Then, rutting tests were applied to the environment treated specimens, and cylindrical specimens with a diameter of 50 mm were cored from the tracking sites of rutting wheel. The void and sound absorption properties of these cylindrical specimens were tested and their re- lationships were analyzed. The results showed that the peak acoustic absorption coefficient correlates better than average acoustic absorption coefficient to the void content and the connected void content. In addition, by com- paring with previous studies, it is concluded that the environmental treatment conditions in this study have no significant impacts on the voids, connected voids and the peak acoustic absorption coefficient of the specimen. It is more effective to use the peak acoustic absorption coefficient to represent the connected voids of OGFC mix- ture under the action of environment and vehicle load.

Abstract:Based on the three-dimensional constant incompressible viscous flow field NS and the equation turbu- lence model, the finite-volume numerical simulation method was used to analyze and calculate the local flow field structure and pressure wave distribution of a 350 km/h high-speed train operating on the long-haul lines and extra long double-track railway tunnels. The study finds that the distribution structure of the air flow field is complex and irregular. As for the train, the static pressure on the side of the train approaching the tunnel is greater than the static pressure on the side near the tunnel center line and the pressure fluctuation on the side of the front windward side. The phenomenon is more obvious, and the static pressure on both sides gradually de- creases along the length of the train; As for the tunnel, the static pressure on the side of the tunnel with the train running and on the side without the train gradually increases along the length of the train, then it drops at the head of the train and gradually descends at the rear of the lee side train. The sudden increase reaches a maxi- mum value, then gradually decreases and tends to be stable. The static pressure on the inner profile of the train is located near the driver's cab of the train head along the length of the train. The phenomenon of pressure fluc- tuation is obvious, and the pressure fluctuation on the windward side is more obvious. The leeward side is more prominent, and there is almost no pressure fluctuation in the no-vehicle side, and the profile static pressure dis- tribution is gradually stable along the bottom of the tunnel toward the top of the tunnel.

Abstract:Through the analysis of vehicle ACWS principle on the basis of single-line laser radar, the AACS performance of hazardous material transportation vehicle was tested and evaluated in accordance with EU(Euro- pean Union)standard ECE R131 and national standard GB/T 33577-2017. The test results show that AACS can effectively remind the driver or take automatic emergency braking measures at the same time to avoid the for- ward or rear-end collision when the hazardous material transportation vehicle has the risk of the forward or rear- end collision. Meanwhile, the existing problems in AACS based on single-line LiDAR were pointed out and rel- evant feasible suggestions were proposed.

Abstract:This paper quoted the Kirchhoff elastic thin plate theory to analyze the roof stress of frame culvert which traversed the railway subgrade. Taking a certain frame culvert of national highway traversing railway sub- grade in Nanchang as the research object, the expression of deflection was set in the form of a double trigono- metric series which were divided into general solution and particular solution to calculate the stress of frame culvert under the load of overlying soil and the load of train. The general constant of the general solution in the expression was determined based on the boundary conditions of the rectangular thin plate. Mathematical comput- ing software Wolfram Mathematica was used for theoretical calculation and the commercial software ABAQUS was adopted to set up the finite element model. The theoretical values obtained from the calculation were com- pared with those obtained by finite element analysis, and the comparison results were in good agreement. It is concluded that this theory can better meet the engineering needs of precision and it is proved that this method has good practical value in the analysis of the stress of frame culvert roof.

Abstract:The characteristics of hot-in-place recycling technology include open construction, unstable construc- tion temperature, uneven gradation and asphalt properties, which cause the pavement quality to be greatly influ- enced by three factors such as rolling temperature, rejuvenators and warm mixing agent. The key problem of pavement quality is moisture stability, whose main indexes include the freeze-thaw splitting tensile strength, the splitting tensile strength, and the freeze-thaw splitting tensile strength ratio. The orthogonal test method was used to calculate the degree of influence of factors by using the range and variance analysis, and the change rule of the evaluation factors and moisture stability was evaluated by the regression of the nonlinear model. The results showed that effects on freeze-thaw splitting tensile strength and splitting tensile strength ranked as rolling tem- perature > rejuvenators > warm mixing agent. However, effects on freeze -thaw splitting tensile strength ratio ranked as rejuvenators > warm mixing agent > rolling temperature. The cross model was used to regress the rela- tionship among rolling temperature, rejuvenators, warm mixing agent and water stability index, which may be ap- plied to measure the actual rolling temperature at the site and estimate the optimum content of rejuvenators and warm mixing agent to ensure the moisture stability of recycled asphalt pavement to meet the requirements.

Abstract:The large foundation investments for civil aviation transportation have long construction cycles and are fiercely proprietary. The quantity of fixed investments should match the scale of civil aviation development. Sci- entific demand forecasting is the basis for rational planning of civil aviation infrastructure and fleet construction. The principle of system dynamics is used to analyze the internal and external factors of air passenger demand, and to build the system dynamics model of China's civil passenger transport market demand forecast. The con- siderations are more comprehensive and the accuracy is improved obviously. Using the model built, based on China's economic and social development level, it is predicted that China's air passenger demand will reach 1 billion people in 2024. The system dynamics model of civil aviation passenger market demand has universal app licability and long-term effectiveness for the prediction and analysis of long-term derived civil aviation trans- portation demand.

Abstract:At present, China's rapid development of e-commerce has led to an increase in urban logistics distri- bution, which has aggravated urban traffic congestion. Correspondingly, urban traffic congestion also seriously af- fects the punctuality rate and service level of logistics and distribution. In order to alleviate the traffic congestion caused by logistics, this paper transfers the ground logistics to the underground, proposes the underground logis- tics distribution mode based on the subway, analyzes the transfer time coordination between the underground lo- gistics and the ground logistics, and introduces the time cost penalty function of the accumulation of goods at the ground transshipment point. Based on the lowest total cost as the objective function, an optimization model based on the subway with time window underground logistics path is established. The genetic algorithm is used to opti- mize the path and the algorithm is implemented in MATLAB. Finally, by taking Nanjing as an example, the model is used to obtain the optimal path and the optimal cost scheduling scheme.

Abstract:Railway crossing safety is an important link for ensuring the safety management of railway operation. However, there are many influencing factors and management difficulties, which make it difficult to prevent re- lated accidents. Aiming at the frequent occurrence of railway crossing accidents, this paper analyzed these five main factors causing the crossing accident safety, such as people, vehicles, crossing characteristics, safety pro- tection devices and environment. Then, it established the crossing safety evaluation index system, introduced the principle of multiple connection number set pair analysis, established the application model of multiple connec- tion number set pair analysis method in crossing safety evaluation, and took China Railway X Bureau Group Co., Ltd., as an example. Based on the background of the railway crossing under the jurisdiction of this unit, the "sit- uation" of crossing safety was probed into and the applicability of the model was verified, and a new method for quantitatively judging the crossing safety evaluation system was proposed.

Abstract:In order to evaluate the operation status of urban traffic network dynamically, based on the two-fluid theory, the two-fluid service level parameter n is deduced and analyzed by introducing traffic flow theory and lo- gistic growth model. It is found that the value of n is not unique because the influence of network speed distri- bution is not taken into account, so the operation status of the network could not be evaluated well and accurate- ly. Based on the basic assumption of the two-fluid theory and the dynamic OD matrix, a new real-time dynamic evaluation method is proposed, which takes the parking time ratio f_s as the index. The simulation results show that this method can avoid the shortcomings of the two-fluid theory in evaluating the road network with parame- ter n, and better evaluate the real-time operation status of the road network. The operation status of the network is better as the ratio f_s decreases. The validity of the evaluation method is verified by an example of Nanjing road network of trunk line.

Abstract:With the rapid development of the Internet, the e-commerce markets of fresh fruits have attracted the attention of investors and consumers. In the fierce market competition, customer satisfaction is one of the impor- tant factors affecting the competitiveness of enterprises. Based on the characteristics of fresh fruits, the customer satisfaction was analyzed with freshness of fruits and timeliness of distribution as the indicators firstly. Then, the mathematic model of the location -routing problem based on classified customer satisfaction was developed. Meanwhile, the genetic algorithm for solving the model was designed. Finally, the model was validated through a case study and numerical analysis.

Abstract:Under fire, the concrete structure is damaged in different degrees, which makes the bearing capacity of the component decrease continuously. It is beneficial to avoid the risk to study the bearing capacity of the rein- forced concrete structure at high temperature. A cellular automaton temperature diffusion model was established to explore the distribution of temperature field and analyze the damage of materials. In this paper, the residual bearing capacity of normal section and oblique section after the fire were analyzed through the study of three sides of fire beams and four sides of fire columns. By comparing with the finite element calculation, it is proved that the calculation model of residual bearing capacity proposed in this paper is accurate.

Abstract:The study of the mechanical properties of engineering materials such as cement paste and cement mortar has become increasingly important with the needs of engineering applications. In this paper, the three- point bending beam test for the U-shaped notched beam specimens with three types of strengths, groove depths and groove root radii were carried out with a new fracture criterion_the theory of critical distance, which consist of 27 combinations in total. Theoretical parameters were obtained and verified by formula calculation and finite element simulation, and a new formula for calculating the maximum load of the notched beam was derived. The observation shows that for the maximum load, the calculated value of the new formula has good precision. The strength of mortar increases, while the theoretical parameter L value increases.

Abstract:Due to large-scale unloading, excavation above the tunnels may cause soil resilience and the deforma- tion to the metro tunnels, which threaten the operation greatly. How to reduce the influence of excavation, and decrease the vertical deformation of tunnels is very important. In this study, a 3-D model for channel excavation was established in ABAQUS. The influence of the excavation sequence on the vertical deformation of tunnels was analyzed in details. The results show that it is a reasonable excavation sequence to excavate the soils above shallow tunnels and the tunnels with little spacing first. The symmetry of excavation area should be paid atten- tion to. Moreover, the excavation sequence is given as references for similar projects.

Abstract:In order to simplify the management of certificates and keys, improve the computation efficiency and the security of the certificateless signcryption scheme at the same time, Chen Hong, et al. proposed a certificate- less signcryption scheme of verifiable security without pairing and claimed that their scheme satisfied confiden- tiality and unforgeability in the random oracle model. Unfortunately, by constructing three types of attacks, the study indicated that Chen Hong’s et al. certificateless signcryption scheme could not resist the public-key sub- stitute attack, the master key and partial private key exposures attack, and the collusion attack. Finally, the causes of the vulnerabilities were analyzed, and the improved scheme was proposed.

Abstract:Since catenary is an associated system consisting of many components, the influence and difference between components should be taken into account in catenary maintenance. In this study, opportunistic mainte- nance model of catenary was established by interval mathematics, and it was transformed into a maintenance de- cision-making optimization problem based on reliability sensitivity. The objective of optimization was to minimize maintenance cost, and the constraints of reliability sensitivity of components and reliability index of catenary op- eration were taken as constraints. The optimal solution algorithm was used to optimize the opportunistic mainte- nance intervals of different components of the catenary. The results show that the optimization model of catenary maintenance based on interval mathematical method can effectively reduce the maintenance cost of catenary and provide guidance for catenary operation and maintenance on the basis of ensuring the reliability of the catenary system.

Abstract:Aiming at the problems of lacking data confidentiality protection, weak computing ability and limited bandwidth in real-time data transmission of power wireless sensor networks, an ultra-lightweight stream encryp- tion scheme was proposed. It consists of three parts: key creation, encryption and decryption. Furthermore, a data encryption transmission protocol for power wireless sensor networks was designed. Besides, the key implementa- tion code and simulation were given. The simulation results show that compared with other algorithms, the effi- ciency is greatly improved and the difficulty of implementation is lower, and it is suitable for the secure trans- mission of data in the application scenarios where the computing power of power wireless sensor network devices is relatively weak.

Abstract:Aiming at the problems of AC side decoupling circuit control in photovoltaic grid-connected power generation system, DSP digital control and 74 series chip analog control were used in the system control at the same time in this study. On the basis of lower hardware cost, the control of micro inverter decoupling circuit can be better realized. It summarized the advantages and disadvantages of the DSP, FPGA and DSP + FPGA con- troller. The power coupling circuit simulation control circuit was designed by taking 74L chip as the core and referring to the double CPU design on the basis of the relevant innovation improvement and the experimental platform was established. The results show that the design is feasible, providing a new perspective for the cou- pling circuit of micro inverter control.