交通运输工程学报

Research status and prospect of seismic response of deep-water bridge pier

ZHAO Qiu-hong, LI Chen-xi, DONG Shuo

Abstract: The dynamic interaction between deep water bridge piers and surrounding water under seismic excitation was analyzed. The mechanisms and calculation methods of hydrodynamic pressure and the analysis methods of water-structure dynamic interaction were summarized. The seismic response characteristics and the influence factors of deep-water bridge piers and the research progress of underwater shaking table test were studied. The calculation methods of hydrodynamic pressure in national standards were also discussed. Research result indicates that the influence of hydrodynamic pressure on the seismic response of bridge pier cannot be neglected in the seismic design of bridges, because it reduces the natural frequency of bridge pier and increases the seismic response of bridge pier. The forms of the bridge piers adopted in current research are simplified and limited. The seismic response of deep-water bridge based on the bridge pier system and bridge system should be studied. In terms of calculation of hydrodynamic pressure under seismicity, most of the current national standards are based on the Morison equation, but the application range is still unclear. It is necessary to carry out the in-depth study on application range of Morison equation and revised methods and to propose an accurate and convenient method for calculating hydrodynamic pressure under seismicity. Currently, the underwater shaking table tests mostly focus on the influence of hydrodynamic pressure on the seismic responses of bridge piers and piles, and the responses are mostly within the elastic range. The nonlinear responses and failure modes of deep-water bridge piers under severe seismicity should be studied. There are few studies on the dynamic responses of deep-water bridge piers under combined seismicity and wave action, and the interaction mechanisms between bridge piers and water under combined action of seismicity, wave and current should be researched out in depth. There is a lack of research on the seismic response of whole bridge structure. It is necessary to carry out whole deep-water bridges analysis and multi table underwater shaking table test.More>

2019, 19(2): 1-13. doi: 10.19818/j.cnki.1671-1637.2019.02.001

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Updating method of bridge finite element model based on real coded genetic algorithm

HAN Wan-shui, LIU Xiu-ping, DENG Lu, DU Qun-le, LI Guang-ling

Abstract: To overcome the local convergence and improve the corrective accuracy in the modified iterative optimization process of traditional finite element model, an updating method was proposed by combining the real coded genetic algorithm (RCGA) and measured data of static and dynamic characteristics. The quadrilateral isoparametric element theory and Newton iteration method were used to compile the macro command to realize the fast automatic loading of vehicle loads in the FEM. The objective function was constructed by the static and dynamic characteristics of the finite element model of the structure, the RCGA was taken as the optimization strategy, and the modification frame of the model was established by the MATLAB platform. Through the numerical simulation of a frame structure, the convergence efficiencies and updating results of the proposed optimization method and other methods were compared to verify the effectiveness of the proposed method. To determine the modified parameters, the Latin hypercube sampling method was used to analyze the parametric influence of finite element model on the dynamic responses of the bridge, and the proposed method was applied to modify the solid finite element model of a reconstructed hollow slab bridge. Analysis result shows that the zero order algorithm and the first order algorithm are depended on the sensibilities and correction ranges of the parameters. When the parameters have less sensitivities or the correction ranges are greater than 50%, the correction result of the model is erroneous. The RCGA is insensitive to the initial inputs, so the local convergence can be avoided. The main parameters to be corrected by the sensitivity analysis are the elastic modulus of hollow slab, the elastic modulus of cast-in-situ layer and the longitudinal and transversal restraint stiffnesses of the supports. After correction, the elastic modulus of hollow slab increases by about 19.13%, the elastic modulus of cast-in-situ layer increases by about 16.00%, the lateral restraint stiffness increases by about 46.21%, and the longitudinal restraint stiffness increases by about 72.72%. The static and dynamic characteristics of the modified finite element model are in good agreement with the measured responses, the errors of static responses are less than 4%, and the errors of dynamic responses are less than 3%.More>

2019, 19(2): 14-24. doi: 10.19818/j.cnki.1671-1637.2019.02.002

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Simplified method of calculating flexural capacity of steel-concrete composite beam after stud corrosion

XU Bo, LIU Yong-jian, ZHU Wei-qing, JIANG Lei

Abstract: In order to forecast the flexural capacity of steel-concrete composite beam after the interface stud corrosion, the deterioration effects of the reductions of stud shear strength, bonding strength with concrete and stud effective area on the stud shear capacity after corrosion were mainly considered, and the concept and calculation formula of shear connection degree of composite beam and the stud shear capacity coefficient after stud corrosion were proposed. Based on the plasticity simplified calculation assumption, the calculation models of flexural capacity of positive and negative moment regions for the composite beam after stud corrosion were established by adopting the shear connection degree of composite beam after stud corrosion to reduce the composite beam flexural capacity. The test results of 23 composite beams were analyzed, and the validity of the model was verified. Test result shows that when the corrosion rate of stud is less than 10%, the test values of flexural capacity of positive and negative moment regions of the test beam are very close to the theoretical value calculated by the proposed formula. The mean ratio between the test value and the calculated value in the positive moment region is 1.00, and the variation coefficient is 0.04. Their mean ratio in the negative moment region is 1.01, and the variation coefficient is 0. It can be seen that the formula calculation results are in good agreement with the test results, and the simplified calculation method can be used for the quantitative and qualitative analysis on the flexural capacity of steel-concrete composite beams when the corrosion rate of interface stud is small.More>

2019, 19(2): 25-35. doi: 10.19818/j.cnki.1671-1637.2019.02.003

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Vertical bearing characteristics of bridge pile foundation under pile-soil-fault coupling action

FENG Zhong-ju, CHEN Hui-yun, YUAN Feng-bin, YIN Hong-hua, LI Xiao-xiong, LIU Chuang, ZHANG Fu-qiang, WANG Meng-meng, LI Shao-jie

Abstract: Based on the Hainan Puqian Bridge, the distance effect and bearing characteristics of bridge pile foundation under the fault-pile-rock interaction were analyzed by the indoor model test and numerical simulation. Research result shows that, in the model test, for a pile foundation with a diameter of 6.3 cm and a length of 60 cm, when the horizontal distance between the fault and the pile foundation increases from 9.45 cm to 22.05 cm, the bearing capacity of pile foundation increases by 26.7%. When the horizontal distance increases from 22.05 cm to 31.50 cm, the bearing capacity increases by only 3.8%, and the influence degree of the horizontal distance on the vertical bearing capacity reduces to 6.5% and may be neglected. When the length of pile foundation is constant and the load is the same, the smaller the horizontal distance, the smaller the change of axial force of pile foundation. The horizontal distance increases from 9.45 cm to 22.05 cm, the side resistance of pile foundation increases by 0.059 kN at the 30 cm of pile foundation length, and the influence degree decreases by 44.5%. When the horizontal distance increases from 22.05 cm to 31.50 cm, the side resistance increases by 0.029 kN, and the influence degree decreases by 8.3%. In the numerical simulation, under the condition that the diameter, length and overburden thickness of pile foundation are 1.5, 30, and 10 m, respectively, when the horizontal distance increases from 1.5 m to 6.0 m, the increment of the bearing capacity reduces from 11.0% to 6.5%. When the horizontal distance increases from 6.0 m to 7.5 m, the increment reduces to 4.9%. When the horizontal distance reduces from 7.5 m to 1.5 m, the axial force of pile foundation decreases gradually along the length direction of pile foundation. When the length of pile foundation is constant and the load is the same, the smaller the horizontal distance, the smaller the change of axial force of pile foundation. When the horizontal distance increases from 1.5 m to 6.0 m, the side resistance of pile foundation at the 16 m of pile foundation length increases by 1.90 MN, and the influence degree of the horizontal distance on the side resistance reduces by 28.0%. When the horizontal distance increases from 6.0 m to 7.5 m, the pile side resistance increases by 0.33 MN, and the influence degree decreases by 5.0%. The results of model test and numerical simulation show that the vertical bearing characteristics of bridge pile foundation are greatly affected by the horizontal distance between the fault and the pile foundation when the horizontal distance is less than five times the pile foundation diameter. When the horizontal distance is more than five times the pile foundation diameter, its influence is smaller or even negligible. The side resistance ratio and influence degrees of the horizontal distance on the bearing capacity and side resistance of pile foundation decrease rapider in the numerical simulation than in the indoor model test. When the horizontal distance is five times the pile foundation diameter, the numerical simulation values reduce by 0.174, 2.2%, and 6.0% compared with the indoor model test values, respectively. Therefore, the numerical simulation result is ideal and can be used as engineering reference.More>

2019, 19(2): 36-48. doi: 10.19818/j.cnki.1671-1637.2019.02.004

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Modification mechanism and performance of polyurethane modified asphalt

SUN Min, ZHENG Mu-lian, BI Yu-feng, ZHU Lin-lin, GAO Yuan

Abstract: To solve the problems such as poor storage stability, easy segregation and aging for polymer modified asphalt, the polyurethane (PU) was used to chemically modify the asphalt. The PU modified asphalt was prepared. The Fourier transform infrared spectroscopy (FTIR) test, dynamic thermomechanical analysis (DMA) test and differential scanning calorimetry (DSC) test were conducted to analyze the modification mechanism of PU modified asphalt. The performances of PU modified asphalt, SBS modified asphalt and 70^# base asphalt were evaluated by the Brookfield rotary viscosity test, dynamic shear rheological (DSR) test, low-temperature bending beam rheological (BBR) test, rotating thin film oven test (RTFOT), and ultraviolet aging test. Research result shows that the disk sawtooth agitator can expose the active group well in the asphalt, and make the PU achieve better modification effect. There are mainly two reactions in the PU modified asphalt. One is the reaction between the isocyanate and polyol to form carbamate, the other is the addition reaction between the isocyanate and aromatic compounds in the asphalt. The high-temperature Brookfield viscosity of PU modified asphalt is higher than that of SBS modified asphalt at the same temperature. The rutting factor of PU modified asphalt at 64 ℃ is about 6 times of that of SBS modified asphalt, showing that its high-temperature performance is excellent. The penetration ratio of PU modified asphalt before to after RTFOT reaches 85%. The softening point change scope of PU modified asphalt is 0.5 ℃, showing that its thermal oxygen aging resistance is excellent. In the ultraviolet aging test, the change scopes of softening point and penetration of PU modified asphalt are 1 ℃-4 ℃ and 0.1-0.3 mm, respectively, indicating that its ultraviolet aging resistance is excellent.More>

2019, 19(2): 49-58. doi: 10.19818/j.cnki.1671-1637.2019.02.005

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Determining method of cohesionless soil state parameter based on resistivity CPTU and liquefaction evaluation

DUAN Wei, CAI Guo-jun, LIU Song-yu, ZOU Hai-feng, CHU Ya

Abstract: In order to study a new method for evaluating the state parameter based on in-situ testing technology, the Suqian-Xinyi Expressway project was taken as the background, the in-situ test of saturated cohesionless soil was conducted by using the resistivity piezocone penetration test (CPTU). By referring to the mean values of the existing in-situ state parameter calculation methods in the literatures, the state parameter calculation method was established by combining the resistivity and soil behavior type index. The state parameter evaluated by the method was applied to the liquefaction evaluation. Analysis result shows that the state parameter is proportional to the soil behavior type index, while the soil behavior type index is inversely proportional to the resistivity and can be used as one of the effective indexes to connect the state and electrical properties of cohesionless soil. The trend of state parameter evaluated by the proposed calculation method of resistivity CPTU state parameters is in agreement with the values of the existing methods. The proposed resistivity CPTU method is mainly applicable to the silt and silty sand whose behavior type indexes are between 1.8 and 2.6. The in-situ state parameter of cohesionless soil calculated by the proposed method has good linear relationships with the relative density, the trend is opposite, and it can be used as an effective alternative parameter for the commonly used index of relative density to evaluate the compactness of soil. The liquefaction resistance ratio of cohesionless soil calculated based on the state parameter from the proposed method is basically consistent with the values of international general methods. It is concluded that the silty sand layer below 8 m is liquefaction layer, which is consistent with the standard penetration test results. The state parameter can be effectively used for the reliable discrimination of liquefaction potential.More>

2019, 19(2): 59-68. doi: 10.19818/j.cnki.1671-1637.2019.02.006

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Transfer rules and effect of stress and deformation of ballastless track under uneven subgrade settlement

XIANG Jun, LIN Shi-cai, YU Cui-ying, YUAN Cheng, SU Wei

Abstract: The finite element models were established base on the characteristics of CRTS Ⅰ and CRTS Ⅱ slab ballastless track structures on the subgrade. The transfer laws of stress and deformation of different slab ballastless tracks and their effects were analyzed under the role of uneven subgrade settlement. Analysis result indicates that the vertical deformation of the upper track structure deforms accordingly with the subgrade after uneven subgrade settlement occurs. The deformation and settlement curves are similar but not completely coincident. The expansion joints that exist in the base plate have great influence on the stress and deformation of track structure. Under the condition of 20 mm/20 m, the vertical displacements of CRTS Ⅰ and CRTS Ⅱ slabs reach 90% and 60% of settlement amplitude, respectively, the vertical displacement of CRTS Ⅱ slab is less affected by the settlement compared with CRTS Ⅰ slab, but the latter is more likely to form a larger range of seam, and the length of the seam is 6.52 m and 1.92 times the length of the seam of CRTS Ⅰ slab. When the settlement amplitude is located at the center of base plate, the seams are mainly concentrated at the expansion joint, settlement end and settlement center. But when the settlement amplitude is located at the expansion joint, the seams are mainly concentrated on both sides of the expansion joint and settlement end. With the change of settlement wavelength or amplitude, it will cause the maximum position of seam to shift. Under the role of uneven subgrade settlement, the longitudinal maximum tensile stress of the base plate of CRTS Ⅰ slab is greater than that of slab, while the CRTS Ⅱ slab is opposite. Considering the strength of concrete, the settlement control standard of CRTS Ⅰ slab should be based on the tensile stress of base plate, while the settlement control standard of CRTS Ⅱ slab should be based on the tensile stresses of slab and base plate comprehensively.More>

2019, 19(2): 69-81. doi: 10.19818/j.cnki.1671-1637.2019.02.007

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Analysis method on time-history characteristics of rail supporting force for mixed passenger and freight railway with ballastless track

REN Juan-juan, YAN Ya-fei, HU Hua-feng, DENG Shi-jie, FENG Xiang

Abstract: The rail supporting force for mixed passenger and freight railway with ballastless track in the Suining to Chongqing Railway was tested on site by the Tekscan pressure measurement system. A Gaussian function type time-history expression of rail supporting force was proposed and verified by the field test data. According to the time-history expression of rail supporting force, the loads were applied to the track structure model through the sequential loading method, and the dynamic response results were compared with those obtained from the vehicle-track-subgrade vertical coupling vibration model and the field test. Research result shows that the maximum field measured rail supporting forces of passenger and freight train are 29.91 and 82.49 kN, respectively. The relative differences are less than 20% in comparison with the test result obtained by the China Academy of Railway Sciences. Therefore, the Tekscan pressure measurement system can accurately measure the rail supporting force. For the passenger and freight train, the correlation coefficients of rail supporting force time-history curves fitted by the Gaussian function and the field measured curves are 0.962 7 and 0.966 7, respectively. The relative differences between the fitted maximum rail supporting forces and the field measured values are 5.15% and 0.46%, respectively, and the relative differences between the fitted minimum rail supporting forces and the field measured values are 7.23% and 24.11%, respectively. Therefore, the Gaussian function can well simulate the time-history curves of rail supporting force under the actions of passenger and freight trains, and the simulation accuracy to freight train is slightly higher than to passenger train. Compared with the results of vehicle-track-subgrade vertical coupling vibration model and field test, the relative differences of the maximum displacements of track slab obtained from the load excitation-track-subgrade model based on the sequential loading method are 5.41% and 2.70%, respectively, the relative differences of the maximum displacements of base plate are 2.86% and 5.71%, respectively, the relative differences of the maximum acceleration of track slab are 14.00% and 23.20%, respectively, and the relative differences of the maximum accelerations of base plate are 13.61% and 8.73%, respectively. Therefore, the load excitation-track-subgrade model based on the sequential loading method and the Gaussian function type time-history expression of rail supporting force is reliable. This method does not need to establish the car body model, and not only ensure the calculation efficiency, but also have a very high accuracy.More>

2019, 19(2): 82-91. doi: 10.19818/j.cnki.1671-1637.2019.02.008

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Distributed dynamics characteristics of water-lubricated stern bearing under offset load

OUYANG Wu, CHENG Qi-chao, WANG Lei, JIN Yong

Abstract: In order to reveal the hydrodynamics behavior of water-lubricated stern bearing with a large length-diameter ratio under offset load, a test method of distributed dynamics characteristics parameters was proposed. A large-size water-lubricated stern bearing with a diameter of 324 mm and a length of 1 200 mm was tested on a large-scale propulsion shafting simulation test stand. Three cross sections of the bearing were selected along the axis direction, and two eddy current sensors perpendicular to each other were arranged on each cross section to obtain the axis orbits. At the same time, four cross sections of the shaft were selected along the axis direction and each section installed with a micro pressure sensor, respectively, and the signals of water film pressure distributions of the sections were obtained by the wireless telemetry. The inclined angle of the axis was adjusted by changing the elevation of the adjacent bearing, and the influence rules of rotation speed and elevation on the water film pressure distribution and running state of journal of test bearing were studied. Research result shows that the pressure test value of the section closest to the cantilever end due to the offset load is obviously larger than that of other sections, and the maximum value is about 3.6 MPa. The lubrication state of the bearing is partitioned along the axial direction, and the closer to the cantilever end, the more obvious the elastohydrodynamic lubrication characteristics. Different bearing segments need different speeds to generate hydrodynamic water film. The "water pocket" at the top of pressure curve of the section closest to the cantilever end appears with the increase of the rotating speed, but it is not obvious at 220 r·min^-1. The negative pressure phenomenon appears in the pressure distribution of each section. The spatial form of the journal in the bearing hole is relatively complex. The journal severely bends down on both sides of the bearing and arches in the middle, and the deflection angles of different bearing sections are different. The farther away from the cantilever end, the larger the axis orbit area. Compared with the bearing with a single lubrication state and a straight journal, the hydrodynamics model of water-lubricated stern bearing with large length-diameter ratio under offset load should take into account the factors, such as the zoning characteristics of lubrication state, the bending state of the shaft and the negative pressure phenomenon.More>

2019, 19(2): 92-100. doi: 10.19818/j.cnki.1671-1637.2019.02.009

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Vertical stability of permanent magnet EDS system with novel Halbach array

LUO Cheng, ZHANG Kun-lun, JING Yong-zhi

Abstract: For the vertical dynamic stability problem of permanent magnet electrodynamic suspension (EDS) system, the critical stable characteristic of permanent magnet EDS system was analyzed. A novel Halbach array mixed with permanent magnets and normal conductor coils was proposed. The active control on permanent magnet EDS system damping was realized by winding active normal conductor coils on the permanent magnet surface. The novel Halbach array was compared with the other two active electromagnetic damping control schemes. The vertical dynamic model of permanent magnet EDS system with novel Halbach array was established, and the suspension controller was designed by adopting the classical PID closed-loop control method. The system vertical dynamic stability was simulated and analyzed under the conditions without external disturbance, with external disturbing force and with track irregularity disturbance, respectively. Research result shows that under the action of disturbing force, the permanent magnet EDS system will oscillate with a constant amplitude, can not suspend stably and even may crash the track under the action of continuous disturbing force. The proposed novel Halbach array has the advantages of convenient coupling calculation in magnetic field and wide force adjustment range. The designed suspension controller can make the system suspend stably at the equilibrium position with a rated air gap of 0.03 m. The coils current is 0, and no loss is generated. The relative errors of suspension air gap and coils current between the simulation results and theoretical analysis results are less than 0.01%. When there exists a track irregularity disturbance, the system can suspend quickly and stably at the equilibrium position with a rated air gap of 0.03 m, and the stable coils current is still 0. Therefore, a zero-power balance of permanent magnet EDS system is realized. When the external disturbing force is ±1 500 N, the system can suspend quickly and stably at the equilibrium position with a rated air gap of 0.03 m, and the stable coils current is 29.68 and-30.40 A, respectively, proving that the permanent magnet EDS system with novel Halbach array can realize the vertical dynamic stability.More>

2019, 19(2): 101-109. doi: 10.19818/j.cnki.1671-1637.2019.02.010

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Mathematical model of ship motion in regular wave based on three-dimensional time-domain Green function method

ZHANG Teng, REN Jun-sheng, ZHANG Xiu-feng

Abstract: The series expansion method was adopted in the short time interval region, the asymptotic expansion method was adopted in the long time interval region, and the precise integration method was adopted in the transitional region between the short and long time interval regions to numerically calculate the three-dimensional time-domain Green function. The radiation and diffraction problems of ship were solved by the linear superposition principle. The ship motion mathematical model in regular wave was formulated. The hydrodynamic coefficients, wave exciting forces and motion time histories of a Wigley Ⅰ hull and a S60 hull were calculated by the numerical method when they sail on the wave with a Froude number of 0.2. Calculation result shows that due to the influence of irregular frequencies, when the dimensionless frequency is 1.7, the numerical result of heave added mass of Wigley Ⅰ hull is 44% smaller than the test result. When the dimensionless frequency is 2.5, the numerical result of pitch damping coefficient of S60 hull is 43% smaller than the test result. As the incident wave frequency increases, for a Wigley Ⅰ hull and a S60 hull, the relative errors of hydrodynamic coefficients and wave exciting forces between most of the numerical results and the test results are less than 30%, and the two have a same variation trend. For a Wigley Ⅰ hull, when the ratio of wave length to ship length is 1.25, the heave response amplitude operator and the pitch response amplitude operator calculated by the three-dimensional time-domain method are 11.3% and 4.8% smaller than the test values, respectively, the heave response amplitude operator calculated by the three-dimensional frequency-domain method is 48.4% larger than the test value, and the pitch response amplitude operator is 48.4% smaller than the test value. When the ratio of wave length to ship length is 1.50, the heave response amplitude operator and the pitch response amplitude operator calculated by the three-dimensional time-domain method are 3.0% and 11.3% smaller than the test values, respectively, the heave response amplitude operator calculated by the three-dimensional frequency-domain method is 9.8% larger than the test value, and the pitch response amplitude operator is 23.6% smaller than the test value. Thus, the three-dimensional time-domain method can accurately simulate the time history of ship motion in wave.More>

2019, 19(2): 110-121. doi: 10.19818/j.cnki.1671-1637.2019.02.011

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Capsizing mechanism of laterite-nickel ore transport ship under wave excitation

CHEN Yun-sai, DUAN Wen-yang, YANG Lei, HUANG Li-min

Abstract: The laterite-nickel ore, kaolin and red sand soil with the characteristics of fluidization typical cargoes were selected to conduct the critical water content test and fluidization test, and the critical water content rate was obtained. Using the excitation rolling device, the excitation rolling motion experiments with different excitation amplitudes and frequencies were carried out. The time history characteristics of overturning force and moment of three different cargoes under different water content rates were compared. Capsizing mechanism test was designed, the laterite-nickel ore with critical water content rate was chose as a sample, and the waves were generated in wave tank to excite rolling motion so as to recreate the capsizing process of the laterite-nickel ore transport ship. The high-speed camera was used to catch the variation of free liquid surface. The free liquid surface was segmented by using the digital processing technology. The changes of floating center and barycenter of laterite-nickel ore transport ship during the capsizing process were also discussed based on the free liquid surface's condition. Analysis result shows that the critical water content rates of the laterite-nickel ore, red sand soil and kaolin are 33.6%, 22.0% and 39.4%, respectively. The sloshing force and moment of soils with different natures show different properties even though their excitation conditions are the same. When the phase differences are 90° and 270°, the asymmetric moment increases 4.37 times as much as that when the phase differences are 0° and 180°. The main reason for the capsizing of laterite-nickel ore transport ship is that the liquid cargo's sloshing results in that the rolling moment increases and the dynamic stability decreases. At the same time, the sloshing moment is related to the nature of goods, period of excitation, viscosity, amplitude of incentive and many other factors.More>

2019, 19(2): 122-135. doi: 10.19818/j.cnki.1671-1637.2019.02.012

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Hierarchical, parallel, heterogeneous and reconfigurable computation model of container terminal handling system

LI Bin

Abstract: Based on computational thinking and computational lens, the loading and unloading operations and the scheduling decisions of container terminals were analyzed. Based on the parallel computation, heterogeneous computation and reconfigurable computation, a hierarchical, parallel, heterogeneous, and reconfigurable computation model of container terminal handling (HPHRCM-CTH) from the perspective of computation logistics was proposed. The design philosophies and operational mechanisms of typical computing architectures in the computer science were generalized, migrated, modified, fused, and customized to the container terminal handling system (CTHS), and the hybrid scheduling strategy for the HPHRCM-CTH was presented. A new abstract computation model and engineering solution to the container terminal scheduling were put forward. Taking a large container terminal as an example, the design and performance evaluation of logistics generalized computation automation were carried out based on the HPHRCM-CTH. Analysis result shows that the HPHRCM-CTH can determine the upper limit of container throughput that is about 2.75 times of the annual design capacity of the container terminal in the example. At the condition of full load, the scheduling strategies of load balancing for the pending queues of containers (LB-PQC) and ship types (LB-PQS) can shorten the logistics generalized computation task latency (LGC-TL) of large container mainline ships by about 17 h. At the condition of obvious job overload, the LB-PQC can reduce the LGC-TL by 100-110 h, while the LB-PQS can reduce the LGC-TL by about 120 h. At the conditions of full load and job overload, the LB-PQC and LB-PQS can reduce the logistics generalized computation memory access time (LGC-MAT) for large container mainline ships by 1-2 h, and the LB-PQS performs better under the conditions of job overload. The LB-PQC and LB-PQS both can give well priority to the key service liners, and have the respective applicable condition and scheduling emphasis, and the terminal manager can choose the right one according to the specific situation.More>

2019, 19(2): 136-155. doi: 10.19818/j.cnki.1671-1637.2019.02.013

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Evaluating model of deployment performance of metro emergency rescue vehicles

ZHANG Yong, FU Zi-yan

Abstract: The rescue operation queue process of metro emergency rescue vehicles (MERVs) responding to metro disasters was analyzed. By defining the state space of MERVs in response to metro disasters, the joint queuing model of MERVs' rescue states was established based on the random birth-death process theory and obtained balance equations. In order to reduce the computation amount and storage space of balance equations, an improved solving algorithm of joint queuing state probability based on the sparse matrix compression was developed. The calculation methods of various performance evaluation indexes of metro rescue system, including the rescue response time, MERVs working intensity and cross-district rescue probability, were given. In order to verify the model and algorithm, the actual metro network was taken as an example, and the performance indexes of three types of MERVs, including the road-rail rescue vehicle, crawler rescue vehicle and portable rescue vehicle, were studied. Calculation result shows that the magnitude of convergence precision reaches 10^-8 after the algorithm iterates 7 times. The average response times of road-rail rescue vehicle, crawler rescue vehicle and portable rescue vehicle are about 14, 20 and 10 min, respectively. The cross-district rescue probabilities of road-rail rescue vehicle and crawler rescue vehicle are about 0.85 and 0.75, respectively, and the magnitude of portable rescue vehicle is 10^-5. For the regions receiving external rescues, the rescue probabilities of road-rail rescue vehicle and crawler rescue vehicle both are about 0.7, while the magnitude of portable rescue vehicle is about 10^-6. For the balance of rescue intensity, they are sequentially decline the road-rail rescue vehicle, crawler rescue vehicle and portable rescue vehicle.More>

2019, 19(2): 156-166. doi: 10.19818/j.cnki.1671-1637.2019.02.014

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Influence of roll and pitch on multipath effect of shipborne GNSS signal

WANG Yu-ming, SHAO Li-min, ZHANG Shang-yue

Abstract: The ship related coordinate system and ship-based GNSS antenna correlation coordinate system were established, and the spatial position relationship model between the GNSS satellite and tilt antenna was constructed. Based on theoretical analysis and dynamic and static experiments, the variation rules of multipath effect of GNSS signal with the tilt angle of receiver antenna under ship swing condition were given. Analysis result shows that when the ship-based antenna is continuously at the swaying and tilting position by the roll and pitch effect, the variation of multipath effect of satellite signal is related to the antenna tilt direction, antenna tilt angle and the difference of satellite relative height angle. When the satellite faces the antenna tilted direction, the multipath effect of satellite signal with a relative height angle greater than the antenna tilt angle is not affected by the antenna attitude change. The multipath effect of satellite signal with a relative height angle smaller than the antenna tilt angle increases as the antenna tilt angle increases, and gradually becomes stable. When the satellite is in the opposite tilted direction of antenna, the multipath effect of satellite signal whose relative height angle is greater than the antenna tilt angle increases slowly with the increase of antenna tilt angle. While the multipath effect of satellite signal whose relative height angle is smaller than the antenna tilt angle increases significantly with the increase of antenna tilt angle, and even some satellite signals are completely unlocked. When the satellite is at the zenith position of inclined antenna, its multipath effect is not affected by the antenna tilt angle. Therefore, determining the signal confidence of each GNSS observation satellite according to the different attitudes of the ship can provide a solution for the error correction problem of dynamic precision positioning and measurement at sea.More>

2019, 19(2): 167-177. doi: 10.19818/j.cnki.1671-1637.2019.02.015

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Slot control optimization of intelligent platoon for dual-lane two-way overtaking behavior

CHEN Jun-jie, CAI Bo-gen, SHANGGUAN Wei, WANG Jian, CHAI Lin-guo

Abstract: A model of single vehicle overtaking a platoon on the dual-lane two-way road was established, and the key factors affecting the range of dangerous overtaking zone were analyzed. The step-by-step algorithm was designed when single vehicle overtakes the platoon. The relationship among the speeds of the vehicles before and after the safety slot, the speed of the overtaking vehicle entering the platoon and the safety slot range of the platoon was studied. The speed matching scheme with the minimum safety slot required for the vehicle to overtake the platoon was proposed. The objective function of the algorithm was established, and the following assumptions were made in the maximum allowable overtaking time: the overtaking vehicle and platoon travelled the longest distance, the overtaking vehicle overtaked the platoon by the most vehicles, and the acceleration and deceleration of front and rear vehicles were the minimum in the forming process of safety slot. The hierarchical constrained multi-objective optimization method based on the improved particle swarm was proposed to provide the algorithm with the optimized three-level speed guidance strategy. Analysis result shows that the overtaking dangerous zone on dual-lane two-way road is positively correlated with the number of vehicles in the platoon and the velocities of the opposite vehicles. The improved particle swarm optimization algorithm has stronger robustness and faster convergence than the traditional algorithm, and the average convergence time reduces by 39.2%. In the step-by-step process that the single vehicle overtakes the platoon, the average speed of the vehicles in the platoon increase by 9.04%, which means that in the forming process of safety slot, although the speeds of some vehicles decrease, the overall average speed of the platoon increases. The average speed of overtaking vehicle increases by 16.8%, which means that in the overtaking process, not only is the safety of overtaking vehicle guaranteed, but also its operating efficiency is improved.More>

2019, 19(2): 178-190. doi: 10.19818/j.cnki.1671-1637.2019.02.016

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2019 Vol. 19, No. 2

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