The complexity and uncertainty of construction projects contribute to low efficiency in the construction industry. This research applied the Takt-time planning method to optimize the construction working process, and proposed a risk control framework based on Value at Risk (VaR) and Conditional Value at Risk (CVaR) approaches to explore and predict a project schedule and cost performance under different scenarios. This research selected a high-rise residential building project for a case study and collected 1672 productivity data samples. Arena Simulation models were established based on 90 combinations of labor assignments to assess Takt-time planning strategies’ impact on project performance in four scenarios. The VaR and CVaR evaluations at 75% and 90% confidence levels were compared to balance project benefits and risks. Without any overtime or additional workers, this research found a Takt-time planning method that can reduce the project duration by 20.2% and labor costs by 2.1% at the same time, using a labor assignment of 12 bar placers, 12 carpenters, and 5 pipefitters. The findings can assist construction managers to achieve a shorter duration, reduced cost, and safer work environment, which will be very effective and beneficial to improve project overall performance.

Rapidly growing construction markets in China and the United States have provided opportunities for contractors to venture into foreign industries. To help project managers understand the fundamental difference in culture and the way projects are managed, it is useful and critical to reveal and compare the causes of delay and construction management practices in China and the US. The research is aimed at identifying and comparing the most prevalent reasons for task-level delay between the two countries, as perceived by various levels of management, and understanding how the culture and tradition influence management practice and performance. A questionnaire survey for public projects contracted to civilian construction companies was administered to contractors, 150 usable responses from China were collected, and the results were compared to the results from a similar survey in the US. The contributions are quantitatively examining the essential constituents causing task delay, discovering the root causes and key differences in construction management culture between the two countries, and developing strategies to help contractors minimize possible task delay when working in different culture and environments. The findings will help construction managers learn the essential differences in culture and their impact on the ways of project operation so that they can take proactive actions to interact with project managers from different counties to minimize delays.

Uncovered muck truck detection aims to detect the muck truck and distinguish whether it is covered or not by dust-proof net to trace the source of pollution. Unlike traditional detection problem, recalling all uncovered trucks is more important than accurate locating for pollution traceability. When two objects are very close in an image, the occluded object may not be recalled because the non-maximum suppression (NMS) algorithm can remove the overlapped proposal. To address this issue, we propose a Location First NMS method to match the ground truth boxes and predicted boxes by position rather than class identifier (ID) in the training stage. Firstly, a box matching method is introduced to re-assign the predicted box ID using the closest ground truth one, which can avoid object missing when the IoU of two proposals is greater than the threshold. Secondly, we design a loss function to adapt the proposed algorithm. Thirdly, a uncovered muck truck detection system is designed using the method in a real scene. Experiment results show the effectiveness of the proposed method.

To investigate the mechanical performance of large plate girders used in boiler-supporting steel structures under eccentric loading, nine 1:5-scaled closed-section HK-type and open-section π-type specimens were designed and tested. The specimens had a span of 5960 mm, an overall length of 6220 mm, and a depth of 1760 mm. Concentric loading and eccentric loading with eccentricities of 30 mm, 60 mm, and 90 mm were considered. The results show that under eccentric loading, the mid-span displacement increased with increasing eccentricity for both HK-type and π-type specimens. Compared with π-type specimens, HK-type specimens exhibited smaller mid-span displacements and higher secant stiffness under the same eccentric loading conditions, indicating better deformation resistance. At a load level of 3000 kN, the secant stiffness of the HK-type specimen decreased from 192.31 kN/mm to 172.81 kN/mm as the eccentricity increased from 0 mm to 90 mm, while that of the π-type specimen decreased from 156.57 kN/mm to 142.18 kN/mm. The measured transverse brace stresses of π-type specimens were higher than those of HK-type specimens, indicating stronger interaction between the π-type girder and the lateral-restraint system under the applied eccentric-loading conditions. Under the adopted eccentric loading and lateral restraint conditions, the HK-type specimens exhibited smaller mid-span displacements, higher absolute secant stiffness, and lower transverse-brace stresses than the corresponding π-type specimens. This study provides experimental data for understanding the deformation behavior, torsional response, and stiffness degradation of large plate girders in boiler-supporting steel structures.

High-frequency monitoring networks raise an alarm whenever a measured value crosses a regulatory threshold, and each alarm consumes scarce investigative capacity; unreliable alarms spend that capacity chasing non-events, yet how reliably these alarms indicate actionable pollution is rarely audited against what field investigators actually find. We audit an operational alarm stream against its own verification records to (i) quantify how many alarms reflect an actionable point-source discharge, (ii) identify the mechanism behind the rest, and (iii) determine how much investigative effort can be recovered. Pairing 281,039 station-hours from a 25-station Chinese river network with investigators’ conclusions for 702 of 1049 alarms, two coders independently coded the narratives (Cohen’s kappa 0.807); only 7.7% of the 428 station-matched modeling alarms (20 of 101 verification-narrative groups) recorded an actionable discharge. Dissolved-oxygen exceedances cluster before dawn (Rayleigh R = 0.311) and scale with temperature, consistent with a strong diel metabolic contribution, though hydrological and anthropogenic oxygen demand cannot be excluded. Under leakage-free validation, no signal-based model beat a station base-rate prior that uses no monitoring data; a simulated triage nonetheless de-prioritizes about two-thirds of narrative groups while retaining 18 of 20 confirmed discharges. We conclude that alarm reliability, not monitoring volume or model complexity, governs the sustainability value of smart-water systems.