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18 September 2020, Volume 39 Issue 09 Previous Issue    Next Issue
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Transport+Big Data and Artificial Intelligence
Traffic & Transportation Engineering
Bridge & Tunnel Engineering
Highway & Railway Engineering
Port & Waterway · Hydraulic & Hydroelectric · Resources & Environment
Vehicle &Electromechanical Engineering


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Transport+Big Data and Artificial Intelligence

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Hierarchical Early Warning of Vehicle Longitudinal Collision Based on Internet of Vehicles SHI Jianjun, WANG Xu, FU Yu 2020, 39(09): 1-7.  DOI: 10.3969/j.issn.1674-0696.2020.09.01 Abstract ( )   PDF (1056KB) ( )   In order to prevent and reduce the occurrences of longitudinal rear-end collision accidents, a hierarchical early warning model of vehicle longitudinal collision based on internet of vehicles was proposed. Firstly, the framework of internet of vehicles based on next generation mobile communication network was constructed. The location information of the preceding vehicle and the target vehicle was collected by the internet of vehicles platform, and the location information was fused based on Kalman filter. The optimal value of vehicle position information at a certain time was obtained, and the real-time distance between the target vehicle and the preceding vehicle was obtained. Secondly, based on the real-time distance between the target vehicle and the preceding vehicle, and the critical early warning distance and critical braking distance obtained by analyzing the braking process of the vehicle, a hierarchical early warning model of vehicle longitudinal collision was established. Moreover, different warning information prompts were designed according to different warning levels, early warning parameters and hazard warning sensitivity parameters. Considering the high cost and safety aspects of vehicle early warning test in the field, the simulation platform of internet of vehicle based on VISSIM and OMNeT ++ was established. The simulation test results show that: compared with the vehicle with traditional fixed threshold warning algorithm, the false alarm rate of the hierarchical early warning model based on the internet of vehicles is reduced by 14.4% and the missing alarm rate is reduced by 3.5%. On the whole, the hierarchical early warning model of vehicle longitudinal collision based on internet of vehicles can reduce the occurrence of longitudinal traffic rear-end collisions and improve the safety of driving more effectively. References | Related Articles | Metrics

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Diagnosis and Repair of Traffic Fault Data Based on Spatio-Temporal Characteristics and Grey Residual LU Baichuan1,2, ZHANG Dongmei1, SHU Qin1, LI Yulian1 2020, 39(09): 8-16.  DOI: 10.3969/j.issn.1674-0696.2020.09.02 Abstract ( )   PDF (4782KB) ( )   The data acquired by traffic detectors may be incomplete or abnormal, and there were temporal and spatial correlations between traffic flow data in the road network, so the traffic fault data diagnosis and repair method based on spatio-temporal characteristics and grey residuals was proposed. Firstly, on the basis of analyzing the characteristics of fault data, the temporal and spatial characteristics of traffic flow data were considered, a fault data diagnosis model based on Mahalanobis distance (MD) was established. Secondly, the correlation coefficients of spatial-temporal dimension were calculated by using grey correlation model, and the time-spatial correlation data of strongly correlated sections were selected to establish the fault data repair model based on grey-genetic wavelet neural network (GM(1,N)-GA-WNN). The case study shows that the average relative error of fault data diagnosis and repair based on GM(1,N)-GA-WNN model is 1.7% lower than that of GM-WNN model and 4.8% lower than that of GM (1, N) model. Meanwhile, the accuracy of fault data repair considering spatio-temporal characteristics is better than that of single time and space repair sequence, which provides reliable data guarantee for road traffic prediction, traffic guidance and other services. References | Related Articles | Metrics

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Safety Effects of Congestion Charge Based on Virtual Synthetic Control Group LI Kejun1, LI Haojie2,3,4, ZHU Manman2,3,4 2020, 39(09): 17-24.  DOI: 10.3969/j.issn.1674-0696.2020.09.03 Abstract ( )   PDF (2424KB) ( )   Taking London as a case study, the causal effect method of virtual synthetic control group was used to estimate the impact of congestion pricing on traffic accident casualties in central London. By comparing the actual number of casualties in London and the number of casualties estimated by the virtual synthetic control group, the total number of casualties in traffic congestion toll area decreased by 4.29%, in which the number of minor injuries and serious injuries decreased by 5.05% and 12.12% respectively. The proposed model was validated by placebo test. The results show that the evaluation effect of congestion charge in London reaches 95% confidence level. The results show that the virtual synthetic control method can be used as an effective research method when there is no suitable comparative control group in traffic safety analysis. References | Related Articles | Metrics

Traffic & Transportation Engineering

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Path Planning and Tracking Control Based on Improved Artificial Potential Field LI Jun, LI Guyue 2020, 39(09): 25-30.  DOI: 10.3969/j.issn.1674-0696.2020.09.04 Abstract ( )   PDF (2212KB) ( )   In view of the imperfection of road potential field when the traditional artificial potential field method was applied in driverless vehicle path planning, an improved artificial potential field model was proposed to obtain the obstacle avoidance trajectory. Firstly, combined with the change of potential energy in the road, the gravitational potential field was improved; the elliptical repulsion potential field was increased to replace the traditional repulsion potential field; the road boundary repulsion potential field was increased to ensure that the vehicle would not drive out of the boundary; the speed potential field of obstacles was increased to improve the rationality of the obstacle. At the same time, a three-degree-of-freedom vehicle dynamics model was established, and the model predictive control algorithm was used for tracking control. The research results show that the improved artificial potential has a good obstacle avoidance path planning, and meets the dynamic constraints in all aspects at the same time. The rotation angle change is within ±3°, and the maximum lateral acceleration is 4.54 m/s2<0.67 μg, which ensures the driving stability and comfort of the planned path. References | Related Articles | Metrics

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Node Correlation Model Based on Coordinated Path YAN Xiaowen 1, XU Jianmin2 2020, 39(09): 31-37.  DOI: 10.3969/j.issn.1674-0696.2020.09.05 Abstract ( )   PDF (641KB) ( )   The signal coordination control method was studied based on the traffic flow path according to the real-time traffic flow data of the road network. Considering the discreteness of vehicle fleet, the concept of path coordination degree was proposed. The coordination main path was selected dynamically according to the path coordination degree and the flow disequilibrium coefficient. According to the traffic wave theory, the dissipation time of red light queuing was calculated. A two-node correlation model and a multi-node correlation model based on the coordinated path were established by comprehensively considering the path traffic volume, distance and queue length at red light. Finally, the simulation test was carried out. Compared with the road segment correlation model and Maxband model, the sensitivity of parameters was analyzed from three aspects, namely, path flow fluctuation, queue length and saturation. The results show that the proposed model can determine the coordination scheme according to the dynamic path traffic volume and can improve the operation index of road network accordingly. References | Related Articles | Metrics

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Probability of Drivers Missing Roadside Traffic Sign Information on the Inner Lane of Six-Lane Expressway YANG Shaowei1, 2, WU Jiyun2, PAN Binghong1, 2 2020, 39(09): 38-45.  DOI: 10.3969/j.issn.1674-0696.2020.09.06 Abstract ( )   PDF (613KB) ( )   When the driver of a small vehicle on the inner lane of the expressway discovered and read the roadside traffic sign information, due to the reasons such as the parallel of multiple vehicles, the drivers sight may be blocked by the large vehicle on the outer lane, which caused the driver to miss important traffic information. Therefore, the probability of the small vehicle drivers sight on the inner lane blocked by the large vehicle on the outer lane within the scope of traffic sign recognition was studied and the probability calculation model for the driver missing the roadside traffic sign information was established, which was based on the shortest time required for the driver to read traffic signs, the distribution of vehicle headway, the geometric relationship between the drivers sight and vehicles and lanes, and the principle of calculus. The proposed model was tested by VISSIM traffic simulation software. The results show that the change of the traffic volume of the small vehicles on the inner lane has less influence on the probability of the small vehicle driver missing the traffic sign information. The increase of the total number of large vehicles on the outer lane will increase the probability of the small vehicle driver on the inner lane missing the traffic sign information. When the speed of small vehicles on the inner lane is constant, the increase of the speed of large vehicles on the outer lane will reduce the probability of the small vehicle driver on the inner lane missing traffic signs. When the speed of large vehicles on the outer lane is constant, the probability of the driver of the small vehicle missing the traffic sign information increases as the speed of the small vehicle on the inner lane increases. In the case of the equal speed difference between the inner and outer lanes, the probability of small vehicle drivers missing traffic signs decreases with the increase of vehicle speed. References | Related Articles | Metrics

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Applicability of Revised SCQ-MD Scale in Airport Pilots LIU Lingli1, YU Meichen1, WANG Yue1, YUN Tianyu2 2020, 39(09): 46-46.  DOI: 10.3969/j.issn.1674-0696.2020.09.07 Abstract ( )   PDF (446KB) ( )   In order to assess the applicability of the SCQ-MD (Safety Climate Questionnaire, Modified for Drivers) scale in measuring the safety climate perception of airport drivers, the questionnaire survey and SPSS 22.0 statistical analysis method were used to study the statistical data of safety climate perception of airport drivers. The research results show that the correlation between the items and the total scores of the SCQ-MD scale has reached significant level, with good item discrimination. Six factors obtained by exploratory factor analysis accounts for 72.124% of the variance variation, which has good structural validity. There is a correlation between the four demographic variables of subjects and the perception of safety climate of airport drivers, which is consistent with previous research results and has good criterion validity. And the four demographic variables include age, driving age, regional distribution and working time in the airport of the tested. Cronbachα coefficient of the proposed SCQ-MD is 0.987, and the Cronbach α coefficient of each factor is greater than 0.9, indicating that the proposed scale has good reliability. The DBQ scale is introduced to empirically analyze the relationship between safety climate and drivers unsafe behavior, and finds that there is a significant negative correlation between the two. The SCQ-MD scale has good reliability and validity, and it is consistent with the previous research conclusions in the application analysis results, which indicates that the proposed scale is suitable for measuring the perception of the safe atmosphere of the airport drivers. References | Related Articles | Metrics

Bridge & Tunnel Engineering

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Threshold Setting and Application Based on Structural Response Characteristics of Small and Medium Span Beam Bridges WU Haijun1, YUAN Guangjie1,2, WANG Tao1,3,QU Haoran4, LI Mingshan2 2020, 39(09): 54-58.  DOI: 10.3969/j.issn.1674-0696.2020.09.08 Abstract ( )   PDF (1597KB) ( )   In view of the relatively few researches and practices on the safety monitoring of small and medium span bridges at home and abroad, the influence of the ratio of live load on the selection of bridge safety monitoring and evaluation methods was analyzed and selected accordingly, and the early warning threshold value based on the structure response characteristics of small and medium bridges was set. The formula of data validity coefficient for dynamic acquisition of small and medium bridges was derived. Taking Luojiaba Bridge as an example, its monitoring data was analyzed. The results show that the small and medium bridges should use the live load response monitoring value to evaluate the safety status during the operation period. According to the setting of the early warning threshold value based on the structure response characteristics of small and medium bridges, the influence of calibration coefficient and data validity coefficient should be considered on the basis of the finite element theoretical calculation value. The applied bridge γ=0.81, the strain index Z1=43 με, Z2=57 με, the deflection index Z1=6.32 mm, Z2=8.42 mm. According to accidental achievement of the first and second warning conditions of strain and deflection index, it is judged that the proposed bridge is in the first level (yellow) early warning state, and there is no safety problem. Therefore, it is necessary to pay attention to the overload vehicles crossing the bridge. References | Related Articles | Metrics

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Euler Beam Element Stiffness Matrix Considering Shear Deformation Based on Shape Function Derivation ZHANG Junfeng1, YIN Huina1, SUN Dayong2, LI Jie1, CHEN Huai1 2020, 39(09): 59-66.  DOI: 10.3969/j.issn.1674-0696.2020.09.09 Abstract ( )   PDF (527KB) ( )   The proposed study was initiated to make clear the derivation process of stiffness matrix of the equal cross-section Euler beam element considering shear deformation. The derivation process of the stiffness matrix of the Euler beam element with shear deformation was systematically given, and the comparison study on stiffness matrix of Beam4 element in ANSYS was carried out on the basis of the shape function, according to the principle of virtual work. The results show that the Beam4 element in ANSYS is a Euler beam element which can take into account the shear deformation. Through the application comparison with Beam188 element, it is clear that its applicability is consistent with Beam188 element, that is, the slenderness ratio should meet the recommended value of ANSYS GAL2/EI>30. References | Related Articles | Metrics

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Three-Dimension Simulation Mechanical Analysis of Deck Pavement of Long-Span and Low-Stiffness Steel Bridge WANG Tao1,2, XU Gongyi3, CHANG Cheng1,2, XIAO Li1,2, WANG Min1,2 2020, 39(09): 67-73.  DOI: 10.3969/j.issn.1674-0696.2020.09.10 Abstract ( )   PDF (3031KB) ( )   In order to study the mechanical response of long-span and low-stiffness steel bridge with different pavement schemes, Midas/civil software was used to establish the finite element model of a certain Yangtze River Bridge in Wuhan, and ANSYS software was used to establish the three-dimensional simulation model of GA+SMA and tri-layer EA pavement scheme. Then, flexural deformation of the main span of the proposed bridge was analyzed, and flexural-tensile strain and interlaminar shear stress of the two pavement schemes under 162 load conditions were calculated. The research results show that: with the increase of heavy traffic volume, there is a large deflection in the mid-span of the bridge, and the maximum deflection reaches 1.02m, which is 132.5% of the initial design value. Under the most adverse load combination, the stiffness of pavement system has a significant impact on the flexural-tensile strain and interlaminar shear stress of the composite structure. In general, the greater the stiffness of pavement system, the greater the longitudinal maximum flexural-tensile strain, and the smaller the transverse maximum flexural-tensile strain and the interlaminar maximum shear stress. The transverse maximum flexural-tensile strain and longitudinal maximum flexural-tensile strain of pavement surface, interlayer and roof surface of the two pavement schemes show a decreasing trend. In addition, the transverse maximum flexural strain is greater than the longitudinal maximum flexural strain of pavement surface. The interlaminar shear stress of interlayer and steel deck surface of the two pavement schemes show a decreasing trend. The transverse maximum flexural-tensile strain of pavement surface and shear strength of waterproof layer should be taken as control indexes, and the fatigue cracking test and shear fatigue test of composite structure should be carried out to determine the adaptability of different pavement schemes and the requirements of material and composite structure indexes, in the design of fatigue cracking and interlaminar delamination displacement index of composite structure for long-span and low-stiffness steel bridge. References | Related Articles | Metrics

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Application of BIM Construction Integrated Management Platform in Tunnel Engineering WANG Chao1, ZHOU Leisheng2，XU Run1, SONG Jie1 2020, 39(09): 74-79.  DOI: 10.3969/j.issn.1674-0696.2020.09.11 Abstract ( )   PDF (10760KB) ( )   In order to achieve more efficient management in the field of tunnel construction, a comprehensive management platform for tunnel construction was developed based on BIM automation modeling technology and combined with GIS and IOT. Moreover, the proposed platform was successively applied in the project management of Jing-Hu Qinglonggu Tunnel. The proposed platform has realized seven functional modules: lightweight integrated model browsing and construction information query, multi-party collaborative management of construction progress, quality and safety, 4D tunnel construction simulation, personnel and equipment positioning and video monitoring, dynamic risk assessment of tunnel construction, monitoring measurement and advanced geological prediction as well as BIM comprehensive management decision-making board. The proposed platform has realized the platform, informatization, specialization and security of tunnel project management, and has provided a solid foundation for promoting the rapid development of BIM technology in tunnel project management. References | Related Articles | Metrics

Highway & Railway Engineering

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Freeway Asphalt Pavement Performance Based on Fuzzy Interval Evaluation Method LI Hailian1,2, LIN Mengkai1,2, WANG Qicai1,2 2020, 39(09): 80-87.  DOI: 10.3969/j.issn.1674-0696.2020.09.12 Abstract ( )   PDF (478KB) ( )   In view of the problem that the evaluation results of expressway asphalt pavement performance were too broad and it was difficult to effectively predict the development trend of pavement performance, the highway asphalt pavement performance evaluation model based on fuzzy interval number theory was established and studied, which adopted the evaluation theory of interval number, fuzzy analysis and rough set incomplete system, combined with the characteristics of asphalt pavement evaluation index system such as structure performance, functional performance, rutting performance and safety performance evaluation index system and the evaluation of the five grades. The interval number was used to scale the weight of each evaluation index and its evaluation results. The effectiveness of the proposed model and the reliability of the evaluation results were verified by a case study. The results show that the proposed evaluation method can not only objectively and effectively evaluate the performance of expressway asphalt pavement, but also make a second-order bias evaluation of its evolution trend. The evaluation results provide reliable basic data for the prediction and maintenance decision of asphalt pavement performance. References | Related Articles | Metrics

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Durability of Hybrid Fiber Modified Asphalt Mixture under Salt Freeze-Thaw Cycles ZHANG Hang1, 2, LING Tianqing1, WANG Xuewu2 2020, 39(09): 88-96.  DOI: 10.3969/j.issn.1674-0696.2020.09.13 Abstract ( )   PDF (1506KB) ( )   Through simulating the salt freeze-thaw cycle conditions, OT test and four point bending fatigue test were used to analyze the influence of different composite fibers on the durability of asphalt mixture with load loss rate and fatigue life times. And the correlation among load loss rate, fatigue life and cumulative dissipation energy was studied. The results show that: with the increase of salt freeze-thaw cycles, the load loss rate of five kinds of asphalt mixtures improves gradually, while the fatigue life and cumulative dissipation energy shows a downward trend. Compared with SBS modified asphalt mixtures, the load loss rate of composite fiber C modified asphalt mixtures decreases significantly after salt freeze-thaw cycles, and the fatigue life and cumulative dissipation energy increases significantly, while the durability of composite fiber B and SBS modified asphalt mixture is almost the same. Under different salt freezing and thawing cycles, the load loss rate of four kinds of modified asphalt mixture is linearly correlated with fatigue life and cumulative dissipation energy, and the correlation coefficients are all greater than 0.9. Therefore, both OT test and four-point bending fatigue test can effectively evaluate the durability of asphalt mixture before and after salt freeze-thaw cycles. References | Related Articles | Metrics

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Influence Factors of RAP Content in Plant-Mixed Hot Recycling Asphalt Pavement MA Hui1, MAO Quan1, LI Ning2 2020, 39(09): 97-104.  DOI: 10.3969/j.issn.1674-0696.2020.09.14 Abstract ( )   PDF (1077KB) ( )   Aiming at the problem of low content of RAP in application of plant-mixed hot recycling asphalt pavement, the influence factors of RAP content were analyzed theoretically and experimentally by taking SMA-13 RAP material as the research object, which had been in service for 11 years in Huaian Bridge of Jiangsu Suhuai-Yancheng expressway. The analysis results show that the RAP content is affected comprehensively by four factors: the recovery of old asphalt performance, the adjustability of RAP aggregate gradation, the quality control of RAP aggregate gradation and asphalt aggregate ratio as well as the heating temperature of new aggregate. In practical engineering, the content of RAP material can be increased by adding regenerant, reducing the proportion of fine material in RAP material, controlling the deviation of the asphalt-aggregate ratio of RAP material and trying to reduce the heating temperature of new aggregate, so as to improve the economic and social benefits of plant-mixed hot recycling technology. References | Related Articles | Metrics

Port & Waterway · Hydraulic & Hydroelectric · Resources & Environment

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Technical Status Evaluation of Regulation Buildings in Upper Reaches of Yangtze River Channel Based on Fuzzy Bayesian Network LI Wenjie1，ZHANG Haoyou1，ZHANG Wen2，YANG Shengfa1，HU Jiang3 2020, 39(09): 112-118.  DOI: 10.3969/j.issn.1674-0696.2020.09.16 Abstract ( )   PDF (764KB) ( )   Aiming at the characteristics of the regulation buildings in the upper reaches of the Yangtze River, taking the functioning status and structural status of the buildings as the research point, a building evaluation index system containing four levels of “objective-criteria-element-indicator” was proposed. Based on Bayesian network method and fuzzy mathematics theory, the evaluation model of waterway regulation building technical condition was established, the 4-level evaluation standard such asⅠ, Ⅱ, Ⅲ and Ⅳlevel was determined. The specific technical condition value of the building was quantified by mathematical expectation formula. Taking the Dongxikou cross dam in the upper reaches of the Yangtze River as an example, the technical status in 2016, 2017 and 2018 were verified and evaluated. The results show that in 2016, 2017 and 2018, the technical status of Dongxikou cross dam in the upper reaches of the Yangtze river is classified as gradeⅠ,Ⅱand Ⅱ level respectively, and the results are consistent with those of the specification; the quantitative technical status values are 83.75, 75.25 and 70.25 respectively, which are consistent with the engineering practice. Related Articles | Metrics

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Experimental Study on Soil Slope Supported by Short Anti-sliding Piles ZENG Hongyan1,2, LIU Wei1,2, ZHOU Cheng1,2, HAN Libiao1,2, TAN Changming3 2020, 39(09): 119-126.  DOI: 10.3969/j.issn.1674-0696.2020.09.17 Abstract ( )   PDF (12033KB) ( )   In order to explore the supporting effect of short anti-sliding piles with different lengths on slope soil, the model test of tractive landslide under natural condition was carried out. The non-cohesive soil slope was reinforced by single row anti-sliding short piles. The length of short anti-sliding piles L equals 0 (no short anti-sliding piles), 18, 28 and 43 cm respectively. Based on the analysis of the displacement characteristics of the model sidewall observation soil strips and small blocks in the slope soil and the distribution law of the slope soil slip surface, the support mechanism of the short anti-sliding piles with different pile length on the soil slope was studied. The results show that the short anti-sliding piles can effectively reinforce deep soil. With the increase of the length of short anti-sliding piles, the thickness of the reinforced soil gradually increases, and the slip surface gradually rises. When the length of the short anti-sliding pile reaches a certain value, the rising rate of the slip surface begins to decrease. In practical engineering, it is suggested that anti-sliding short piles and toe retaining wall should be used together to reinforce deep soil and shallow slope soil, so as to ensure the stability and safety of the whole slope. References | Related Articles | Metrics

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Performance of Alternate Vacuum Saturation and Drying Cycles of Sandstone Based on Electrical Resistivity Test HE Ye1,2, ZHAO Mingjie1, WANG Kui1, JI Yuehui1 2020, 39(09): 127-131.  DOI: 10.3969/j.issn.1674-0696.2020.09.18 Abstract ( )   PDF (3373KB) ( )   Considering the characteristics of periodic changes of water level, the test study on typical sandstone in the Three Gorges reservoir area was carried out. Firstly, six groups of sandstone specimens were subjected to alternate vacuum saturation and drying cycling, when the vacuum saturation and drying cycles n was 0 (natural state), 1, 3, 5, 9 and 13 respectively. Secondly, the electrical resistivity test was carried out on each group of saturated or dry sandstone specimens, and the saturated specimens were subjected to physical and mechanical tests. The variation rule of saturation electrical resistivity Res and drying electrical resistivity Red of sandstone specimens changing with the vacuum saturation and drying cycles n was analyzed. The correlation among Res, porosity P, saturated water content ws, uniaxial compressive strength σc, elastic modulus E and n were studied. Finally, combined with the SEM results of saturated sandstone specimens, the correlation between electrical resistivity and physical, mechanical performance indexes, as well as microscopic characteristics was analyzed. The results show that: after one time of water saturation of sandstone specimens at natural state, the saturated electrical resistivity Res decreases by 81.6%, and Res increases with the increase of n, and the growth trend is relatively stable. When n increases from 5 to 9, the dry electrical resistivity Red increases a leaping manner, and when n is in the range from 5 to 9, cracks in the sandstone specimens can be found from the SEM images. Compared with Res, Red changes more greatly. When n equals 5, Res, P, ws, σc, and E of sandstone specimens all have characteristic points. Moreover, the variation rule of Res, P, and ws changing with n are basically the same, which indicates that Res can be used as an effective index for analyzing the macro-micro characteristics of alternate vacuum saturation and drying cycle sandstone. References | Related Articles | Metrics

Vehicle &Electromechanical Engineering

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Rollover Tendency of Minibus Single-Parameter LI Shengqin, FENG Xinyuan 2020, 39(09): 132-139.  DOI: 10.3969/j.issn.1674-0696.2020.09.19 Abstract ( )   PDF (1411KB) ( )   Taking a minibus as a reference prototype and the suspension of the whole vehicle as the research object, a 9-DOF vehicle simulation model was established. On this basis, the rollover stability of the vehicle during turning was studied. Under certain road excitation, the influence of vehicle structure and operation parameters such as suspension vertical stiffness, suspension damping, tire radial stiffness, running speed, sprung mass and centroid height on rollover tendency of minibus were analyzed by step steering test. Orthogonal test was used to analyze the influence of each parameter on vehicle rollover tendency, and the optimal scheme was found out. The optimal scheme was verified by fishhook simulation test and J-turn test. The results show that the vehicle centroid height has the most obvious effect on rollover tendency, while the suspension damping has the least effect; under the optimal scheme, the vehicle can maintains good rollover stability. References | Related Articles | Metrics

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Vibration Reduction Characteristics of Ship Engine Based on Phononic Crystal ZHANG Jie1,2, DENG Yu1,2, PENG Zhongbo1, SHI Liyong1 2020, 39(09): 140-145.  DOI: 10.3969/j.issn.1674-0696.2020.09.20 Abstract ( )   PDF (6363KB) ( )   Phononic crystals have broad application prospects in vibration and noise reduction, such as the introduction of the concept of phononic crystals into our daily research on vehicle vibration reduction. A phononic crystal plate based on local resonance theory was designed for the vibration and noise problems of the ship. The structure was composed of a plurality of composite cylinders periodically arranged in the matrix. Through COMSOL finite element software analysis, the band gap characteristics, vibration transmission loss, and sound insulation effects were calculated. Finally, the designed phononic crystal plate was subjected to vibration experiment to analyze its actual vibration damping effect and compared with the epoxy resin substrate. The resesearch shows that: in the range of complete band gap, the vibration transmission has obvious loss, and the sound insulation is also significantly better than the substrate. Through the vibration experiment analysis, the attenuation effect of the phononic crystal plate on the low frequency excitation is also better than that of the substrate, and the overall comparative analysis has a 5~10 unit attenuation effect compared with the substrate. References | Related Articles | Metrics

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Static-Dynamic Multi-objective Topology Optimization of Industrial Robot Arm HU Qiguo, HU Yanmin 2020, 39(09): 146-152.  DOI: 10.3969/j.issn.1674-0696.2020.09.21 Abstract ( )   PDF (2165KB) ( )   In order to balance the requirements of the industrial robot arm with higher static-dynamic strength and lighter weight, static-dynamic multi-objective topology optimization was carried out. Taking the RB08 industrial robot big arm as the research object, based on SIMP variable density method topological optimization, the multi-level tolerance sequence planning method was combined with the comprehensive programming method, and the multi-level optimization objectives were processed in different levels. The optimization structure of the big arm with the highest dynamic low-order frequency and the minimum flexibility under static multi-operating conditions was obtained. According to the optimization results, the big arm was improved. Through analysis and comparison, it can be seen that the mass of the optimized big arm is reduced by 11.9%, the dynamic low-order natural frequency and the static stiffness of each working condition are improved to varying degrees. References | Related Articles | Metrics