Abstract:In order to study the uniform corrosion and pitting corrosion of highstrength bridge wires, a total of 30 steel wire specimens on six corrosion levels were prepared by using the acetic acid salt spray test. The variation of uniform corrosion depth and pitting depth was evaluated by using weight analysis and three dimension scanning. The results show that the measured uniform corrosion depth follows the powerlaw distribution. The coefficient of variation of uniform corrosion depth decrease with the corrosion time. The pitting depth follows the normal distribution and maximum pitting depth follows the extreme value distribution. Finally, the prediction models for uniform corrosion depth and maximum pitting depth were established and then applied to the real cables on the bridge.

Abstract:In order to investigate the fatigue properties of precorroded highstrength bridge wires, a total of 30 steel wire specimens on six corrosion levels were prepared by using the acetic acid salt spray test. Fatigue tests were conducted with the specimens. The effects of corrosion level and stress amplitude were analyzed and the law of fatigue strength degradation was studied. The test results show that the fatigue life of bridge wires decreases significantly under corrosion. Bilinear SN curves of precorroded bridge wires were established and the logarithm of fatigue life decreased linearly with the weight loss at the same stress. Finally, the fatigue surface equations of precorroded highstrength bridge wires were established based on the test results and the recommended fatigue strength at different assure rates were proposed．

Abstract:Compacted bentonite has been selected as the potential buffer/backfill materials for the deep geological repository of highlevel radioactive nuclear waste; consequently the swelling pressure of compacted bentonite is the key index of its buffering performance. Based on the swelling process of compacted bentonite, the swelling mechanism, prediction models, and experimental verification of swelling pressure were systematically summarized. The existing predication models of bentonite swelling pressure are mainly based on the diffused doublelayer (DDL) theory. The laboratory tests demonstrate the influences of dry density, initial water content, sand content, and other factors on the final swelling pressure of compacted bentonite. The comparison between the model predication and the experimental results shows that the existing models have less fitting to the compacted bentonite with higher montmorillonite content and higher initial dry density. In fact, the swelling process of compacted bentonite includes crystalline swelling and DDL swelling, but the predication models are only used for estimating the DDL swelling, which cannot very well describe the crystalline swelling. The existing prediction models are only applicable to estimating the final swelling pressure of bentonite, but it is difficult to reflect the evolution process of swelling pressure caused by environmental changes during the longterm operation of repository.

Abstract:Cast-in-situ underground concrete structures suffer from both sulfate and sulfatechloride attack and are also affected by alternate dryingwetting conditions. Concrete specimens were manufactured and immersed in sulfate and sulfatechloride solutions. The wettingdrying tests of concrete specimens were also considered. The size and weight changes were recorded and the compressive strength tests were conducted. The sulfate concentrations in concrete after different immersion period were measured. The SEM, XRD, and EDS were also conducted and analyzed to reveal the degradation mechanism of concrete. The results show that the existence of chlorides accelerates the degradation of concrete caused by sulfate attack and the situation becomes ever worse after wetdry cycles. The strength of concrete specimens immersed in sulfatechloride solutions, experiencing wetdry cycles, suffers from remarkable decline. Chloride has a positive effect on accelerating the diffusion and the accumulation of sulfates in specimens subjected to composite attack, especially in the condition of alternative wetdry cycles. The degradation of castinsitu concrete due to sulfate attack can be accelerated by the existence of chlorides. The chloride ions, in the condition of alternative wetdry cycles, accelerate the diffusion and the accumulation of sulfate ions in concrete.

Abstract:To improve the coastal environment, an ecological restoration project for tourism beach was developed between Bailu Island and Tangzizhai in Shanhaiguan. A threelayer gridnested model, covering the waters of Bohai Sea, Qinhuangdao, and Shanhaiguan, is established based on Delft3D and validated by field measurement. Then, the model is used to investigate the influence of the engineering project on the hydrodynamic characteristics. The results indicate that since the tidal current field remains basically unchanged, the water exchange capacity is kept and there is no negative effects on the ecology. Offshore submerged breakwaters dissipate wave energy with a degree of reducing 10% normal wave and 20% storm wave in height. In a word, the ecological restoration project of Shanhaiguan tourism beach not only maintains the hydrodynamic environment, but also weakens the beach erosion, which is conducive to maintaining the ecological environment and stability of local tourist beaches.

Abstract:Full-scale fire experiments were conducted to study the fire safety distance of novel straw fireproofing houses. Room temperatures, ambient temperatures and thermal radiation intensities were measured to analyze the behavior of straw fireproofing houses during the fire. The formula for the maximum outdoor thermal radiation intensities of straw fireproofing house at various distances was obtained by regression analysis, and this equation could be used to calculate the fire safety distance. It is found that the fire spread is significantly restricted by using straw fireproofing material. For the straw fireproofing houses, the fire safety distance is suggested to be 2.34 m. Furthermore, for the straw fireproofing houses under severe weather conditions with strong wind, the fire safety distance is suggested to be 2.51 m.

Abstract:With the development and application of information technology, it is becoming a new research direction to analyze complex traffic flow based on experimental methods. One of the basic problems is the reproduction of the actual traffic flow in the experiment. Based on the framework of a traffic flow experimental system, this paper proposes an experimental method to reproduce the real traffic flow in virtual environment by giving the observation data of traffic flow in real environment whose system framework includes the nonparametric model of traffic flow and the Bayesian learning algorithm. Subsequently, the experimental method was numerically verified in the scene of traffic flow on signal control. The results show that the method proposed could realize the approximate dynamic traffic flow on signal control in virtual environment.

Abstract:Relocation Cost Optimization Model of Electric Vehicle Sharing Based on User Incentive

Abstract:To meet the requirements of intelligent maintenance assistant decisionmaking of airport cement pavements, 356 sets of valid data from 26 civil airports in China were selected. The correlation of pavement performance indexes was analyzed, and PCI, PCN, void condition and surface roughness were finally confirmed as the pavement performance variables. Considering management requirements of pavements, available funds, allowable delays, expected benefits and project safety were proposed, and their attribute levels were determined respectively. Besides, 8 kinds of common maintenance measures were also summarized. Subsequently, the maintenance decisionmaking tree by using the C5.0 algorithm of the data mining technology was trained to establish the maintenance assistant decisionmaking model. The evaluation and application of the established model were also conducted. The results show that the model is more accurate in forecasting. The results also show that the decisionmaking is reasonable and the engineering application of the model is more feasible.

Abstract:This paper presented an improved backcalculation method for rigid pavement and its regression model. Based on the modeling and a thorough analysis of the traditional AREA, the index of barcentric horizontal distance was proposed to replace the AREA index, and then the radius of relative stiffness was calculated by using each sensor deflection information. The modulus of subgrade reaction was calculated to minimize the error of filedtest deflection basin. With the above two features, the improved method can theoretically solve the problem of multiple backcalculation solutions of the traditional AREA. Taking the typical structural style of rigid pavement as a study case, the best number of sensors and the reliability of improved method were comprehensively analyzed. The numerical analysis results demonstrate that the improved method can significantly improve the reliability of backcalculation and effectively handle the measured error. The fieldtest validation results using the FWD deflection basin has also proved that compared with other methods, the improved method has a stronger ability to decrease the fitting error of measured deflection. For the improved method, five times polynomial was adopted to establish the unbiased regression model, which greatly improve the efficiency of the inversion.

Abstract:The consequences of frequent occurrence of turnout fault on the railway, are often very serious, which requires a more complete operation of the state monitoring mechanism and intelligent fault diagnosis methods to improve the safety and reliability of turnout equipment. First, according to the curves of various turnout faults obtained on site, the reference curves of several typical faults were selected as a template curve of diagnosis. Then, according to the similarity based on the Fréchet distance，the similarity degree between the test curve and the template curve was calculated, and the failure mode corresponding to the template curve with the largest similarity was output as the diagnosis result of the test curve. The experiments show that this method does not need a lot of training samples, and it is not necessary to extract the segmentation feature of the action current curve. The diagnostic method has a high accuracy, a high speed, and a strong adaptability.

Abstract:Wind tunnel test CFD（computational fluid dynamics）and SEA（statistical energy analysis） are used to study the vehicle dynamic pressure and sound field of the external gas artery of the car at 140 km/h to obtain the vehicle SEA model with high accuracy. Based on the model, the transmission of aerodynamic pulsation and the aerodynamic noise from the exterior of the vehicle to the interior space is investigated. The results show that the main contribution of aerodynamic noise in the vehicle comes from the window, the front and the rear windshield. The pulsating pressure outside the vehicle is far higher than the sound field. The sound field dominates in the higher part of the middle frequency noise, while the pulsating pressure dominates in the lower part. It is found that the glass of window has obvious characteristics.

Abstract:The influence of windshield inclination on the dynamics evolution of the Apillar vortex produced by Dihedron models is investigated both experimentally and numerically. The timeaveraged aerodynamic drag and surface static pressure are captured by wind tunnel experiment, and detachededdy simulation (DES) is employed to characterize the details of the topology of Apillar vortex. The DES results are validated by experimental results both herein and from the reference paper. The breakdown phenomenon of Apillar vortex is described by the DES results. The Apillar vortex demonstrates different flow patterns with windshield inclination variation, which is dominated by the vorticity balance theory in the primary vortex. Both experimental and numerical results show that the aerodynamic drag of Dihedron models increases when enlarging the windshield slant angle. The breakdown trend of longitudinal vortexes is discussed and a potential drag reduction scheme is visualized. Finally, wall dynamics of Dihedron models and its influence on the incabin noise are emphasized.

Abstract:By comparing the one dimensional simulation results of the evaporator refrigeration capacity, ventilation resistance and evaporator internal resistance with the experimental values, it is found that the KewCornwell heat exchange correlation in the two phase heat exchange zone of the refrigerant side, the DitusBoeleter heat transfer correlation in the superheated area, and the Dong Junqi model in the air side are appropriate. The error is controlled within 5%. The influence of the opening angle of blinds, the spacing of fins and the height of fins, the width of the tube, the number of channels and the number of flat tubes in each process of evaporator on the performance of the evaporator are studied. According to the above analysis, the structure of the evaporator is optimized. Finally, a scheme with the best comprehensive performance is selected, which makes the ventilation resistance drop by 19%, the internal resistance of the evaporator drop by 8.4%, and the refrigeration capacity is increased by 130 W.

Abstract:The flow and heat transfer characteristics of the single row finned tube bundle with longitudinal vortex generator are modeled using a validated laminar flow model. The cases of four different distance and five angles from the tube center are studied. It is found that the effect of vortex generator on the finned tube bundle is manifested in two aspects. One is the change of the size of the weak heat exchange zone behind tubes and the other is the change of vorticity intensity along the flow direction. Vortex generators can postpone the pipe flow separated point, mix the fluid of local and core areas, and increase the temperature gradient of the fluid. The results indicate that vortex generators have a good effect with an angle of 130 degrees and a distance ratio of 1.36 for single row finned tube in the Re range of 600 to 2 600, and the corresponding comprehensive performance increased by 7% to 30%. The application of the above optimization theory in 2row find tube heat exchangers indicates that the comprehensive performance of both inclined and staggered tube arrangements reaches the largest when the second row vortex generator is placed about 120 degrees around the related tube center, improving by 15% and 28% respectively.

Abstract:This paper proposed an optimization design method based on QFD (Quality Function Deployment). The EHA (ElectroHydrostatic Actuator) system parametric relationship matrix (PRM) and constraint conditions were defined with the minimum energy consumption and the lightest actuator mass as the objective to establish its optimal design model. Finally, the genetic algorithm was used to optimize a certain type of EHA design parameter as an example. After optimization, the weight of EHA was reduced by 23.57% and the energy consumption was reduced by 36.46%. The optimization results show that this design method is worthy of promotion and application in EHA design.

Abstract:A novel analytical model of electromagnetic force for switched reluctance motor (SRM) was presented to calculate and analyze the radial electromagnetic force quickly. The model takes the influence of saturation into account, and reflects the distributing characteristics of electromagnetic force for the SRM. The magnetomotive force (MMF) and airgap equivalent permeance was computed based on the flux tube method, and an analytical model of airgap magnetic field was established based on the magnetomotive forcepermeance theory. The influence of saturation on SRM was analyzed, and the previous airgap magnetic field model was improved by considering the saturation effect. A mathematical model of radial distributive electromagnetic force was built based on the Maxwell’s tensor method, and the accuracy of the model was validated by comparing with the simulation results. The proposed model establishes the relationship between the electromagnetic force and the motor parameters, which is suitable for fast computation of the radial electromagnetic force in the design stage and analysis of the NVH behavior of the SRM.

Abstract:Combined with positioning technology and laser ranging technology, a novel method for transmission lines fault location is proposed by machine vision. The unmanned aerial vehicle carries a visible light camera for shooting work of transmission line. The aerial images are transmitted back to the ground station in real time for further processing. The image processing and pattern recognition methods are adopted to detect and recognize faults on transmission lines, where the mathematical morphology algorithms are applied in image processing. The initial positioning is used to obtain the longitude and latitude coordinates of unmanned aerial vehicle by using the inertial measurement system. An airborne laser ranging module is used to correct the coordinates by measuring the distance from the fault point to the unmanned aerial vehicle. Finally, accurate position coordinates of fault points are calculated after coordinate transformation between the space geodetic and space rectangular coordinate system as well as datum transformation between two rectangular coordinate systems. The positioning accuracy has been greatly improved and the space rectangular coordinate measurement accuracy can be as high as 0.11 m.

Abstract:This paper mainly studies acceleration methods of the Monte Carlo simulation method for the pricing of European call options under the assumption of the CIR(CoxIngersollRoss) stochastic interest rate model. A new control variable based on the combination of the conditional expectation formula and the control variable technique is presented. The theoretical analysis and numerical results show that this method, with a new control variable, can improve the computation efficiency. Then it is applied to the computation of Greeks. The numerical results illustrate that the new method is more accurate and stable than the classical Monte Carlo method. It can also be applied to basket options, Asian option, and other high-dimension cases.

Abstract:The logarithm of the stock price is described as a combination of a Brownian motion and a compound Poisson process in the jump diffusion model proposed by Merton, which can capture the negative skewness and high kurtosis of stock returns observed from the financial market. However, existing methods for the Asian option pricing under the jump diffusion model is quite expensive. Thus, an efficient and accurate willow tree method is proposed in this paper and its theoretical convergence is analyzed. Besides, some numerical experiments are conducted to demonstrate the efficiency and accuracy of the proposed method.