In real-world graphs, node attributes are often incomplete due to acquisition costs or privacy restrictions, reducing representation quality and harming downstream predictions in graph neural networks (GNNs). A common remedy is feature-propagation-based imputation. However, cold-start effects arising from attribute resetting and low-degree nodes impede effective propagation and convergence in these methods. To address these challenges, we propose AttriReBoost (ARB), a propagation-based method that mitigates cold-start issues in attribute-missing graphs. ARB enhances global feature propagation (FP) by redefining initial boundary conditions and strategically integrating virtual edges, thereby improving node connectivity and ensuring stable and efficient convergence. The method supports gradient-free attribute reconstruction with low computational overhead, and we provide a rigorous convergence analysis. Extensive experiments on several real-world benchmark datasets demonstrate the effectiveness of ARB, achieving an average accuracy improvement of 5.11% over state-of-the-art methods. In addition, ARB exhibits remarkable computational efficiency, processing a large-scale graph with 2.44 million nodes in just 16 s on a single GPU. Our code is available at https://github.com/limengran98/ARB.

The integration of cloud computing and edge computing is an effective way to achieve global consistent and real-time multi-robot Simultaneous Localization and Mapping (SLAM). Cloud computing effectively solves the problem of limited computing, communication and storage capacity of terminal equipment. However, limited bandwidth and extremely long communication links between terminal devices and the cloud result in serious performance degradation of multi-robot SLAM systems. To reduce the computational cost of feature tracking and improve the real-time performance of the robot, a lightweight SLAM method of optical flow tracking based on pyramid IMU prediction is proposed. On this basis, a centralized multi-robot SLAM system based on a robot-edge-cloud layered architecture is proposed to realize real-time collaborative SLAM. It avoids the problems of limited on-board computing resources and low execution efficiency of single robot. In this framework, only the feature points and keyframe descriptors are transmitted and lossless encoding and compression are carried out to realize real-time remote information transmission with limited bandwidth resources. This design reduces the actual bandwidth occupied in the process of data transmission, and does not cause the loss of SLAM accuracy caused by data compression. Through experimental verification on the EuRoC dataset, compared with the current most advanced local feature compression method, our method can achieve lower data volume feature transmission, and compared with the current advanced centralized multi-robot SLAM scheme, it can achieve the same or better positioning accuracy under low computational load.Note to Practitioners—The purpose of this paper is to reduce the communication load of a Cloud-Edge-Robot system by compressing and transmitting of keyframes and non-keyframes, respectively, which is suitable for a multi-robot SLAM system and can realize multi-robot joint localization and sparse map reconstruction under efficient communication. Currently, remote SLAM or centralized multi-robot SLAM is usually implemented by transferring the whole image or the features and descriptors of the image. In this paper, lightweight SLAM optical flow tracking based on pyramid IMU prediction is implemented to track non-keyframes. At the edge server, tracking between non-keyframes is realized only by transmitting keypoints. For keyframes, the pose estimation is realized by transmitting compressed features and descriptors. Multi-robot localization and map fusion are realized in the cloud through key frame feature information. Experiments on public datasets show that this method is feasible and can achieve high-precision joint positioning with a low amount of transmitted data. In future studies, we will apply this framework to more real-world systems, while achieving rich, accurate map fusion with more advanced features.

With the development of intelligent connected vehicle technology, human-machine shared control has gained popularity in vehicle following due to its effectiveness in driver assistance. However, traditional vehicle following systems struggle to maintain stability when driver reaction time fluctuates, as these variations require different levels of system intervention. To address this issue, the proposed human-machine shared vehicle following assistance system (HM-VFAS) integrates driver outputs under various states with the assistance system. The system employs an intelligent driver model that accounts for reaction time delays, simulating time-varying driver outputs. Acontrol authority allocation strategy is designed to dynamically adjust the level of intervention based on real-time driver state assessment. To handle instability from driver authority switching, the proposed solution includes a two-layer adaptive finite time sliding mode controller (A-FTSMC). The first layer is an integral sliding mode adaptive controller that ensures robustness by compensating for uncertainties in the driver output. The second layer is a fast non-singular terminal sliding mode controller designed to accelerate convergence for rapid stabilization. Based on the driver-in-the-loop experimental results using the intelligent cockpit system, the performance of the HM-VFAS was evaluated. Results show that the proposed control strategy maintains a safe distance under time-varying driver states, with the actual acceleration error relative to the target acceleration maintained within$\pm 0.6\!\ \text {m/s}^{2}$and the maximum acceleration error reduced by$1.3\!\ \text {m/s}^{2}$. Compared to traditional controllers, the A-FTSMC controller offers faster convergence and less vibration, reducing the stabilization time by 26.8%.

Cloud detection is an essential step in remote sensing (RS) image processing, contributing to various applications. However, existing fully supervised cloud detection methods rely on massive pixel-wise annotations, which are expensive and time-consuming. To alleviate the annotation burden, weakly supervised cloud detection (WSCD) has received extensive attention recently. One standard approach performs cloud detection within a classification paradigm, which inevitably faces category ambiguity when detecting semitransparent clouds. To tackle this problem, we propose a novel WSCD framework based on the diffusion model, termed CLDiff. Specifically, a multiscale feature rectification (MFR) module is introduced to extract multiscale semantic features in the encoder, enabling a definite identification of clouds and mitigating interference from bright objects in the background. Considering that clouds exhibit varying optical thicknesses, a diffusion decoder is developed to model the intraclass variations of clouds in a generative strategy, improving thin cloud detection. Initially, it devises a Gaussian modulation function to recalibrate ambiguous cloud activations and emphasize semitransparent clouds. Subsequently, these modulated activations serve as semantic guidance to optimize the diffusion process. This approach enables CLDiff to activate cloud contours under definite semantic conditions and avoids the additional branches for semantic learning as found in previous methods. Experimental results demonstrate that CLDiff achieves state-of-the-art performance in WSCD. A public reference implementation of this work in PyTorch is available athttps://github.com/YLiu-creator/CLDiff.

With the capability of communicating with surrounding vehicles and infrastructures, connected and automated vehicles (CAVs) can safely drive closer with reduced headway, thereby potentially improving traffic efficiency. However, their superiority is compromised in the mixed traffic environment because of the interruption of human-driving vehicles (HDVs). In this circumstance, researchers proposed to physically separate CAVs and HDVs by deploying CAV-dedicated lanes (CAV-DLs). Nevertheless, the CAV-DLs may be underutilized, especially in low CAV penetration rate (PR) cases which may even reduce traffic efficiency. To solve this problem, two novel strategies were proposed in our study to better manage the CAV-DLs and magnify the benefit of CAVs: The first one is to dynamically allocate the right-of-way for CAV-DLs based on the predicted CAV-DLs’ effective utilization rate so that the HDVs can be allowed to use the dedicated lanes when they are not adequately occupied. The second strategy is motivated by the economic instrument, which allows HDVs to use the CAV-DLs by paying a toll. The toll is determined by the travel time difference between CAV-DL and general lane (GL), and these tolls can be utilized as subsidies to stimulate drivers to purchase CAVs for promoting their adoption. The two strategies were evaluated using the case study designed based on the network of Edmonton downtown area in Canada, and the results demonstrated that both methods can significantly reduce travel time. Besides, the two strategies were compared comprehensively in terms of their effectiveness and policy enforceability, which can provide some guidance for both traffic policymakers and practitioners.

Electric Vehicles (EVs) are cost-effective and widely recognized for their significant role in reducing greenhouse gas (GHG) emissions. However, concerns surrounding range anxiety and charge anxiety have hindered their widespread adoption. To address these concerns, traffic engineers have been working on developing control strategies to reduce energy consumption (EC). Unlike traditional gasoline-powered vehicles, EVs experience a notable increase in EC at speeds exceeding 25km/h. Consequently, minimizing EC often results in reduced speed and longer total travel time (TTT). In light of this, our paper proposes a novel trajectory and signal control method that leverages connected and automated vehicle (CAV) technology to realize a tradeoff between EC and TTT. Initially, the approach assumes all vehicles are connected and automated electric vehicles (CAEVs) capable of communication and coordination, to which a cooperative adaptive cruise control (CACC) model was applied. Then, the vehicles were controlled to avoid stops and achieve smoother trajectories at the intersections. Finally, the signal control was integrated to further reduce EC and TTT. The proposed method was evaluated with a simulation conducted in SUMO based on a busy corridor in the City of Edmonton, Canada. The developed method successfully balanced energy and traffic efficiency, reducing both EC and TTT by 14% and 38% respectively. More importantly, the computational burden of our method is considerably lighter compared to existing studies, making it highly suitable for real-time applications. Overall, the results presented in our study showcase the potential of achieving a more efficient and sustainable traffic system with the future existence of CAEVs.

Signal phase optimization at signalized intersection is of great importance to urban traffic control and management yet is very challenging. The traditional approaches for signal phase optimization heavily rely on the traffic engineering practitioners’ experience. To tackle these challenges, a novel data-driven method is proposed to realize signal phase optimization and recommendation solely using limited amount of real signalized intersection samples. Firstly, all of discrete features related to signal phase design, encoded by one-hot representation, are sampled by the Gumbel-SoftMax distribution, which is a continuous approximation to a multinomial distribution. With this approximation distribution, the generative adversarial network (GAN) is applied to produce the most acceptable signal phase samples among all acceptable choices, dealing with the problem of insufficient samples and uneven sample distribution in real word. Thirdly, a decision-tree based classifier is established to realize signal phase recommendation automatically. We conducted extensive experiments to evaluate our proposed method on three cities in China, including Beijing, Tongxiang and Chaozhou. The experimental results showed that the proposed method could effectively improve the signalized intersection operation efficiency. Moreover, the proposed method has already been deployed in several cities, and it successfully keeps serving hundreds of signalized intersections. This confirms that SPSRec is a practical and robust solution for large-scale real-world signal control services.

The benefit of real-time joint dynamic route guidance and signal control (DRG-SC) is usually compromised by a centralized framework since it naturally leads to an un-timely solution with the growing data-processing needs and problem-solving complexity. Mobile edge computing (MEC) pushes the data storage and computation from the remote cloud to local infrastructures and hence reduces response time and improves network bandwidth when further combined with 5G. As such, our study first develops a novel distributed framework to facilitate DRG-SC in connected vehicle (CV) environment with clarifying the MEC’s vital role. The method captures the interaction of vehicles’ routing and signal control, wherein we use a more realistic and accurate way to define the relationship between travel time and traffic volume. Vehicles make route decisions and cooperate to reach user optimal (UO) or system optimal (SO) traffic state. In tandem, the developed adaptive signal control (ASC) adjusts the signal timing plan with considering both the adjacent intersections’ traffic volume and the vehicles’ waiting time. Our method achieves significant reductions in vehicles’ average departure delay, waiting time and travel time when justified by a comprehensive case study implemented in SUMO. Moreover, the effectiveness of adopting such a distributed framework in saving computation time is verified. Overall, our study provides valuable and practical insights into the intelligent operation and control.

This study focuses on the dynamic route control (DRC) problem for connected and automated vehicles (CAVs). The problem is usually solved using two popular methods, i.e., dynamic shortest path (DSP) and dynamic system optimal assignment (DSO). However, the DSP algorithm is unproductive under congested conditions, while the DSO, although can achieve system optimal, possesses considerable algorithm complexity. Furthermore, the two methods are usually solved in a centralized system due to the need for global information of the entire network, which is both communicationally and computationally ineffective. With the emergence of mobile edge computing (MEC), a new distributed DRC method only relying on local information is more achievable and practical. In this context, this research developed a novel DRC algorithm based on the distributed Backpressure (BP) principle for the MEC-enabled CAVs. The BP herein is modified as a function of the real-time density, which avoids the unrealistic point queue assumption in the original BP algorithm. In addition, the real-time traffic state is pre-identified to determine whether re-routing is essential, thereby reducing the possibility of CAVs guided to unnecessarily long routes. Results from the case study simulated by the traffic simulation software Simulation of Urban MObility (SUMO) indicate that the proposed method outperforms the BP method without congestion identification in low-demand cases, and the performance is significantly better than the DSP while approximating the DSO in congested cases. More importantly, both communicational cost and algorithm execution time was greatly reduced when compared with the DSO.

In this paper, a roadside equipment (RSE)-assisted positioning method, i.e., global positioning system (GPS)-received signal strength (RSS) hybrid, is developed for lane-level positioning, which is fundamental to many applications in intelligent transportation systems. By exploiting the potential of RSE in existing pilots all over the world, this key component in connected vehicle networks can be used to achieve greater positioning accuracy than GPS positioning. The proposed method utilizes RSS data, which is commonly available in all connected vehicle networks, to update the GPS position and improve its accuracy based on a Bayesian approach. A method for lane positioning at a specific point is presented first, and then an extension to enable real-time lane positioning is proposed. Two typical types of RSE deployments for different traffic flow demands are considered, and the performance of the proposed method in each deployment is assessed. The proposed method features higher accuracy than existing GPS positioning methods and low complexity. To evaluate the proposed method, simulations are conducted, and the results demonstrate high accuracy and robustness. Moreover, field tests are also conducted, and the outcomes show that the proposed method can recognize the lane in which the target vehicle is traveling.

With the dramatic development of image processing technology, a growing number of traffic flow detection and analyses have been conducted by using video data. Time to collision (TTC) and postencroachment time (PET) are two major parameters used to indicate the severity of a potential collision and to capture an imminent vehicular accident. However, microlevel pedestrian-involved collisions are less studied because they are hard to observe or record. This paper tries to extract the traffic object locations from video data, to define the time difference to collision (TDTC) parameter as a variation from TTC and PET to fit the pedestrian-involved potential collisions/conflicts, analyze the interaction behavior between pedestrian and vehicles, and validate the TDTC parameter in indicating pedestrian safety performance by using 100 groups of interaction data. The results show that the interaction cases with larger TDTC values are safer, whereas the cases with continuously closer to zero TDTC values are more dangerous. About 80% of the cases classified by the TDTC parameter have the same result with the independent observation; if TDTC is combined with vehicle speed, the classification result can be improved. More mixed traffic scenes will be conducted based on this research in the future.