Construction operation sequencing is vital for effectively managing construction job sites. In this regard, it is important that junior engineers learn construction operation sequencing on construction sites. In Taiwan, senior engineers teach construction operation sequencing to junior engineers by using documents or two‐dimensional (2D) shop drawings. However, many junior engineers find it difficult to understand construction operation sequencing when their instructors use 2D illustrations. With the COVID‐19 public health crisis serving as a catalyst for changes in the nature of training across fields, there is an opportunity to review the traditional approach for training in construction operation sequencing. Therefore, this study develops a construction building information modeling (BIM)‐based learning and training (CBLT) system to train junior engineers employed by general contractors. The proposed approach and system are applied to a building project in Taiwan as a case study to verify their effectiveness in practice. The results demonstrate that a CBLT system is an effective visual learning and training platform for junior engineers to learn construction operation sequencing. The CBLT system not only increases learning and training efficiency but also facilitates the transfer and reuse of senior engineers’ knowledge and experience for effective construction operation sequencing at job sites, which is particularly valuable for junior engineers.
[Objective] To achieve cost efficiency and low-carbon transformation in rail transit, the planning, design, and implementation of green and low-carbon urban rail transit systems is investigated. [Method] Aiming at life-cycle sustainable development, through comprehensive route selection and laying methods optimization (mainly elevated), Shenzhen Metro Line 6 innovatively applies systematic technologies such as comprehensive vibration and noise reduction technology for elevated lines, prefabricated and assembled green construction (such as U-shaped beams and floating plate tracks), distributed photovoltaic power generation, regenerative braking energy feedback, ecological sponge vehicle depot design, intelligent cloud platform and TOD (transit oriented development) model intensive land utilization, etc., to explore green and low-carbon planning, design and practice paths. [Result & Conclusion] The green and low-carbon technology system of Shen-zhen Metro Line 6 has demonstrated remarkable outcomes: construction costs are reduced by approximately 45% (10.9 billion yuan) compared to a fully underground scheme, with a 2.4 million-ton carbon emission reduction in construction-phase. The operational energy consumption is decreased by 40% (annual electricity savings of 33.6 million kW·h), with accumulated carbon emission reduction of 580 000 tons in 25 years. The annual power generation and energy saving by using photovoltaic and regenerative braking technologies are 6.78 million kW·h；the land development income is expected to reach 30 billion yuan（RMB）. This case provides a replicable technology integration solution for urban rail transit to achieve the carbon peak and carbon neutrality（shorten as "dual carbon"）goals, proving that the green, low-carbon and high-quality sustainable development can be collaboratively achieved through systematic innovation.
Skyler Hawkins, Jaya Sravani Mandapaka, Logan McCorkendale
et al.
The increasing size of the Uncrewed Aircraft System (UAS) ecosystem necessitates effective infrastructure and Collision Avoidance (CA) systems to facilitate high-density UAS traffic in urban environments. Unfortunately, current-generation Air Traffic Management (ATM) and CA systems used for crewed aircraft cannot be used with UAS due to scalability issues and operational constraints. This paper introduces a novel UAS intersection called the Roundabout, specifically designed for facilitating UAS traffic in structured airspace. This paper also proposes the methodology for a CA system based on Vehicle-to-Vehicle (V2V) communications, specifically UAS-to-UAS (U2U) communications, for Tactical Deconfliction (TD) between UAS in real-time. Simulation results demonstrate the system's efficacy in handling the deconfliction process between two quadrotor UAS and can be expected to generalize to deconfliction scenarios involving UAS of all types, given that the proper control systems and trajectory generation methods are available. Overall, these findings highlight the Roundabout's potential for enhancing UAS operations in the National Airspace System (NAS).
Transportation engineering, Transportation and communications
The opening of the Qiongzhou Strait during the Holocene was a significant geological event in the Beibu Gulf, profoundly influencing sediment provenance and ocean circulation systems. Due to the scarcity of geological records documenting this event, the understanding of regional Holocene sedimentary evolution has been constrained. To investigate the impact of this event on sediment provenance and ocean currents in the Beibu Gulf, geochemical analyses were conducted on sediment core SO-31 retrieved from the South China Sea. The sediments in core SO-31 were stratigraphically divided into three units based on vertical geochemical profiles, reflecting changes in sea level and shifts in sediment provenance within the study area. The Th/Cr vs. Th/Sc scatter plot for core SO-31 indicate that sedimentary materials primarily originated from the Red River during 11,400–7700 a BP, and a significant change in provenance occurred in the study region around 7700 a BP, characterized by increased contributions from the Qiongzhou Strait and decreased contributions from the Red River. This suggests that the opening of the Qiongzhou Strait significantly influenced the sediment supply to the central Beibu Gulf around 7700 a BP. These findings provide critical geochemical evidence for studying the Qiongzhou Strait opening event and enhance our understanding of Holocene sedimentary evolution and “source–sink” transitions in the Beibu Gulf.
Generating realistic and diverse driving scenarios is essential for effective scenario-based testing and validation in autonomous driving and the development of driver assistance systems. Traditionally, parametric models are used as standard approaches for scenario generation, but they require detailed domain expertise, suffer from scalability issues, and often introduce biases due to idealizations. Recent research has demonstrated that AI models can generate more realistic driving scenarios with reduced manual effort. However, these models typically focused on single scenario types, such as cut-in maneuvers, which limits their applicability to diverse real-world driving situations. This paper, therefore, proposes a unified generative framework that can simultaneously generate multiple types of driving scenarios, including cut-in, cut-out, and cut-through maneuvers from both directions, thus covering six distinct driving behaviors. The model not only learns to generate realistic trajectories but also reflects the same statistical properties as observed in real-world data, which is essential for risk assessment. Comprehensive evaluations, including quantitative metrics and visualizations from detailed latent and physical space analyses, demonstrate that the unified model achieves comparable performance to individually trained models. The shown approach reduces modeling complexity and offers a scalable solution for generating diverse, safety-relevant driving scenarios, supporting robust testing and validation.
The destroying of Tafel region in many cases is not due to complication u'ith mass transfer , but
due to IR - drop effsct specially in dilute solutions ( i.e., of high resistivity) . Accordingly, the
corrosion behavior of reinforcement in reinforced concrete was investigated using electro -
chemical measurements. The work was carried out with small steel rods: cleaned and previously
oxidized embedded in resistance Portland cement concrete cylinders exposed to dry conditions' In
this investigation a theoretical model equation has been adopted including IR- drop term:
AE =AEA +RAi = -bclogicorr.+ bclog/Ai/+R /Ai/
In order to determine corrosion paiameters of iystem investigated (i.e., icorr., bc, and Rc. A)
equation above was based on the analysis of cathodic Polarization curve free from mass transf'er
effect .It has been found that the corrosion curent of pre- oxidized steel is higher than the cleaned
one , and this corrosion rate is concrete contaminant & time of exposure dependant. because of the
importance of electrical resistance of concrete & its relationship to the corrosion rate of reinforcing
steel. An attempt was made to find this resistance from the IR-drop term in the above mentioned
equation.
As a result of the growth of economic, demographic and building activities in Iraq, that necessitates carrying out geotechnical investigations for the dune sand to study behavior of footings resting on these soils. To determine these properties and to assess the suitability of these materials for resting shallow foundation on it, an extensive laboratory testing program was carried out. Chemical tests were carried out to evaluate any possible effects of the mineralogical composition of the soil on behavior of foundation rested on dune sands.
Collapse tests were also conducted to trace any collapse potential. Loading tests were carried out for optimum water content and different shapes of footing. Loading test recommends manufacturing of steel box and footing models with different shapes and dimensions. The results indicated that, Affek dune sand is predominantly fine sand with non-plastic fines.
Because the content of sulphate (as SO3) is only 0.05%, and the alkalinity of dune sand, which reduces the corrosion potential, ordinary Portland cement can be used in concrete foundation construction in/on dune sands. The results of collapsing tests showed that Affek dune sand exhibit a slight to moderate potential depending on stress level. Due to Soaking by water, the reduction in bearing capacity of optimum state was about 45%. The bearing capacity of square footing was greater than those of the circular and rectangular footings.