Table of Content

25 November 2018, Volume 46 Issue 11

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Food Science & Technology

Interaction Between Memory-Enhancing Chinese Herbal Medicine and Walnut Peptides#br#

XIONG Jian XIE Liping ZHANG Ting LIANG Min YUAN Erdong REN Jiaoyan

2018, 46(11):  1-8.  doi:10.3969/j.issn.1000-565X.2018.11.001

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The corresponding active ingredients were extracted by water from five traditional Chinese herbal medicines (Ginseng, Polygalaceae, Poria, Longan and Ginkgo biloba) which can improve memory. The interaction and binding of five active substance to walnut peptides modify its physicochemical properties and antioxidant activity.The result showed that the extracted herbal active substances have ability of antioxidant and eliminating free-radicals. The enzymatic hydrolysis process of walnut was optimized with the protein recovery and antioxidant activity as the index, and the total amino acid composition of the hydrolyzate was analyzed. Based on the evaluation of antioxidant properties and fluorescence spectroscopy, the experiment investigated the interaction between Chinese herbal active substances and walnut peptides, and the effects of different interaction conditions such as ratio, temperature and pH. The results indicated that the active substance extracted from Chinese herbal medicine declined the fluorescence of walnut peptides and their interacted led to a synergistic effect on antioxidant effect. In addition, the suitable ratio is more favorable to the synergistic effect. It was found that the effect of temperature on the interaction was obvious, and the effect of pH on the interaction between polysaccharide and polypeptide was significant. The experimental results provide a scientific foundation for the practical production.

Effects of Edible 0il and Heating Methods on the Structure and in Vitro Digestibility of Wheat starch

HUANG Qiang DING Li SHU Qin LI Ping GUAN Nannan ZHANG Bin

2018, 46(11):  9-15,38.  doi:10.3969/j.issn.1000-565X.2018.11.002

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The effects of common edible oils and heating methods on starch structure and in vitro digestibility of wheat starch were studied. The edible oils such as butter, palm oil and soybean oil were blended with wheat starch at the ratio of 1: 5 (w / w), and then were treated with constant high temperature heating and consecutive heating up respectly to prepare starch-lipid complexes. The lipids content, particle morphology, crystalline structures, thermal properties and in vitro digestibility of the complexes were determined. The results showed that complexed-lipids content of wheat starch increased significantly, and the crystalline structure of wheat starch changed from A type to A+V type after complexed with lipids. Among them, palm oil was easier to form stable complex with wheat starch. Compared with constant high temperature heating treatment, the complexes formed by consecutive heating up treatment were more stable, and the content of slow digestible starch (SDS) and resistant starch (RS) of complexes were significantly increased. After constant high temperature heating treatment, the starch-soybean oil complex showed the highest SDS content (15.8%), while the starch-palm oil complex showed the highest SDS content (16.4%) using consecutive heating up treatment.

Effects of Soluble Soybean Polysaccharides on Freezing Denaturation and Structure of Aristichthys Nobilis Surimi Protein

GAO Wenhong HUANG Yangping ZENG Xin’an

2018, 46(11):  16-22.  doi:10.3969/j.issn.1000-565X.2018.11.003

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In this paper the changes of solubility, Ca2+-ATPase activity and total sulfhydryl content of myofibrillar protein of Aristichthys nobilis surimi were investigated after they were frozen with 0%, 1%, 3%, 5% soluble soybean polysaccharides (SSPS) for 12 weeks at -18oC. Myofibrillar protein structure changes during frozen storage were also analyzed based on the Fluorescence spectra and Raman Spectra. Results showed that the protein solubility, Ca2+-ATPase activity as well as total sulfhydryl content of frozen Aristichthys nobilis surimi presented two phases of dropping trend. They decreased sharply during the previous four weeks, but to a lower extent during the subsequent eight weeks. The addition of SSPS could reduce these changes to some extent and the best effect was obtained by 5% SSPS. The Fluorescence spectra and Raman spectra of 12-week frozen surimi also indicated that SSPS could prevent the exposure of aromatic amino acid residues, such as tryptophan and tyrosine, to a polar microenvironment on the myofibrillar protein surface. SSPS could also reduce the decrease of ɑ-helix content and prevent the conformational changes of disulfide bonds from gauche-gauche-trans (g-g-t) to gauche-gauche-gauche (g-g-g). The best effect was obtained by 5% SSPS. The results showed that SSPS could effectively mitigate the myofibrillar protein denaturation of Aristichthys nobilis surimi and improve their quality during the 12-week frozen storage. Therefore SSPS is promising as a new protein cryoprotectant.

Effects of Storage Time on Components of Dancong Tea and its Inhibition Activities on Lipase and α-Glucosidase

YUAN Erdong DUAN Xuefei XIANG Limin SUN Lingli LAI Xingfei LI Qiuhua ＲEN Jiaoyan SUN Shili

2018, 46(11):  23-28.  doi:10.3969/j.issn.1000-565X.2018.11.004

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Previous studies have shown that oolong tea has an effective effect on losing weight. As Dancong tea used in this study is a kind of the oolong tea, we speculated that it could also help to reduce fat. The Dancong tea samples with different storage years were obtained from the same producer, and they were produced by the same processing technology. Their compositions were detected and the inhibition of the tea samples on lipase and α-glucosidase activity in vitro was also measured. At the same time, we have analyzed the correlation of these data. The results demonstrated that there was no significant change in caffeine content between the different tea samples. The contents of tea polyphenol, catechins and free amino acid in Dancong tea stored for years were lower than that of the fresh tea, while the contents of aqueous extract, total soluble sugars, gallic acid and theaflavin in Dancong tea stored for years were higher than the fresh tea. Moreover, there was a significant negative correlation between catechin content and theaflavins content, which further proves that TF is the product of catechin oxidation. The experiments in vitro indicated that Dancong tea is able to inhibit lipase activity and α-glucosidase activity. The inhibition of Dancong tea in 1996 on lipase activity was the highest at 43.01%, while it’s the lowest in 2016 at 26.98%. After correlation analyses, it was speculated that gallic acid in tea might be the main effective component of inhibiting lipase activity and reducing weight. On the other hand, the inhibition on α-glucosidase activity was highest in 2016 at 94.48%, while it’s the lowest in 2006 at 89.04%. the correlation analyses showed that caffeine could be the main biological active component to reduce blood sugar. The results provide a theoretical basis for the further development and value-added utilization of single cluster tea.

Structural，Antioxidant Activity and Immunomodulatory Activity of Polysaccharides Isolated from Undaria pinnatifida#br#

YOU Lijun HUANG Shiming ZHENG Guiqing ZHAO Zhengang HAN Ｒui MENG Hecheng

2018, 46(11):  29-38.  doi:10.3969/j.issn.1000-565X.2018.11.005

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Undaria pinnatifida, which is mainly distributed in Liaoning, Shandong and Zhejiang province in China, is a kind of edible seaweed belongs to Phaeophyta. In the present study, a sulfated polysaccharide named as UPP was extracted by hot water from Undaria pinnatifida with a yield of 11.00 ± 0.25%. The molecular weight of UPP was 691.05 kDa, and the contents of carbonhydrate, uronic acid, sulfate and protein were 50.02 ± 1.14%, 14.98 ± 0.52%, 11.19 ± 0.40% and 2.37 ± 0.17%, respectively. UPP was composed by glucose, xylose, mannose, arabinose, fucose, galactose and rhamnose, while glucose and xylose contributed to a total molar percentage of 71.39%. UPP consisted of (1→2) or (1→4) glycosidic bond by 62.36% as well as (1→3) glycosidic bond by 35.78%. Fourier transform-infrared (FT-IR) spectra indicated that UPP have characteristic functional groups of polysaccharides. Three different methods were applied to investigate the antioxidant activity of UPP in vitro. The results showed that oxygen radical absorbance capacity(ORAC), ABTS scavenging capacity value and DPPH scavenging capacity value of UPP were 164.54 ± 4.85 μmol TE/g，64.93 ± 4.76 μmol Trolox/g and 46.80 ± 6.06 μmol Trolox/g. In addition, the immunomodulatory activity of UPP was examined by murine macrophage RAW264.7 cells model. The results indicated that UPP presented unsinificant cytotoxicity to RAW264.7 cells with the concentration of 50~1500 μg/mL. Meanwhile, RAW264.7 cells showed the strongest pinocytic capability (113.22 ± 2.75% to the control) when the concentration of UPP was 600μg/mL. Furthermore, UPP obviously promoted the production of NO, which ranked the highest when the concentration of UPP was 600μg/mL. The mRNA of iNOS increased significantly with the concentration of UPP increased from 100~800μg/mL. These results above suggested that UPP possessed excellent antioxidant ability and immunodulatory activity and could be applied to industrial production of healthy foods as an effective component.

Materials Science & Technology

Research on Thermal Performance Of Bi-In-Sn-Sb Quaternary Alloy Interface Materials

LI Jing CHEN Xuyang LEI Rubai ZHANG Ding FAN Chunlei

2018, 46(11):  39-46.  doi:10.3969/j.issn.1000-565X.2018.11.006

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Alloy interface materials with excellent thermal contact resistance elimination rate are widely used in the electronics industry to improve the thermal conductivity between material contact surfaces. In this paper, a novel Bi-In-Sn-Sb quaternary alloy was fabricated by adding a small amount of expandable metal Sb to Bi-In-Sn ternary alloy and smelting it in a tube furnace at 700 ℃. This alloy has a low melting point (~ 61 ℃), high thermal conductivity (~ 23.8 W m-1 k-1) and extremely low thermal contact resistance (~ 12.3 mm2 K W-1). The eliminating efficiency of thermal resistance between ceramic substrates is up to 95.9%, which can greatly improve the heat transfer performance between the substrates. The results show that the volumetric expansion rate of Bi-In-Sn-Sb quaternary alloy is as high as 88.6% after phase change (at 80 ℃), which can effectively reduce the residue of air gap between interfaces and improve the quality of contact surfaces. Therefore, the expandable phase change Bi-In-Sn-Sb quaternary alloy most likely becomes a good candidate of high performance thermal interface materials.

Experimental Ｒesearch on Fracture Energy of Glass Fibre-Ｒeinforced Cement#br#

CHENG Congmi ZHANG Jian GAN Wei LUO Zheng-tang ZHANG Yafang HE Juan

2018, 46(11):  47-52,67.  doi:10.3969/j.issn.1000-565X.2018.11.007

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Fracture energy is an important technical specification to evaluate the anti-cracking capacity of glass fiber reinforced cement (GRC). The effects of glassfibre length and content, water-to-binder ratio and sand-to-binder ratio on the fracture energy of GRC produced by premixed casting were studied through experiments. The results show that glassfibre significantly improves the fracture energy of cement-based materials. When the glassfibre content does not exceed 3% of the solid component mass, the fracture energy of GRC increases greatly with the increase of glassfibre content, which is approximately linear. When the glassfibre content is constant, the fracture energy of GRC increases first and then decreases with the increase of glassfibre length. When the glassfibre length is 20mm, GRC has higher fracture energy. The fracture energy of GRC is mainly derived from the extraction energy of glassfibre. Both the water-to-binder ratio and the sand-to-binder ratio have a significant effect on the extraction energy of glassfibre. The increase of water-to-binder ratio will reduce the flexural strength of GRC, but the fracture energy of the GRC increases significantly with increasing water-to-binder ratio. The water-to-binder ratio increased from 0.32 to 0.50, and the fracture energy of GRC increased by 227%. The fracture energy of GRC decreases with the increase of sand-to-binder ratio.

Research on durability of metakaolin concrete based on long-term exposure experiment at in-situ marine splash zone

ZENG Junjie FAN Zhihong XIONG Jianbo WANG Shengnian

2018, 46(11):  53-60.  doi:10.3969/j.issn.1000-565X.2018.11.008

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Concrete containing metakaolin (MK) and ternary blends of MK and fly ash (FA) were prepared. A long-term exposure experiment at in-situ marine splash zone for the prepared concretes were carried out. Total and free chloride content of the exposed concretes were tested. SEM-EDS was used to analyze the morphology and element composition of the hydrates, while XRD was used to determine the phase component of the exposed concretes. The results show that the chloride content and chloride diffusion coefficient of concrete under actual marine environment are decreased with the application of MK, while the chloride binding capacity is enhanced. The improvement effect becomes more significant when FA is applied in the MK concrete. A denser structure of concrete can be obtained by the use of MK. Higher A/S and lower alkalinity of the hydrates of MK concretes promote the formation of Friedel’s salt. In addition, the application of MK did not have detrimental effect on sulfate resistance of the long-term exposed concretes.

Influences of Heterogeneous Property of Material Under Line Contact Loads on Material’s Rolling Contact Fatigue

YANG Wanyou WANG Jiaxu ZHOU Qinghua HUANG Yanyan XIONG Lindong

2018, 46(11):  61-67.  doi:10.3969/j.issn.1000-565X.2018.11.009

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Rolling contact fatigue is one of early failure modes that usually happen in such mechanical transmission parts as rolling bearings and gears． In addition，inhomogeneities，inclusions and cavities existing unavoidably in engineering materials severely affect the performance of contact pair material． In this paper，a numerical equivalent inclusion method was utilized to analyze the influences of distributed inhomogeneities with the shapes such as el- lipse，rectangle and triangle in x-z section on the stress field of matrix，and rolling contact fatigue quantified by vo- lumetric stress integral was used to explore rolling contact fatigue regularity of heterogeneous materials． The results show that the shapes，Young’s moduli，depths and volume fractions of distributed inhomogeneities，as well as the frictional coefficients，all play an important role in volumetric stress integral of heterogeneous material under line contact loads．

Influence of Si and heat treatment on microstructures and corrosion behavior of Al–Zn–Mg–Cu alloys

JIAO Huibin CHEN Kanghua YANG Zhen CHEN Songyi WANG Huiping MA Yunlong

2018, 46(11):  68-75.  doi:10.3969/j.issn.1000-565X.2018.11.010

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Stress corrosion cracking (SCC) behavior of Al-Zn-Mg-Cu alloys with different Si contents and heat treatments was studied using slow strain rate test. Grain boundary microstructures were identified by transmission electron microscopy (TEM) and statistical analysis. It was found that the SCC resistance of alloys is improved by increasing Si contents and aging degree. Grain boundary precipitates (GBPs) area fraction was found to be an important parameter to evaluate the SCC susceptibility. The results reveal that for Al-Zn-Mg-Cu-0.16Zr-0.04Si(wt%) alloy with different aging degrees, hydrogen induced cracking dominates the SCC when the area fraction of GBPs is relatively low. For peak-aged Al-Zn-Mg-Cu alloy and Al-Zn-Mg-Cu-0.16Zr-0.02Si(wt%) alloy, anodic dissolution dominates the SCC when the area fraction of GBPs is sufficiently high.

Mesoscopic and Stochastic Research on Chloride Ion Transport in Unsaturated Concrete

SHEN Lin CHEN Dingshi LI Wanheng ZHAO Shangchuan

2018, 46(11):  76-82.  doi:10.3969/j.issn.1000-565X.2018.11.011

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In order to study the law of chloride ion erosion in unsaturated concrete of concrete bridges on service, a multi-factor modified model of chlorine ion transport for saturated concrete was established based on the characteristics of moisture migration in dry-wet circulation process and the influence factors of chloride ion transmission.It derived the coupling equations of water-chlorine transport convection-diffusion under non-saturated conditions.By integrating the macroscopical numerical model of chloride ion erosion with the mesoscopic random concrete model, a random mesoscopic study method for non-saturated chloride ion-eroded concrete was presented,and it summarize the rules that chloride ion transport in unsaturated concrete. The results indicate that the concentration of chloride ion concentration around the aggregate was significant.Different from the surface of concrete ,the aggregates have a great influence on the size and position of the chloride ion concentration peak. The concentration increased in wetting process , and decreased in drying stage due to the combined effect of convection and diffusion for the interior area .The research results for non-saturated concrete chloride ion transport mechanism provides a reference.

Traffic & Transportation Engineering

Comparative Study on Motorcycle Crash Injury Severity Estimation Based on Nested Logit and Ｒandom Parameters Logit Models

WEN Huiying TANG Zuogan

2018, 46(11):  83-91.  doi:10.3969/j.issn.1000-565X.2018.11.012

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To analyze the factors affecting the injury severity of motorcycle crashes, Nested Logit and Random Parameters Logit models were developed. Motorcycle crashes data from 2013 to 2015 in Indian were collected with a total of 1947 single-vehicle motorcycle crashes occurring during that time period. The parameters of Nested logit and Random Parameters Logit models were estimated under full information maximum likelihood (FIML) method and Monte Carlo method separately. Two model estimation results all show that female, age, helmet use, alcohol use, speeding, run off of road, passenger on vehicle, vehicle age over 10 years old, wet pavement, horizontal curve with slope, intersection, speed limits over 50mph, months of April and July, nights without street lights, rural area, fixed collision objections (guardrail, tree, wall, curb, pole, culvert) are significantly related to motorcycle injury severity. By compared with the AIC value and BIC value of Nested logit and Random Parameters Logit models, showing that the overall model fit of Random Parameters Logit model is better than Nested logit model. The paper can provide a reference and guidance for further analysis of crash injury severity in domestic motorcycle crashes.

Numerical Simulation Analysis of Transient Hydrodynamic Pressure on the Road Surface Based on COMSOL Multiphysics

SHEN Aiqin SONG Pan GUO Yinchuan LI Peng

2018, 46(11):  92-101.  doi:10.3969/j.issn.1000-565X.2018.11.013

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Abstract:Aimed at the fact that instantaneous dynamic water pressure caused by tires is the main reason for water-damage of pavement materials and skid of vehicle that may be endanger the safety of the vehicle in rainy condition. In order to explore the risk speed of water-skidding and the water-damage process of the pavement material subjected to the dynamic water erosion. In this paper, the Audi A4L and Shaanxi Auto Catron F3000 as the main research object, and the AH-E type instantaneous dynamic water pressure sensor was used to measure the instantaneous dynamic water pressure data of the two vehicles under the condition of different driving speeds on the cement concrete road surface, and based on the COMSOL Multiphysics software platform, the fluid structure interaction analysis model of the tire-water film-road surface interaction was established. This model was used to analyze the regularity of the influencing factors of instantaneous dynamic water pressure on the road surface, and calculate the risk velocity of water-skiing. The results show that the instantaneous dynamic water pressure on the road surface increases with the increase of the thickness of water film, the velocity of driving and vehicle axle load. There are dynamic water positive pressure zone and negative dynamic water pressure zone at the same time in the tire-water film-road surface interaction region, and under the effect of positive dynamic water pressure and negative dynamic water pressure, the dynamic water to form a strong scour circulation function in the pavement material. At the same time, with the increase of the thickness of the water film layer of the road surface, the speed at which the vehicle can take the risk of water-skiing is decreasing. At the same speed, the sedan is more prone to water-skidding risks than trucks.

Quantitative Evaluation Method of Carbon Emissions in Asphalt Surface Construction and its Application

PENG Bo HE Juan CAI Chunli WANG Xunjie YANG Zhengwen

2018, 46(11):  102-109.  doi:10.3969/j.issn.1000-565X.2018.11.014

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In view of the lack of applicable evaluation methods for the carbon emissions in asphalt surface construc- tion that results in the difficulty in constraining the carbon emission effectively，this paper investigates and detects the carbon emission of 13 asphalt pavements under construction in several areas in China，and establishes a formula to calculate the carbon emission due to the combustion of energy and the high-temperature decomposition of asphalt． Then，based on the carbon emission inventory，quantitative evaluation grading standards for carbon emission are put forward to establish an evaluation system，and the key process and measures of carbon reduction are determined by means of principal component analysis． The results show that the ratios of Grade Ⅰ (excellent)，Grade Ⅱ (good)，Grade Ⅲ (medium) and Grade Ⅳ (poor) are respectively 15%，31%，46% and 8%; and that the pivo- tal processes of carbon emission reduction include aggregate heating，asphalt heating and asphalt mixture rolling， and the carbon emission of the former two processes are mainly affected by the type of raw material’s heating ener- gy，while the carbon emission of asphalt mixture rolling is mainly affected by the type of asphalt．

Evolutionary Model of Traffic Flow in Crowded and Charged Routes Considering Heterogeneous Travelers

TIAN Sheng XU Kai

2018, 46(11):  110-116.  doi:10.3969/j.issn.1000-565X.2018.11.015

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In order to study the evolution of day-to-day traffic network traffic under the toll road network at the departure time and the travel route, the travelers are divided into three categories according to the time value difference. According to historical experience, it updates the parameters related to the travel route, unifies the time value with the toll collection fee, and introduces the theory of prospect to describe the travel behavior of the traveler. The model of traffic transfer between departure time is established based on the maximum probability of punctual arrival. The objective of this method is to chase the maximum path foreground value and establish the traffic transfer model between each departure time. Finally, the model and algorithm are validated by examples. The results show that the traffic flow in the toll road segment and time segment is small, and the traffic flows to other road segments and time segments. Compared with homogeneous travelers, heterogeneous travelers tend to have more transitions and more moderate rates of overall traffic evolution.

Control Strategy of Driving Torque Distribution for Two-Axle Drive Electric Vehicles#br#

XIONG Huiyuan HE Shan ZHA Hongshan ZHU Xionglai

2018, 46(11):  117-124.  doi:10.3969/j.issn.1000-565X.2018.11.016

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Aiming at the driving torque distribution between front and rear motor of two-axle drive electric vehicles, an optimization model is established based on the motor’s MAP characteristics, in order to maximize the utilization efficiency of dual-motor, then an optimal torque distribution model of dual- motor is obtained under the demand of different speed and torque. For two-axle drive electric vehicles, three driving modes of normal, power and economy are designed. And based on this optimization model, three dual- motor’s torque distribution strategies of three driving modes are worked out. Finally, a united simulation model of Carsim/Simulink is built for a lightweight electric minibus. And 0-60km/h acceleration time is used to verify the dynamic performance, and the economic performance of NEDC is used to verify efficiency. The results of simulation show that, the strategy studied in this paper can not only shorten the acceleration time of electric minibus by a small margin, but also extend the range of NEDC, which has increased 2.2%, 4.56% and 6.6% respectively under three driving modes. It provides an optimization method of dual- motor’s torque distribution for two-axle drive electric vehicles.

Analysis on Merging Position Distribution Characteristics of On-ramp Vehicles at Urban Expressway

CHEN Yongheng XIONG Shuai BAI Qiaowen LIU Xinshan TAO Chuqing

2018, 46(11):  125-131.  doi:10.3969/j.issn.1000-565X.2018.11.017

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A field survey was first conducted to collect merging information of on-ramp vehicles at urban expressway. Then clustering analysis was used to divide merging maneuvers into three clusters: the forepart, the midpiece and the endpiece. Five distribution models were selected to fit the distribution of merging positions in each cluster. Model parameters were determined by maximum likelihood estimation, and the goodness of fit to these models was also given by Kolmogorov-Smirnov test. It was found that the Johnson SB model obtains the best result in the forepart cluster, the Log-logistic model is the most suitable for the midpiece merging maneuvers, and the Gen. extreme. value model provides the best fit for the endpiece cluster. At last, a regression model was proposed to describe the relationship among the distribution of merging positions, the density of the shoulder lane, the merging velocity of an on-ramp vehicle. The result of sensitivity analysis shows that the density and the velocity have significant effect on the distribution of merging position in the same cluster.

Asphalt Thin-layer Thickness Detection Method Based on WRELAX Algorithm for Time-Delay Estimation

SONG Bo ZHANG Jinxi XUE Zhongjun YE Shengbo ZHANG Tao

2018, 46(11):  132-141.  doi:10.3969/j.issn.1000-565X.2018.11.018

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Concerning the overlap of ground penetrating radar (GPR) signal reflections at the different asphalt layers, which reduces the measurement accuracy of asphalt surface thickness, the WRELAX algorithm for time-delay estimation was applied to analyze the air-launched GPR signal reflections with 1GHz center frequency to improve the detection accuracy of thin layers of asphalt pavement in this paper. The results were verified by simulation experiment and field test. The research results show that the WRELAX algorithm detects iteratively strong reflections and then subtracted from the original signal to reveal the weak reflections. Time-delay and amplitude can be calculated by the WRELAX algorithm. The WRELAX algorithm in 1GHz GPR signal processing can effectively detect thin layers of asphalt pavement, and variation ranges of estimation errors are relatively small. The algorithm is robust and its effect is better than 2GHz GPR signal processing. The maximum relative estimation error of thin layer estimated by the WRELAX algorithm is less than 5%, which meets the requirements for detection and evaluation of asphalt thin layers.

Effect of 3D Laser Data Scanning Density on Pavement Macrotexture Depth Measurement

HUI Bing GUO Mu LIU Xiaofang

2018, 46(11):  142-149,156.  doi:10.3969/j.issn.1000-565X.2018.11.019

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In order to study the effect of 3D laser data scanning density on the measurement results when the 3D laser technology is applied to acquire the asphalt pavement mean texture depth (MTD). Using 3D laser Laboratory Testing System, to capture the surface data of asphalt pavement specimens involved AC10、AC13、AC16, considering 16 combinations types of scanning density to calculate the results of MTD on several laser scanning density, and the influence of 3D laser data scanning density on the result of MTD was analyzed. The results show that:3D laser scanning technology has a good reliability on MTD calculation of asphalt pavement; when the laser data scanning density drop from 0.5mm×0.5mm to 5mm×5mm, the MTD averages among three types asphalt pavement specimens declined the most with a 36.52% drop, and the variation coefficient increases to 0.543mm. In addition, only change the direction interval of laser data scanning density is not significant to the results of MTD calculation. There is a significant logarithmic correlation between the MTD of the three types of asphalt pavement and the drop ratio of the laser data density, and the correlation coefficient is above 0.95. The pavement with larger particle size is more affected by the change of laser data scanning density.

Flexible transit scheduling model based on dynamic bus stops rating and differential tickets pricing

PEI Mingyang CHEN Haihua LIN Peiqun PANG Chonghao

2018, 46(11):  150-156.  doi:10.3969/j.issn.1000-565X.2018.11.020

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Abstract: The flexible transit is a new kind of public transit that are more customized. But it doesn’t work well because the lack of reasonable and effective bus stops dynamic hierarchical management measures and operation scheduling method. In this paper, we use the data of bus stops and passengers, including passengers’ OD demand, travel time, bus stop land use, road network and population intensity etc. We evaluate the bus stops dynamically according to their score and rate rules, then select the bus stops which to be serviced and priced the tickets fee. The optimal model can reach a good overall system income in flexible transit system at different hours. The case study shows that the system profit is improved by 5% during the peak hours and 18.09% during off-peak hours, which means that the bus company and the passengers could be mutually beneficial preferably.