Search Results (163)

Musculoskeletal disorders (MSDs) remain one of the most persistent occupational health challenges in the U.S. construction industry, where physically demanding tasks such as heavy lifting, kneeling, and working in awkward postures contribute to elevated injury rates. This study aims to identify significant job-related determinants of MSDs in construction-sector occupations. By integrating publicly available datasets from the Survey of Occupational Injuries and Illnesses (SOII) and the Occupational Information Network (O*NET) datasets, a stepwise multiple regression analysis was conducted on 344 occupation-condition observations representing 86 construction occupations, yielding a final model that explained 49% of the variance. Ten significant predictors of MSD events were identified and classified as either risk amplifiers or mitigators. Amplifiers included factors such as exposure to noise, disease, hazardous conditions, and time pressure, all of which heightened MSD risk, while mitigators—such as reduced cramped-space exposure and regulated work environments—were associated with lower risk. MSDs resulting from sprains, strains, or tears accounted for 62.8% of all cases, frequently leading to days away from work (36.3%) or job restrictions (26.5%). The findings underscore that ergonomic risk in construction extends beyond physical strain to include scheduling, equipment design, and work organization. These results provide actionable insights for employers and safety professionals to redesign tools, optimize task rotation, and implement realistic work pacing strategies, ultimately reducing MSD incidence and improving productivity in this high-risk sector. Full article

Wind-induced response poses a significant challenge to the stability of extra-large-span heavy steel box girders during synchronous lifting operations. This study adopted a method combining numerical simulation with on-site monitoring to investigate the aerodynamic characteristics the beam during the overall hoisting process of the Xiaotun Bridge. A high-fidelity finite element model was established using Midas NFX 2024 R1, and fluid–structure interaction (FSI) analysis was conducted, utilizing the RANS k-ε turbulence model to simulate stochastic wind fields. The results show that during the lifting stage from 3 m to 25 m, the maximum horizontal displacement of the steel box girder rapidly increases at wind angles of 90° and 60°, and the peak displacement is reached at 25 m. Under a strong breeze at a 90° wind angle and 25 m lifting height, the maximum lateral displacement was 42.88 mm based on FSI analysis, which is approximately 50% higher than the 28.58 mm obtained from linear static analysis. Subsequently, during the 25 m to 45 m lifting stage, the displacement gradually decreases and exhibits a linear correlation with lifting height. Concurrently, the maximum stress of the lifting lug of the steel box girder increases rapidly in the 3–25 m lifting stage, reaches the maximum at 25 m, and gradually stabilizes in the 25–45 m lifting stage. The lug stress under the same critical condition reached 190.80 MPa in FSI analysis, compared with 123.83 MPa in static analysis, highlighting a significant dynamic amplification. Furthermore, the detrimental coupling effect between mechanical vibrations from the lifting platform and wind loads was quantified; the anti-overturning stability coefficient was reduced by 10.48% under longitudinal vibration compared with lateral vibration, and a further reduction of up to 39.33% was caused by their synergy with wind excitation. Field monitoring validated the numerical model, with stress discrepancies below 9.7%. Based on these findings, a critical on-site wind speed threshold of 9.38 m/s was proposed, and integrated control methods were implemented to ensure construction safety. During on-site lifting, lifting lug stresses were monitored in real time, and if the predefined threshold was exceeded, contingency measures were immediately activated to ensure a controlled termination. Full article

Accurate interpretation of multimodal wearable data remains challenging in occupational environments due to heterogeneous sensing modalities, motion artifacts, and dynamic work conditions. This study proposes and validates an adaptive multimodal clustering framework for occupational health monitoring. The framework jointly models physiological, activity, and location data from 24 highway-maintenance workers, incorporating a silhouette-guided feature-weighting mechanism, multi-scale temporal change-point detection, and KDE-based spatial analysis. Specifically, the analysis identified three distinct and interpretable behavioral–physiological states that exhibit significant physiological differences (p < 0.001). Notably, it reveals a predominant yet heterogeneous baseline state alongside acute high-intensity and episodic surge states, offering a nuanced view of occupational risk beyond single-modality thresholds. The integrated framework provides a principled analytical workflow for spatiotemporal health risk assessment in field settings, particularly for vibration-intensive work scenarios, while highlighting the complementary role of physiological indicators in low- or static-motion tasks. This framework is particularly effective for vibration-intensive tasks involving powered tools. However, to mitigate potential biases in detecting static heavy-load activities with limited wrist motion (e.g., lifting or carrying), future extensions should incorporate complementary weighting of physiological indicators such as heart rate variability. Full article

In agricultural workplaces, upper-body strain arises not only from lifting and carrying harvest crates but also from pushing, pulling, twisting, and squatting motions. Drawing inspiration from the momentary shoulder contraction and whole-body coordination characteristic of traditional Japanese martial arts, this study proposes a method for “moving efficiently with minimal exertion” across multiple task actions, specifically, lateral pushing, fore-aft pulling, and trunk rotation. Each action is modeled as a control system, and mechanical-engineering simulations are employed to derive optimal muscle-output patterns. Simulation results indicate that peak muscular force can be lowered compared with conventional techniques. A simple physical test rig confirms the load-reduction effect, showing decreases in both perceived exertion and electromyographic activity. These findings offer practical knowledge that can be immediately applied not only to agriculture but also to logistics, nursing care, and other settings involving repetitive handling of heavy objects or machine operations. Full article

Automated storage and retrieval systems for long and heavy unit loads (LH AS/RSs) are already applied in industrial environments. However, the existing literature does not provide quantitative analyses of how the load-mass distribution influences energy consumption and energy regeneration. The present study addresses this gap by implementing an analytical model and developing an advanced simulation model that evaluates how the mass distribution of transport unit loads (TULs) affects the energy behaviour of LH AS/RSs. The model considers three velocity profiles under two storage strategies: random storage and class-based storage. The class-based storage strategy incorporates vertical mass-based zoning, in which the storage height of each TUL is assigned according to the statistical distribution of TUL masses. The simulation results show that mass-based zoning can reduce energy consumption by up to 9% for the combined movement of the stacker crane and lifting platform and by up to 11% for the vertical movement of the lifting platform alone. In addition, both the random and class-based storage strategies achieve approximately 35% energy regeneration. These findings provide the first explicit quantification of the energy savings achievable through mass-based vertical zoning in LH AS/RSs and offer practical guidance for warehouse designers and managers on how to leverage TUL mass distribution when selecting storage strategies and configuring storage rack layouts to improve energy efficiency, support sustainability goals, and enhance LH AS/RS performance. Full article

The increasing size and weight of deep-water topside modules necessitate reliable and efficient installation methods. The twin-barge float-over technique presents a viable alternative to conventional heavy-lift operations; however, its critical tri-vessel load transfer phase involves complex hydrodynamic interactions and continuous load redistribution that are not adequately captured by traditional staged analyses. This study develops a fully coupled time-domain dynamic model to simulate this process. The framework integrates multi-body potential flow hydrodynamics, mooring and fender systems, and Deck Support Units (DSUs). A novel continuous mass-point variation method is introduced to replicate progressive ballasting and the dynamic load transfer from single- to dual-barge support. Numerical simulations under representative sea states reveal significant narrow-gap resonance effects, direction-dependent motion amplification, and transient DSU load peaks that are overlooked in conventional quasi-static approaches. Beam-sea conditions are found to induce the largest lateral DSU loads and the highest risk of barge misalignment. The proposed framework demonstrates superior capability in predicting motion responses and load transitions, thereby providing critical technical support for the safe and efficient application of twin-barge float-over installations in complex marine environments. Full article

In 1897, King Leopold II of Belgium opened the Brussels International Exposition, which, in the Palace of the Colonies, showcased objects and people from the Congo Free State. They were displayed as the property of the King, who was the founder and sole owner of the Congo Free State from 1885 to 1908. The Palace of the Colonies was a combination of classically inspired imperial architecture and references to the Congo. The exposition was a huge success. As a result, the King built Africa Palace, a permanent ethnographic museum dedicated to his idea of Congo. It was located adjacent to his palace in Tervuren, now a suburb outside of Brussels. In 2018, the museum reopened as AfricaMuseum. This paper examines the inherent colonial frame of AfricaMuseum, both physically and ideologically, that continue to limit a significant socio-political shift for the museum, and the contemporary art pieces by Congolese and Burundian artists that have been tasked with the heavy lifting in shifting the narrative. Full article

This paper introduces a structured methodology for bridging the gap between theoretical modeling and high-fidelity simulation of multirotor Unmanned Aerial Systems (UAS) through the construction of digital twins in PX4 v1.12 Software-in-the-Loop (SITL) environments. A key challenge addressed is the absence of standardized procedures for translating physical UAV characteristics into simulation-ready parameters, which often results in inconsistencies between virtual and real-world behavior. To overcome this, we propose a hybrid parametric identification pipeline that combines analytical modeling with experimental characterization. Critical parameters—such as inertial properties, thrust and torque coefficients, drag factors, and motor response profiles—are obtained through a combination of physical measurements and theoretical derivation. The proposed methodology is demonstrated on a custom-built heavy-lift quadrotor, and the resulting digital twin is validated by executing autonomous missions and comparing simulated outputs against flight logs from real-world tests. Full article

This study introduces a computational framework that formalizes rollover risk in heavy-duty vehicles by integrating simulation-informed physical modeling with sensor-driven decision logic. The approach combines high-fidelity fluid–structure interaction modeling (via CFD) with multibody vehicle dynamics simulations to capture the complex behavior of rotating, partially filled mixer tanks under dynamic conditions. Rollover thresholds were identified by extracting the maximum safe speeds across a range of maneuvers (e.g., steady-state turning and step steering), using tire lift-off as the critical indicator. These thresholds were then formalized into decision rules using onboard sensor data, such as lateral acceleration, steering input, and tank rotation speed, allowing a real-time rollover warning system to continuously compare current vehicle states against critical limits. By systematically extracting critical force and moment responses and translating them into limit values provided by conventional onboard sensors (lateral acceleration, roll angle, steering input), the framework bridges high-fidelity simulation and real-time monitoring. A concrete truck mixer is used as a case study to demonstrate the utility of this approach in formalizing rollover thresholds for real-world decision support. Beyond the specific vehicle type, this work contributes to the broader discourse on how computational methods can contribute to new control or assistance strategies for safety-critical systems. Full article

This study conducts a diagnostic analysis of an extremely heavy rainfall event and its causative factors that occurred in Libya, North Africa on 10 September 2023. The Weather Research and Forecasting (WRF) model was also employed to perform some sensitivity experiments for this heavy rainfall event and further reveal its causes. Results indicate that the primary synoptic system responsible for this extreme precipitation event was an extratropical cyclone (storm) named “Daniel”. During the formation and development of this cyclone, the circulation at the 500 hPa level from the eastern Atlantic to western Asia exhibited a stable “two troughs and one ridge” pattern, with a upper-level cold vortex over the eastern Atlantic, a high-pressure ridge over central Europe, and a cut-off low over western Asia, collectively facilitating the formation and development of this cyclone. As this cyclone moved southward, it absorbed substantial energy from the Mediterranean Sea; following landfall, the intrusion of weak cold air enabled the cyclone to continue intensifying. Meanwhile, the northwest low-level jet stream to the west of the extratropical cyclone moved alongside the cyclone to the coastal regions of northeastern Libya, where it converged with water vapor transport belts originating from the Ionian Sea, the Aegean Sea, and the coastal waters of northeastern Libya. This convergence provided abundant water vapor for the rainstorm event, and under the combined effects of convergence and orographic lifting on the windward slopes of the coastal mountains, extreme precipitation was generated. In addition, the atmosphere over the coastal regions of northeastern Libya exhibited strong stratification instability, which was conducive to the occurrence of extreme heavy precipitation. Although WRF successfully reproduced the precipitation process, the precipitation amount was underestimated. Sensitivity experiments revealed that both the topography in the precipitation area and the sea surface temperature (SST) of the Mediterranean Sea contributed to this extreme heavy precipitation event. Full article

This paper, based on the CFD-DPM model coupled with sliding grid technology, constructs a simulation analysis method for the aerodynamic effects of propellers and wings under heavy rainfall. The mechanism of the influence of raindrops on the aerodynamic characteristics of this configuration is deeply analyzed, and the influence of the laws of different rainfall parameters is explored. The conclusion indicates that the local attack angle of the propeller decreases due to the influence of the falling speed of raindrops, resulting in a decrease in blade thrust and a maximum loss of 2.35%. The torque increases due to the increase in the rotational drag of the propeller. The maximum torque increment reaches 2.15%. With a decrease in the local angle of the attack and the effects of raindrop impact, film covering, and splashing, the maximum lift loss is 1.84%, and the drag increases by more than 12%. Raindrops will further influence the pitching, rolling, and yawing moment variation effect, combined with the rotation of the propeller. The greater the terminal velocity, diameter, and rainfall are, close to the surface of the propeller–wing combination configuration, the more severe the deterioration of the blade performance, and the stronger the lift reduction, drag increase, and moment variation effects of the wing. Full article

This study investigates the multi-scale processes associated with one type of typical heavy rainfall event in North China, focusing on the interplay among synoptic circulation, mesoscale dynamics, and topographic influences. The synoptic setting, characterized by the East Asian Great Trough, the South Asian High, and a northward-extended Western Pacific Subtropical High, created favorable conditions for moisture transport and convective activity. The event unfolded in two distinct phases: nocturnal and afternoon phases. During the nocturnal phase, an intensified 850 hPa low-level jet transported substantial meridional moisture into North China. Terrain-induced convergence along the Taihang Mountains enhanced lifting, resulting in concentrated precipitation at the foothills. In contrast, during the afternoon phase, the eastward movement of a Mongolian low trough and its associated cyclonic circulation shifted rainfall toward the plains east of the Taihang Mountains. Convective clusters developed locally due to surface heating and were organized along the low-level jet on the eastern flank of the cyclone, further intensifying precipitation. These results underscore three key mechanisms: nocturnal low-level jet-driven moisture convergence, synoptic-scale trough propagation, and terrain-modulated mesoscale convection. Understanding their diurnal variability offers valuable insights for operational forecasting, monitoring, and early warning systems for high-impact rainfall events in North China. Full article

As offshore wind power moves into deeper waters, large-scale electrical platforms are key to efficient power transmission. However, their heavy topside modules create major installation challenges. As traditional lifting methods are inadequate, the float-over method has become a viable solution for installing topside modules, but it is essential to study the structural responses to collisions during the process to ensure construction and equipment safety. This study establishes a physical model of the offshore converter station at a 1:65 scale based on the elastic force-gravity similarity principle. Assuming the barge carrying the topside module descends at a constant speed, the study investigates the dynamic response of the platform during the float-over mating process. Float-over collision tests are conducted to obtain the platform’s acceleration, strain, and displacement responses and to analyze the effects of collision speed, offset position, and Leg Mating Unit (LMU) stiffness on the dynamic structural response characteristics. The results show that as collision speed increases from 10 mm/s to 50 mm/s, the topside acceleration response increases up to 5.7 times. Beam strain remains mostly unchanged, and displacement increases first, then decreases. Under fixed descent velocity, x-offset increases jacket strain and converter valve acceleration, while y-offset raises platform acceleration and reduces valve acceleration by approximately 20 percent. At 50 mm/s, higher LMU stiffness causes the acceleration response to first drop, then rise. These findings support safe float-over installation. Full article

Offshore reservoirs in the high water-cut stage present significant development challenges, including declining production, complex remaining oil distribution, and the inadequacy of conventional evaluation methods to capture intricate flow dynamics. To overcome these limitations, this study introduces a novel approach based on flow diagnostics for performance evaluation and potential adjustment. The method integrates key metrics such as time-of-flight (TOF) and the dynamic Lorenz coefficient, supported by reservoir engineering principles and numerical simulation, to construct a multi-parameter evaluation system. This system, which also incorporates injection–production communication volume and inter-well fluid allocation factors, precisely quantifies and visualizes waterflood displacement processes and sweep efficiency. Applied to the QHD32 oilfield, this framework was used to establish specific thresholds for operational adjustments. These include criteria for infill drilling (waterflooded ratio < 45%, remaining oil thickness > 6 m, TOF > 200 days), conformance control (TOF < 50 days, dynamic Lorenz coefficient > 0.5), and artificial lift optimization (remaining oil thickness ratio > 2/3, TOF > 200 days). Field validation confirmed the efficacy of this approach: an additional cumulative oil production of 165,600 m³ was achieved from infill drilling in the C29 well group, while displacement adjustments in the B03 well group increased oil production by 2.2–3.8 tons/day, demonstrating a significant enhancement in waterflooding performance. This research provides a theoretical foundation and a technical pathway for the refined development of offshore heavy oil reservoirs at the ultra-high water-cut stage, offering a robust framework for the sustainable management of analogous reservoirs worldwide. Full article

With the rapid expansion of offshore wind power, efficient installation methods for 10 MW offshore wind turbines (OWTs) are increasingly being required. Conventional approaches using installation vessels, heavy-lift barges, and mooring systems incur high costs, long schedules, and weather-related constraints, particularly in harsh seas such as the West Sea and Jeju. This study investigates an anchor-free installation method for jack-up-type OWTs employing tugboats instead of specialized vessels. Environmental loads were estimated with MOSES and AQWA, and frequency-domain analyses were performed to evaluate wave responses and towline tensions. Results showed that maximum tensions remained below both the Safe Working Load of towlines and the Effective Bollard Pull of tugboats during all spudcan lowering stages. Even under conservative OPLIM conditions, feasibility was confirmed. The findings indicate that the proposed tug-assisted method ensures adequate station-keeping capability while reducing cost, construction time, and weather dependency, presenting a practical alternative for large-scale OWT installation. Full article