西南交通大学学报

Mechanical Performance of Novel Prefabricated Composite Girder with Top Flange of Ultra Hight Performance Concrete Waffle Deck Panel

ZHANG Qinghua, HAN Shaohui, JIA Donglin, BU Yizhi

2019, 54(3): 445-452. doi: 10.3969/j.issn.0258-2724.20170906

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Abstract:
A novel prefabricated composite girder with the top flange of an ultra-high-performance concrete (UHPC) waffle deck panel in place of a normal concrete deck panel was proposed, to resolve problems associated with the high self-weight and high probability of cracking in conventional steel-concrete composite structures. To investigate the mechanical behaviour and application of the structure in continuous bridges, a whole bridge model and mid-support region girder model of a typical three-span continuous bridge were established by finite element analysis (FEA). The mechanical behaviour of the novel composite girder under various load modes was studied, and the influence of the key design parameters for the UHPC waffle deck panel on the mechanical behaviour of the novel composite girder was analysed. In addition, the influences of the composite dowel-type shear pocket and stud-type shear pocket on the mechanical performance of the novel composite girder were compared. The maximum tensile stress at the bottom of the longitudinal ribs and the top deck of the UHPC waffle deck panel meets the tensile strength limit of reinforced UHPC under the composite action of dead loads and live loads; when the longitudinal ribs and transverse ribs are 90 mm in width, 200 mm in height, 700 mm in the space of the longitudinal ribs, 600 mm in the space of the transverse ribs, and 60 mm in the thickness of the top deck, the UHPC waffle deck panels exhibit better mechanical performance than before. The composite dowel-type shear pocket is more applicable to the novel prefabricated composite girder than the stud-type shear pocket.

Synthesis of Non-Stationary Seismic Waves Based on Phase Difference Spectrum and Its Application

JIA Hongyu, LAN Xianlin, CHEN Hang, ZHENG Shixiong, LI Xi, ZHANG Yongshui

2019, 54(3): 453-460. doi: 10.3969/j.issn.0258-2724.20180284

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A synthetic method of multi-dimensional and multi-point non-stationary seismic waves (MMNSWs) based on phase difference spectrum is proposed to simulate the non-stationarity and multi-dimensionality of real ground motions in hope to overcome the deficiencies of the traditional trigonometric series method, such as the arbitrariness in selection of the envelope function and loss of non-stationarity feature in frequency domain. First, the traveling wave effect, coherence effect, local site effect and multi-dimensional property of ground motions are modelled using the random field theory. Then, the phase difference spectrum is determined and used to characterize the non-stationarity of intensity and frequency of ground motions. Finally, the synthetic non-stationary ground motions are applied to an actual bridge for seismic analysis, and the generated dynamic responses are compared with the equivalent response spectrum obtained by response spectrum method. Results show that the MMNSWs generated based on phase difference spectrum does not need the envelope function to control the waveform of seismic waves, and hence can exclude the arbitrariness of artificial selection of the intensity envelope function. Since it has taken into account the relevance and multidimensionality of seismic ground motions, the proposed method is better than the traditional trigonometric series method for synthesis of ground motions. In addition, the results generated by the proposed method are basically consistent with those by the traditional response spectrum method. The difference between the values of shear force and bending moment at two pier bottoms, calculated by the response spectrum method, is in the range of 10% and 17%, respectively, while the difference is less than 9% and 12%, respectively, by the proposed method.

Influence of Shield Construction on Pressure Fluctuation of Segment Grout

WANG Mingnian, HUANG Haibin, TANG Yuan, WANG Chuang, LIU Dagang

2019, 54(3): 461-467, 586. doi: 10.3969/j.issn.0258-2724.20170199

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In order to investigate the cause of slurry pressure instability segment tracking changes in the process of synchronous grouting segment, the variation law of external load of segments and the grouting lag time during shield tunneling were obtained, by means of the field test and construction parameter statistics of the Maliuzhou tunnel project in Zhuhai. The relationship between the volumetric strain of the shield tail and the grouting pressure was deduced by treating the clearance of the shield tail as a closed vessel filled with high pressure liquid and the shield driving as changing the boundary conditions of the vessel.The applicability of the research results was verified by the monitoring results of the Qianjiang tunnel and the Sohpia tunnel. The results show that the fluctuation of slurry injection pressure, the diffusion of serous fluid when the lining is out of the shield, the lag effect in the construction process of synchronous grouting compared with tunnel excavation are the main factors that cause the change of slurry pressure instability behind segment. The average lag time of the grouting phase compared to the shield propelling in the Maliuzhou tunnel is 86 s, when the volumetric variable is 1 × 10^–4, the change of slurry pressure reaches to 0.218 MPa, which verify the phenomenon that the lag effect makes the soil pressure behind segment reduced sharply when the shield is pushed from stationary to tunneling.

Creep Buckling Analysis of Concrete-Filled Steel Tubular Columns

ZHAO Renda, WU Debao, WANG Yongbao, JIA Yi, LIAO Ping

2019, 54(3): 468-474. doi: 10.3969/j.issn.0258-2724.20170371

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In order to investigate the influence of concrete creep on the long-term stability of concrete-filled steel tubular (CFST) columns under axial load, based on the energy method and age-adjusted effective modulus method, the long-term stability equations for the critical force of CFST columns with different boundary conditions considering creep and pre-buckling deformation were deduced using an instability criterion. The influence of the critical force and strength of the core concrete were studied. In addition, the value of the current standard and critical loads were compared. The results show that the critical load for creep stability of CFST columns is related to the creep coefficient; CFST columns with the same calculated length but different boundary conditions have the same long-term critical load. The influence of creep on the stability of the column decreased with increasing core concrete strength. When designing CFST columns with low-strength concrete using the current code for the design of concrete structures, additional attention should be paid to the influence of creep buckling. The long-term stability of the critical forces of CFST column was reduced obviously reduced in the first 60 days, which accounts approximately for 80% of the total decline. The bearing capacity of the steel tube tends to be stabilize after 100 days.

Research Progress on Building Isolation Based on Electromagnetic Levitation Techniques

PAN Yi, ZHOU Meng, GUO Rui, HU Siyuan, LIN Yongjun

2019, 54(3): 475-482. doi: 10.3969/j.issn.0258-2724.20170413

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Isolation is viewed as one of the most promising technologies to protect buildings from strong earthquakes. The application of electromagnetic levitation techniques for isolation of building structures is a frontier research field in structure engineering. Compared to conventional rubber isolation bearings, an electromagnetic levitation device has an active control capability for both vertical and horizontal isolation of the structures. However, the research on this topic is scarce. Herein, the background and basic concepts of electromagnetic levitation isolation technology is introduced with a focus on the research progress and current development of two electromagnetic levitation isolation systems, namely permanent magnet-electromagnet and armature-electromagnet. Furthermore, some key issues that remain to be addressed in the practical application of electromagnetic levitation isolation are listed. In addition, some suggestions are provided for future research on isolation of building structures based on electromagnetic levitation techniques.

Seismic Behavior of Rectangular High-Strength Concrete-Filled Steel Tube Frame Structure

GUAN Minsheng, HUANG Xianqi, DU Hongbiao, ZHANG Jingang

2019, 54(3): 483-491. doi: 10.3969/j.issn.0258-2724.20170809

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In order to study the failure mechanism and seismic performance of rectangular high-strength concrete-filled steel tube (RHCFT) frames, the cyclic loading test as well as the finite element (FE) analysis was conducted on a single-span and two-story RHCFT frame. During the test, the formation process of plastic hinge in the specimen including the location, sequence and degree of plastic development of the plastic hinge was investigated to study the failure mechanism, and thus the failure mode of the specimen. According to the hysteretic curves and backbone curves from the experiment, the seismic performance of the RHCFT frame, including the bearing capacity, the deformation ability, the energy dissipation capacity as well as the strength and stiffness degradation, was examined. On this basis, the FE analysis model of the RHCFT frame specimen was created using Perform-3D. The effects of the axial compression ratio, the steel yield strength, and the lateral load pattern on the seismic performance of the structure were examined. The results show the RHCFT frame demonstrates a strong column and weak beam failure mode, and has the characteristics of high bearing capacity, deformation capacity, and energy dissipation capacity. The average peak load of the specimen is 1.68 times higher than the yield load. The maximum inter-story drift ratios of the top and bottom stories are 1/30 and 1/27, respectively, which exceed 66.7% and 85.2% of the limit specified in the specification. The ductility coefficients exceed the prescribed limit by 58.5% and 60.0% respectively. The axial compression ratio has a significant effect on the seismic performance of the structure. When the axial pressure ratio is greater than 0.6, the bearing capacity and deformation capacity of the structure decrease drastically. The lateral load pattern have a great influence on the bearing capacity of the structure. The load capacity of the structure is the largest under uniform loading pattern, the smallest under vertex loading mode, and the inverted triangle loading pattern is between them. The research results can provide reference for the seismic design of rectangular high-strength concrete-filled steel tubular frame structures.

Analytical Finite Element for Timoshenko Beams

XU Jing, LI Shiyao, WANG Bintai, LI Jing, JIANG Xiugen

2019, 54(3): 492-498. doi: 10.3969/j.issn.0258-2724.20180176

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To improve the calculation accuracy and efficiency of structural force and deformation of deep beams, the deflection control equation of a deep beam was built by Timoshenko beam theory, and analytical displacement shape functions for deflection, section flexural angle and shear angle of deep beam were constructed. Then, potential energy functions for the beam model were established using the potential energy principle; analytical element formulations for beams and the total element stiffness matrix were obtained via the variational principle of potential energy stationary value. Finally, the proposed analytical finite element method was applied to calculate the end deflections of a cantilever deep beam and a simply supported deep beam; and the calculation results were compared with those by theoretical solution and interpolation polynomial method. The results show that the solutions of end deflection and rotation obtained from the proposed analytical element by one element number is in accordance with the theoretical solutions; the maximum relative error between the results calculated from interpolation shape function method and the theoretical solution is 19.785%. To verify the influence of shear deformation on the deflection, the proposed element was also compared with the Euler beam element. The comparison results show that, for cantilever beams subjected to distributed load, the relative error between the results calculated from the Euler beam theory and the proposed element derived by the Timoshenko beam theory is 50%. For simply supported beams subjected to a concentrated bending moment at the end, the relative error is 10.769%. It is proved that the proposed analytical beam element can satisfy the high accuracy and efficiency requirement and avoid shear locking problems.

Face Stability of Shield Tunnel in Sandy Cobble Stratum with Continuum-Based Discrete Element Method

XUE Yadong, ZHANG Sen, LI Xing, GE Jiacheng

2019, 54(3): 499-506, 586. doi: 10.3969/j.issn.0258-2724.20170406

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The instability mechanism of shield tunnel excavation working face in a sandy cobble stratum was explored, and the CDEM (continuum-based discrete element method) was adopted to establish a quasi-continuous numerical model. Triaxial compression tests of sand-cobble soil were carried out numerically to analyse its macro–mesoscopic mechanical characteristics. Based on the features of " particle flow”, " soil arch effect”, and " over-excavation”, a 2D dynamic discrete element model was established to simulate the tunnel working face over-excavation with plane triangular blocks. The progressive instability mechanisms of the tunnel face (such as soil arch effect and cavity zone) were studied. The results show that the macroscopic stress-strain curve of the sandy cobble soil triaxial compression test can be divided into linear elastic, elastoplastic, and ideal plastic stages. The cobble enhances the soil structure as coarse granular particles. The contact surface of the cobble and sand weakens the macroscopic strength. The Hopper flow calibration test with the soil arching effect as the calibration criterion can effectively obtain the friction angle transformation relationships of discrete plane triangles of different scales. The arching effect is notably ahead of the face, develops gradually with over-excavation, and finally dissipates gradually after reaching the limit state. Void regions start from the bottom of the screw conveyor, develop forward and upward gradually with over-excavation and finally cut through the load-bearing arch, reaching the ground surface and forming water-drop shaped void regions. Three types of control standards for over-excavation are proposed based on different strategies.

Analysis of Limit Support Pressure due to Shield Tunnelling with Shallow Overburden under Seepage

CAO Liqiang, ZHANG Dingli, LI Xinyu, LI Ao, SUN Zhenyu

2019, 54(3): 507-515. doi: 10.3969/j.issn.0258-2724.20180482

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Based on the semi-contained water model, comprehensively considering the permeability of the shield-crossing soil layer and the overburden layer when shield passed through the permeable soil, the analytical solution of the head distribution along the tunnelling direction within the shield-crossing soil layer was derived, combining this, the analytical solution of the two-dimensional seepage field was extended to the corresponding three-dimensional approximate solution. Meanwhile, the active and passive failure modes of shallow-buried soil under steady-state seepage were obtained using numerical method, and the corresponding cylinder-arc-corner shaped model was established, after that, the calculation formulas of the two limit support pressures at tunnel face were obtained by introducing the above-mentioned three-dimensional seepage solution, and the calculated results were compared with the existing one, the current results were closer to the numerical solution. Besides, the study found that the disturbance of the seepage field in front of the tunnel face is limited to three times the tunnel diameter, the values of active and passive limit support pressure increased linearly with the increase of the head difference. The shield diameter and head difference were two main factors affecting the active limit pressure, and the overburden thickness and the shield diameter were two major factors affecting the passive limit pressure. During tunnelling, the support pressure should be as close as possible to the in-situ transverse earth pressure using approach calculating separately for soil and water, and should be slightly fluctuated in the vicinity (preferably above it). The fluctuation range should be determined according to the deformation control standard.

Calculation Method of Trailing Edge Failure Surface of Retrogressive Landslide

SUN Lijuan, CUI Kai, YANG Tao, CHENG Qihang

2019, 54(3): 516-525. doi: 10.3969/j.issn.0258-2724.20170873

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Slope failure is induced by retrogressive slide, forming a trailing edge tension crack surface. The shape of the trailing edge surface has an important influence on landslide stability analysis and thrust calculation. However, it is difficult to determine the spatial characteristics of the landslide. In order to explore the formation mechanism and calculation theory of the trailing edge fracture surface, a reasonable mathematical and mechanical model was established. The calculation method of the trailing edge fracture inclination angle was put forward, from which the most dangerous fracture inclination angle of each level slider was found. Finally, the fracture surface was used as a stripe type to calculate the stability coefficient of each level slider and carry out the stability analysis of the landslide progressive failure process. Simultaneously, an indoor model test was conducted for verification. A new model test device was developed as well. Its main body was composed of a number of permeable boxes, thereby forming sectional sliding surfaces of various geometric shapes. By injecting water into different permeable boxes, step-by-step instability process of retrogressive landslide was realized. Then the trailing edge inclination of the final form of the sliders at each stage was measured. The results show that the calculated value of the inclination of the trailing edge is in good agreement with the test value. It is mainly concentrated at about 70°, with a relative error between 2% and 4%. The stability of the sliders is different at each level. Thus, the stability of the first stage is the worst, whereas the stability of the backside of the landslide body is better. These research results can provide a new procedure for conducting the stability analysis of retrogressive landslide.

Test Study on True-Triaxial Loading and Unloading for Marble with Unloaded Single Face

XU Wensong, ZHAO Guangming, MENG Xiangrui, LI Yingming, CAI Jinlong, GAO Liang

2019, 54(3): 526-534. doi: 10.3969/j.issn.0258-2724.20180542

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To accurately evaluate rock stability around the excavation face of roadway（tunnel）, a true-triaxial unloading disturbance testing system is applied in the loading and unloading tests of marble samples, where single-face was unloaded in the direction of the minimum principal stress. Through the analysis on instability mechanism of rock around roadway excavation face with high geostress, two kinds of failure modes, including energy accumulation failure and stress concentration failure, were simulated in different loading and unloading paths. Then, stress-strain curves, and failure and strength characteristics were further analyzed. The results indicate that there is dilatancy when the stress on unloading surface decreases; the main failure surface is near the free face; moreover, with the increase of the axial load, the splitting failure area extends and the critical unloading value increases. With the increase of the confining pressure, the stress peaks and yields increase, and the curve slope between the yield and peak is reduced. The composite failure mode with local tension-splitting-shear failures develops into the overall splitting failure. Under the same confining pressure, the unloading failure strength is 80% of the loading failure strength, and the marble sample in unloading is more likely to fail than in loading. The Hock-Brown criterion is modified using the calculated fracture strength value.

Assessment for External Influence Factors of High-Speed Train Transmission Reliability

LIU Yumei, CHEN Yun, ZHAO Congcong, XIONG Mingye, QIAO Ningguo

2019, 54(3): 535-541. doi: 10.3969/j.issn.0258-2724.20170563

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For the study of external influence factors besides its components impact on the high-speed train transmission reliability, the external influence factors of the CHR3 high-speed train transmission reliability are analyzed based on fuzzy influence diagram (FID). First, Frequency fuzzy sets, state fuzzy sets and fuzzy relation were built by the expert questionnaires. The relational layer, number layer and function layer of FID were constructed for the transmission reliability. Furthermore, the frequency matrix of extrinsic impact factors such as personnel, infrastructure, environment, maintenance and management is calculated based on the fuzzy set theory. Finally, get the reduced state cumulative probability and the cumulative increase probability of external influence factors. The reduced state cumulative probability of the personnel situation and the management level is 39.9% and 42.5%, and the cumulative increase probability is 77.6% and 90.9%, and the cumulative probability distribution is similar to the reliability of transmission probability distribution..In summary, the staff and management are the key extrinsic impact factors for the transmission reliability, and other factors are secondary.

Field Measurements Study on High-Altitude Wind Characteristics of Bridge Site in Deep Gorge

ZHANG Mingjin, LI Yongle, YU Chuanjin, WU Lianhuo

2019, 54(3): 542-547. doi: 10.3969/j.issn.0258-2724.20170370

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Long-span bridges built in deep gorges are usually inaccessible and it is difficult to obtain wind characteristics of these bridge sites from the wind-resistant design code owing to the complex terrain and the great gap between the deck and the valley bottom. To confirm the high-altitude wind characteristics of a bridge site in a deep gorge, field measurements of such properties were conducted using 3D sonic anemometers located in the mid-span and arranged on the catwalk during the construction process. A total of 7 899 valid fluctuating wind speed time series were obtained. On the basis of this data, the high-altitude wind characteristics of the bridge site were studied, including the average wind speed velocity, wind direction, wind attack angle, turbulence intensity, turbulence integral, and power spectrum densities. The results show that the impact of the landscape on the high-altitude wind characteristics of the bridge site in the deep gorge weakened substantially, while the wind attack angle tends to 0. Simultaneously, the turbulence integral at high altitude is more characteristic of that in plain regions, where the mean value is greater than that recommended by the wind-resistant design code.

Fire Resistance Analysis of RC Beam Supporting Column Transfer Structure Joints

KONG Weiyi, FU Chuanguo, LIU Weiqing

2019, 54(3): 548-555. doi: 10.3969/j.issn.0258-2724.20170875

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To provide the basis for the fire prevention design of reinforced concrete beam supporting column transfer structures, according to the structural characteristics, two kinds of full size beam supporting column transfer structure joints are designed. The reinforced concrete beam supporting column transfer structure joints are exposed to fire, and their fire resistance is tested. Based on the test results, using ABAQUS —a finite element analysis software, considering the influence of raising temperature curve, loading ratio, protective layer thickness, additional steel bars, the number of surfaces in fire of a transfer girder, the fire resistance of beam supporting column transfer structure joints is analyzed and the variation of the fire resistance for these beam supporting column transfer structure joints is summarized. The analysis results show that heating curve and maximum temperature have a significant influence on fire resistance; the fire resistance limit of joint units with load ratio of 0.6 is smaller than that of joint units with load ratio of 0.4; the thickness of the protective layer of the longitudinal tensile reinforcement of the joint unit differs, while the fire resistance limit ranges from large to small for protective layer thickness of 50 mm, 40 mm, and 25 mm, respectively; hanging steel bars in the transfer girder can improve the fire resistance and help avoid sudden damage. The more surfaces of the transfer girder are in fire, the shorter is the fire resistance. Under the same loading ratio, two kinds of beam supporting column transfer structure joints have different damage characteristics and fire resistance.

Microstructural Characteristics and Modification Mechanism of Inorganic Fine Particles in Buton Rock Asphalt

WU Huairui, YE Fen, XU Xiaolong

2019, 54(3): 556-564. doi: 10.3969/j.issn.0258-2724.20180582

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The properties of natural inorganic fine particles in Buton rock asphalt (BRA) and the effects of asphalt modification on these particles were analyzed in order to study the role of the natural inorganic fine particles in the process of asphalt mixture modification. First, X-ray diffraction (XRD) patterns and microscopic images of the inorganic fine particles were obtained using X-ray diffraction and scanning electron microscopy (SEM). Secondly, the mineral composition, microscopic characteristics, and mechanism of the formation of the natural inorganic fine particles in BRA were analyzed through the K value method and grayscale image processing. Finally, the effects of the inorganic particles on the performances of mastic and asphalt mixtures were determined using the dynamic shear rheological test (DSR) and mixture performance tests. The results show that the natural inorganic fine particles in BRA contain approximately 85% carbonatite, which is mainly formed from the remains of ancient halobios and partially retained the primary structure. The content of non–carbonate inorganic minerals reaches 15%, of which the proportions of quartz, muscovite, and gypsum are approximately 7:6:1. The surface area of the particles covered by micro-rough structures composed of layered and tabular crystals can reach more than 80%. The preservation of the original microstructural characteristics, recovery, and the enhancement of the organic binder filling state of the microstructure are the main factors responsible for the modification effect of the natural particles. The partial substitution of artificial mineral particles by natural inorganic fine particles can increase the rutting factor of the asphalt mastic, dynamic stability, and freeze-thaw tensile strength by 0.524 kPa, 18.8%, and 5.1% respectively, and the tensile strength ratio can increase to more than 83.5%. The use of natural inorganic fine particles as an aid in compound modifiers improves the performance of the mastic and asphalt mixtures. When the mastic or mixture is modified with natural asphaltene, the natural inorganic fine particles increase the rutting factor of the asphalt mastic, dynamic stability, and freeze-thaw tensile strength by 0.674–0.910 kPa, 21.1%–25.6%, and 3.5%–5.6% respectively, and the tensile strength ratio increases from 85% to more than 90%.

Multi-Objective Robust Optimisation Method for Stochastic Time-Dependent Vehicle Routing Problem

DUAN Zhengyu, LEI Zengxiang, SUN Shuo, YANG Dongyuan

2019, 54(3): 565-572. doi: 10.3969/j.issn.0258-2724.20170617

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The vehicle routing problem (VRP) is a core issue of distribution logistics. In order to improve the timeliness of deliveries, a multi-objective robust optimisation model based on the minimax criterion was proposed for the stochastic time-dependent vehicle routing problem (STDVRP) with hard time windows, considering both the stochastic and time-varying nature of link travel times. A non-dominated sorting ant colony optimisation (NSACO) algorithm was designed to solve this multi-objective optimisation model for the STDVRP. The NSACO algorithm was compared with the non-dominated sorting genetic algorithm II (NSGA-II) through computational instances. The results show that for the Pareto boundary of the minimised number of vehicles, the average number of vehicles for NSACO is 3.33% less than that of NSGA-II, and for the Pareto boundary of the minimised worst travel time, the average worst travel time for NSACO is 17.49% less than that of NSGA-II.

Modeling and Verification of Control System Specification for Railway Level Crossings Based on Formal Method

WANG Keming, WANG Zheng

2019, 54(3): 573-578, 603. doi: 10.3969/j.issn.0258-2724.20180607

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To improve the reliability of the control system design for the railway level crossings, a formal method is used to model and verify this system. By analyzing the management standards of the railway crossingss, the requirement properties and event processes were obtained; moreover, a multilayer Event-B model was established by using the UML diagram method and refinement policy. After theorem proving of the proof obligations generated by the invariants, the design properties of safety and time were verified; meanwhile the defect of requirement specifications were detected, with an improved event flow being proposed to enhance the robustness, thereof the system prototype was revised as well. Finally, by checking the invariant violations and deadlock, the model was validated on its correctness. The proposed method helps to improve the accuracy and hierarchy of the formal modeling process. In addition, the research result indicates that a defect exists in the current specification, i.e. the clearance of the crossings cannot be guaranteed when the train enters the level crossings. It’s concluded that the formal process presented in this paper can be used to verify the requirement specification of the railway crossings control system, so as to help developing a reliable prototype that can greatly improve the safety of the railway level crossings.

System Dynamics Analysis Method of Evolutionary Game Dynamics for Supervision of High-Speed Railway Operation Safety

LI Kehong, ZHANG Yadong, GUO Jin, WANG Zicheng

2019, 54(3): 579-586. doi: 10.3969/j.issn.0258-2724.20180034

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On the issue of no-incentive restraint mechanism and the regulator not independent in the entrusted transportation management model of high-speed railways (HSR) in China, an evolutionary game model of the HSR operation safety supervision system has been established through the analysis of the current situation and principal-agent model of the system based on the optimization assumptions that enhance the status and authority of the HSR company. The system was composed of the HSR company, a third-party regulatory agency (RA), and commissioned railway bureau (RB). The results of the evolutionary game theory combined with system dynamics (SD) simulation revealed the behavioural characteristics and steady-state decision-making by the three parties in the system. The SD simulation results showed that eight pure strategy equilibrium solutions and two mixed strategy equilibrium solutions of the model did not comply with the evolutionary stable strategy. Under the initial strategy of any non-equilibrium solution, the game evolution process of both the HSR company and commissioned RB continually fluctuate; however, the safety regulation rate of the RA will always evolve towards the state of real-time supervision, indicating that the introduction of an independent third-party RA and a clear incentive restraint mechanism can improve the safety regulation rate of the HSR operations safety supervision system effectively.

Modelling Passenger Evacuation from Metro Platforms Considering Passenger Flow Guidance and Small Group Behaviour

LI Fang, DI Yue, CHEN Shaokuan, JIA Wenzheng

2019, 54(3): 587-594. doi: 10.3969/j.issn.0258-2724.20170668

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Passenger flow guidance and small group behaviour during the actual evacuation process in metro stations greatly affect the behaviours of individual passengers and the evacuation result. To make a better simulation on the actual evacuation situation, the social force model was explored, which can take into account passenger flow guidance and small group behaviour. The model was modified by analysing the influence of passenger flow guidance and small group behaviour on the expected velocity of passengers. A multi-agent technique that involves realistic perception and decision processes was employed to develop a model for simulating passenger evacuation from a metro platform. Xizhimen metro station in Beijing was used as a case study object to verify the proposed model. Results indicate that both passenger flow guidance and small group behaviour have obvious effects on the evacuation time and efficiency, bottleneck areas, and detour distances. Passenger flow guidance increases the evacuation efficiency by 18%-45% and small group behaviour leads to an increase of 17% in the detour distance.

Axiomatic Design Based Logistics System Evaluation in Mass Customization Context

CHEN Maolu, WANG Zengqiang, PU Yun

2019, 54(3): 595-603. doi: 10.3969/j.issn.0258-2724.20170190

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Evaluating logistics systems in the context of mass customisation is uncertain and complex., As linguistic information is utilized in the evaluation of of logistics systems rather thanprecise and quantitative indexes, this paper presents a methodology based on the linguistic information and axiomatic design. In this methodology, firstly, an approach based on the integration of fuzzy scale evaluation is presented to obtain the normalised weight vector. Secondly, the expectation-outcome consistency for each alternative is determined by the executive team, followed by the calculation of the comprehensive evaluation indexes using axiomatic design. Finally, the most suitable logistics system can be identified by the ranking of the comprehensive appraisal indexes. The proposed method synthesized the linguistic-based decision-making theory and applied the information axiom in the axiomatic design for a computer company to select the logistics system. Six decision-makers determined six key indices of the logistics system and their expected values, and the index weight vector was calculated through linguistic information processing. Seven alternatives of logistic systems designed by the third-party logistics enterprises were determined, and the corresponding methods were employed to handle three types of index expectation. The obtained reasonable alternative has validated the feasibility and effectiveness of the proposed method.

Indoor Geomagnetic Positioning Based on Joint Algorithm of Particle Filter

HUANG He, QIU Kaiyue, LI Wei, LUO Dean

2019, 54(3): 604-610. doi: 10.3969/j.issn.0258-2724.20170927

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Abstract:
The indoor geomagnetic field is affected by the presence of a steel structure and other ferromagnetic materials, causing local anomalies in the magnetic field region and and a unique indoor magnetic field. Indoor geomagnetic positioning technology can be realized by exploiting this phenomenon. However, in large buildings, the specificity of the geomagnetic field is weakened, which leads to the distortion of positioning results. To overcome this problem, an indoor geomagnetic positioning technology based on path matching was proposed, which increases the number of matching features. A new joint algorithm was used combining the dynamic time warp algorithm with the particle filter algorithm, which can track the target in a path matching mode. In the matching process, the similarity between the paths was determined by calculating the Spearman correlation coefficient, to assist the positioning. Finally, experimental verification was performed using a measuring robot loaded with a magnetic sensor. The results show that the path matching exhibits a sufficient number of geomagnetic features, which can overcome the phenomenon of blurring the positioning results under the condition of weakening specificity, and the positioning accuracy is higher than 1 m.

Multi-objective Indoor Path Planning Method with Dynamic Environment Awareness

ZHOU Yan, CHEN Hong, ZHANG Yeting, HUANG Yueying, ZHANG Pengcheng, YANG Weijun

2019, 54(3): 611-618, 632. doi: 10.3969/j.issn.0258-2724.20180098

[Abstract](520)

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Abstract:
A dynamic environment-aware multi-objective indoor path planning method is proposed, aimed at satisfying the multi-objective navigation requirements of users in complex indoor environments. Multi-dimensional indoor environment semantics such as indoor path complexity, the degree of congestion, and blocking events were take into account. The node-edge representation indoor navigation network model was also expanded, and a navigation traffic cost function was established by precisely quantifying the multi-dimensional indoor environment semantics. The value of the navigation traffic cost function was then taken as the side length of the model, and a multi-objective indoor path planning algorithm based on Dijkstra was designed and implemented. The results of the simulation show that navigation path planning can avoid unavailable connection edges by adding the vertical components with directional semantics and considering the blocking events factor in the extended indoor navigation network model. After the path complexity and traffic congestion were considered, the travel time is saved by an average of 17% in three traffic patterns, i.e., light, mild and heavy congestion.

Comparative Study on the Curving Performance of Chinese Railway Heavy Haul Freight Bogies

YANG Chunlei, HUANG Yunhua, LI Fu

2019, 54(3): 619-625. doi: 10.3969/j.issn.0258-2724.20180178

[Abstract](542)

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Abstract:
The low dynamic interaction performance of the 27 t axle load cross-braced bogie and the sub-frame radial bogie developed in China were compared in order to study their curving performance. Based on the theory of vehicle-track coupling dynamics and the actual structures of the two bogies, two vehicle-track coupling dynamic models were established separately. The optimum matching design method was adopted, and the curving performance of the two bogies were simulated. This method included parameters such as yaw of wheel-set, lateral force, and wear power to evaluate the curving performance, and the results were compared with the conventional three-piece bogie. The simulation results indicate that, on a curved track with a radius of less than 800 m, compared to the conventional three-piece bogie, both the bogies developed in China can lower the dynamic interaction. Furthermore, the sub-frame radial bogie has the advantage of reducing wheel/rail wear. However, with the increase in curve radius and excitation of track irregularities, the radial action of the sub-frame radial bogie weakens gradually. However, when the curve radius is greater than 1000 m, the wheel/rail wear of both bogies are equal, which means that using radial bogies to reduce wheel/rail wear has very little effect.

Simulation and Verification of Dynamic Response of Railway Wagon on Railway Track

YU Yuebin, ZHAO Shangchao, LI Xiangwei, LI Qiang

2019, 54(3): 626-632. doi: 10.3969/j.issn.0258-2724.20170412

[Abstract](369)

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Abstract:
For resolving errors between a simulation analysis and the test results of a large system, a multi-body simulation model of a railway wagon with 26 degrees of freedom was created using test data from a real test rig on a railway track and by incorporating the wagon body’s subsystems into the simulation object in order to realise a simulation calculation of the dynamic response of the railway wagon. The results show that the maximum RMS (root mean square) error between the simulation and the test of the wagon body bolster’s vertical and lateral vibration acceleration is 9%. Furthermore, the RMS error between the simulation and test of the wagon body bolster’s vertical and lateral vibration acceleration is less than 8.57% in the 1.5–15.0 Hz frequency range. Finally, the response signal waveforms of the dynamic stress of the simulation and that of the wagon body’s key welds are almost identical. The comparison and validation of the simulation and test results show that the simulation results substantially reproduce the dynamic response conditions of the railway wagon running along a railway track.

Fault Diagnosis of Rolling Bearing Based on EEMD-Hilbert and FWA-SVM

ZHANG Min, CAI Zhenyu, BAO Shanshan

2019, 54(3): 633-639, 662. doi: 10.3969/j.issn.0258-2724.20170435

[Abstract](593)

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Abstract:
To effectively extract the non-stationary characteristics of the rolling bearing vibration signal and improve the fault diagnosis efficiency, a feature extraction method based on the ensemble empirical mode decomposition (EEMD) and Hilbert transform was proposed. The support vector machine (SVM) classification parameters were optimised using the fireworks algorithm (FWA) for the rolling bearing fault diagnosis method. The EEMD method was used to decompose the target signal into several modal functions. The instantaneous frequencies of the modal functions were obtained through Hilbert transforms. Statistical feature extraction and dimensionality reduction were respectively performed for the modal function and instantaneous frequency. The fireworks algorithm model was used to optimise the SVM parameters as well as the multi-classification fault diagnosis with training and test sets drawn from 600 datasets. The accuracy of the signal is estimated to be 99.633%, which is 0.4% and 0.2% higher than that of the traditional genetic algorithm and particle swarm optimisation algorithm, respectively. Further, the ability of iterative convergence is also seen to have obvious advantages. The feasibility and validity of the algorithm models are thus verified.

Railway Fastener Detection Using Gaussian Mixture Part Model

HE Biao, LI Bailin, LUO Jianqiao, WANG Kaixiong

2019, 54(3): 640-646. doi: 10.3969/j.issn.0258-2724.20180077

[Abstract](433)

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Abstract:
Herein, the shape deformations in the collected images of railway fasteners, the large illumination difference in the fastener image, and the partial occlusion of the fastener by foreign objects is addressed. A Gaussian mixture part model (GMPM) algorithm is proposed to address these issues. This model is based on previous research of deformable part model; however, it was further refined by combining with a Gaussian mixture model (GMM) algorithm. The image gradient was calculated by combining the edge characteristics of the fastener image and application of the improved Roberts operator to the image. Normalized histogram of oriented gradient (HOG) features were used as the basis of the GMPM algorithm. The image was divided into a number of regions considering the shape of the fastener, and a star connection was used to measure the relative positions of the various subsections of the subdivided image. Cosine similarities were computed to measure the similarity of the HOG features of the different parts of the image. The part model was solved iteratively by using the GMM with an expectation-maximization algorithm. By using the GMPM algorithm to detect defects in railway fasteners, an average accuracy of 90.27% for detection rate is achieved, while the average missed detection rate, and the average false detection rate are 3.16% and 9.80%, respectively.

Parallel Algorithms for Text Sentiment Analysis Based on Deep Learning

ZHAI Donghai, HOU Jialin, LIU Yue

2019, 54(3): 647-654. doi: 10.3969/j.issn.0258-2724.20160948

[Abstract](421)

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Abstract:
In the case of big training set and test set, based on semi-supervised auto encoder (Semi-Supervised RAE), the text sentiment analysis algorithm is accompanied by slow training rate and output rate of test results. To solve these problems, the corresponding parallel algorithms are proposed in this paper. For the big training data set, the method of " separate operation” is adopted to divide the data set into blocks. Each data block is inputted into Map nodes to calculate its error, and the errors of all data blocks are stored in the buffer. The block errors are read by Reduce nodes from the buffer to calculate the optimization objective function. Then, the limited-memory Broyden-Fletcher-Goldfarb-Shanno (L-BFGS) algorithm is called to update the parameter set, and the updated parameter set is reloaded into the cluster. The above process is iterated until the optimization objective function converges; therefore, an optimal parameter set is obtained. For the big test data set, the parameter set obtained by the above steps is used to initialize the cluster. The vector representation of each sentence is calculated in Map nodes and temporarily stored in the buffer. Then, the sentiment label of each sentence is calculated by the classifier in the Reduce node using the vector representation. The experimental results demonstrate that in the standard MR (movie review) corpus, the accuracy of the algorithm is 77.0%, which is almost the same as the accuracy of the original algorithm (77.3%), at the same time the training time is decreased greatly along with the increase of compute nodes in the massive training data sets.

Influence of Phosphorus Control on Coupling System ofWinery Wastewater and Microalgae Cultivation

YU Jiang, TAO Hongqun, WANG Yating, WANG Yizheng, PENG Weidong, RAN Zongxin, HE Yulong

2019, 54(3): 655-662. doi: 10.3969/j.issn.0258-2724.20180585

[Abstract](412)

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Abstract:
To investigate the optimum phosphorous condition for the coupling system of winery wastewater and microalgae cultivation, changes in growth of Chlamydoomonas reinhardtii and Scenedesmus dimorphus were observed under single culture and co-culture conditions, and the absorption and removal efficiency of nutrients were determined in the wastewater. The effect of different phosphorus concentrations on the dry weight, specific growth rate, protein content, and the removal amount and removal rate of total nitrogen (TN), total phosphorus (TP) and chemical oxygen demand (COD) were studied by the control variable method. The results showed that the demand of Chlamydoomonas reinhardtii for phosphorus was greater than that of Scenedesmus dimorphus. When the initial total phosphorus concentration was 16.40 mg/L and the initial nitrogen to phosphorus ratio was 2.45, as for Chlamydoomonas reinhardtii, the final biomass reached 839.50 mg/L, the algal protein content reached 53.37 mg/L, and the removal rates of TN, TP and COD were 93.48%, 91.75%, 67.90%, respectively; as for Scenedesmus dimorphus, the final biomass reached 650.00 mg/L, the algal protein content reached 131.04 mg/L, and the removal rates of TN, TP and COD were 95.76%, 73.93%, 83.43%, respectively. Under co-culture conditions, the growth curves of the two microalgae were between their growth curves under single culture conditions, the removal rates of TP and TN were 83.66% and 95.24%, respectively, and the removal of COD was similar to that of Scenedesmus dimorphus. It was also found that through the winery wastewater-microalgae cultivation coupling system, whether it is single or co-culture condition, the wastewater can meet the total phosphorus requirements of class Ⅳ water quality specified in the Environmental Quality Standard for Surface Water（GB3838—2002）.

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2019 Vol. 54, No. 3