China Journal of Highway and Transport , the 1st in the field of road transport, is supervised by China Science and Technology Association and sponsored by Highway and Transportation Society of China. It is the most authoritative academic journal of the highway transportation industry. Launched in 1988, it has been walking in the forefront of road traffic technology development. Its scope covers the achievements in road construction and transportation, including road engineering, bridge and tunnel engineering, traffic engineering, road building and machinery engineering.
The journal is included by CA, JST, Pж(AJ), EI, CSCD.
To realize the optimal energy management for electric vehicles, the spatial driving cycle for the city bus was implemented including both the speed and road grade. With the sampled data in Xi’an city, the short trip including speed and information of road grade was extracted, and the spatial driving cycle was synthesized by the principal component analysis method and hierarchical clustering methodology. Meanwhile, the error between characteristic parameters of synthetic conditions and the source data was compared. Then the energy management strategy for a plug-in hybrid electric vehicle (PHEV) was simulated with the typical methods including the charge depletion and charge-sustaining (CD-CS) and dynamic programming (DP) based on 20 consecutive new running cycles, which reached approximately 100 km. Meanwhile, the influence of spatial and plane driving cycle and road grade on the energy management was analyzed and further compared. The results showed that the maximum and average errors of characteristic parameters were 9.44% and 4.63%, respectively. For CD-CS and DP strategies, the braking energy in the spatial driving cycle increased by 32.80% and 33.03%, respectively, compared with the braking energy in the plane cycle. The recovery energy obtained during the braking would increase with the increasing grade scalar. Besides, it is impossible for the DP strategy to realize the optimal energy distribution corresponding to the actual working conditions, without considering the braking power during the process of upslope and minus grade. The energy consumption cost for both strategies increased by 14.69% and 10.43% respectively in consideration of road grade. Moreover, the energy cost would increase dramatically with the increasing scalar of road grade, whilst in particular, the energy cost of the CD-CS method presented a more rapid growing rate than that of the DP method.
To develop the opposing left-turn traffic conflict model of the signalized intersections, the traffic conflict data and traffic volume data were extracted from 101 hours video data at 12 signalized intersections in Vancouver by the computer vision techniques. Given the impacts of traffic flow status on the traffic conflicts, the traffic flow status was divided into four scenarios based on the
v/
c indicator. The traffic conflict model based on multivariate Poisson-lognormal distribution under multiple scenarios and the traffic conflict model based on Poisson-lognormal distribution under the single scenario are developed. The posterior distribution of the models parameters are derived by the Bayesian estimation method. Based on the Markov Chain Monte Carlo simulation, model parameters are estimated. Using the deviance information criterion (DIC) and the models’ expectation variance, the goodness-of-fit and the precision of the models are compared. The results show that the goodness-of-fit of the multivariate Poisson-lognormal based traffic conflict model is superior to the single Poisson-lognormal based traffic conflict model. The precision of multivariate Poisson-lognormal based traffic conflict model under the 4 scenarios is 2.0 times, 1.5 times, 2.0 times, and 1.4 times larger than that of the single Poissonlognormal based traffic conflict model. The conflicting volumes have different impacts on traffic conflicts under different traffic flow status. Results of elasticity analysis show that a 1% increase in traffic flow of through movement may increase the opposing left-turn conflict frequency by 0.36%, 0.56%, 0.17%, and 0.78% for traffic scenario 1, 2, 3, and 4 respectively, given that the left-turn traffic flow remains the same. Accordingly, a 1% increase of the traffic flow in the left-turn may increase the opposing left-turn conflict frequency by 0.40%, 0.67%, 0.40%, and 0.51% for traffic scenario 1, 2, 3, and 4, respectively, given that the through traffic flow remains the same.
To establish the settlement calculation method of rigid pile composite foundation considering the pile-soil slip characteristics and unequal compression deformation of soil between piles under the embankment load, the equivalent reinforced unit of single pile in rigid pile composite foundation with equal length of pile under the uniform load was taken as a research subject. Based on the three-section distribution pattern of pile-soil interaction that contains the upper plastic zone of negative friction, the central elastic zone of coordinate deformation and the lower plastic zone of friction bearing, the elastic-plastic model of ultimate shear displacement with equal per unit length in consideration of the variation of shear stiffness and the ultimate friction with the influence of normal stress was adopted, and a distribution model for friction on pile-soil interface describing the nonlinear elastic-zone and nonuniform plastic-zone was developed. Considering the pile-soil slip characteristics and unequal compression deformation of soil between piles, the formulas of the settlement of rigid pile composite foundation and stress ratio of pile-soil under the embankment load were derived according to the pile-soil load transfer differential equations of the calculated unit cell. What’s more, the effect of the embankment load and the flexibility coefficient of cushion layer on the settlement and pile-soil stress ratio were analyzed. The results showed that the settlement increased with the increasing of the embankment load as well as the flexibility coefficient of cushion layer. The pile-soil stress ratio decreased with the increase of the flexibility coefficient of cushion layer, whereas it increased at the beginning and decreased afterwards with the increase of the embankment load. The technical principle of the design of the bearing capacity and the settlement of rigid pile composite-foundation under the embankment load was put forward by the maximum stress concentration ratio.
In order to precisely and optimally control the articulated heavy vehicles under the various conditions, the stability control strategy based on the linear simplified model with realtime parameters was presented. The brake system, the layered control method and linear quadratic regulator (LQR) algorithm were adopted in the strategy to achieve the comprehensive control combined with the yaw, jackknife stability and roll stability. Meanwhile, various vehicle states were chosen as feedback states. On account of the genetic particle swarm optimization algorithm, the weight coefficients of strategy were obtained by the optimization algorithm using the comprehensive indexes of yaw, jackknife and roll stability to realize the optimal control of articulated heavy vehicles stability under the various conditions. The HIL test bench of articulated heavy vehicles was constructed, whilst the test verification was operated. The results showed that, after adopting the proposed control strategy, the maximum improvement rates of the slip angle of the tractor, the yaw velocity of the tractor, the slip angle of the trailer and the yaw velocity of the trailer were 38.6%, 13.8%, 15.8%, 8.4%, respectively. The maximum improvement rate of the hitch angle was 5.1%. The maximum improvement rates of the lateral acceleration of the tractor, the roll angle of the tractor, the lateral acceleration of the trailer and the roll angle of the trailer were 10.4%, 15.4%, 10.8%, 17.7%, respectively. The stability of the yaw, jackknife and roll were synthetically improved under the normal working condition. Articulated heavy vehicles was controlled accurately to avoid vehicle rollover under the ultimate working condition.
In order to enhance the accuracy of experimental results about ultimate bearing capacities of pile foundation in permafrost region, taking the warm and ice-rich permafrost pile foundation as an example, the research on the ultimate bearing capacities of pile foundation in permafrost region under different loading methods was carried out, by dint of indoor model experiment. The loading methods in the current specifications included fast, slow and stable load-keeping methods. The
S–P–T curved surface in consideration of the rheological effect of permafrost was proposed. Relative to the traditional judgment methods of the ultimate bearing capacities based on
S–P curve,
S–P–T curve, taking time effect into consideration, were much better to determine the bearing capacities of pile foundation in the permafrost, when considering rheological effect of piles and soil. On this basis, new damage criteria of determining the ultimate bearing capacities of pile foundation under different loading methods were put forward, and the ultimate bearing capacities of pile foundation in the permafrost region under different loading methods were analyzed. The results showed that pile soil rheological effect can effectively influence the bearing capacity. The ultimate bearing capacities calculated by dint of fast and slow load-keeping methods in the current specifications were larger than actual values, seemingly thanks to failing to consider or fully consider the rheological effect of piles and soil. In order to overcome the shortcoming, it is necessary to deploy correction coefficient to make the existing specifications of detecting bearing capacities in permafrost region meet the rheological effect of piles and soil method.
