摘要：
This study systematically introduces a floating slab track (FST) with rubber vibration isolator (RVI) and investigates its behavior in urban rail transit. The FEM is used for modal analysis to clarify the modal parameters of the FST system. A vehicle–slab track coupling sub-model and a tunnel–soil coupling sub-model were established and the propagation law was analyzed by calculating the vertical vibration accelerations beneath the shield wall as well as the vertical vibratory acceleration levels of the surrounding soil. A wheel-set drop test was carried out to verify the actual vibration isolation effect compared with the numerical models. The results reveal that the vibratory acceleration levels at the distance of 20 m from the tunnel center-line basically meet the requirements for vibration in most areas of a city. The variation trend of the vibratory acceleration level measured in laboratory tests agrees well with the calculated values from the numerical simulation. The attenuation amplitude of the levels reaches 19.33 dB with the German high disturbance irregularity and 20.05 dB with the short-wave irregularity in the simulation, and the levels are reduced by 45–58 dB in laboratory tests which demonstrate the FST with RVI performs well in vibration isolation.
摘要：
Particle breakage alters particle size, shape, surface roughness, and co-ordination number, which in turn changes macro-mechanical behaviour including compressibility and shear strength. This study conducted a series of one-dimensional (1D) compression tests on quartz sands with different initial void ratios, ending the tests at various stress levels up to 13.5 MPa. The size and shape of particles were quantified using a dynamic particle shape analyser, while the surface roughness of thirty randomly selected particles for each sample was measured by an optical interferometer and quantified using flattened root-mean-square roughness (RMSf). The results demonstrate that a unique normal compression line is defined due to extensive particle breakage, with denser sample exhibiting a higher yield stress. Prior to yielding (vertical stress < 6 MPa), the changes in the three shape descriptors are limited, as the primary particle damage modes are abrasion and grinding. Conversely, at high stress level, a greater number of particles undergo splitting or explosive damage, leading to the creation of more irregularly shaped particles. The occurrence of plastic deformation at particle asperities under one-dimensional compression is identified, resulting in a decrease in surface roughness. This study highlights the significant role of the initial void ratio in shaping the evolution of surface roughness of particles under 1D compression.
摘要：
The accuracy and reliability of hydrodynamic models are sensitive to both hydraulic state variables and model parameters, particularly the bed roughness, while their simultaneous real-time corrections and corresponding effects still need to be well-established and understood. This paper presents a real-time data assimilation model that corrects channel-bed roughness and water level in a river network hydrodynamic model, ensuring its accuracy and reliability. Experiments and parameter analysis evaluated the effect of initial roughness and observation noise level on model performance. Correcting both roughness and water level improved filtering time and forecasting accuracy by up to 63% and 80%, respectively, compared to methods only correcting water level. The filtering time was reduced by 44-63%, and the water level forecasting RMSE decreased by up to 80%. Both models experienced increased filtering time and forecasting error as observation noise increased, but the proposed model had a lower increase. With accurate hydraulic state measurement (e.g., 0.005m error), the model achieved negligible water level forecasting error after 7h of data assimilation. The model's accuracy depended on the initial channel-bed roughness, and the algorithm enables real-time roughness correction, making it useful for flood forecasting.
关键词：
Red clay;Crack resistance;Lignocellulose;Guar gum;Shear strength;Tensile strength
摘要：
Desiccation cracking is a common problem of red clay under wet and dry conditions. The presence of cracks could reduce soil strength properties, which is the major reason for shallow failure of red clay slopes. This study aims to propose some additives to improve the crack resistance as well as the strength of red clay. To this end, three natural fibers and three natural gels were primarily selected to modify red clay. Desiccation crack tests were conducted to identify the best fiber and gel in terms of crack resistance. Then, direct shear tests and uniaxial tensile tests were performed on the soil specimens modified by the best fiber and gel to determine the optimal dosages regarding strength improvements. The results demonstrated that natural gels reduced the crack resistance of red clay, while natural fibers could enhance the crack resistance. Lignocellulose was the best additive in improving the crack resistance of red clay, and the modified effect was positively correlated with the fiber dosage. Adding 1.5% lignocellulose into red clay could reduce the crack rate from 2.19% to 0.30%, with a reduction of 0.86 times. The tensile strength, shear strength and its parameters of lignocellulose-modified red clay showed a trend of increasing first and then decreasing with increasing lignocellulose dosage. At the optimal lignocellulose dosage of 0.75%, the shear strength and tensile strength were increased by 44.63% and 18.21%, respectively. The strength of red clay modified by both lignocellulose and guar gum was positively correlated with the dosage of guar gum, and the desirable dosage of guar gum was 1.0%. In engineering practice, the wet red clay mixed with 0.75% lignocellulose and grass seeds can be employed as planting soil and is sprayed uniformly onto the slope surface after excavation using a spraying planting machine. To further improve the strength of the planting soil, 1.0% guar gum solution can be sprayed on the soil surface. The findings could provide useful guidance for the protection of red clay slopes.
摘要：
潮间带潮滩由于受到潮汐周期性淹没的影响导致难以精准确定其空间分布, 因此, 迫切需要利用遥感技术了解潮滩受潮汐淹没的光谱变化特征, 构建潮滩提取指数, 对潮滩的精准解译提供方法及基础数据支持。 基于多时相Sentinel-2多光谱影像, 通过分析高、 低潮影像上不同地物的光谱反射率特征差异, 优选出能反映潮滩特征的波段, 构建一种海岸带潮滩提取指数。 在此基础上, 从三方面对已构建潮滩指数的可行性进行论证: (1)将潮滩提取指数应用到3个不同潮滩类型的研究区, 研究了潮滩指数的可分离性及对不同潮滩类型区域的适用性, 研究结果表明: 与其他地类相比, 构建的潮滩提取指数对潮滩具有较好的可分离性, 并且适用于砂质、 泥质不同种类的潮滩; (2)研究了潮滩提取指数对不同分类方法(包括最小距离法、 极大似然法、 支持向量机)的适用性, 研究表明: 采用所选取的三种分类方法进行潮滩解译时, 其总体精度均大于93%, Kappa系数均大于0.85, 潮滩提取指数对不同的分类方法均具有普适性, 且可有效提高潮滩的解译精准度; (3)研究了潮滩提取指数对不同数据源的适宜性, 采用“珠海一号”数据与本文Sentinel-2多光谱数据解译潮滩并对比结果, 研究显示: 构建的潮滩提取指数适用于不同数据源, 且取得了较好的潮滩分类精度。 该方法提高了海岸带潮滩遥感提取的准确度, 丰富了潮滩遥感解译理论, 对海岸带潮滩生态系统的科学管理与保护提供了理论指导与意义。 It is difficult to accurately determine the spatial distribution of tidal flats in intertidal zones due to periodic tidal inundation. Therefore, it is urgent to use remotely-sensed technology to detect the spectral variation characteristics of tidal flats, construct a tidal flat extraction index, and then provide methods and basic data support for flat tidal interpretation. Based on multi-temporal Sentinel-2 images, this research analyzed the spectral reflectance differences of different land cover types in the high- and low-tide images and then determined the bands that can reflect flat tidal characteristics. Finally, a tidal flat recognition index was proposed by mathematical combination. The proposed tidal flat index is studied: (1) the proposed tidal flat recognition index was applied to three study areas with different tidal flat types, and the tidal flat recognition index’s separability and applicability to different tidal flat types are studied. The results showed that the proposed tidal flat recognition index showed a good performance on tidal flat separability compared with other land cover types and is applicable to different types of sandy and muddy tidal flats; (2) the applicability of the tidal flat recognition index to different classification methods (including minimum distance method, maximum likelihood method and support vector machine) is studied. The results showed that the overall accuracy is greater than 93%, and the kappa coefficient is greater than 0.85 for distinguishing tidal flats. The tidal flat recognition index is universal to different classification methods and can effectively improve the accuracy of distinguishing tidal flats; (3) the suitability of the tidal flat recognition index to different remotely-sensed data sources is studied. Compared the Sentinel-2 images with OHS images, the results showed that the tidal flats are distinguished, and the tidal flat recognition index proposed is applicable to different data sources, achieving a higher classification accuracy. This study improves the accuracy of distinguishing tidal flats using remote sensing data, enriches the theory of flat tidal interpretation, and provides theoretical guidance and significance for the scientific management and protection of the coastal.
通讯机构：
[Han, WW ; Su, M ] C;Changsha Univ Sci & Technol, Sch Civil Engn, Changsha 410114, Peoples R China.;Changsha Univ Sci & Technol, Sch Traff & Transportat Engn, Changsha 410114, Peoples R China.
关键词：
Horizontally near -surface -mounting;CFRP strip;Embedding depth;Bond behavior;Finite element model;high specific strength;fatigue resistance;corrosion resistance;good
摘要：
Horizontally NSM CFRP strip reinforcing concrete structures are a new type of reinforcing method, as they require a small groove depth compared with that of the traditional NSM strengthening method. In order to explore the effect and mechanism of the embedding depth of horizontally NSM CFRP strip on interfacial bond performance, the single shear pull-out test was used to compare and analyze the bond properties of concrete specimens reinforced with horizontally NSM CFRP strips, EB CFRP strips, and NSM CFRP strips, and explore the effect of horizontally NSM reinforcement methods. Then, the influence of the embedding depth on interface bonding was studied. Finally, the finite element software was used to establish a finite element model for nu-merical simulation to verify the test results of horizontally NSM CFRP strips. The results show that the specimens reinforced with horizontally NSM CFRP strips have better bonding capacity and interface bonding stiffness. The embedding depth of the CFRP strip affects the bond efficiency between the CFRP strip and concrete, and the interfacial bonding performance is the best when the embedding depth is 12 mm. The maximum bond capacity, strain distribution, and load-end slip curve of CFRP strip under finite element numerical simulation are in good agreement with the experimental results. This indicates that the bonding performance between the horizontally NSM CFRP strip and concrete can be analyzed by the finite element method. This provides a theoretical basis for the application of horizontally NSM CFRP strip reinforcement technology in practical engineering.
通讯机构：
[Yingli Gao] S;School of Traffic and Transportation Engineering, Changsha University of Science & Technology, Changsha 410114, People’s Republic of China
摘要：
The use of waste rubber powder modified asphalt (RA) in road engineering can lead to environmental and economic benefits. However, there are still some concerns over the performance of the pavement with RA, especially the rheological properties under heavy traffic conditions. This paper aims to investigate the improvement effects of graphene on the rheological properties of RA using multiple-scale experimental characterizations combined with molecular dynamics simulation. Special attention was paid to the influence of geometric characteristics of graphene on the modification efficiency. The experimental findings demonstrated that the physical blending of graphene and RA could enhance viscoelasticity, persistent deformation, and mobility resistance of modified asphalt, while its low-temperature performances were marginally improved with the graphene. Graphene with a single layer or a few layers was more efficient in enhancing the high-temperature deformation and rutting resistance and microstructures of RA than that with multiple layers. The molecular dynamics simulation results showed that graphene could improve the shear viscosity of the modified asphalt and inhibit the diffusion of asphalt components, and the effect on the low-temperature performance is related to the size effect. Moreover, the size of graphene particles could strongly influence the performances of the modified asphalt. Specifically, increasing the graphene size decreased the shear viscosity, free volume fraction, and glass transition temperature, indicating the improved deformation resistance. The change in the number of graphene layers was more effective in altering the modification effect of small-sized graphene compared to large-sized graphene. This research can offer a theoretical guideline for optimizing the use of graphene in modified asphalt.
摘要：
Automated code compliance checking plays an important role in moving the construction industry forward. While traditional drawing review relies on the identification of industry experts, the purpose of this study is to realize automatic code review by using BIM technology and knowledge graph technology. The method is based on knowledge graph to transform the specification provisions involved in the review of drawings into a computer-recognizable structured language using natural language processing technology to form a human-machine-readable knowledge graph pattern. For the review of BIM models, the BIM model information is exported and the global resource description framework of the building model is obtained in protégé, and the review report is finally obtained after mapping rules and review rules. Finally, the feasibility of the method is verified by an example. This study can effectively solve the problems of "manual dependency" and "inefficiency" in the process of review.
摘要：
OBJECTIVE: The study investigates the relationship between traffic accidents in expressway tunnels and their influencing factors, with the aim of predicting traffic accidents within tunnels and presenting reasonable recommendations to improve tunnel safety. METHODS: The study utilizes a dataset of 586 traffic accidents occurring exclusively within 8 tunnels along a Guangdong Province expressway from 2017 to 2021. It applies the geometric alignment consistency principle to segment road sections, defines tunnel boundaries based on driving behavior, and employs a Bayesian-modified negative binomial regression model (B-NB model) to identify 6 significant variables from a pool of 17 factors. RESULTS: The predictive performance of the B-NB model demonstrated similarities to that of the fixed parametric model. This outcome might be attributed to the chosen prior distribution settings and the limited amount of data. Nonetheless, the model effectively captures relationships among variables, leading to improved accuracy in accident prediction and the predictive model achieves a 76.1% accuracy rate. CONCLUSIONS: Drawing from the estimation results, practical measures are suggested across three dimensions: road geometric alignment design, tunnel traffic safety facilities, and traffic emergency management. These proposals aim to ameliorate the severe consequences of tunnel accidents. Future research will explore an in-depth comparison of estimation results, considering the impact of time and variable correlation on the prediction model by expanding the existing data. This will guide the direction of subsequent research endeavors.
摘要：
The present work aims to study the efficiency of root exudates of Sudan grass on the degradation of organochlorine pesticides (OCPs) and the consequent impact on the microbial and ecological characteristics of the soil, including population composition, quantity dynamics, and community structure. Pot experiments were carried out to study the effect of root exudates on the degradation of OCPs at initial concentrations ranging from 66.67 to 343.61mg/kg. In addition, the influence of root exudates on the rhizosphere microbial growth and their community structure was studied by monitoring the microbial biomass carbon, microbial biomass nitrogen, and phospholipid fatty acids (PLFAs) in the soils. In the range of OCP content (66.67 ~ 343.61mg/kg), the soil-microbial system mediated by root exudates significantly promoted the removal of OCP pollutants. The removal rate of OCPs in the rhizosphere soil (TR(2)) was as high as 79.32%, 36.86% higher than that in the OCP-contaminated group (TR(1)) and 60.63% higher than that in the sterilized treatment group (CK). Under the same treatment conditions (pollution level and additive dose), the enhanced removal rate of HCHs, toxaphene, HCB, aldrin, and γ-chlordane by root exudates was much higher than the total amount of OCPs, while the extent of enhanced dissipation of DDTs, mirex, endosulfanI, dieldrin, and heptachlor epoxide was always lower than that in the corresponding soils. During the experiment, the phospholipid fatty acid content of bacteria was dominant, followed by that of fungi, and their variation trend was consistent with the degradation characteristics of OCPs in soil. Root exudates of Sudan grass might change the rhizosphere bacterial and fungal community structure during the process of phytoremediation, leading to enhanced OCP degradation.
期刊：
IEEE Journal on Miniaturization for Air and Space Systems,2023年4(3):232-241
作者机构：
[Xuemin Xing; Li Huang; Zhongming He; Tengfei Zhang] School of Traffic and Transportation Engineering, Changsha University of Science and Technology, Changsha, China;[Yikai Zhu] Chinese Antarctic Center of Surveying and Mapping, Wuhan University, Wuhan, China
摘要：
Objectives: The Airport South Expressway in China is built in a soft soil area, which may induce great hidden danger to airport traffic safety operations. Technology or Method: A new method to improve multitemporal interferometric synthetic aperture radar (MT-InSAR) technology, based on a novel time-series InSAR deformation model and an improved parameter estimation algorithm, is proposed for soft soil expressways monitoring. The functional relationship between the deformation and the creep parameters (viscosity and elastic modulus) based on the Maxwell model in 1-D linear rheology replaces the traditional InSAR linear model, and the creep physical parameters can be solved simultaneously in the solution process. The least squares method with inequality constraints (LSICs) is induced to solve the unknown parameters. In total, 19 TerraSAR-X radar satellite images covering the South Expressway were utilized to validate the proposed method. The creep parameters for each pixel along the expressways and the time-series deformation sequences from January 2012 to July 2014 were obtained. Results: As the results showed, the maximum settlement along the expressway was up to 125 mm, and the accuracy verification results showed that the modeling accuracy was 1.6 mm, with an improvement of 36.0% compared to the traditional linear model; the internal accuracy of the deformation results was ±1.9 mm, accounting for 1.5% of the maximum deformation. Clinical or Biological Impact: Our method can provide data support and a reference for long-term health monitoring and early warning of infrastructure and traffic operation management in poor soil regions.
作者机构：
[Zhiming Liu] Institute of Geotechnical Engineering, Southeast University , Nanjing 211189 , China;[Long Wang; Jun Wang; Guangya Ding] College of Civil Engineering and Architecture, Wenzhou University , Wenzhou 325035 , China;[Mengqi Zhou] School of Traffic & Transportation Engineering, Changsha University of Science & Technology , Changsha 410114 , China
通讯机构：
[Zhiming Liu] I;Institute of Geotechnical Engineering, Southeast University , Nanjing 211189 , China
摘要：
Developing smart transportation and advocating green transportation are the main directions of future transportation development. In recent years, with the rapid development of intelligent structures and intelligent materials, a variety of energy harvesting technologies in road environment have gradually become a research hotspot. However, due to the low energy conversion efficiency and high cost, the application of some energy harvesting technologies is limited. Among them, vibration energy capture technology based on piezoelectric effect has been widely concerned by scholars because it does not need external power supply and can supply power for low-power wireless sensors. Therefore, this paper summarizes the current state of road energy harvesting technology, with emphasis on piezoelectric systems. It includes the mechanism of piezoelectric effect, the structure of the collector, and its road application. Based on extensive review research, this paper provides a comprehensive insight into road energy harvesting technologies. Specifically, the paper discusses the social and environmental benefits and challenges of road energy harvesting technologies. Finally, research on the durability, safety, and life cycle cost of road piezoelectric energy capture technology is still scarce. It is recommended to carry out such research in order to promote the positive contribution of piezoelectric energy exchange technology in the construction of intelligent transportation.
通讯机构：
[Jianrong Cai] S;School of Civil Engineering, Hunan City University, Yiyang 413000, China<&wdkj&>Author to whom correspondence should be addressed.
摘要：
Reversible lanes constitute an important solutions for sustainable transportation, with the aim to solve the practical problem of reversible lane optimization of urban road networks constrained by adjustment time. Considering the relationship between the number of lanes and the capacity of sections, a mixed-integer bilevel programming model of reversible lane optimization constrained by adjustment time is constructed in order to minimize the total travel time of the system. The results show that the model can effectively obtain the optimal strategy for any number of reversible sections subject to adjustment time constraints. With the increase of the number of reversible sections that can be optimized within the adjustment time, the cumulative reduced system time increases monotonically and the road network optimization effect improves, but as a whole, the optimization effect of the newly added reversible sections in each stage shows a decreasing trend. When the number of reversible sections that can be optimized within the adjustment time reaches a certain number, increasing the number of reversible sections will have a limited further effect on the overall system. For the reversible lane optimization problem of urban road networks, only efficient reversible sections need to be optimized to achieve a good optimization effect.
