Abstract:A mechanical model is proposed to describe the behavior of a damaged strand suspender with asymmetric broken wires in this paper, and the relations between the coefficient of interwire friction, the external contact force between sheathing and wires, the affected length of the suspender with broken wires, and the remaining tensile force of the suspender are investigated. Results show that forces in the broken and unbroken wires of the suspender are not equal over the affected length, centered at the break, but are equal beyond. The unbroken wire strains within the affected length are not uniform and have maximum strains occurring in the unbroken wires adjacent to the broken wires, but the rest of unbroken wires are significantly associated with the forms of broken wires. The strain in the broken wire is zero at the wire break and increases exponentially with distance from the break. The strain in the unbroken wires is a maximum at the wire break and decreases exponentially with distance from the break. Within the affected length, the remaining prestress fraction approaches a lower limit, which is a little more than the loss of the crosssectional area of the suspender. Meanwhile, the stress redistribution of a damaged suspender with asymmetric broken wires is significantly affected by contact forces between sheathing and outer wires, and frictions between broken wires and king wires.

Abstract:A damageidentification method based on effective shorttime crosscorrelation (STCC) was proposed to identify wire breakage, in the case of low signal-to-noise (SNR) ratio with the magnetic flux leakage (MFL) detection of bridge cables. The corresponding signal fragment from repeated tests of the cable was extracted for effective STCC analysis. The effective STCC was renormalized to combine with the characteristics of short-time energy. Then, the double threshold method was used to identify the broken wire damage. A full-scale cable model with various kinds of wire breakage was made for MFL examination, and the experimental results were used to verify the proposed method. The results show that the proposed method improves the damagerecognition accuracy by about 15.7%~16.9% compared with the existing methods, and obtains high identification accuracy even with low SNR ratio.

Abstract:A singlebox doublecell test girder with corrugated steel webs was made to study the transverseal force and girder frame deformation of bridge deck.In order to calculate the transverse internal force, a rigid frame model was put forward with a combination of test results and mechanical characteristics of corrugated steel box girder. Then, a comparative analysis was made among the method described above and girder frame model and board model of highway bridges. Furthermore, an outcome based on the comparison of the three models and test results was presented. The results of rigid frame model and girder frame model are close to test results, the differences are less than 10%. But board model results are more conservative, the differences are about 20%. Compared to the rigid frame model, the girder frame model is more complicated, and the effects of relative ratios of web line stiffness to deck line stiffness on bridge deck transversal force are considered.

Abstract:Under the planesection assumption and the premise that no relative slip exists, a calculation theory of shear stress in the variable depth and width box sections with corrugated steel webs based on elastic beam elements is given. The calculation theory proposes that shear, moment and axial force will all produce shear stress, and the latter two can produce shear stress only in the case of variable cross section. For further analysis, a finite element model is established, and a comparison among the traditional calculation theory, the calculation theory and the results of the finite element model is conducted. The calculation theory is proven to be reliable.

Abstract:The behavior of high strength steel flush endplate connections on postfire was simulated according to the test results using finite element software Abaqus. Comparison between the analysis results of finite element method (FEM) and all representative experimental results on momentrotation relationship, failure mode and stress distribution of flush endplate connections shows that good agreements exist. Based on above，parametric analysis on Q460 high strength steel endplate connections and Q345 mild steel endplate connections was conducted. Results show that: the degradation of mechanical behavior of the connections is not significant after cooling down from fire temperature 550 ℃; the material property of the endplate has no impact on the initial stiffness of the connections but has important impact on the bending capacity of the connections; a connection with thinner high strength steel endplate can achieve similar bending capacity and equivalent or even higher rotation capacity after fire in comparison with a connection with thicker mild steel endplate.

Abstract:In order to clarify the lift mechanism of downstream cylinder at a high Reynolds number Re=1.4×105, the large eddy simulation (LES) method was adopted to investigate the aerodynamic forces and flow pattern of two staggered circular cylinders. The ratio of centertocenter pitch (P) to the diameter of cylinder(D) is 4 and the incidence angle is 0° to 90°. The mean and fluctuating lift mechanisms of downstream cylinder were discussed as well. With the incidence angle increasing, the flow pattern of two cylinders is classified into the vortex impinging flow pattern, the vortex impinging and shearlayer interaction flow pattern, the shearlayer interaction flow pattern and the wake interaction flow pattern. For the vortex impinging flow pattern, the vortex impinging and shearlayer interaction flow pattern, the vortex of upstream cylinder impacts with downstream cylinder, hence the downstream cylinder experiences a higher fluctuating lift than the single cylinder. For the shearlayer interaction flow pattern, the downstream cylinder is subject to a significant mean lift, which is ascribed to the combined effects of two factors, i.e., the shift of stagnation point, and the interaction between the vortex of the upstream cylinder and the shearlayer or vortex of the downstream cylinder.

Abstract:The effects of sensor errors on link flow inference in sensor location flowobservability problem are discussed in this paper. By using the equations of traffic flow conservation system and the model of network sensor location problem based on turning ratios at intersections, a general sensitivity analysis method is proposed to analyze the impact of sensor errors on the link flow reckoning. Firstly, the key factor is defined to represent the errors of link inferring caused by the sensor errors. Then, the total effect of multiple sensor errors on the link flow inferring is proved theoretically to be the linear superposition of the effects of single sensor error. Finally, a square road network is used to test the proposed method. Two sensor location schemes of installing sensors on the only entrance links or exit links of the road network respectively are adopted, which can both support the unique link flow inferring results. The effect of sensor errors on link flow inferring is given by using the key factor method.

Abstract:For truck escape ramp (TER) allowing two vehicles to enter，we abstract the stopping positions of the two vehicles that have entered TER one after another as independent events, and establish a probabilistic model that both vehicles can successfully enter TER. The results based on simulation data show that: when the mainline is straight, the probability that the two vehicles successfully enter TER is higher than when the mainline is curved. Even if the mainline is straight and the arrest bed width is 5 times of the vehicle width, the probability of the two vehicles successfully entering TER is still no more than 15%. It indicates that it is impossible to ensure the second vehicle entering TER successfully by only widening the width of the arrest bed without setting the required length of approach road.

Abstract:Under the condition of continuous data, the stability and representativeness of parking demand characteristics index was investigated. The stability and representativeness of parking demand characteristics index based on the continuous data analysis is quite different from the assumptions in the traditional application process. It is shown that there are some defects in the previous empirical random sampling and processing methods. However, the group differences were effectively suppressed after the peak ratio conversion of parking demand characteristics index. By simultaneous statistical inference technique, there is no significant difference between each group among all parking demand characteristics indexes tested, which suggests that the parking demand characteristics index has the stability and representativeness within the fluctuation range of each index.

Abstract:In order to employ the dynamical evolution process of voided sleeper, an iterative computation method based on the vehicletrack coupled system dynamics model and subgrade settlement model is proposed in this paper. Simulation results indicate that when one end of the sleeper has an initial gap between the sleeper and subgrade, the sleepersubgrade contact force at this area decreases obviously. On the other hand, the sleepersubgrade contact force at the adjacent areas increases. Therefore, the sleeper voided area expands from one end to central part. Moreover, with the increased voided area the supporting capability of the sleeper deteriorates largely and most of the train loads are shared by the other sleepers. Due to this reason, the voided degree of the sleeper trends to be stable, and most areas have a gap about 1.5 mm.

Abstract:A rail wear prediction model was established, including a modern trams vehiclerail coupling dynamics calculation model considering independent rotating wheels, a wheelrail contact model based on grooveshaped rail multipoint contact characteristics, and an Archard material wear model. The validity of the model was verified by comparing with the relevant literature results and the effect of rail cant on the wear of grooveshaped rail of modern trams when a train passing through small radius curve was analyzed. The results show that when the rail cant is 1/60 and 1/20, the wear on the inner and outer grooveshaped rail surface and rail shoulder is relatively concentrated, and the rail wear near X=18 mm is less affected. In terms of rail’s wear analysis, setting the rail cant at 1/20 is beneficial to reduce rail wear.

Abstract:The MooneyRivlin hyperelastic model and the Prony series viscoelastic constitutive model were used to verify the selected calculation parameters by finite element analysis compared with stress relaxation test data. Then, the AnsysPDS module was used to analyze the sensitivity values of all random parameters to surface contact stress and the influence of hyperelastic and viscoelastic parameters on the surface contact stress relaxation. The results show that parameter values are reasonable. Random parameters which have great influence on the surface contact stress are α2 and C10, followed by α1、τ1 and C01, and the effect of τ2 is negligible. Relaxation mainly occurred on the first day of loading and remained basically stable within 1 year. The larger the values of hyperelastic parameters, the smaller the stress attenuation is, and the opposite of viscoelastic parameters.

Abstract:Based on testing demands for automated vehicles such as decisionmaking and environment perception, the stateoftheart testing technologies were systematically summarized from the aspects of testing methods, testing tools, and testing acceleration. Features and application scopes of these technologies were analyzed. Furthermore, the future developing trend of testing technologies for automated vehicles was given.

Abstract:Based on lightduty diesel engine bench test platform, the effect of the length of diesel oxidation catalyst’s(DOC) carrier on the emission reduction performance of aftertreatment system was studied. The results show that, increasing the length of the DOC’s carrier can increase the oxidation rate of carbon monoxide(CO), total hydrocarbons(THC) and nitric oxide(NO). However, excessive increase in the length of the DOC carrier has limited improvement on the oxidation performance and will reduce the emission reduction effect of DOC under low temperature and low load. The reduction rate of DOC coupled catalyzed diesel particulate filter(CDPF) on particle number(PN) is less affected by the length of the DOC carrier. From the perspective of balancing cost and performance, appropriately increasing the length of the DOC carrier can effectively improve the emission reduction effect, but the excessive increase has little effect on the improvement of emission reduction effect.

Abstract:A detection method for threedimensional parking slot was proposed by using multiple timeofflight (ToF) cameras. The local scene of a parking lot was jointly captured and mapped by using multiple ToF observations in real time, and structural semantics such as walls, ceilings, floors and obstacles were segmented in the scene for the detection of parking slots. The detection rate of 94.83% was achieved in the experiment. The precision of detected width and height of parking slots are 14.4 cm and 12.4 cm respectively.

Abstract:To improve the total electron content (TEC) accuracy retrieved by multimode GNSS(global navigation satellite system), this paper addresses the distinctions of TEC retrieved from GPS(global positioning system) and GLONASS（global orbiting navigation satellite system） using global and Chinese GNSS stations. It indicates that TEC retrieved from GPS is more accurate than that from GLONASS. The regional model results in China show that the GPS/GLONASS TEC correlation coefficients increase with latitude and GLONASS underestimates TEC compared with GPS. The difference has the relationship with constellation configuration, signal system and orbit design difference. The TEC difference has latitude and local time dependency, and critical frequency of F2 layer (foF2) has similar phenomena with local time and geographic latitude dependency. Based on the study, a newly weighting function is designed for GLONASS measurements. The results show that the method will improve the bias and the root mean square (RMS) by 15% and 20% respectively in GPS and GLONASS combine mode.

Abstract:Based on the theory of behavior safety, the literature analysis and personnel interviews, the early warning system for the safety behavior of construction workers was established from a crosslevel systematic perspective. According to the system, the questionnaire was designed, the data were collected from construction sites, and the system was trained and tested by back propagation (BP) neural network. The results show that output values of the simulation accord well with the actual safety behavior data, and the simulation ability of the trained neural network model is competitive. The evaluation system could effectively evaluate and predict the safety behavior of the construction workers. At the same time, safety behavior was sorted into three grades (excellent, good and poor) according to the threshold, and different safety intervention programs should be adopted to enhance the safety management ability and improve the projects’ safety performance.

Abstract:An efficiency evaluation of inner structure for universities was proposed based on data envelopment analysis (DEA). The operational efficiency of the universities was divided into operational stage and profitability stage. The efficiency of the profitability stage was decomposed into educational and research efficiencies. Both efficiencies were estimated for parallel structure system. To prove the rationality and effectiveness, the case study of a specific 985project university was investigated based on the data of its inner colleges. The method provides more effective operational management suggestions for the universities.

Abstract:To achieve more effective topic discovery of stock bar forum, this paper presents a framework with short text clustering based on frequent itemset and latent semantic (STC_FL). The important frequent itemsets are acquired with the concept vector space based on HowNet, and then a combination pattern of statistics and latent semantics is used to realize the selfadaptive clustering of important frequent itemsets. Finally, the algorithm of text soft classifying based on similarity threshold and nonoverlapping (TSCSN) is proposed. Text soft clustering is selected and controlled with parameter optimization. By taking the real stock bar forum data as a specific case of empirical analysis, it is shown that STC_FL framework and TSCSN algorithm can fully exploit the latent semantic information of text and reduce the dimension of feature space, which realizes the deep information mining and topic classification of short texts.