Abstract:As a new type of semi-active controller, magnetorheological (MR) brake has been widely used in various braking occasions. In this paper, the working principle of the MR brake was described, and the improvement of the typical MR brake structure was analyzed in order to solve the problems of small braking torque and heat dissipation during operation. At the same time, on the basis of structural improvement, some different optimization methods were discussed. Finally, partial applications and future development issues of MR brake were introduced. The relevant analysis and conclusions can provide certain reference for the design of MR brake.

Abstract:The impedance of traction network is the basis of analysis and calculation of traction power supply system. In this paper, the penetration depth of electromagnetic wave in soil is calculated for the possibility of horizontal stratification of earth in the tunnel, and the impedance expression of overhead traverse and earth loop in the case of horizontal stratification of earth are derived. Combined with the two traverse systems in the tunnel, the conductor impedance is calculated and the variation rule is analyzed. The results show that the resistance of the calculation of the impedance of the traverseground loop is greatly affected by the first layer soil resistivity. When the thickness of the first layer of soil is less than 16 m, the resistance part of the impedance of the wireground loop is greatly affected, while the reactance part is hardly affected. It can be used as a reference to calculate the impedance of overhead traverse-ground loop when the ground is stratified.

Abstract:The classical traction network impedance calculation formula use the solid circular wire model and the Carson series method, but it is based on the power frequency (50 Hz) during the derivation process, which is not suitable for high frequency calculation. In order to accurately describe the high-frequency impedance characteristics of the traction network, the hyperbolic cotangent approximation and the Sunde ground impedance calculation method are used to summarize the calculation formula for the high-frequency impedance of the traction network. Combined with the scientific calculation and simulation of Python, the traction grid of the power supply arm of the east section of Shanghai-Nanjing Wuxi Substation is used as an example, and the relationship between the high-frequency impedance of the traction grid and the erection height and earth conductivity is analyzed. The results show that the conductivity and height of the earth have little effect on the impedance value under low frequency currents, but the effect of the earth conductivity and erecting height on the impedance of the traction network at the high frequency, especially when the frequency is higher than 10⁴ , cannot be ignored. In the simulation of high frequency or fast transient, the values of ground conductivity and erection height need to be accurate.

Abstract:In order to understand the change of internal temperature stress of the pavement in the cold region of Inner Mongolia and study the temperature stress behavior and structural performance for different base pavement in the cold region, this paper obtained the temperature stress of pavement in large temperature difference environment with daily temperature difference of 20 ℃, 30 ℃ and 40 ℃ by using Abaqus software and the sequential coupled-field method. The mechanical response of different base pavement under the coupled effect of dynamic load was analyzed. The results show that the combined base pavement has the best mechanical performance in the cold region with large temperature difference, and still has the advantage under the coupling effect of temperature and dynamic load. The temperature stress of each layer is the minimum, and all mechanical indexes are small under the coupling effect of low temperature and dynamic load, and the shear stress of asphalt layer is better under the coupling effect of high temperature and dynamic load.

Abstract:Corrosion of steel bars will lead to cracking of rubberized concrete and reduce the durability of rub-berized concrete. The variation of rust expansion reaction caused by corrosion of steel bars can roughly reflectthe cracking process of rubberized concrete. Therefore, in this paper, the reaction force caused by uniform corro-sion and expansion of a single steel bar in rubberized concrete is studied through meso numerical simulation.The results show that : With the increase of corrosion degree of reinforcement, the steel rust expansion reactionfirst increases and then decreases, and the time of the inflection point of rust expansion reaction corresponds tothe time of concrete cracking; With the increase of corrosion degree of reinforcement, the mortar in the upperhalf of the reinforcement is always damaged first; and the smaller the thickness of concrete protective layer, theeasier the rubber aggregate concrete cracks; The thickness of the protective layer remains unchanged, and thelarger the diameter of the reinforcement, the easier the rubberized concrete cracks; In the calculation model, thesize relation of the average rust expansion reaction of reinforcement corresponds to the rubber aggregate contentof 10%>5%>8%. The research results of this paper have guiding significance for the study of corrosion reactionof rubberized concrete.

Abstract:In order to study the influence of the pier structure on the seismic performance of the high-pier continuous beam bridge, the software Ansys was applied to establish three bridge models with various pier cross sections including solid rectangular thin -walled pier, double -column pier and hollow rectangular thin -walled pier to further analyze the dynamic characteristics and seismic performance of the models. The results show that the response results of the bridge pier under earthquakes of E1 and E2 are the same in the response spectrum analysis: the displacement of double-column pier top is larger than that of rectangular thin-walled pier, and the pier base bending moment is smaller than that of rectangular thin-walled pier. Under uniform excitation, the internal force at the bottom of a hollow rectangular thin -walled pier is smaller than that of a solid rectangular thin-walled pier, but the displacement at the top of the pier is larger; compared with the rectangular thin-walled pier, the internal force at the bottom of the double-pillar pier is smaller and the displacement at the top of the pier is larger. Through response spectrum analysis and consistent excitation analysis, it is found that the doublepillar pier can reduce the internal force response of the whole bridge structure when earthquake occurred which accord with the displacement calculation possessing excellent seismic performance.

Abstract:Based on the case of a deep soft soil foundation pit project in the Pearl River Delta region, this paper optimizes the method of row piles into the rock, and explores the effect of the row piles into the rock + skirt reinforced support method on the foundation pit deformation. A representative section in the middle of the foundation pit was selected, and a three-dimensional calculation model was established by using MIDAS / GTS NX finite element software to compare the horizontal displacement of row piles, uplift of the pit bottom, surrounding surface settlement, engineering cost and construction difficulty. Piling without rock and proper skirt reinforcement can effectively reduce horizontal displacement of piles, uplift of pit bottom, and surrounding ground settlement. After the depth of reinforcement exceeds a certain range, the effect on reducing deformation of foundation pit is not obvious; The cost and construction difficulty of the optimization scheme project are similar to the original plan, which can provide reference for similar engineering design.

Abstract:In order to improve the efficiency of bus operation and reduce the impact of bus emission on the environment, this paper proposes a new skip station scheduling strategy. The new strategy improves the efficiency of public transportation system by reducing the number of stops. This paper takes the operation of a single bus line as the research object, and makes decisions on the specific stops to be stopped. The optimization objective is the weighted sum of the proportion of the passenger travel time, bus operation time and bus emission to the original scheme. Given the OD arrival rate data of public transport, the genetic algorithm is used to solve the optimization model, and the optimal station skipping scheme is obtained. The final results show that the new scheme can reduce the travel time of passengers by 3.09%, the running time of vehicles by 0.92%, and the exhaust emission at the station by 4.4%.

Abstract:Aiming at the difficulty in predicting the duration of highway traffic accidents, a traffic accident duration prediction model based on factor analysis and back propagation neural network(BPNN) is established. Based on real traffic accident data collected from Baomao Expressway, factor analysis is utilized to extract the common factors influencing the duration of traffic accidents. The extracted public factors are taken as the input, and BP neural network is used to predict the duration of traffic accidents. The experimental results show that compared with the typical regression algorithm and the support vector machine, the improved BPNN method with factor analysis proposed in this paper can not only improve the prediction accuracy by7.8%, but also solve the problems of low data processing efficiency and slow iteration speed of traditional BP neural network.

Abstract:This paper investigates the temporal and spatial distribution characteristics of connecting time for Air China’s connections at its hub airport–Beijing International Airport (PEK) for domestic to international connecting flights. Three indicators, i.e., maximum connecting time, feeding ability and feeding utilization index,were proposed to characterize the indirect connections. A multivariate regression model was further established to study their impacts. The result shows that the threshold of maximum connecting time varies among different regions. Meanwhile Air China does not fully explore the nonstop flights of origin airports when creating indirect connections. The model shows that factors representing the characteristicsof connecting time have significant impacts on the number of indirect flights. The results will provide a theoretical basis for Chinese full-service carriers to build wave-system structureintheir hub airports.

Abstract:The effective identification and scientific decomposition of the driving factors are important foundation for formulating the airport’s aircraft carbon emission reduction policies. Taking nine civil airports in Jiangsu Province as the research objects, the total carbon emissions of aircrafts in the airports from 2007 to 2016 were calculated by using the landing and take-off (LTO) cycle calculation method recommended by ICAO; then the LMDI method was used to analyze the driving factors of the evolution of airfield aircraft carbon emissions from five perspectives including airport operation scale, emission intensity, unit revenue throughput, unit energy consumption income and unit LTO energy consumption. Finally, based on the results of factor decomposition, suggestions for reducing emissions were put forward.

Abstract:Aiming at the low confidence in the dynamic configuration ofterminal check-in system to minimize the sum of facility usage costs and passengers time costs, a multi -objective optimization method is proposed. The multi-objective algorithm was applied to the dynamic configuration process of check-in system. The optimization targets of counter operating costs and check-in waiting time for airlines and passengers were set respectively, and dynamic configuration model of terminal check-in system was built to configure the opening number of Disland check-in counters in the Nanjing Lukou International Airport Terminal 2 dynamically.The NSGA-Ⅱ algorithm was employed to obtain the Pareto optimal solution, at the same time, a posteriori evaluation based on TOPSIS was used to compare and analyze the different configuration schemes. Finally, the dynamic configuration results of the D-island check-in system for the whole day were obtained. The research effectively eliminates the difference between cost and time dimensions, which is beneficial for airlines and airports to achieve unique optimization strategies and provides a new method for dynamic configuration of check-in resources.

Abstract:As a key index affecting the market efficiency of transportation, ticket pricing is directly related to the economic benefits of society and enterprises. In order to determine the reasonable ticket price level of intercity rail transit, this paper provides a fare pricing model based on BLPP algorithm. Considering the constraints of government price limit and enterprise cost, the function of upper passenger flow and fare is constructed, and the relationship between fare adjustment and passenger flow is obtained. The model is applied to the intercity rail transit from Hangzhou to Shaoxing. Combined with the passenger flow survey data, the intercity rail transit ticket price is set as a variable, and the optimal ticket price solution is obtained on the premise of maximizing the enterprise benefit. The calculation results show that this pricing strategy can significantly improve the ticket revenue of the operation and management enterprises, and provide a scientific basis for the pricing of intercity rail transit.

Abstract:The composite phase change material of graphene aerogel was successfully prepared in this paper by a one-pot method. The three-dimensional network structure not only serves as a support carrier to solve the leakage of phase change materials, but also provides thermal conduction channels for heat transfer of phase change materials. Compared with pure phase change materials, the enthalpy of composite phase change material of graphene aerogel slightly reduced, but the thermal conductivity and light-to-heat conversion efficiency increased much. After the material was kept at a constant temperature of 90 ℃ for 60 min, no liquid leakage occurred. The results provide new ideas and theoretical basis for the experiments of composite phase change materials with high thermal conductivity, leakage resistance and high light-to-heat conversion efficiency.

Abstract:In order to study the dynamical response of heavy trucks collision with piers at different speeds, the nonlinear dynamic analysis was carried out by using the finite element software LS-DYNA. Considering the influence of superstructure on collision process, the superstructure was simulated by mass block. Taking Dongfeng Tianlong heavy truck as a prototype to establish a finite element model. The weight of 30，40，50 t vehicles were simulated at 50，80，110 km / h respectively, and the influence of impact velocity and impact mass on pier displacement and collision force was obtained. The law of energy variation with time was analyzed to verify the rationality of the finite element model. The peak value of collision force was compared with the relevant literature and codes. The results show that the current anti-collision design code is difficult to meet the requirement of bridge collision prevention in practical engineering.

Abstract:Rolling elements slippage aggravates the wear and bearing vibration, which has an important impact on the life and stability of high-speed train axle box bearings. In this paper, with the double-row cylindrical roller bearing of high-speed train as the object of study, considering the factors such as pocket clearance and radial clearance, a two-dimensional finite element model of the bearing was established. The model’s explicit dynamics was solved by central difference method, and the slippage characteristics of roller elements under steady conditions, deceleration conditions and track excitation conditions were analyzed. The results show that the RMS value of the sliding speed between the rolling elements and the outer ring is lager under stable conditions and track excitation conditions; the RMS value of the sliding speed between the rolling elements and the inner ring is larger under the deceleration conditions, and the increase is more obvious as the deceleration increases.

Abstract:This paper proposes a fast assessment method of the photovoltaic capacity that can be absorbed by the distribution lines in the station area with voltage as the constraint condition. The problem of voltage overload of the distribution line in the station area is solved. This method analyzes the change of line voltage when photovoltaic power is connected and establishes an evaluation model of its maximum capacity. The main parameter of this model is the sensitivity coefficient. The sensitivity coefficient of each line parameter is calculated, and then the influence of maximum capacity on each line parameter is obtained by using multiple linear regression method. The influence of capacity on the parameters of each line can be predicted to a certain extent by judging whether the line is heavily overloaded or not. Finally, experiments on the Huxi Tower Yuangong Substation and the Huxi Zhonggetian Platform verify the effectiveness of the proposed model.

Abstract:Electronic medical records are vital and highly sensitive private information in medical data and need to be shared frequently between hospitals. Sharing medical data is considered a key method to improve the quality of medical services and reduce medical costs. However, electronic medical records are currently stored in different hospitals, which hinders the sharing of patient medical data and poses a serious threat to patient privacy. In order to solve these problems, a secure medical record sharing scheme based blockchain (SMRSBC) is proposed. In SMRSBC, the original EMR is securely stored in the cloud storage server, and the index is kept in the tamper-resistant alliance blockchain. This means that the risk of medical data leakage can be greatly reduced, and at the same time, the index in the blockchain ensures that the EMR cannot be arbitrarily modified. Through the patient's predefined access rights, the secure sharing of electronic medical data can be automatically completed through smart contracts on the blockchain. In addition, the use of elliptic curve encryption and asymmetric encryption technology in the patient's electronic medical data storage and extraction phases can protect the patient's privacy well. Analysis shows that SMRSBC is a safe and effective method to realize EMR data sharing.

Abstract:For the strategic bidding problem in electricity market, differential evolution algorithm (DE) was used to solve the model. This method was applied to the biding problem of PJM electricity market in the United States. The results show that, compared with the marginal cost method (MC) , the sequence least squares programming method (SLSQP) and the particle swarm optimization algorithm (PSO), the DE algorithm has advantages of good algorithm stability, short running time and high profit. This result can meet the solution requirements of strategic bidding problem in the PJM electricity market.

Abstract:After the distributed wind power energy is incorporated into the distribution network, the system is lack of energy consumption capacity, and the utilization rate of wind power is not high. In this paper, a new energy consumption mode is proposed, which combines wind power consumption with distribution network reconstruction. Considering the uncertainty of load, the fluctuation and randomness of wind power output and the number of switching operations, the objective of the model is to minimize the proportion of wind power to be consumed and the number of switching operations. In order to solve the problem of premature convergence and local optimization, a new multi-objective quantum differential evolution algorithm is proposed, which effectively enhances the individual diversity and optimization speed. The IEEE33 node system connected to distributed power supply is taken as an example to analyze.