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Comparative analysis between single-train passing and double-train intersection in a tunnel

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第5期25卷 429-442页

作者： Jianming DU Qian FANG Xuan ZHANG Hualao WANG Bridge and Tunnel research Center Research Institute of Highway Ministry of TransportBeijing 100088China Tunnel and Underground Engineering research Center of ministry of Education Beijing Jiaotong UniversityBeijing 00044China

Aerodynamic pressure significantly impacts the scientific evaluation of tunnel service *** aerodynamic pressure of two trains running in a double-track tunnel is considerably more complicated than that of a single *** used the numerical method to investigate the difference in aerodynamic pressure between a single train and two trains running in a double-track ***,the numerical method was verified by comparing the results of numerical simulation and on-site ***,the characteristics of aerodynamic pressure were ***,the influence of various train-tunnel factors on the characteristics of aerodynamic pressure was *** results show that the aerodynamic pressure variation can be divided into stage I:irregular pressure fluctuations before the train tail leaves the tunnel exit,and stage II:periodic pressure declines after the train tail leaves the tunnel *** addition,the aerodynamic pressure simultaneously jumps positively or drops negatively for a single train or two trains running in double-track tunnel *** pressure amplitude in the two-train case is higher than that for a single *** maximum positive peak pressure difference(P_(STP))and maximum negative peak pressure difference(P_(STN))increase as train speed rises to the power from 2.256 to 2.930 in stage *** P_(STP) and P_(STN) first increase and then decrease with the increase of tunnel length in stage *** P_(STP) and P_(STN) increase as the blockage ratio rises to the power from 2.032 to 2.798 in stages I and II.

关键词： Railway tunnel Aerodynamic effect Pressure characteristic Train speed Tunnel length Blockage ratio

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Effects of Atmospheric Pressure on Developmental Characteristics and the Stability of Air Entraining Agent for Concrete

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Journal of Wuhan University of Technology(Materials Science) 2024年第4期39卷 979-989页

作者：李立辉牛开民 TIAN Bo CHEN Xin FU Ziqian ZHU Xuwei School of Civil Engineering Chongqing Jiaotong UniversityChongqing 400074China transportation Science and Engineering Harbin Institute of TechnologyHarbin 150090China research institute of highway Ministry of TransportBeijing 100088China

In order to ascertain the effects of atmospheric pressure on developmental characteristics and the stability of AEA(air-entraining agent)solution bubbles,AEA solution experiments and AEA solution bubble experiments were,respectively,conducted in Peking(50 m,101.2 kPa)and Lhasa(3,650 m,63.1 kPa).Surface tensions and inflection-point concentrations were tested based on AEA solutions,whilst developmental characteristics,thicknesses and elastic coefficients of liquid films were tested based on air bubbles of AEA *** study involved three types of AEAs,which were TM-O,226A,and *** experimental results show that initial sizes of TM-O,226A,and 226S are,respectively,increased by 43.5%,17.5%,and 3.8%.With the decrease of ambient pressure,the drainage rate and the drainage index of AEA solution bubbles *** experiments show that the liquid film thicknesses of all tested AEA solution bubbles are in micron *** the atmospheric pressure decreases from 101.2 to 63.1 kPa,the liquid film thicknesses of three types of AEA solutions decrease in various degrees;and film elasticities at critical thicknesses *** film of 226S solution bubbles is the most stable,presenting as a minimum thickness *** should be noted that elastic coefficient of liquid film only represents the level at critical thickness,thus it can not be applied as the only evaluating indicator of bubble *** a type of AEA,factors affecting the stability of its bubbles under low atmospheric pressure include initial bubbles size,liquid film thickness,liquid film elasticity,ambient temperature,etc.

关键词： air-entraining agent surface tension bubble size liquid film thickness liquid film elasticity atmospheric pressure

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A Combination Prediction Model for Short Term Travel Demand of Urban Taxi

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Computers, Materials & Continua 2024年第6期79卷 3877-3896页

作者： Mingyuan Li Yuanli Gu Qingqiao Geng Hongru Yu School of Traffic and transportation Beijing Jiaotong UniversityBeijing100044China transport Planning and research institute Ministry of TransportBeijing100028China

This study proposes a prediction model considering external weather and holiday factors to address the issue of accurately predicting urban taxi travel demand caused by complex data and numerous influencing *** model integrates the Complete Ensemble Empirical Mode Decomposition with Adaptive Noise(CEEMDAN)and Convolutional Long Short Term Memory Neural Network(ConvLSTM)to predict short-term taxi travel *** CEEMDAN decomposition method effectively decomposes time series data into a set of modal components,capturing sequence characteristics at different time scales and *** on the sample entropy value of components,secondary processing of more complex sequence components after decomposition is employed to reduce the cumulative prediction error of component sequences and improve prediction *** this basis,considering the correlation between the spatiotemporal trends of short-term taxi traffic,a ConvLSTM neural network model with Long Short Term Memory(LSTM)time series processing ability and Convolutional Neural Networks(CNN)spatial feature processing ability is constructed to predict the travel demand for urban *** combined prediction model is tested on a taxi travel demand dataset in a certain area of *** results show that the CEEMDAN-ConvLSTM prediction model outperforms the LSTM,Autoregressive Integrated Moving Average model(ARIMA),CNN,and ConvLSTM benchmark models in terms of Symmetric Mean Absolute Percentage Error(SMAPE),Root Mean Square Error(RMSE),Mean Absolute Error(MAE),and R2 ***,the SMAPE metric exhibits a remarkable decline of 21.03%with the utilization of our proposed *** results confirm that our study provides a highly accurate and valid model for taxi travel demand forecasting.

关键词： Urban transport taxi travel demand prediction CEEMDAN-ConvLSTM modal components

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Contribution of Surface Waves to Sea Surface Temperatures in the Arctic Ocean

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Journal of Ocean University of China 2024年第5期23卷 1151-1162页

作者： WEI Meng SHAO Weizeng SHEN Wei HU Yuyi ZHANG Yu ZUO Juncheng College of Oceanography and Ecological Science Shanghai Ocean University China Waterborne transport research institute Ministry of Transport of the People's Republic of China

The aim of our study was to examine the contribution of surface waves from WAVEWATCH-III(WW3) to the variation in sea surface temperature(SST) in the Arctic Ocean. The simulated significant wave height(SWH) were validated against the products from Haiyang-2B(HY-2B) in 2021, obtaining a root mean squared error(RMSE) of 0.45 with a correlation of 0.96 and scatter index of 0.18. The wave-induced effects, i.e., wave breaking and mixing induced by nonbearing waves resulting in changes in radiation stress and Stokes drift, were calculated from WW3, ERA-5 wind, SST, and salinity data from the National Centers for Environmental Prediction and were taken as forcing fields in the Stony Brook Parallel Ocean Model. The results showed that an RMSE of 0.81℃ with wave-induced effects was less than the RMSE of 1.11℃ achieved without the wave term compared with the simulated SST with the measurements from Argos. Considering the four wave effects and sea ice freezing, the SST in the Arctic Ocean decreased by up to 1℃ in winter. Regression analysis revealed that the SWH was linear in SST(values without subtraction of waves) in summer and autumn, but this behavior was not observed in spring or winter due to the presence of sea ice. The interannual variation also presented a negative relationship between the difference in SST and SWH.

关键词： Arctic Ocean sea surface temperature sea surface wave

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Small-scale fire tests in the underwater tunnel section model with new sidewall smoke extraction

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Deep Underground Science and Engineering 2024年第2期3卷 247-254页

作者： Shunyu Yue Ruifeng Miao Huihang Cheng Maohua Zhong Xiujun Yang Department of Engineering Physics Institute of Public Safety ResearchTsinghua UniversityBeijingChina Shanxi Province Expressway Group Limited Liability Company Shanxi Expressway Group Shuoshen Co. LtdShuozhouChina research institute of highway ministry of transport RIOH Transport ConsultantsLtdBeijingChina

The Shenzhen–Zhongshan Bridge is a 24‐km‐long bridge and tunnel system,including a 6.8-km-long super cross section subsea *** solve the smoke exhaust problem of a super large cross-section subsea tunnel,the tunnel has a new smoke exhaust system that combines a horizontal smoke exhaust cross section at the top and sidewall smoke exhaust *** order to evaluate the potential fire hazards of this type of tunnel,a 1:30 tunnel model was established and 140 smallscale experiments on underwater tunnel fires were *** changing the fire power,fire location,and fan operation mode,different scenarios of submarine immersed tunnel fire were simulated and the related key parameters such as fire smoke diffusion behavior and smoke temperature distribution were *** this basis,the optimal smoke control strategy was proposed for different fire *** research results indicate that the new smoke exhaust system can fully utilize the smoke flow characteristics,significantly improve smoke exhaust efficiency,and increase available evacuation time,thus further enhancing the fire safety of super large cross-section subsea tunnels.

关键词： sidewall smoke extraction system small‐scale fire tests smoke control

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Study on Spray and Combustion Characteristics of F-T Diesel Blending Oxygenated Fuel Based on Constant Volume Combustion Chamber

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Journal of Traffic and transportation Engineering(English Edition) 2024年

作者： Limin Geng Yang Zhao Fujia Liu Shiyu Shan Nan Gao Zhao Liu Hao Chen Shaanxi Key Laboratory of New transportation Energy and Automotive Energy Saving， Chang'an University research institute of highway ministry of transport

In this work， 20% of PODE and n-butanol are blended with F-T diesel by volume， respectively，referred to as FFP20 and FBU20. Based on the constant volume combustion chamber (CVCC)， the spray characteristics and combustion characteristics of diesel， F-T diesel， FP20 and FBU20 under high ambient temperature and pressure are studied by using high-speed photography combined with MATLAB image processing technology. Results show that the steady-state liquid spray tip penetration and spray projection area of FP20 and FBU20 are smaller than those of F-T diesel due to their good evaporation. Combustion characteristics studies show that compared to D100， the ignition delay and flame lift-off length of FT100 decrease by 22.9% and 43.6%， respectively. Compared to FT100， the flame lift-off length of FP20 and FBU20 increases by 36.8% and 44.1%， respectively. Due to the addition of high cetane number and high oxygen content PODE， the ignition delay of FP20 is shortened by 3.7%， and the ignition delay of FBU20 is prolonged by 40.1% due to the effect of high latent heat of vaporization and low cetane number of n-butanol. Compared to D100， the peak flame area of FT100 increases by 8.5%， while the peak flame luminosity decreases by 18.2%. Because PODE and n-butanol can improve evaporation and increase the oxygen content of fuel and then reduce the formation of soot， compared to FT100， the peak of flame area and flame luminosity of FP20 and FBU20 are decreased. The results of two-color method show that after adding PODE and n-butanol into F-T diesel fuel， the generation of soot and combustion temperature of the mixed fuel are reduced. Moreover， FP20 has higher oxygen content and better atomization characteristics， so the effect of reducing soot is better than that of FBU20.

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Analysis of Sea Surface Temperature Cooling in Typhoon Events Passing the Kuroshio Current

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Journal of Ocean University of China 2024年第2期23卷 287-303页

作者： HU Yuyi SHAO Weizeng SHEN Wei ZUO Juncheng JIANG Tao HU Song College of Marine Sciences Shanghai Ocean UniversityShanghai 201306China East China Sea Environment Monitoring Ministry of Natural ResourcesShanghai 201206China China Waterborne transport research institute Ministry of TransportBeijing 100088China

The aim of this study is to investigate the sea surface temperature(SST) cooling as typhoons pass the Kuroshio Current.A numerical circulation model,denoted as the Stony Brook Parallel Ocean Model(sbPOM),was used to simulate the SST,which includes four wave-induced effect terms(i.e.,radiation stress,nonbreaking waves,Stokes drift,and breaking waves) simulated using the third-generation wave model,called WAVEWATCH-Ⅲ(WW3).The significant wave height(SWH) measurements from the Jason-2 altimeter were used to validate the WW3-simulated results,yielding a root mean square error(RMSE) of less than 0.50 m and a correlation coefficient(COR) of approximately *** water temperature measured from the Advanced research and Global Observation Satellite was applied to validate the model ***,the RMSE of the SST is 0.92℃ with a COR of approximately *** revealed in the sbPOM-simulated SST fields,a reduction in the SST at the Kuroshio Current region was observed as a typhoon passed,although the water temperature of the Kuroshio Current is relatively *** variation of the SST is consistent with that of the current,whereas the maximum SST lagged behind the occurrence of the peak ***,the Stokes drift plays an important role in the SST cooling after analyzing four wave-induced terms in the background of the Kuroshio *** sensitivity experiment also showed that the accuracy of the water temperature was significantly reduced when including breaking waves,which play a negative role in the inside part of the *** variation in the mean mixing layer depth(MLD) showed that a typhoon could enhance the mean MLD in the Kuroshio Current area in September and October,whereas a typhoon has little influence on the mean MLD in the Kuroshio Current area in ***,the mean MLD rapidly decreased with the weakening of the strong wind force and wave-induced effects when a typhoon crossed the Kuroshio Current.

关键词： typhoon wave sea surface temperature Kuroshio Current

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An Intelligent Bridge Multi-Dimension Deflection IoT Monitoring System Based on Laser Datum and Imaging

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Journal of Traffic and transportation Engineering(English Edition) 2024年

作者： Dan Zhao Huifeng Wang Hao Du Haoyi Cheng Lu Peng Yaru Liang He Huang Yunmeng Li School of Electronic &Control Engineering， Chang'an University research institute of highway ministry of transport State Key Laboratory of Traction Power， Southwest Jiaotong University

Aiming at the all-weather automatic monitoring of bridge structure health monitoring， an embedded bridge multi-dimensional (horizontal and vertical) deflection monitoring system based on dual laser references is proposed. The controller turns on the laser reference transmitter through instructions to emit the laser reference. The intelligent target system located in the middle of the span will calculate the multi-dimensional deflection and deformation information of the bridge structure according to the laser spot projected on the diffuse optical target， and pass this information through the wireless network communication unit transmits to the cloud platform to realize real-time monitoring of the bridge structure status and other parameters. Through the laboratory platform， it is found that the measurement error of this method is less than 300 μm， and the data update rate is less than 66 ms， which meets the requirements of bridge structural health monitoring. This method solves the problem of low efficiency of artificial bridge deflection monitoring， realizes all-weather online real-time monitoring of bridge deflection detection， and ensures the accuracy and efficiency of the measurement system.

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Developing a multi-method approach to identifying e-scooter hazard hotspots

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Journal of Traffic and transportation Engineering(English Edition) 2024年第4期11卷 667-680页

作者： Michael Hardinghaus Simon Nieland Rebekka Oostendorp Jan Weschke German Aerospace Center (DLR) institute of transport research

In recent years, e-scooters have been introduced in many European cities. In several places we have witnessed a rapid uptake of this new mode of transport mainly as a result of public sharing schemes. A number of incidents, injuries and even fatalities have given rise to questions regarding the safety of these vehicles. These questions are being researched mainly using official crash data and data specifying injuries and hospital treatment. Until now, the research has focused on investigating typical injury patterns and estimating risk levels. Very little is known about exactly where conflicts and crashes occur. Knowledge of hazard hotspots is crucial when investigating risk levels and improving safety for all road ***, this paper develops an approach to investigating locations with potentially dangerous interactions within the active mobility system in the city of Berlin. The approach consists of explorative expert interviews, an online poll, and quantitative analyses. For the latter we combine three datasets. First, we research crash hotspots using official data. Second, we use data based on acceleration sensors from cyclists' smartphones to find locations of sudden movements. Third, we use trip data from the operators of escooter sharing systems. The information gathered is used in a conclusive expert workshop to identify hazard *** show that many of the conflicts with pedestrians are caused by parked escooters. Second, e-scooter trips are concentrated in the inner city and along specific routes. In moving traffic, various data sources are used to identify hotspots at intersections and in areas between *** present research lays the foundation for important further studies to investigate interactions at hotspots in detail by determining nine specific locations in the city of Berlin.

关键词： E-scooter Accidents Crashes Active mobility Micromobility Road safety

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Determination of riding comfort on cycleways using a smartphone application

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Journal of Traffic and transportation Engineering(English Edition) 2024年第4期11卷 747-760页

作者： Anna Niska Leif Sj?gren Peter Andrén Christian Weber Tineke de Jong Aslak Fyhri Department of Infrastructure Maintenance Swedish National Road and Transport Research Institute (VTI) Department of Safety and Behavior Institute of Transport Economics

Well maintained cycleways will encourage more people to cycle, as the condition of cycleways is important for the safety, accessibility and riding comfort of cyclists. Despite that, only a few models used to describe the quality of service for cyclists take the surface condition into account. Objective measuring methods are needed to enable reliable and effective assessment of surface conditions, and measurable performance criteria related to the needs of cyclists should be developed. The purpose of this study has been to test the reliability and validity of using accelerometers in smartphones to assess the riding comfort on cycleways. A smartphone application converting three-dimensional accelerometer measurements into a single indicator for cycleways has been used to assess road surfaces in two field studies, in Sweden and Norway, respectively. Both studies assessed test sections of varying quality. To relate the measurements to subjective riding comfort assessments by cyclists, recruited cyclists collected quantitative data using the app, whilst also rating their perceived riding comfort by completing a survey. Measurements were also related to standard road surface condition indicators, generated from a road surface tester equipped with 19 laser sensors: international roughness index(IRI), mega-and macrotexture. The results show that it is possible to describe the unevenness of a cycleway using the technology present in smartphones. A software application can be used to collect and analyse data from the acceleration sensors in the phone, which can then be used to describe the riding comfort of cyclists. It is mainly the unevenness in the 50-1000 mm sizerange that create the greatest discomfort for cyclists, and intermittent vibrations are perceived as more uncomfortable than more evenly distributed vibrations. Therefore, IRI is not a relevant measurement for describing the riding comfort of cyclists.

关键词： Cyclist Comfort Assessment Road surface measurement Smartphone application

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