作者机构：
[Qiuling Wang; Kailiang An; Wenying Guan] School of Transportation Engineering, Chang'an University, Xi'an 710064, China;[Zhizhen Liu] School of Traffic and Transportation Engineering, Changsha University of Science and Technology, Changsha 410114, China
通讯机构：
[Qiuling Wang] S;School of Transportation Engineering, Chang'an University, Xi'an 710064, China
关键词：
Connected and automated vehicles;Cyberattack;Propagation dynamics;Game theory;Vehicle control
摘要：
In order to ensure the safety of connected and automated vehicles (CAVs) threatened by cyberattack in the confluence area and mitigate the adverse impact of cyberattack propagation, a framework is built to depict the impact of cyberattacks on traffic operation. Based on this framework, corresponding propagation suppression strategies are proposed for different types of cyberattacks in different periods. Under centralized control, game theory is used to solve the confluence sequence corresponding to the strategies. The results show that the proposed method can effectively inhibit the spread of cyberattacks on the premise of security. The initial control effect is the best. Compared with uncontrolled condition, in the 100 timesteps, 11 susceptible vehicles are finally added, and the second is the immunity period, in which 10 susceptible vehicles were protected from cyberattack. Outbreak and latency control strategies also protect some vehicles. Under the control strategy of each stage, the peak value of infected vehicles and the duration of cyberattack are improved compared with the uncontrolled strategy. In addition, the traffic efficiency in the confluence area is also improved. This method can also be extended to such road types as diverging section, weaving section and intersection, so as to reduce the impact of cyberattacks on road network scale.
摘要：
To evaluate the fatigue-creep damage coupling effect of asphalt mixture under different loading frequencies, three tests-tension-compression fatigue, direct tensile fatigue, and static creep-were carried out with haversine cyclic loading at four loading frequencies of 5, 10, 20, and 50 Hz, respectively. In this research, the elastic modulus was selected as a damage variable for evaluation, and the evolution of fatigue damage and creep damage was analyzed by the Chaboche model and the Kachanov model, respectively. Then, based on haversine fatigue stress decomposition, tension-compression fatigue damage, direct tension fatigue damage, and creep damage under four loading frequencies were compared, and the fatigue-creep damage coupling model under those loading frequencies was established. The results indicated that, with the increase in loading frequency, the corresponding damage under the same standardized coordinate decreased, the growth rate of the damage evolution curve decreased, and the damage increased more rapidly when the asphalt mixture was damaged. It was found that the direct tensile fatigue damage of the asphalt mixture under repeated loads was not the direct superposition of pure fatigue and pure creep damage, but a coupling effect of fatigue-creep damage. In the direct tensile fatigue tests, the fatigue-creep damage coupling effect was negative and during the coupling effect the creep effect was more obvious. The model proposed in this result can better characterize the fatigue-creep damage coupling effect and damage evolution process of asphalt mixtures under different loading frequencies.
通讯机构：
[Chaochao Liu] N;National Engineering Laboratory of Highway Maintenance Technology, Changsha University of Science & Technology, Changsha 410004, China<&wdkj&>Author to whom correspondence should be addressed.
摘要：
Collusion between governments and enterprises has occurred in many economies around the world in the context of government investment projects and tenders. Not only is collusion an illegal act, but it may also lead to learning and imitation by non-colluding parties. Therefore, to control collusion and ensure the quality of government investment projects, investigating the spread of collusion in the bidding process of such projects is important. This study presents a simulation of the diffusion process of collusion among multiple entities through NetLogo, drawing on a contagious disease model. The effectiveness of the hypothesised control tools is validated through the changing trend of collusion in bidding in China. The findings provide a new approach to controlling collusion based on the perspective of the proliferation of bidding behaviour and have some reference value for the government to formulate policies.
通讯机构：
[Suxun Shu] S;School of Civil Engineering and Architecture, Wuhan Institute of Technology, Wuhan 430205, China<&wdkj&>Author to whom correspondence should be addressed.
摘要：
This study introduced phosphogypsum coupled with steel slag powder to prepare the phosphogypsum based filler (PF) for asphalt mixture. Penetration, penetration index, softening point, ductility, equivalent softening point, moisture stability of asphalt mortars with different steel slag powder content, filler-asphalt ratio, and PF content were studied. Mechanical properties of PF based asphalt mortar (P-AM) were then analyzed to determine the optimum steel slag content in PF. Overall desirability method was used to determine the optimum replacement ratio of PF content in limestone filler. Rheological properties of P-AM were also analyzed through dynamic shear rheometer. Volumetric performance, high-temperature performance, low-temperature performance, and moisture stability tests were carried out on PF based AC-20 asphalt mixture. Results showed that P-AM presented the optimum performance when the content of steel slag powder was 23% by mass of phosphogypsum. Fatigue and rutting factor of asphalt mortar were enhanced by PF. The optimum PF content in replacing limestone filler was 75% through overall desirability evaluation. PF developed the high-temperature performance and moisture stability of asphalt mixture. Additionally, volumetric and low-temperature performance were not significantly affected by PF. It is suggested that using PF which is based on phosphogypsum as a filler of asphalt mixture to partially replace traditional limestone filler was adequate.
摘要：
The excavation and unloading of silty mudstone slopes often precipitate slope instability and collapse. While abundant research addresses the macro deterioration of rock strength, the micro-damage mechanism of silty mudstone remains largely uncharted. To bridge this gap, our study innovatively utilized nano-materials to prepare silt-like mudstone subjected to the triaxial unloading test considering multiple paths. Then we delved into the variation in microstructure using Scanning Electron Microscopy (SEM), binarization, and fractal dimensions. Our findings reveal that: (1) The peak stress, residual stress, and residual strain of silt-like mudstone display a decreasing trend with an increase in initial deviatoric stress while the peak strain initially increases and subsequently decreases; (2) Following unloading, the crack propagation on fracture surface is dictated by both confining pressure and initial deviatoric stress, which profoundly impact porosity, particle fragmentation, and pore expansion; (3) As confining pressure and initial deviatoric stress elevate, the average morphology coefficient rises with a reduction in rate of change. The impact of unloading confining pressure on pore morphology diminishes; (4) The fractal dimension increases with increased confining pressure and initial deviatoric stress, with a transition in the pore surface from smooth to rough.
关键词：
green building;spatiotemporal evolution;influence factors;GeoDetector
摘要：
This paper explores the spatiotemporal evolution characteristics and spatial correlation patterns of green building development differences in 41 cities in the Yangtze River Delta region from 2012 to 2020 by means of the gravity center analysis model and spatial autocorrelation analysis. In addition, it further clarifies the impact factors of the spatial differentiation pattern of green building development in combination with GeoDetector based on four dimensional factors of population and economy, market environment, policy, and other factors. The results showed that: (1) According to the analysis of the number of green buildings in each city from 2012 to 2020 and the natural discontinuity method, the development pattern of green buildings in the Yangtze River Delta region city clusters shows an imbalance, being highly concentrated in the eastern coastal areas with Suzhou (1) and Shanghai as the core. The overall trajectory of the center of gravity shows the development from southeast to northwest. (2) The global Moran's I of green buildings in the Yangtze River Delta region city clusters is greater than 0, and all passed the significance test (Z > 1.96, p < 0.01), indicating that the green buildings in the Yangtze River Delta region city clusters show typical spatial aggregation characteristics. By using the local LISA index, it is found that in the H-H spatial autocorrelation distribution pattern with Suzhou (1) and Shanghai as the core, the core city has a strong attraction ability and relatively low radiation ability. (3) Based on the explanatory power mean, the main driving factors of the spatial differentiation pattern of green building development in the Yangtze River Delta region city clusters are education level (0.6656), technical level (0.6269), and the gross domestic product (0.6091). The factor interaction shows a two-factor enhancement and nonlinear enhancement effect, and there is neither a weakening nor an independent relationship.
摘要：
The influences of Cl- concentration on the corrosion behaviour of Al-Mg-Si alloy were studied by using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical analysis. The results show that the microstructures primarily consist of precipitate free zone (PFZ), largesize MgSi-riched dispersed phase and beta' precipitates. The corrosion type and corrosion behaviour of Al-Mg-Si are greatly affecting by Cl- concentration. With the increase in Cl- concentration, the open circuit potential (OCP) and corrosion resistance of the alloy decrease. In 1.0 wt. % NaCl solution, slight pitting corrosion occurs around MgSi phase. In 3.5 wt. % NaCl solution, obvious intergranular corrosion (IGC) and hemispherical pitting corrosion appear. In 5.5 wt. % NaCl solution, corrosion kinetic of the Al-Mg-Si alloy are significantly enhanced, making it susceptible to severe overall corrosion. High concentration of Cl- leads to rapid dissolution of the passivation film and serious corrosion.
关键词：
Engineering fundamentals;Highway and road management;Highway transportation;Highways and roads;Infrastructure;Models (by type);Numerical models;Traffic delay;Traffic engineering;Traffic flow;Traffic management;Traffic models;Traffic safety;Traffic speed;Transportation engineering;Vehicles
摘要：
The information exchange among vehicles and road infrastructure with wide sensing range can be accomplished by roadside units (RSUs). Communication delays occur and are influenced by different approaches of deployment of RSUs, which increases the complexity of vehicle automatic control in a mixed traffic flow. Therefore, a speed control strategy was proposed for mixed traffic flow considering RSU deployment distance, interaction radius, and communication delay, aimed at enhancing traffic safety and efficiency. The characteristics of RSU deployment were modeled as functions, where an adaptive efficiency function was proposed to evaluate different RSU deployment plans. An improved speed control model was then developed based on the characteristics of the RSU in the mixed traffic flow. In addition, numerical analysis and simulation were carried out to evaluate vehicle stability and traffic throughput based on the improved speed control model. The analysis results show that the proposed model is stable under different updating frequencies, with the best stability achieved when the velocity update frequency is 500 and the velocity update time interval is 0.01 s. Moreover, it was found that the spatial occupancy rate increases with the increment of penetration rate of autonomous vehicles, which improves the rate by at least 20% compared to the no-control scenario. Additionally, the average speed is also increased by 30% while under the influence of communication delays. This paper investigated the relationship between characteristics of RSUs and traffic performances, which is essential for DOTs to develop an effective RSU plan to adapt to the mixed traffic flow.
作者机构：
[Gaspare Giancontieri; Usman Ghani; Chiara Mignini; Gabriella Buttitta; Silvia Milazzo] Department of Engineering Ed.8, University of Palermo, Viale Delle Scienze, 90128 Palermo, Italy;Author to whom correspondence should be addressed.;[Fan Gu] School of Traffic & Transportation Engineering, Changsha University of Science and Technology, Changsha 410114, China;[Davide Lo Presti] Department of Engineering Ed.8, University of Palermo, Viale Delle Scienze, 90128 Palermo, Italy<&wdkj&>Author to whom correspondence should be addressed.
通讯机构：
[Davide Lo Presti] D;Department of Engineering Ed.8, University of Palermo, Viale Delle Scienze, 90128 Palermo, Italy<&wdkj&>Author to whom correspondence should be addressed.
摘要：
Even though alternative paving materials, like rubberized asphalt, are sometimes present in specifications, these are still not widely adopted from road agencies mainly due to a lack of experience, reticence in changing work habits and, often, a lack of evidence of real gains in the change. Authors believe that performance-based laboratory characterization is a solution to highlight differences with conventional asphalt mixtures. Hence, this research wants to highlight the differences between designing asphalt mixtures modified with engineered crumb rubber (ECR) on the basis of conventional indirect tensile testing (ITS), as prescribed by Italian specifications, and by means of performance-related characterization. ECR allows to asphalt mixtures to be modified through a dry process without inconveniences such as uncontrolled swelling and the generation of fumes; on the other hand, performance-related characterization focuses on highlighting rutting behavior by using a basic approach, still based on ITS, and a more advanced viscoplastic methodology using the asphalt mixture performance tester (AMPT). As a result, performance-related characterization is necessary to highlight clear gains in the rutting behavior of the asphalt mixtures modified with ECR. Advanced methodology by means of AMPT provides a fine-tuned characterization; however, the basic approach by means of ITS already highlights the differences in performance. ECR could be widely used to improve the properties of dense mixtures for roads with low traffic; in fact, it solves many of the practical issues of adding crumb rubber through a dry process and greatly improves paving material properties compared to conventional asphalt mixtures, with an increase in cost of only 10%.
摘要：
This paper presents numerical investigations into the particle crushing effect on the shear properties of gravel under direct shear condition. A novel particle crushing model was developed based on the octahedral shear stress criterion and fragment replacement method. A series of direct shear tests were carried out on unbreakable particles and breakable particles with different strengths. The evolutions of the particle crushing, shear strength, volumetric strain behavior, and contact force fabric during shearing were analyzed. It was observed that the number of crushed particles increased with the increase of the shear displacement and axial pressure and decreased with the particle strength increasing. Moreover, the shear strength and volume dilatancy were obviously decreased with particle crushing. The shear displacement of particles starting to crush was close to that corresponding to the peak shear stress got. Besides, the shear-hardening behavior was obviously affected by the number of crushed particles. A microanalysis showed that due to particle crushing, the contact forces and anisotropy decreased. The mechanism of the particle crushing effect on the shear strength was further clarified in terms of the particle friction and interlock.
摘要：
The cold patching asphalt liquid (CPAL) is an environment-friendly paving material, which is more preferable in pavement construction and has lower energy consumption than the hot mix asphalt. However, the CPAL is mainly applied in the quick repair of potholes because of the limitation in its cost and storage stability. This study primarily investigates the effect of the compositions and contents of CPAL on its road performance through the multivariate analysis to develop a low-cost and storable CPAL. In this study, the CPAL was synthesized by base asphalt, diesel, diethylene glycol (DG), oleic acid (OA), and coconut oil acid diethanolamine (COAD). Orthogonal experiments with four factors and four levels were performed to optimize the mechanical properties of CPAL. The microstructure and characteristic functional groups of different CPAL schemes were analyzed to further understand the influence of different components of CPAL on its pavement performance. Results show that the proposed multivariate evaluation method in this study can accurately evaluate the significant relationships between different functional components and properties of CPAL. Furthermore, the dosage of diesel should be strictly controlled in the productions considering that only the t value of diesel passes the inspection. The optimal design scheme of CPAL in this study is 20% diesel, 0.6% DG, 6% OA, and 6% COAD, and its mixture has high adhesion, strength, and good storage stability in pavement engineering. The multivariate evaluation method is also conducive for scientifically developing a green and high-performance road material.
