China Academy of Transportation Sciences

Crack segmentation on building surfaces is challenging due to the thin, curvilinear crack morphology and background interference from textures and illumination variations. This study proposes SDCrackSeg, a U-shaped network combining frequency-domain enhancement with geometry-adaptive convolution. The core Frequency Spatial Convolution module integrates two branches: Adaptive Frequency Convolution enhances high-frequency crack details, while Dynamic Snake Convolution adapts sampling to curvilinear structures. A topology-aware loss based on persistent homology further regularizes structural connectivity. Experiments on CHCrack5K demonstrate state-of-the-art performance with Precision 0.900, mIoU 0.816, F1-score 0.888, and Dice 0.675, while maintaining nearly 200 FPS inference speed. Results confirm that frequency–spatial fusion with topology regularization effectively improves crack detection reliability for practical building inspection.

Aeolian sand is abundant in arid deserts, but its high replacement in cement-stabilized bases can reduce strength and raise cracking risk. Strain localization and crack evolution are also poorly quantified. This study aimed to optimize the early age performance of cement-fly ash stabilized aeolian sand gravel (CFSAG) and clarify its failure mechanism. A Box–Behnken response surface methodology varied the cement content, cement-to-fly ash ratio, coarse aggregate gradation, and aeolian sand content. The 7-d unconfined compressive strength (UCS) and splitting tensile strength (STS) were tested. Digital image correlation (DIC) recorded full-field strains and crack metrics in compression and splitting. SEM–EDS was used to interpret microstructural changes. The aeolian sand content dominated UCS, whereas the cement content and cement-to-fly ash ratio mainly controlled STS. Factor interactions were non-negligible and supported the joint optimization of the two strength indices. DIC identified a crack propagation threshold near 0.9 Pmax in splitting. Excess aeolian sand (>50%) caused earlier localization, more cracks, and wider openings. In the appropriate amount of aeolian sand mixtures, hydration products filled voids and improved paste continuity. SEM–EDS indicated that excessive fines increased porosity and weakened the interfacial transition zone. Overall, the combined RSM–DIC–SEM approach links mix design with deformation and microstructure evidence. It provides practical guidance to balance strength and cracking resistance at early ages for cement-stabilized bases in desert highway engineering.

Against the backdrop of China’s dual-carbon goals, traditional road transportation has relatively high carbon emissions and is in urgent need of a low-carbon transition. The intermittency of photovoltaic (PV) power generation and the stochastic nature of electric vehicle (EV) charging demand introduce significant uncertainty for PV-energy storage-charging systems in highway service areas. Existing approaches often struggle to balance economic efficiency and reliability. This study develops a min-max-min robust optimization model for a full-route PV-energy storage-charging system. A box uncertainty set is used to characterize uncertainties in PV output and EV load, and a tunable uncertainty parameter is introduced to regulate risk. The model is solved using a column-and-constraint generation (C&CG) algorithm that decomposes the problem into a master problem and a subproblem. Strong duality, combined with a big-M formulation, enables an alternating iterative solution between the master problem and the subproblem. Simulation results demonstrate that the proposed algorithm attains the optimal solution and, relative to deterministic optimization, achieves a desirable trade-off between economic performance and robustness.

The highway transportation industry is an important component of the transportation industry and one of the key industries contributing to global climate change.To identify the carbon emission level of highway transportation enterprises, this article uses a set of panel data from China's highway and waterway transportation enterprises to calculate the carbon emissions from the movement of trucks in highway freight transportation enterprises.The research results indicate that: (1) both economic efficiency and carbon emission efficiency exhibit spatial agglomeration characteristics, but in 2021, the degree of spatial agglomeration decreased.(2) From 2020 to 2021, the carbon emission efficiency rankings of various regions remained relatively stable, with the western, eastern, central, and northeastern regions ranking in order of carbon emission efficiency; Due to the impact of COVID-19, the economic efficiency of various regions fluctuated to some extent in 2020-2021, and the fluctuation of unified efficiency was closer to the fluctuation of economic efficiency.(3) The results of the impact analysis on carbon emission efficiency are as follows: the faster the Internet develops and the more stringent the urban environmental requirements are, the higher the carbon emission efficiency of road transport enterprises will be; The more diversified the business model and the longer the transportation distance, the higher the carbon emission efficiency of the enterprises.

<div class="section abstract"> <div class="htmlview paragraph">To alleviate the congestion in general-purpose lanes while exclusive bus lanes remain idle, this paper proposes absolute-priority bus lane design with clearance distance. By establishing specific clearance distances and lane-changing rules, the proposed design method not only enhances overall road utilization efficiency but also ensures unimpaired bus speeds, thereby maintaining bus priority. The simulation is performed based on cellular automaton (CA) model and the results demonstrate that this design is effective when general-purpose lane traffic density ranges between 0-50 vehicles/km/lane, with greater improvements in other non-public vehicle speeds under longer bus dispatch intervals. These results provide a theoretical basis and practical guidance for future bus lane management.</div> </div>