2018 volumne 39卷 Issue 01
Ma Genghua1,Du Muqing2,Zhang Xiaoli2
Abstract: Because of the uncertainties of the travel demands, system supplies and travelers’ behaviors in transportation systems, the capacity of the comprehensive transportation networks is usually changing irregularly. The comprehensive transportation network is a complicated transport system. Ignoring the uncertain factors inside or outside of the system may causes mistakes when people make decisions in transportation planning and management. An assignment model for comprehensive transportation network is built, in order to compute the network capacity of the comprehensive transportation system. Utilizing the Monte-Carlo method, in which the capacity at each individual link is assumed to be changed randomly, the capacity reliability of the comprehensive transportation network is analyzed with numerical experiments. In the example, the effectiveness of the proposed model and solution method is demonstrated. Therefore, the proposed approach provides an efficient tool for evaluating the system reliability of the comprehensive transportation networks.
Feng Zhengang1,Sun Anshi1,Zhang Dongyang2,Li Xinjun1,Li Peilong1
Abstract: In this paper, the dynamic modulus of pyrolysis carbon black (PCB) modified asphalt mixture was tested by the simple performance tester (SPT). The influence of different temperature and load frequency on dynamic modulus and phase angle of the asphalt mixture was investigated. The dynamic modulus and phase angle master curves were fitted by numerical method to analyze the viscoelastic characteristic of PCB modified asphalt mixture. Experimental results showed that the dynamic modulus and phase angle of PCB modified asphalt mixture were dependent on the change of temperature and load frequency. At lower temperature and higher frequency, the dynamic modulus of asphalt mixture increased but phase angle decreased greatly with the addition of PCB, indicating that the elastic behavior of PCB modified asphalt mixture was enhanced while the viscous behavior was weakened. At higher temperature and lower frequency, the PCB showed little influence on the viscoelastic characteristic of asphalt mixture.
Wang Juan1,Wang Huijuan2,Xu Yaoqun1,Wu Xiaopeng1
Abstract: Based on meso-numerical simulation technology, a new method was developed for the determination of the RVE (representative volume element) (RVE) of concrete. The uniaxial tensile and compressive strength of concrete specimens with various RVE size were calculated by means of the interfacial spring element model. Then the RVE size was determined quantitatively by analyzing the discreteness of concrete strength and the increase trend of concrete strength. Results showed that the RVE size for concrete uniaxial tensile and compressive strength were 5 times and 6.5 times of maximum aggregate diameter of concrete respectively, which were close to the RVE sizes for concrete micro-structure. This study can enrich the numerical methods for strength analysis of concrete and lay a foundation for multi-scale analysis of concrete.
Zheng Liang, Zhang Dapeng, Guo Hong, Yan Shumao, Wang Long, Wu Yanlong
Abstract: Many studies of concrete-filled steel tubular (CEST)colimn push-out test, failed to consider the impact of core concrete expansion on the bond performance between the steel ppe and core concrete. This study aimed to examine the influence of core concrete expansion on the bond performance between steel pipe and core concrete, with pipe wall thickness and height、core concrete stress level, aspect ratio and coefficient of sliding friction between steel pipe and concrete core as change parameters. It designed a total of three groups of 10 cotrete filled steel tube column specimens to carry on push-out test. Test results showed Loaddisplacement curve was basically the same trend under this two stress state, but it had a higher carrying capacity under high stress conditions. Under high stress conditions, when the load was small, the amount of the introduction and the amount of compression were basically the same, but with the increase of load, the increase of amount of compression is faster than the rate of the increase of the increase of the amount introduction. Core concrete expansion had a greater impact on the bond performance between steel pipe and core concrete. By buttering steel pipe inner surface to reduce the friction coefficient between the steel pipe and core concrete, it had a clear impact on th relative displacement between the steel and concrete. 
Huang Jinyao1,Yan Shilun1,Chen Chaoyang2
Abstract: Combustion performance of DME fueled homogeneous charge compression ignition(HCCI) engine under different exhaust gas recirculation (EGR) rate and different coefficient of excess air (?) was studied numerically by using the software CHEMKIN. Influences of EGR and ? on the combustion performance of DME HCCI engine were analyzed. The result showed that at a specific ?, the pressure, temperature and the heat release rate decreased with the increase of EGR rate and the high temperature reaction was delayed. With a specific EGR rate, the pressure, temperature and the heat released rate in cylinder decreased with the increase of ? . And the low temperature reaction advanced while the high temperature reaction delayed. It could be recognized that the ignition time of HCCI engine could be controlled by changing the EGR rate or ? .
Chang Yulin1,Zheng Xianyu2,Zhang Peng2
Abstract: To decrease the negative influence from the saturation volume of left turning on the arterial volume of crossing road, this advanced model added part of the left turning phase for crossing road into straight phase for arterial after calculating the bandwidth of the green-wave for downstream section of the crossroad, the sequence of the two phases related also should be mentioned when solving the model. In order to check the reliability of the model, balanced and unbalanced traffic were imported into the simulation network respectively. The result of the solution and the simulation indicated that compared with the Multiband model, both the advanced model could obtain a wider bandwidth, as well as a shorter travel delay and a smaller possibility of pulling up the car. The advanced model had a better performance especially if the left turning phase for crossing road was appeared behind the straight phase for arterial.
Du Chaowei1,Zheng Yuanxun2,Cai Yingchun2,Gan Chao3,Han Yuxiao4
Abstract: In order to study the fatigue properties of prestressed hollow slab beams under the action of carbonization, according to the structural parameters of 20 m span prestressed concrete hollow slab beams which are commonly used in practical bridges engineering, the prestressed concrete hollow slab beam model (ratio of similitude is 0.1) was designed and manufactured based on the similarity principle. The carbonation erosion durability test (two kind of erosion degree: light and heavy) was carried firstly, then the static load failure test and the structural fatigue test were performed to study the effect of carbonation corrosion on dynamic and static parameters and fatigue life, and the influence of fatigue loading on dynamic and static strain, deflection and fundamental frequency of the test members, based the test results, the relationship between the degree of carbonation erosion and the structural fatigue properties were established. The results show that with the increase of the degree of carbonization corrosion, the fatigue life of the test plate will gradually reduced and the fatigue brittleness destroy appear, especially for heavy carbonation test plate, the fatigue life will drastically reduce. And with the increase of fatigue loading times, the dynamic and static parameters of the structure will gradually decrease.
Yang Limin1,Guo Jinjun2,Han Yichen2,Hao Yingying3
Abstract: To explore the road construction technology across the mined-out area, the relative position between goaf and road and the active state of the mined-out area were considered to analyzed the deformation law of subgrade. The improved creep constitutive model was adopted to simulate settlement and horizontal displacement of road. The critical safety range for road construction was determined in the mined-out area. The prediction model of subgrade settlement was proposed and compared with the accrual engineering monitoring data. The result shows that the model calculation results are in good agreement with the actual data, and the prediction model can be applied to the design and construction of the road above the mined-out area.
Cui Yunliang1,Xiang Pengfei2,Wang Xinquan1,Zhang Shimin1
Abstract: The disturded stste constitutive (DSC)model, proposed by Dwsai only condidered the affect of plastic deviatoric strain on disturbance stste, without considering the plastic volumetric strain. The disturbance function of the disturbed stste constitutive(DSC)model was improved by introducing a coupling-form disturbance variable of plastic deviatoric stain trace and plastic volumeric strain trace on the basis of original disturbance function. Triaxial consolidated undrained (CU)test, triaxial consolidated drained (CD)test and one dimensional compression test were performed on the wenzhou natural  structured soft clay. The DSC constitutive model with the improved disturbance function was validated by the test datd. The validation results showed that the unimproved model predictsed a slightly higher strength of both undrained and drained test of the natural structured soft clay, and the prediction of the improved model was more accurate.
Wei Chaofeng1;Li Qionglin2,Jiang Jiandong3,Tang Yuzheng2,Wang Chun3
Abstract: Accurate line loss calculation is the basis of realizing economic operation of power grid. The harmonic pollution in distribution network is becoming increasingly serious. Because of harmonic factors, the distribution network operation state and equipment parameters have changed greatly, and the additional losses arising therefrom have not been neglected. Based on the analysis of the traditional calculation method of line loss, this paper systematically analyzes the mechanism of harmonic effect on distribution transformer and power line. By introducing the transmission line AC resistance coefficient and transformer harmonic loss factors, a loss calculation model considering harmonic is put forward. Then, combined with the typical distribution transformer and transmission line, the harmonic loss was calculated quantitatively. Finally, the validity and accuracy of the model are verified by modeling and simulation.
Xia Xingyu1,Gao Hao1,Wang Chuangye2
Abstract: The computation time of some Multi-level threshold segmentation techniques needs were too long to bear, and it grew exponentially with the number of thresholds increased. This paper proposed a particle swarm optimization with an equilibrium strategy for shorting its computation time. First, during iterations, a balance operator for individuals to have more chances to search in the global area was introduced. Furthermore, for enhancing the local search ability of our proposed algorithm, a disturbance operator was also been introduced in this paper which enabled the individual had more opportunities to make a precise search. The improved algorithm enables particles had more chances to jump out of a local area for enhancing their global search ability. Meanwhile, a valuable point to guide the search direction of the particles was introduced. Then it accelerated the convergence rate of the improved algorithm. Kapur method was used in this paper to test the performance of the proposed method. Experimental results showed that our proposed algorithm showed more power and fast search ability when compared with the other population-based algorithms.
Wu Huachun, Yang Shiping
Abstract: Conventional bearingless motor integrated the rotation and radial suspension function with advantages such as contact-free, friction-free, but the torque and radial suspension force were inter-constraint. Thus, the thickness of permanment magnet must be taken into consideration. A novel bearingless motir was designed based on lorentz force. It could generate torque and axial suspension force at the same time, and the radial suspension of rotor depended on radial permanent magnet bearings(PMB). The mathematical model of Lorentz force at axial direction was deduced by using Ohm’s law of magnetic circuit. The influence of the air gap length, thickness of permanent magnet and current to axial Lorentz force was analyzed by using finite element method. The results showed that if the thickness of permanent magnet was increased, the axial bearing capacity would be larger,meanwhile, the optimal thickness of permanent magnet was 3mm.
Mu Ruijie
Abstract: The layout of passenger guide sign in subway station is important and complex. This paper proposes a genetic algorithm to solve the passenger guide sign layout problem. Wuyi Park station of Zhengzhou subway line 1 is taken as an example. The passenger guided quantity is set as the objective function and various constraints are considered. The used data are taken from the site passenger flow diagram. The experiments are conducted to find out the optimal layout and the stability of the results is also analyzed, The results that the used method is able to generate reasonable layout and the efficiency of the entry and exit is improved as well.
Wang Jianming, He Xunchao, Zheng Linbin
Abstract: In order to capture the free surface under transient flow field and get the spatial distribution of desulfurizer dispersion, the VOF(Volume of Fluid)model and DPM(Discrete Phase Model)model, as well as static and dynamic grids based on the multiple reference frame and gas - liquid- solid three phases flow modeling technology were used. The numerical simulations of free surface vortex depth and height were in good agreement with the water model experiments. Results showed that the rotational speed and stirrer immersed depth significantly affect the distribution axial velocity and radial velocity, and maximum speed mainly distributed in the blender blade tips. The vortex depth of free surface increased with the increase of stirring speed significantly, and when the vortex extended to the mixer upper, the indrawn desulfurizer flux from the bottom of vortex began to disperse into the internal flow field and diffuse completely through four circulation flow in the stirred vessel.
Bian Jie, Huo Changqing, Wang Ping, Tang Guang
Abstract: Endpoint extension was introduced into intrinsic time-scale decomposition (ITD) method to improve its endpoint effect. Then, the improved ITD method (IITD) was employed to structural modal parameter identification and method of modal parameter identification based on the IITD method (IITD-MPI) was proposed. The IITD-MPI was used in the modal parameter identification of a displacement simulation signal and the frequency testing signal of a lubricant oil pipe. The research results demonstrated that for the displacement simulation signal, compared with the theoretical values, the maximum error of the modal frequencies identified by the IITD-MPI method was less than 0.6%, and the maximum error of the damping ratios was 1%. And for the frequency testing signal of the lubricant oil pipe, the differences between the modal frequencies identified through the IITD-MPI method and the test modal frequencies were within 0.15%, and the differences of the damping ratios identified using the proposed method and the half power bandwidth method were not greater than 3%. Thus, the results verified the effectiveness and practicality of the IITD-MPI method.
Tianye, Yang Jiamin, Cheng Shaoan, Lu Junhong, Li Yanbin, Du Yukun
Abstract: Accidents like leakage or pipeline bursting frequently happened in urban drainage network. Real time monitoring of gas concentration and other relevant parameters is in urgent need. Aiming to overcome the lack of monitor devices, the inconvenience of changing batteries and the high expense of waste water treatment, in this study, microbial fuel cell(MFC) was applied to dispose sewage water and provide electric power for monitor and lighting equipment simultaneously. The original drop-like and buoy-type structure of MFC reactor ensureed that the cathode remains in gas-liquid interface, while avoiding potential destruction from high-speed flow. Energy harvesting module collected the tiny amounts of energy and monitored parameters periodically through low-power-consumption energy managing module.
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