2011 Vol. 11, No. 3

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Double iteration solving method of resistance partial factor
YAN Lei, ZHANG Xue-lin, HE Shuan-hai
Abstract: The characteristics of nested loop for reflection transformation method and interpolation method were analyzed, a double iteration solving method of resistance partial factor was presented, and its program was designed by using VB. The resistance partial factors of bridge components were calculated when the effect ratios of living load to dead load were 0.10, 0.25, 0.50, 1.00, 1.50, 2.50. The resistance was modified by multiplying load effect combination value by resistance partial factor, and the corresponding reliability index was checked. Computation result indicates that component reliability index computed by using the method is larger than its target index. Their relative deviation is between 0.62%-0.92% under general operation state for vehicle, and it is between 0.62%-0.74% under dense operation state for vehicle. The result shows that the method is reliable and emphasis on safety.More>
2011, 11(3): 1-5. doi: 10.19818/j.cnki.1671-1637.2011.03.001
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Effect of hot weather on compressive strength of steel slag concrete
SELMAN M H, HE Shuan-hai
Abstract: Steel slag concrete specimens were molded, in which the mass fractions of steel slag were respectively 10%, 30% and 50%. Ordinary concrete specimens and steel slag concrete specimens were respectively put into the waters with 40 ℃, 50 ℃ and 60 ℃, their compressive strengths and ultrasonic pulse velocities (UPV) were measured, and the effect of hot weather on the compressive strength of steel slag concrete was analyzed. Analysis result shows that the compressive strengths of concretes cured in hot weather do not decrease at different ages.The maximum compressive strength of steel slag concrete is 61 MPa at age 90 d, and is 18% bigger than that of ordinary concrete.Obviously, steel slag concrete has higher compressive strength in hot weather compared with ordinary concrete.More>
2011, 11(3): 6-9. doi: 10.19818/j.cnki.1671-1637.2011.03.002
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CBR particle flow simulation of aggregate and design of coarse aggregate skeleton gradation with strong interlocked force
DAI Xue-zhen, JIANG Ying-jun, REN Jiao-long, DONG Guo-jun, SUN Ting-xuan, LIU Gen-chang
Abstract: California bearing ratio (CBR) test was simulated by using PFC2D, CBR changing laws of single coarse aggregate, synthetic coarse aggregate and coarse-fine combined aggregate were analyzed, a coarse aggregate skeleton gradation with high interlocked force was put forward, and its performances were verified through laboratory test. Test result shows that the main skeleton structure composed of the aggregate with diameter 19-31.5 mm has high interlocked force, and the optimal mass fraction is 50%-70%. The aggregates with diameter 9. 5-19 mm and 4.75-9.5 mm have the effects of filling the void of main skeleton structure and interfering its composing, and the optimal mass fraction of the aggregate with diameter 4.75-9.5 mm is 10%. When the optimum proportion of coarse aggregate to fine aggregate is 65∶35, the CBR value of coarse-fine combined aggregate reaches the highest point, and is more than 540%. The CBR value and compressive strength of the mixture composed of the coarse gradation are over 1.19 times and 1.10 times than that of standard gradation respectively, so the coarse gradation has better mechanical properties.More>
2011, 11(3): 10-15. doi: 10.19818/j.cnki.1671-1637.2011.03.003
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Rutting test improving methods of asphalt mixture
GUAN Hong-xin, ZHANG Qi-sen, LIU Jing
Abstract: The difference between laboratory rutting test conditions and actual pavements was analyzed. Rutting test improving methods were proposed, which included reducing loading speed under heavy loading condition, developing full-thickness rutting tests as conventional rutting tests' complement, forming thermal gradient in full-thickness rutting samples. Rutting tester was improved, and the testing duration times at different loading speeds and the dynamic stability calculating methods were confirmed. Rutting tests were carried out by using improving rutting tester under different conditions. These tests included asphalt mixture's rutting tests under heavy loading and low speed, full-thickness rutting tests under uniform temperature field and under thermal gradient. The anti-rutting performance evaluation method of asphalt mixture was proposed based on the improving methods. Test result shows that dynamic stability of asphalt mixture reduces by 50%-70% when loading speed decreases by 2/3, and the dynamic stability of full-thickness sample is 20%-50% lower than that of surface course asphalt mixture. These can fully explain the rutting disease of asphalt pavement at upgrade section, and the improving methods are feasible.More>
2011, 11(3): 16-21. doi: 10.19818/j.cnki.1671-1637.2011.03.004
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Influence of backfilling construction on mechanical performance for soil-covered corrugated steel arch bridge
WANG Quan-lu, LIU Bao-dong, YANG Cheng-dong, FENG Li, WANG Yuan-feng
Abstract: On the basis of finite element software and the parameters of arch bridge in Inner Mongolia, 2D beam element beam3 was used to simulate corrugated steel, 2D solid element plan42 was used to simulate backfilling soil, and a plane model based on the interaction between backfilling height and arch ring was set up. The bending moments and axial forces of arch ring under different backfilling heights were calculated, and the influence of backfilling height on the stress and deformation of arch ring was analyzed. Calculation result shows that during symmetric backfilling construction process, the maximum radial absolute displacement of arch ring is about 0.9 mm, and the maximum and minimum stresses of arch ring are about 10, -27 MPa respectively. During asymmetric backfilling construction process, the maximum radial absolute displacement of arch ring is about 1.4 mm, the maximum and minimum stresses of arch ring are about 12, -18 MPa respectively, and the maximum radial absolute displacement and the maximum stress appear at 1/8 span on the right of arch ring. During backfilling construction process, the stress and displacement at 1/8 span on the right of arch ring must be mainly monitored.More>
2011, 11(3): 22-28. doi: 10.19818/j.cnki.1671-1637.2011.03.005
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Contact relationship of wear wheel and curved rail
ZHANG Jun, JIA Xiao-ping, SUN Chuan-xi, SUN Li-ping
Abstract: The wear wheel profile of JM3 type of SS4 locomotive and the profile of rail with small radius curve were measured by using wheel/rail instrument, and wheel geometric profiles were obtained by using spline curve fitting method. Five different degrees of wheel profiles were chosen, a 3D wheel/rail contact finite element model was built, and wheel/rail contact plaque areas and contact stresses were calculated. Calculation result indicates that when Ⅰ type wheel contacts with wear rail, contact plaque area is smallest, only 183 mm2. The maximum Von Mises stress is 1 459 MPa, and contact stress mainly concentrates wheel flange root. WhenⅡtype wheel contacts with wear rail, contact plaque area is 294 mm2. When Ⅲ type wheel contacts with wear rail, contact plaque area increases significantly. The maximum Von Mises stress is 1 137 MPa, contact stress distribution is relatively uniform, and flange wear slows down. When Ⅳ type wheel contacts with wear rail, the maximum Von Mises stress is 890 MPa, When Ⅴ type wheel contacts with wear rail, the maximum Von Mises stress is 953 MPa, but flange wear has reached limit state.More>
2011, 11(3): 29-33. doi: 10.19818/j.cnki.1671-1637.2011.03.006
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System dynamics of long and heavy haul train
CHI Mao-ru, JIANG Yi-ping, ZHANG Wei-hua, WANG Yong
Abstract: Cycle-variable method was utilized to resolve the freedom problem of long and heavy haul train, the coupling relationship among the longitudinal, lateral and vertical performances of the train was considered, a 3-D coupling dynamics model of the train was set up, and the dynamics performances of the train under traction, braking and idling conditions on straight track, curved track and ramp were simulated. Simulation result shows that under traction condition, the dynamics performances of front and rear vehicles were worse than that of middle vehicles. Under braking condition, the dynamics performances of middle vehicles were worse than that of front and rear vehicles. Under idling condition, the dynamics performances of all vehicles have little difference. On curved track, the influences of three conditions on the dynamics performances are greatest, so, while through straight track, train will be in traction or braking condition. While through curved track, train will be in idling condition.More>
2011, 11(3): 34-40. doi: 10.19818/j.cnki.1671-1637.2011.03.007
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Braking mode curve arithmetic of high-speed train above 250 km·h-1
SHANGGUAN Wei, CAI Bo-gen, WANG Jing-jing, WANG Jian, WANG Li
Abstract: The braking system of high-speed train above 250 km·h-1 was studied, and the running resistance, braking force and braking distance of high-speed train were analyzed. Based on curve theory of target distance mode, the piecewise iteration model of braking mode curve for high-speed train was proposed. With MATLAB/Simulink software, the changes of running resistances on flat-straight line, direct ramp with grade 15‰ and direct ramp with grade 25‰ for CRH2-300 type high-speed train were analyzed, and the normal braking curves and emergency braking curves of CRH2-300 type and CRH3 type high-speed trains at initial braking speed 300 km·h-1 were compared. Calculation result indicates that the emergency braking distance of CRH2-300 type high-speed train is 2 786. 68 m on direct ramp, the emergency braking distance of CRH3 type high-speed train is 3 319. 37 m on direct ramp, and both of them are less than 3 700 m, which is the maximum braking distance of braking requirement. Simulation braking curves almost consistent with actual braking curves, which verifies the validity of piecewise iteration algorithm.More>
2011, 11(3): 41-46. doi: 10.19818/j.cnki.1671-1637.2011.03.008
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Influence of polygonal wheel on running safety of vehicle
WU Lei, ZHONG Shuo-qiao, JIN Xue-song, LI Ling
Abstract: Timoshenko beam and Euler beam were respectively used to simulate rail, linear induction motor (LIM) stator and reaction plate, concentration mass block and 3D entity finite element were respectively used to simulate ballast track and slab track, and vehicle/track coupling dynamics models with LIM were established.The influence of wheels with different wear degrees on wheel/rail normal contact forces and derailment coefficients on the two ballasts was analyzed.Calculation result shows that when vehicle passes the curved track with radius 300 m at 60 km·h-1, the minimun and maximum wheel/rail normal contact forces on slab track are 55.34, 112.53 kN, and the maximum derailment coefficient is 0.290.The maximum and minimun wheel/rail normal contact forces on ballast track are 123.00, 60.70 kN, and the maximum derailment coefficient is 0.289.When vehicle passes the curved track with radius 600 m at 60 km·h-1, the minimun and maximum wheel/rail normal contact forces on slab track are 52.93, 107.59 kN, and the maximum derailment coefficient is 0.064.The minimun and maximum wheel/rail normal contact forces on ballast track are 59.45, 112.33 kN, and the maximum derailment coefficient is 0.071.When vehicle passes the pits with wavelength 100 mm and three depths at 60 km·h-1, the minimun and maximum wheel/rail normal contact forces on slab track are 49.54, 114.36 kN, and the maximum derailment coefficient is 0.024.The minimun and maximum wheel/rail normal contact forces on ballast track are 50.19, 134.29 kN, and the maximum derailment coefficient is 0.031.The derailment coefficients under various working conditions are never more than safety limit, and polygonal wheel can't cause vehicle derailment.More>
2011, 11(3): 47-54. doi: 10.19818/j.cnki.1671-1637.2011.03.009
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Calculation method of interior aerodynamic noises with middle and high frequencies for high-speed train
LIU Jia-li, ZHANG Ji-ye, ZHANG Wei-hua
Abstract: The external unsteady flow field of high-speed train was calculated by using SST k-w turbulence model, and the fluctuating pressure of body surface was extracted. Based on the statistical energy analysis(SEA) theory, the analysis model of interior aerodynamic noises with middle and high frequencies for high-speed train was established, the parameters of each subsystem in the model were determined, and the interior aerodynamic noise induced by external fluctuating pressure was calculated. Calculation result shows that the change of fluctuating pressure on the head car of high-speed train is most dramatic. For middle and high frequencies, the sound pressure levels of cab and passenger room decrease with the increasing of frequency. When frequency is 0.5 kHz, the maximum sound pressure level of cab is 93.79 dB, and the maximum sound pressure level of passenger room is 81. 99 dB. For each frequency, the maximum difference of sound pressure levels for the three cavities of cab is 3. 89 dB. The maximum difference of sound pressure levels of the three cavities of passenger room is 8.69 dB. The sound pressure level of cab is larger than that of passenger room, the sound pressure level of the middle cavity of cab is largest, and the main energy inputs of middle cavity of cab are from window and floor. The interior aerodynamic noise can reduce through the effective design of window and improving the interior sound-absorbing performance of hig-speed train.More>
2011, 11(3): 55-60. doi: 10.19818/j.cnki.1671-1637.2011.03.010
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Transportation status of Chinese expressway network in 2009
XIAO Run-mou, CHEN Yin-san, LI Bin
Abstract: Based on the database of expressway network toll system and the typical sampling investigation data at toll stations, the transportation status of Chinese expressway network was analyzed. Compared with the transportation status in 2008, in 2009, passenger transportation density in expressway network rises by 7.96%, and 43.30% of passenger turnover volume is produced by mini-type buses (the seat amount of every bus is less than 8), which rises by 2. 29%. The average speeds of Ⅰ-type (the seat amount of every bus is less than 8) and Ⅳ-type buses (the seat amount of every bus is more than 40) decrease slightly, but the average speeds of Ⅱ-type and Ⅲ-type buses (the seat amount of every bus is between 8 and 40) rise slightly. Freight transportation density rises by 4.58%, and 76.14% of freight turnover volume is produced by tractor-trailer vehicles. The percentage of empty to loaded truck kilometers of trucks is 19. 84%, which decreases slightly. The percentage of trucks with overweight more than 30% is 4.62%. In 2009, the transportation of Chinese expressway network keeps high-speed growth, but the rate of traffic accidents on expressways declines steady, and decreases by 13.40%.More>
2011, 11(3): 61-67. doi: 10.19818/j.cnki.1671-1637.2011.03.011
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Calculation method of overtaking sight distance for dual-lane highway
WANG Run-qi, ZHOU Yong-jun, XIAO Chuan-en
Abstract: 5 factors affecting the overtaking sight distance of dual-lane highway were analyzed from the view of safe driving. The running sketch map of overtaking car, overtook car and opposite car on dual-lane highway was designed. The mathematic model of calculating overtaking sight distance for overtaking car from beginning overtaking to finishing overtaking was established. The calculating parameters were defined such as braking distance and space headway on same lane etc, and the specific calculating formula of overtaking sight distance was proposed by means of mathematic analysis method. According to different design speeds and driving speeds, the overtaking sight distances of car and truck on dual-lane highway were calculated. Analysis result indicates that the overtaking sight distance of dual-lane highway is concerned with the design speed of highway, the overtaking speed of overtaking car, the speeds of overtook car and opposite car, and space headway on same lane. When the speeds of overtook car and opposite car are less than a half of overtaking speed, the calculated value of overtaking sight distance is just close to its specified value. Specified overtaking sight distance of dual-lane highway is smaller from safety view.More>
2011, 11(3): 68-73. doi: 10.19818/j.cnki.1671-1637.2011.03.012
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Parallel ant colony optimization of location problem for limited single allocation hub
CUI Xiao-yan, LI Xu-hong, MAO Hai-jun, ZHANG Yong, YANG Ping-le
Abstract: The characteristics of location problem for limited single allocation hub were analyzed. The sum of total network transportation costs and fixed facility costs was taken as the minimum objective function, and a mixed integer linear programming model with fewer variables was set up. Parallel ant colony optimization (P-ACO) was used to solve the model, and correlative simulation test was carried out combined with Australia post data. Calculation result indicates that for the most difficult problem with 50 nodes and double tight constraints, the computational time of proposed model is 3.59 s, which is minimum compared with the other algorithms, and the calculation errors are not more than 0.09%. So, P-ACO has good solution efficiency and calculational stability.More>
2011, 11(3): 74-81. doi: 10.19818/j.cnki.1671-1637.2011.03.013
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Selection model of risk control option based on dominance degree
BAO Jun-zhong, LIU Zheng-jiang, WANG Li-dong
Abstract: The one-sidedness in selecting risk control option (RCO) with reference to single index was analyzed, and a multi-index selection model of RCOs based on dominance degree was proposed by considering the ranking and difference degrees of samples on indexes. The model combined the subjective factors of experts and data objectivity by fully employing information contained in data, and highlighted the function of certain index in the ranking of RCOs by adjusting weight vectors. RCOs in formal safety assessment reports on oil tankers and general cargo ships submitted to International Maritime Organization were taken as examples, and the model was applied in RCO optimization. Analysis result shows that the options 2, 5, 6 in example 1 have higher dominance degrees under all weight vectors, and the same is true of options 1, 2, 3, 6, 13 in example 2, and these RCOs are ideal options. The dominance degrees of options in example 2 decrease gradually with the increasing of gross cost of averting a facility (GCAF), and GCAF can be taken as a preferred selection index of RCOs. So the model has higher adaptability.More>
2011, 11(3): 82-87. doi: 10.19818/j.cnki.1671-1637.2011.03.014
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Collision risk model of turning air-route
QU Yu-ling, HAN Song-chen, ZHANG Ming
Abstract: Time variable and time interval variable were introduced, and nominal separation and collision risk at any time were analyzed. Time interval distribution, flow rate, the proportion of aircraft types and turning angle were determined by using two flight segments at the turning point, and a collision risk model was proposed. With the model, the collision risk of turning air-route was calculated, and the influences of different parameters on the collision risk were analyzed. Analysis result shows that the larger the distance from the initial point of flight segment to the turning point and aircraft rate are, the larger collision risk is. But the larger the minimum time interval at the turning point is, the smaller the collision risk is. It can be seen that the proposed model is reliable and simple.More>
2011, 11(3): 88-92. doi: 10.19818/j.cnki.1671-1637.2011.03.015
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Reverse logistics programming model of electronic wastes with fuzzy parameters
LIU Mei-lian, LI Dan, QIU Jian-wei
Abstract: A reverse logistics network structure was established for six kinds of electronic wastes including color TV, refrigerator, air conditioner, washing machine, computer and mobile phone, and the reverse logistics programming model of electronic wastes with fuzzy parameters was built. Tolerance approach was used to make fuzzy constraints clear, the fuzzy programming model was turned into a deterministic linear programming model, and the model was solved by using WinQSB software. Considering Guangxi transportation development situation and the disposal costs of electronic wastes in other regions, the locations of remanufacturing centers, testing centers and landfills in Guangxi were calculated respectively at different confidence levels, and the reverse logistics network of electronic wastes in Guangxi was determined. Analysis result indicates that when confidence levels are 0.80, 0.90, 0.95 respectively, the node functions of reverse logistics network for electronic wastes in Guangxi remain unchanged, and the processing quantities of remanufacturing centers are 24 532.2, 25 089.7, 25 368.5 t respectively.More>
2011, 11(3): 93-99. doi: 10.19818/j.cnki.1671-1637.2011.03.016
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Constant error analysis of two-point comprehensive calibration in gimbaled inertial navigation system
YANG Xiao-dong, DENG Tai-guang
Abstract: In order to estimate and compensate the comprehensive calibration errors caused by various factors, the influences of exoteric measuring information error and inertial platform horizontal error angle in two-point comprehensive calibration of gimbaled inertial navigation system (INS) on the calibration effect of constant gyro drift were studied in theory. The relation between the maximum values of constant gyro drift error and calibration interval was deduced. Two-point calibration process affected by exoteric measuring information error was simulated. Analysis result shows that under current precision levels of exoteric measuring information error and platform horizontal error angle, the magnitudes of the maximum values induced by the two errors are both 0.001 (°) ·h-1 when the interval time of two adjustments is 10 h. The two kinds of errors are both linear with the estimation error of two-point calibration approach on constant gyro drift. In order to improve the precision of two-point calibration, it is important to increase exoteric measuring information precision and inertial platform horizontal precision efficiently.More>
2011, 11(3): 100-104. doi: 10.19818/j.cnki.1671-1637.2011.03.017
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Multi-objective optimization method of traffic signal based on CTM
YANG Dong-xia, JU Yong-feng
Abstract: The signal control and optimization problems of urban traffic were studied. The total delay, fuel consumption and vehicle exhaust emission of road network were taken as optimization objectives, their calculation formulas were derived based on cell transmission model (CTM), and a multi-objective optimization method based on CTM for urban traffic signal control was presented. The solution of traffic signal was optimized by using multi-objective genetic algorithm. Simulation result shows that green wave bands form under mild, moderate and heavy traffic flow conditions, the coordination control of traffic signals can be achieved, and the optimization settings of intersection traffic signals are realized.More>
2011, 11(3): 105-111. doi: 10.19818/j.cnki.1671-1637.2011.03.018
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Coordination control method of regional traffic flow
LIANG Chao, FAN Bing-quan, HAN Yin
Abstract: On the basis of agent technology and fuzzy control method, a coordination control method of regional traffic flow was proposed. Section congestion degree and green light duration were taken as input variables, green light's correction prolong time was taken as output variable, the acquiring methods of variable data and the corresponding relationships among the variables were determined, and a coordination controller was designed. According to different schemes of time assignments at downstream intersections, various fuzzy control rules were formulated, control strategy was corrected, and corresponding simulation was carried out by MATLAB. Simulation result shows that after using the control method, average total delay is 127.431 s·km-1, and decreases by about 9.9%. Average section density is 18.828 veh·km-1. Average section flow is 9 597 veh·h-1. Average speed is 17.798 km·h-1, and rises by about 6.3%. It can be significantly seen that with the method section density decreases, and traffic condition is improved.More>
2011, 11(3): 112-117. doi: 10.19818/j.cnki.1671-1637.2011.03.019
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Traffic data interpolation method of non-detection road link based on Kriging interpolation
ZOU Hai-xiang, LE Yang, LI Qing-quan, YE Jia-an
Abstract: From the diffused characteristic of traffic flow and prior knowledge, Kriging interpolation was adopted to interpolate the traffic data of non-detection road link. Based on the spatial correlation of traffic data, a spatial model of traffic data was built. The spatial distance was adopted as metric to estimate the unsampled traffic data of road link. The road link travel speeds of Nanchang's road network were used as experiment data, which were collected from urban floating car system, and the method was verified. Experiment result shows that the standard errors of speed interpolations are always lower than 8 km·h-1 in different urban traffic time periods. Downtown zone and lake zone have different road network structures, and their mean absolute errors of speed interpolations are 2-5 km·h-1.So the method has good temporal and regional portabilities.More>
2011, 11(3): 118-126. doi: 10.19818/j.cnki.1671-1637.2011.03.020
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