Abstract:On the basis of traditional concrete rigid frame bridge， the hybrid beam rigid frame bridge formed by replacing a part of the main span with steel beam has effectively achieved a breakthrough in the span of the beam bridge and an improvement in structural performance. So， it has become a very promising bridge structure and has been more and more widely applied in actual engineering. In order to explore the reasonable arrangement and simplified calculation method of the mechanical performance of the three-span steel-concrete hybrid beam rigid frame bridge structure system， the simplified mechanical model during construction and completion was derived. The calculation precision of the model was verified by the finite element models and testing results of an actual project. Based on the model， taking the internal forces of the control sections as the objective functions， the effects of λ （the ratio of side-span and mid-span） and μ （the ratio of the steel beam length and main span length or the position parameter of the steel-concrete composite segment ） on the mechanical performance of the hybrid beam rigid frame bridge were calculated and analyzed. The research results show that based on the reasonable mechanical performance of the structure， the reasonable value range of λ and μ is obtained. Considering the risk in the construction and operation of the bridge， it is suggested that λ takes 0.4 and μ takes 0.4 ~ 0.5， which can be used as the design reference of the hybrid beam rigid frame bridge.

Abstract:When drilling in methane hydrate-bearing sediments， the variation of temperature and seepage pressure around the wellbore likely leads to the hydrate dissociation， reducing the safety of wellbore. The analytical solution for wellbore mechanical analysis is derived accounting for the ideal elastic-plastic behavior of the formation， the Mohr-Coulomb yield criterion and non-associated flow rule. Based on a steady-state axisymmetric plane strain model considering the effect of hydrate dissociation on temperature， seepage flow and mechanical property， the stress and displacement solutions are presented under unbalanced and overbalanced drilling conditions. The analytical solutions agree well with the results by numerical methods under the same assumptions， as well as the complex conditions. The results show that the increase of the size of dissociated region leads to the expanding of plastic zone obviously within a certain range. The size of plastic zone is decreased with the reduction of Young's modulus of dissociated region under unbalanced drilling condition， while the result is inverse under overbalanced drilling condition.

Abstract:A bolt-slip model was proposed for the simulation of high-strength bolted connections and the method for determining the real constant of nonlinear spring element was also put forward. The reliability of the proposed bolt-slip model was validated and the results were obtained by the proposed model and the refined FE model. The comparison results indicate that the sliding phenomenon can be well captured and the friction force with enough accuracy can be derived by the proposed bolt-slip model. Time for computing reduces by 90% with the same accuracy. In addition， the parametrical analysis was conducted to explore the computational error in different conditions. The influence of pretightening force， thickness of steel plate， bolt diameter and yield strength on accuracy of the proposed bolt-slip model were investigated. Results show that the proposed model is powerful in terms of the convergence and accuracy.

Abstract:The shield method is widely applied in the construction of subways and instability of the excavated surface of shield tunnels will be induced if insufficient support pressure is exerted， resulting in significant economic losses and casualties. The hydraulic states will be changed by the excavation and the induced water flow not only introduces the seepage force but also deteriorates the mechanical behavior of the surrounding soils. Therefore， more attention should be paid to the stability of the tunnel face under seepage conditions. The permeability of the surrounding soils is mostly simplified to be isotropic， which is in fact anisotropic due to the effect of the depositional environments. Based on the bounding theory， a three-dimensional computational limit analysis method is established by the combination of the simplex strain finite element method and the semi-definite programming. Through the incorporation of seepage analysis， the effect of permeability anisotropy on the seepage field， the limit supporting pressure and the collapse mechanism of the shield tunnel face is discussed. The present paper can provide important guidance to the construction of shield tunnels.

Abstract:The pedestrian level wind environment around a single square cross-sectional high-rise building （within 12 meters of bottom area） was investigated in the wind tunnel， and the distribution and variation of the parameters such as speed-up ratio and R_M （mean wind velocity ratio） at different wind direction angles were studied. Meanwhile， by employing the meteorological data of Guangzhou and the Lawson criterion of wind comfort， the pedestrian level wind environment under strong wind in this region was evaluated. The results show that the maximum speed-up ratios at different wind direction angles are approximately equal to 1.9， and all appear at the corner of the leeward side of the building. The areas with the R_M greater than 0.75 also appear at the corner of the leeward side of building， which is likely to cause pedestrian wind discomfort. Besides， the area of pedestrian wind discomfort is the largest when the wind direction is perpendicular to the wall. Attention should be paid to the increase of wind speed caused by the downwash effect at pedestrian level. In the wind direction angle range of 20 to 70 degrees， the area with unfavorable ventilation is quite large， which may cause adverse results in diffusion of air pollutants. The greatest gust equivalent mean wind speed appears at the corners of the windward and leeward sides of the building， and pedestrian activities in these areas should be restricted or reminded.

Abstract:The research adopted the traffic big data such as driving behavior，maps，traffic conditions and user volume collected by the navigation software to develop a traffic order index and evaluate the road safety risks.By analyzing the traffic safety features of road alignment，traffic control devices，traffic signals at intersection entrance，a structural equation model of intersection was build，the causes of risk at intersection entrance were analyzed in depth.The results show that the number of lanes in all directions，signal phase，the number of lanes related to the entrance，the number of U-turn lanes，the type of cross section，the type of median strip and the number of illegal behavior monitoring equipment have significant impact on traffic safety of the intersection.Congestion factors have the greatest impact on traffic safety of the intersection，then traffic signal factors and road alignment factors，and illegal behavior monitoring equipment have the least impact on traffic safety of the intersection.On improving the safety of intersection entrance， people are encourged to travel at off-peak hours to avoid the congestion，and all-red signals are proposed.In road designing， lanes should be increased in the entrance direction and median strip should be set，and the U-turn lanes should be set if the space allows.A safety evaluation method of intersection roads，facilities and signals based on driving behavior data collected by navigation software is proposed，which provides a reference for safety evaluation and cause analysis of other road types and transportation network.

Abstract:Based on the GPR A-scan data， in order to further implement rapid intelligent detection of highway diseases， first of all， through data collection， sampling， data pre-processing and expert interpretation， road disease datasets with labels were established. A comparative analysis on different diseases and its degrees of severity was carried out to fully explore the characteristics of underground diseases. Based on the dimensions of time and frequency domain， the energy， variance， kurtosis and log power spectrum of A-scan were selected as the features to research the distribution of various road diseases. Finally， a state-of-art classification named Extreme Gradient Boosting algorithm （XGBoost， Extreme Gradient Boosting） was introduced to train and classify the data. The results show that the XGBoost classification algorithm achieves the accuracy of more than 90% for voids， looseness， cracks recognition.

Abstract:A qualitative analysis was made to investigate the major influencing factors in predicting the probability of the train fault happening on urban rail main line. Then， a discrete dataset was collected about a single train’s fault in running for 120 000 km . Three alternative models were established on the basis of the data characteristics， Poisson distribution and zero-inflated Poisson distribution as well as the potential fault forms. According to the comparative study results，a Poisson distribution-based prediction model of train fault probability is finally proposed. Study results show that the train fault probability tends to increase with the increasing of train formation. It decreases first and then increases with the cumulative running kilometers，and the minimum train fault probability occurs in the fourth 120 000 km period， but the initial value is exceeded in the seventh 120 000 km period.

Abstract:The geometrical shape characteristics of the particles have a significant influence on the mechanical properties of the ballast. To quantitatively study the morphological characteristics of railway ballast， this paper took the first-order ballast particles of the real scan as an example， used 3D laser scanning to obtain the point cloud data of the ballast particles， and introduced the description indices of overall morphological characteristics （long axis， middle axis， short axis， sphericity index）， and proposed the local morphological characteristics index （curvature index） of the ballast granules. The probability density distributions of above-mentioned overall and local morphological characteristic indicators were established. On this basis， based on the intrinsic orthogonal decomposition （POD） and radial basis function （RBF） neural networks， a regenerative algorithm based on the probability density distribution of particle morphological indicators was proposed to reconstruct the ballast particle sample library. The above-mentioned re-generation algorithm reconstructed 600 and 4 000 particle turnouts， respectively. The results show that the statistical distribution of the morphological characteristics of the rebuilt ballast sample were close to those of the scanned samples， indicating that the method can quickly establish any number of turnout samples based on the probability density distribution of the particle morphological indicators.

Abstract:According to the designed and the measured stock and curved switch rail profiles of the No. 18 high-speed single-way turnout， a vehicle-turnout dynamic model was established to analyze the wheel loading position transfer， normal contact stress in the stock and curved switch rails and their fatigue damage indexes during train passing turnout along reverse and side direction. The reason that the fatigue crack in curved switch rail was presented. The results show that the switch rail machined depth to the stock rail was not as enough as the standard one which made the loading position transferred early and rapidly for the outer wheels of both the front and rear wheelsets in the same bogie respectively. With the wear’s coming into being between the wheel and rail profiles， this situation got worse. Then， large normal contact stress occurred in the curved switch rail especially by the outer wheel of the front wheelset in the bogie which contributed the most to the rolling contact fatigue crack at the gauge shoulder and corner of the curved switch rail. The fatigue crack would appear first in the curved switch rail with the top width of about 20 ~ 50 mm.

Abstract:The research on flexible job-shop scheduling problems （FJSP） can help the production in practical to meet the ascending demands of personalization and customization from special customers. On the basis of a full study of scheduling criteria on FJSP， the paper proposes a gaming particle swarm optimization algorithm gaming PSO） with novel encoding and decoding schemes. In comparison with the traditional PSO， the communication mechanism of the proposed PSO is improved by a gaming solution set， which takes advantages of the contradictions among the scheduling criteria. Finally，based on a test of the standard benchmarks and a comparative study of the test results with those by other improved PSOs， the proposed gaming PSO proves to be effective in minimizing the maximum completion time of FJSP.

Abstract:Aiming at the potential network attack for vehicles， an abnormal intrusion detection algorithm based on support vector machine is proposed for the controller area network with flexible data-rate （CAN-FD） bus. With the framework of common intrusion detection framework （CIDF）， the method uses message identifier （ID）， time period and data field as intrusion detection features. Using the binary classification and small sample features of the support vector machine algorithm， the identification of intrusion message data in CAN-FD network environment is realized. The simulation data show that the proposed method has a high accuracy of intrusion detection， and this method can be used for periodic packets and aperiodic messages.

Abstract:By taking the lithium-ion power battery cell as the research object， the impedance characteristics of the battery cell in different frequency bands are measured to characterize the battery characteristics， and the electrical model is used to fit the impedance characteristics of the entire frequency band， and the impedance characteristics of the battery cell and BUSBAR are combined to establish the entire power. The electrical characteristics model of the battery pack. The electric drive system is the main source of electromagnetic interference in automobiles. On the basis of research and analysis of motor characteristics and control strategies， the electromagnetic interference model of the power battery system including the electric drive system is established. The total current change on the DC bus of the power battery system is obtained through simulation and compared with the actual vehicle test results. This paper is of great significance to study the electromagnetic interference and its influence mechanism of the power battery system itself， to find and solve potential electromagnetic interference problems in a timely and correct manner， and to improve the performance of the battery pack system， the vehicle and the reliability of the system.

Abstract:Based on system theory process analysis （STPA）， a safety development method for high level autonomous driving decision systems was proposed. The proposed method was applied to the prototype of an urban autonomous driving decision system. 70 Unsafe Control Actions （UCAs） for the entire system were found through safety analysis. Focusing on 3 function states of the system， 10 reasons for UCAs and 9 safety strategies were put forward. One strategy got implemented and validated through model-in-the-loop simulations. Test results show， the safety strategy is effective and the proposed method can enhance the safety of autonomous driving decision systems.

Abstract:An investigation was made of the data of the gem enterprises listed before the end of the year 2017，and an evaluation system for the growth of the innovative enterprise was established by factor analysis and catastrophe progression method， which could reflect the profitability， innovation， operation， risk control and development capabilities of innovative enterprises. On the basis of the calculation of the growth scores of sample enterprises， a fuzzy-set qualitative comparative analysis was also made to integratedly evaluate the influencing factors of the growth of innovative enterprises. It is found that the internal emphasis on R & D and the external market， education， business environments and the policy as well as the enterprise agglomeration are not the necessary conditions for high-growth innovative enterprises. Finally， 9 kinds of condition configurations of high-growth innovative enterprises are presented.

Abstract:University technology transfer is a complex process with four participants （enterprises，intermediary organizations， universities， and the government） and multi-targets. However， previous research normally focused on signal participant or signal stage， rather than from system perspective. In order to narrow this gap， this study attempts to investigate the process of university technology transfer comprehensively to find the most significant impact factors.The questionnaire was designed and set to 204 responses coming from universities， research institutes， enterprises， intermediary organizations， and different government departments in Shanghai. The factor analysis method and structural equation model was adopted. Study results show that both technology supplying and demanding need improving. In order to promote university technology transfer， the reasonable management mode should be employed according to latest incentive policies. In addition， from the public policy perspective， the government should put more emphasis on enterprises’ technological absorptive capacity.

Abstract:Urban infrastructure plays a key role when city responses to climate change. In order to explore the vulnerability of urban infrastructure systems and their spatial distribution characteristics in climate change， we combined three-element theory of vulnerability and spatial analysis methods and constructed spatial analysis framework of unban infrastructure vulnerability in climate change. Empirical analysis was carried out through the data of Yangtze River Delta urban agglomeration. Based on the analysis of spatial distribution and spatial correlation of the three elements of vulnerability， it is found that the spatial distribution characteristics of the three types of elements are different. The vulnerability depends more on the administrative level， economic level， and administrative region of the individual urban unit. The strategic system for reducing infrastructure vulnerability should be involved in the regional integration policy.