2015 Vol. 15, No. 5

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Evaluation of asphalt demulsification and viscosity of modified asphalt emulsion mortar based on Gompertz model
ZHANG Jiu-peng, ZHU Hong-bin, PEI Jian-zhong, LUO Zi-jun
Abstract: Aiming at the deficiency of quantitative evaluation on the demulsification time of modified asphalt emulsion, the different types of fine aggregates were added into modified asphalt emulsions to prepare the asphalt mortars, Gompertz model was applied to analyze the variation laws of mortar viscosity with time, and a mathematic model was established to quantitatively evaluate the demulsification of modified asphalt emulsion. Analysis result indicates that the initial viscosity of modified asphalt emulsion mortar is low, but increases with the demulsification time and finally tends to be stable. With the same size aggregates, the granite asphalt mortar has the biggest viscosity, the basalt asphalt mortar has smaller viscosity, and the limestone asphalt mortar has the smallest viscosity. However, the increasing rates of viscosity are basically same for the different types of asphalt mortars, and conform to the characteristic of growth function. Gompertz model can be used to reflect the variation laws of viscosity with time because the biggest relative error between the calculated and measured values is lower than 15%. Then, an evaluation index was proposed based on Gompertz model to evaluate the demulsification, and the viscosity variation of asphalt mortar is stable when the index value ranges from 0.97 to 1.00. At the moment, the modified asphalt completes the demulsification. On the other hand, the measured viscosity can be used to calculate the parameters of Gompertz model, and to predict the required time to complete the demulsification for the modified asphalt emulsion.More>
2015, 15(5): 1-7. doi: 10.19818/j.cnki.1671-1637.2015.05.001
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Design method of LSCR based on mortar theory
JIANG Ying-jun, FU Zhi-peng, LI Ning-fang
Abstract: In order to improve the mechanical strength of lime-fly-ash-stabilized crushed rock(LSCR), LSCR was regard as a dispersed system with 3-level spatial reticular structures, including lime-fly-ash mortar(LAM)micro dispersed system, lime-fly-ash fine aggregate mortar(LFAM)fine dispersed system, and LSCR coarse dispersed system. Based on the principle of optimal compressive strength, the mass ratio of LAM and LFAM was computed by using vertical vibration test method(VVTM). Based on the principle of optimal density, the gradation of coarse aggregate was confirmed by using step-by-step filling method. Based on the principle of optimal compressive strength, the optimal amount of LFAM in the LSCR was determined. The design method of LSCR was proposed based on mortar theory, and its performance was verified by using indoor experiment and field experiment. Verification result indicates that the mechanical properties and shrinkage properties of LAM are optimal when the mass ratio of lime to fly-ash is 2:5. When the decreasing coefficient of quality passing rate of fine aggregate is 0.65, the mass ratio of lime-fly-ash to fine aggregate is 3:2, the mechanical strength of LFAM is maximum. When the mass ratio of aggregates with particle size range of 19-37.5, 9.5-19, 4.75-9.5 mm is 17:11:6, the density of mixing coarse aggregate is maximum. Compared with the mechanical strength of LSCR specimen designed by traditional method, the early stage(7 d)mechanical strength of LSCR specimen designed by mortar theory increases by more than 10%, and the late stage(180 d)mechanical strength increases by more than 20%. The average ratio of compressive strength of VVTM specimen to specimen of site is 0.909, and the average ratio of splitting strength is 0.904. The average ratio of compressive strength of static pressure compaction specimen to specimen of site is 0.457, and the average ratio of splitting strength is 0.531. The LSCR designed by VVTM is more scientific than static pressure method.More>
2015, 15(5): 8-14. doi: 10.19818/j.cnki.1671-1637.2015.05.002
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Failure mode analysis of hinged voided slab with gate-type steel rebars at bottom of junction surface
WU Qing-xiong, CHEN Yue-chi, CHEN Kang-ming
Abstract: Focused on the full-depth hinged joint with gate-type steel rebars at the bottom of junction surface between voided slab and hinged joint, a full-scale model with one span of 8 m according to the standard drawings of hinged voided slab bridge issued by Ministry of Transportation in 2007 was designed. With experiment and nonlinear finite element method, the failure modes of hinged voided slab under vehicle load were studied, including failure type, failure position and cracking load. Analysis result indicates that the nonlinear finite element model can properly simulate the mechanical properties of hinged voided slab under vehicle load by comparing with experimental result. The vertical relative slip is regarded as the index of cohesion failure of junction surface in three directions of bonding-slip relationship. Under vehicle load, the weakest position is the junction surface between voided slab and hinged joint. The surface starts to crack when the load reaches 69 kN(0.99 times of vehicle load), but the crack appears at the middle of voided slab when the load reaches 85 kN(1.21 times of vehicle load). Compared with the experiment on hinged voided slab with full-depth joint without gate-type steel rebars, when the gate-type steel rebars are laid at the bottom of junction surface, the cracking load increases unobvious, but the load that through cracks appear along the intersection between slab and hinged joint increases from 140 kN(2.00 times of vehicle load)to 199 kN(2.84 times of vehicle load), and through crack along longitudinal direction can be prevented.More>
2015, 15(5): 15-25. doi: 10.19818/j.cnki.1671-1637.2015.05.003
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Computation methods of axial forces for main cables and short hangers of suspension bridges
CENG Sen, MA Xin-wei, CHEN Shao-feng
Abstract: To solve the problem that the axial forces of short hangers can not be measured by vibration method, nodal equilibrium method and analogy method were provided to estimate the axial forces of main cables and short hangers of suspension bridges. Nodal equilibrium method took the suspension points as analytical object to set up the over determined equilibrium equations in which the axial forces of main cables were unknown, the least squares solution of axial forces of main cables was obtained, and the axial forces of short hangers were determined. Analogy method analyzed the relationship between the axial forces of long hangers and the bending moment of equivalent beam, set up the relationship equations between the linetypes of main cables and the axial forces of long hangers to ultimately determine the horizontal tensions of main cables and the axial forces of short hangers. Guizhou Nanpan River Suspension Bridge was taken as an example, and the axial forces of main cables and hangers were estimated by using the two methods respectively. Computation result shows that calculation values by the two methods are close to the values measured by vibration method. The errors of axial forces of main cables by nodal equilibrium method are -4.3%(upstream)and 3.1%(downstream), and the errors by analogy method are -8.6%(upstream)and -0.1%(downstream). The maximum error of axial forces of long hangers by both methods is about 10%. The average errors of axial forces of upstream hangers are less than 2%, and the errors of downstream hangers are about 9%. So nodal equilibrium method and analogy method are effective to determine the axial forces of main cables and short hangers.More>
2015, 15(5): 26-33. doi: 10.19818/j.cnki.1671-1637.2015.05.004
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Crossing pressure wave characteristics of high-speed trains in tunnel
MEI Yuan-gui, SUN Jian-cheng, XU Jian-lin, ZHOU Chao-hui
Abstract: The geometric model of train and 3Dunsteady-compressible turbulence model were set up by using the computational fluid dynamics(CFD)software based on the finite volume method(FVM), and the whole crossing processes of high-speed trains were simulated in constant-speed and variable-speed conditions.The smooth starting method was coupled into the moving mesh technique of arbitrary sliding interface(ASI)to study the pressure fluctuation characteristics, the air velocity varition and the forming processes of pressure waves at tunnel sections in the whole crossing processes.Study result shows that the pressure fields and velocity fields in high-speed trains passing process in tunnel are clearly depicted via the 3Dfluid flow model.Though the pressure fluctuation trends of monitoring points at a tunnel cross section are consistent with that of cross-section average pressure, the pressure differences of monitoring points are considerably high, and the maximal difference is 53.5%.The pressure fluctuation amplitude at the middle section of tunnel is largest in constant-speed crossing, and the negative pressure peak value is about-7kPa.In constant-speed crossing, when the speed of lower-speed train decreases, the peak values of positive and negative pressures for higher-speed train decrease, while the positive pressure peak value of lower-speed train is about 1.5kPa higher than that of higher-speed train.The negative pressure peak value at the cross section where two train noses meet together isproximately direct proportional to the speed square of lower-speed train.More>
2015, 15(5): 34-43. doi: 10.19818/j.cnki.1671-1637.2015.05.005
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Reproduction simulation of emergency brake fault feature for subway train
ZUO Jian-yong, HAN Fei, HU Wei
Abstract: The working principle of emergency braking loop and the characteristics of emergency pneumatic braking system for subway train were introduced.The diagnostic rules of the faults of emergency electromagnetic valve were provided based on comprehensive braking command and volume-chamber pressure of relay valve.Three kinds of fault characteristics for emergency electromagnetic valve are analyzed respectively corresponding to three kinds of cases, in which emergency brake was invalid with emergency braking command, emergency brake occurred without emergency braking command and volume-chamber pressure of relay valve was abnormal without emergency braking command.The detailed process of fault diagnosis for emergency electromagnetic valve was analyzed.The pneumatic braking system model was set up by using AMESim, three types of faults were simulated based on fault reappearance method, and the contrast test of the first type fault was conducted on the pneumatic control test bed.Test result shows that in triggering the emergency braking signal under normal condition, the volumechamber pressure delays 1.1s and reaches its goal.Under artificially disconnecting the signal wire of emergency electromagnetic valve and triggering the emergency braking signal, thevolume-chamber pressure is zero and remains unchanged.After 2.6s, the system alarms the faults of emergency braking electromagnetic valve.So, the braking system model can effectively represent the emergency braking fault features, the fault feature identification method is feasible based on braking command and volume-chamber pressure of relay valve, and it can be used for emergency braking fault's on-line monitoring and service status tracking.More>
2015, 15(5): 44-49. doi: 10.19818/j.cnki.1671-1637.2015.05.006
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Kinetic energy uphill performance of heavy-haul train based on multi-particle model
WANG Kai-yun, HUANG Chao
Abstract: Train multi-particle longitudinal dynamics model was used to analyze the influences of train initial speed, train marshalling, slope length and slope gradient on the kinetic energy uphill performance of train.A comparison between multi-particle model and single particle model was made.A specific example was given to illustrate the difference of the maximum tractive tonnages between the two models in the kinetic energy uphill.Analysis result indicates that the higher the uphill initial speed is, the better the uphill performance is.The uphill performance declines with the increases of train marshalling, slope length and slope gradient.The difference of train uphill lowest speed of two models increases with the decrease of train uphill initial speed.The difference of the uphill lowest speeds of two models is 5.29km·h-1 when the initial speed is 60km·h-1.The calculation result of single particle model is more and more conservative with the increases of train marshalling, slope length and slope gradient.Train maximum tractive tonnages are 8 250 t and 8 750 t based on single particle model and multi-particle model respectively, in which the latter is 6.1% higher than the former.It is suggested that the multi-particle longitudinal dynamics model can be adopted to calculate train maximum tractive tonnage in kinetic energy uphill.More>
2015, 15(5): 50-56. doi: 10.19818/j.cnki.1671-1637.2015.05.007
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Motion model of sail-assisted ship
SHEN Zhi-peng, JIANG Zhong-hao
Abstract: The forces of sail in complex environment were analyzed, and the force functions of sail under the best attack angle were obtained.Based on the coupling relationship between ship motion and ship main diesel engine revolution, the fitting function of main diesel engine output torque and throttle lever position of ship was deduced.76 000 DWT large ocean-going bulk ship'Wenzhuhai'was taken as research object, a sail-assisted ship motion model with four degrees of freedom was constructed based on real ship parameters.Simulation result shows that after adding sail, ship speed increases and roll angle decreases, but ship yaws more.Ship journey in the same time, ship speed under the best attack angle, and roll amplitude increase with the increase of wind speed after adding sail.Roll angle is less than 15° within safe range.Analysis result is consistent with the motion laws of real ship, so the model is effective.More>
2015, 15(5): 57-64. doi: 10.19818/j.cnki.1671-1637.2015.05.008
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Flow field characteristics of catalytic muffler for medium-heavy duty truck
XU Xiao-ming, JIANG Hao-bin, GONG Ran
Abstract: Aiming at catalytic mufflers with different air inlet structures and shapes of mediumheavy duty truck, the air inlet uniformity of carrier front face and the total pressure difference between the inlet and outlet were calculated by Fluent software, and the flow field characteristics were analyzed.Calculation result indicates that the flow field characteristics of catalytic muffler are related to engine exhaust.The air inlet uniformity of carrier front face and the total pressure difference between the inlet and outlet are very important for analyzing the flow field characteristics.The air inlet uniformity and the total pressure difference increase after adding baffle, and the flow field characteristics are best after adding erect baffle.The flow field characteristics are good when inlet pipe diameter shrinks by 40 mm and outlet pipe diameter expands by 40 mm.After optimizing catalytic muffler, the air inlet uniformities of carrier front face respectively increase by 1.2%and 1.6%, and the total pressure differences between the inlet and outlet respectively decrease by 57.5%and 63.9%compared to the values before optimization when engine rotation speeds are 900r·min-1 and 1 900r·min-1 respectively, which shows that structure optimization significantly decreases the total pressure difference.Compared to barrel shape catalytic muffler, the air inlet uniformity of carrier front face for box shape catalytic muffler increases.Spatial arrangement and utilization efficiency should be considered as well forchoosing catalytic muffler.More>
2015, 15(5): 65-71. doi: 10.19818/j.cnki.1671-1637.2015.05.009
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Parameter identification method of motion platform of helmet mounted display servo system
LI Peng, GU Hong-bin, WU Dong-su
Abstract: The nondeterminacies and time-varying characteristics of parameters for motion platform of helmet mounted display servo system(HMDSS)were analyzed, the identification processes of continuous-discrete extended Kalman filter(CDEKF) and continuous-discrete square-root unscented Kalman filter(CDSR-UKF)were derived, the parameter identification model of motion platform of HMDSS was presented based on the system dynamics model, and the identification effects of CDEKF and CDSR-UKF were compared by simulation.The mutation experiment of parameters for motion platform was designed and implemented to verify the practicability of CDSR-UKF.Simulation result indicates that the standard error ratios, convergence time ratios and root mean square error ratios of CDEKF to CDSR-UKF are 1.9-6.3, 1.0-27.7and 1.4-11.0, which means that CDSR-UKF has higher identification precision, stability and convergence velocity than CDEKF.The average convergence time of CDSR-UKF is about 0.002 s, so CDSRUKF has better capacity of real-time identification.The online estimation error of CDSR-UKF is less than 10%, and the convergence times against large parameter mutation and normal parameter mutation are about 0.30 sand 0.04 srespectively, so CDSR-UKF can well trace changingprocesses of identification parameters and satisfy parameter identification requirements of motion platform of HMDSS in normal usage environment.More>
2015, 15(5): 72-84. doi: 10.19818/j.cnki.1671-1637.2015.05.010
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Trend analysis of expressway transportation based on big data
XIAO Run-mou, LI Bin, CHEN Yin-san
Abstract: Based on the database of expressway network toll system and the typical sampling investigation data at toll stations, the transportation changing trend of Chinese expressway network in 2008-2014 was analyzed.Analysis result shows that the proportions of buses kilometers in expressway network remained between 58% and 69% from 2008 to 2014.Due to the continuous growth of car travel, the passenger volume in expressway network rose to 1.67×1010 peoples in 2014 and increased by 14.99% compared with the value in 2013, and the annual average growth rate was 15.21%in past 6years(2009-2014).Passenger turnover volume reached1.47×1012 peoples·km and increased by 12.07% compared with the value in 2013, and the annual average growth rate was 13.57% in past 6years.The trend that the growth rate of passenger turnover volume was further greater than the growth rate of freight turnover volume was strengthened.Because of macroeconomic impact, the freight turnover volume in expressway network reached 2.33×1012 t·km in 2014, an increase of about 2.35% was lowest in 6years, and the annual average growth rate was 11.69% in past 6years.The percentage of empty to loaded trucks kilometers was 24.15%, and remained a stable situation.The percentage of trucks with the overweight more than 30% decreased from 5.59%in 2008 to 2.85%in 2014, so the effect of charge-by-weight policy was significant.More>
2015, 15(5): 85-90. doi: 10.19818/j.cnki.1671-1637.2015.05.011
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Multi-target locating method of surface ship based on monocular vision
LIU Chen-guang, CHU Xiu-min, XIE Shuo, WANG Le
Abstract: Aiming at the multi-target real-time locating of surface ship, an algorithm for real-time locating and motion parameters calculating of ship was proposed.The proposed algorithm was realized by processing the images captured by monocular camera with fixed position and perspective. The captured images were preprocessed with Gaussian filter and distortion correction, and a multi-target recognition method was proposed based on ship color features, size characteristics, and kinematic characteristics(every target could be identified individually).A transformation model between image coordinate system and real coordinate system, and a computing model for ship speed, course and trajectory calculation were built.A real locating system was built in experimental pool, a real-time locating program was developed, and the locating precision and trajectory tracking performance were verified.Verification result indicates that in the circumstance with disturbances, the precise recognition of two ships can be realized by using proposed locating algorithm.The average locating errors in lateral and longitudinalorientation are 0.058 m and 0.209 mrespectively before amendment, 0.038 m and 0.124 m respectively after amendment.The update frequency of camera locating data is 8 Hz, which can meet the control requirements.The real-time position, speed and course of ship can be correctly calculated, and the trajectory is smooth without any abnormal location point.More>
2015, 15(5): 91-100. doi: 10.19818/j.cnki.1671-1637.2015.05.012
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Control method of probability of adequate depth ensuring navigation safety of depth model
JIA Shuai-dong, ZHANG Li-hua, PENG Ren-can, WANG Tao, DONG Jian
Abstract: Considering the drawback of charted depth in ensuring the navigation safety currently, a control method of probability of adequate depth was proposed, thus the navigation safety of depth model was ensured.The surface of triangulated irregular network(TIN)-based depth model was constructed based on the mark point of charted depth, and the common formula for calculating the depth of model surface at arbitrary position was deduced.Considering the influence of uncertainty of depth source data on navigation safety, the influence of representation uncertainty of depth model at arbitrary position was analyzed quantitatively.The uncertainty was appended on the model point to control the influence of representation uncertainty, and the probability of adequate depth of depth model was controlled to meet the required value.On the charts with the scales of 1∶2 000, 1∶5 000, 1∶10 000, 1∶50 000, respectively, the proposedsurface control method was verified and compared with traditional method and point control method.Analysis result indicates that the acceptable rates of probability of adequate depth controlled by using surface control method on the charts are respectively 51.72%, 49.37%, 38.71%, 28.39% higher than the rates by using traditional method, and are 4.10%, 5.00%, 5.06%, 9.65% higher than the rates by using point control method.When the scale decreases, the acceptable rates of probability of adequate depth controlled by traditional method increase, and the rates by using point control method decrease, however, the rates by using surface control method are always 100% for both considering the uncertainty of source data and the representation uncertainty of depth model.The probability of adequate depth controlled by surface control method meets the required value(97.5%), but traditional method and point control method cannot satisfy the demand, which demonstrates the advantages of surface control method.More>
2015, 15(5): 101-109. doi: 10.19818/j.cnki.1671-1637.2015.05.013
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Computation method of ship domains in restricted waters based on AIS data
XIANG Zhe, HU Qin-you, SHI Chao-jian, YANG Chun
Abstract: In order to obtain the ship domains in restricted waters, a method was proposed by using large volume of AIS data.The AIS data of target ships were selected, and the waters nearby target ships were gridded.The occupy frequencies of other ships in each grid were calculated, and the grid frequency graph of single ship was extracted.The ship sizes were considered in the calculation process.Through overlying all grid frequency graphs of target ships with certain length, the grid frequency graph of specific ship was achieved.The grids in the grid frequency graphs were filled with colors according to different frequencies, then the shape of specific ship domain was observed clearly.Through fracturing and measuring the surface of ship domain, the length of ship domain was acquired.The proposed method was verified by using the AIS data from ships navigating in Nancao Restricted Waters of Shanghai Port.The domains of ships with the lengths of 60-79, 80-99, 100-119, 120-139, 140-159 m were calculated.Analysis result indicates that since the ship sizes are taking into consideration, the direction of ship domain's long axis has a portside deflection angle to heading, the angles are 3.37°, 9.46°, 17.53°, 10.78°, 8.13°respectively for the five types of ships.The length ratios of ship domain to ship decrease with the increase of ship length, and the ratios are 6.00, 5.80, 5.67, 5.43and5.13 respectively for the five types of ships.So the shape of ship domain in restricted waters is irregular ellipse, and the length ratio of ship domain to ship is not constant.More>
2015, 15(5): 110-117. doi: 10.19818/j.cnki.1671-1637.2015.05.014
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Recognition method of road speed limit information based on data mining of traffic trajectory
LIAO Lu: -chao, JIANG Xin-hua, LIN Ming-zhen, ZOU Fu-min
Abstract: The spatiotemporal variability of speed limit information was analyzed, and an automatic recognition method of road speed limit information was proposed based on the mining technique of trajectory data.To fast process the massive traffic trajectory data, the pretreatment algorithms such as rapid map matching and data cleaning were researched.The speed distribution features of traffic trajectory data and the maximum speed limit index were analyzed.Based on the speed features at road section, a road feature vector model was constructed to rapid extract the latent characteristics information from the massive trajectory data was achieved.In order to implement a rapid recognition of speed limit information, a classification algorithm based on multi-voting K-nearest neighbor(MV-KNN)algorithm was proposed for the training and learning process of data feature.The training, learning and cross-validation experiments were completed by using the sample sets constructed by actual floating car trajectory data and traffic network in Fuzhou City.Experimental result indicates that the highest system recognitionaccuracy of proposed method is up to 93% by using 1 200 samples in the training process, and the system recognition accuracy is 75% by using only 150 samples.The near-linear processing performance of proposed method is revealed, and the system operating time is only 46 ms in processing 1 000 000 samples of road speed limit information.More>
2015, 15(5): 118-126. doi: 10.19818/j.cnki.1671-1637.2015.05.015
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