AbstractBecause of labor-intensive and physically demanding tasks, construction workers are known to be at a higher risk of developing physical fatigue. Recent studies have shown that construction ...workers are also often exposed to considerable mental stresses. While a number of studies have proposed methods and tools to measure and monitor physical and mental stress disjointedly, there is a need to explore their interaction. The literature indicates that no previous study has endeavored to evaluate the effect of mental stress on physical stress for construction tasks. This investigation is necessary to better comprehend work demands of construction tasks. Accordingly, entailing a randomized crossover design and simulated manual material handling experiment, this study evaluated the effect of cognitive task-led mental stress on physical stress using both subjective (ratings of perceived exertion) and objective measures (heart rate, skin temperature, and skin conductance). The results revealed that cognitive task-led mental stress led to a significant increase in subjective ratings of perceived exertion accompanied by an increase in skin temperature and skin conductance, while heart rate remained unaffected. The findings of this study add to the body of knowledge by highlighting that traditional benchmarking of task demands using only physiological measures may not be comprehensive. Rather, it might be suggested that additional psychological measurements are also essential because they might affect physical stress development. Furthermore, the current study has increased our understanding related to the interaction of physical and mental stress by revealing interindividual differences among the participants. Accordingly, by examining each worker separately, practitioners and safety managers can develop better mitigation strategies and individualized training programs, especially for more vulnerable workers, which can enhance overall health and safety on construction job sites.
The current systematic review aimed to summarize prevalence rates of work-related musculoskeletal disorders (WRMSDs) and quantify the associations between physical or psychosocial risk factors and ...WRMSDs in construction workers. Literature searches were conducted in Web of Science, PubMed, Medline, CINAHL, and EMBASE from January 1, 2000 to September 30, 2020. The methodological quality of the included studies was assessed by a validated risk of bias assessment tool used in population-based prevalence studies. Nineteen cross-sectional studies and one cohort study involving 194,863 participants were included. Eleven, five, and four included studies were classified as having high, moderate, and low quality, respectively. The 12-month prevalence rates of WRMSDs in construction workers were high (ranging from 25% to 96%). There was strong evidence to support the relationships between awkward postures (e.g., twisting, bending, or cramping positions) odd ratio (OR) = 2.4, manual material handling (MMH) (OR = 2.2), prolonged works (OR = 4.0), high job demands (OR =1.6) or mental stress (OR =1.8) and WRMSDs in construction workers. Additionally, there was moderate evidence for the associations between overhead works (OR = 3.1), use of vibration (OR = 3.2), or low job satisfaction (OR = 1.5) and WRMSDs in construction workers. Furthermore, there was very limited evidence for the associations between repetitive works, low job control, or high job insecurity and WRMSDs in construction workers. Although many physical and psychosocial risk factors were associated with WRMSDs in construction workers, the causal relationships between these factors and the prevalence of WRMSDs remain unclear. Future prospective studies should determine whether these factors can predict future WRMSDs and whether the modification of these factors can reduce the incidence and/or prevalence of WRMSDs in construction workers.
CRD42019135027.
•Work-related musculoskeletal disorders (WRMSDs) are common in construction workers.•This review updated the prevalence rates of WRMSDs in construction workers.•This review summarized new evidence regarding the risk factors of WRMSDs.•There were associations between some physical or psychosocial factors and WRMSDs.
•Laboratory simulated loss of balance events are conducted.•Wearable insole pressure system was used for data collection.•Four main spatial foot regions are detected from foot plantar pressure ...patterns.•Significant changes in biomechanical gait stability parameters are reported.
Falls on the same level are a leading cause of non-fatal injuries in the construction industry, and loss of balance events are the primarily contributory risk factors associated with workers’ fall injuries. Previous studies have indicated that changes in biomechanical gait stability parameters provide substantial safety gait metrics for assessing workers’ fall risks. However, scant research has been conducted on changes in biomechanical gait stability parameters based on foot plantar pressure patterns to assess workers’ fall risks. This research examined the changes in spatial foot regions and loss of balance events associated with biomechanical gait stability parameters based on foot plantar pressure patterns measured by wearable insole pressure system. To test the hypotheses of this study, ten asymptomatic participants conducted laboratory simulated loss of balance events which are often initiated by extrinsic fall risk factors. Our results found: (1) statistically significant differences in biomechanical gait stability parameters between spatial foot regions, especially with the peak pressure parameter; and (2) statistically significant differences in biomechanical gait stability parameters between loss of balance events when compared to normal gait (baseline), especially with the pressure-time integral parameter. Overall, the findings of this study not only provide useful safety gait metrics for early detection of specific spatial foot regions but also allow safety managers to understand the mechanism of loss of balance events in order to implement proactive fall-prevention strategies.
The sandwich foam materials of wind turbine blades are mainly polyvinyl chloride (PVC) and styrene–acrylonitrile (SAN) foams due to their good mechanical properties. However, PVC foam is unrecyclable ...and not resistant to high‐temperature conditions, while SAN foam is more expensive than PVC foam. Polyethylene terephthalate (PET) has irreplaceable advantages than both PVC and SAN foams because of its better mechanical performance, fantastic heat‐resistant, low cost, and environmental friendliness (100% recyclability). In this article, the mechanical properties, thermal stability, resin uptake, and cellular morphology of PET T92, PVC H60, and SAN T400 foams were discussed. The results showed that the mechanical properties of T92 were equivalent to the existing H60 and T400, and even exceed their properties. It was found that the thermal stability of T92 was better than H60 and T400 under the same high temperature. Moreover, the pore of T92 was more uniform and regular than H60 and T400. Furthermore, the overall cost of T92 was lower than H60 and T400. The findings suggest that PET foam with a density of 100 kg/m3 can completely replace PVC 60 kg/m3 and SAN 71 kg/m3 foams from the perspective of mechanical performance, cost, thermal stability, and environmental protection.
Polyformaldehyde (POM) and Polyamide 66 (PA66) are engineering plastics with excellent mechanical properties and thermal stability. Producing microcellular injection molded POM and PA66 parts with ...high dimensional accuracy would be beneficial to reduce material cost and product quality. In this research, foamed POM and PA66 gear parts were fabricated by using microcellular injection molding with supercritical nitrogen as the blowing agent. Compared to conventional injection molded parts (parts that foaming is not involved), the foamed POM and PA66 gear parts achieved 5% and 10% average weight reduction, respectively. The foamed parts displayed a lower shrinkage ratio when compared to the solid counterparts, which was attributed to the cell expansion that offset part of the inward shrinkage stress. Moreover, POM gear parts with a higher crystallinity degree presented more serious shrinkage ratio compared to the PA66 gear parts, which contributed to the denser polymer molecular chains arrangement. The shrinkage ratio in both directions of PA66 foamed gear parts depended on the injection volume, and the lowest shrinkage ratio of 0.043‰ was obtained at the injection volume of 74 mm, when the polymer reached the maximum foaming ratio. The findings from this study could provide practical guidance for preparing microcellular injection molded products with high dimensional accuracy.
Microcellular injection molding is capable to reduce the shinkage ratio and enhance the dimensional accuracy of engineering plastics, such as PA and POM.
Display omitted
•PDA/CB composite non-woven PP fabric was prepared for solar energy harvesting.•Hierarchical structure and synergetic effects of CB/PDA contributed to high light absorbance.•The ...evaporation rate of 1.68 kg m-2h−1 with a solar steam efficiency of 91.5% was achieved.•The solar evaporator demonstrated superior salt resistance and ability to purify seawater and various wastewaters with high efficiency.
The utilization of solar energy for steam generation is a highly efficient and sustainable technology for seawater desalination to solve the long-standing water crisis. Carbon-based materials have shown promising thermal-heat conversion efficiency due to their broadband solar absorption. Herein, carbon black (CB) was combined with polydopamine (PDA) to develop a high-performance, low-cost, and scalable PDA/CB@PP composite non-woven fabric was fabricated by dip-coating of CB and in situ polymerization of PDA. The hierarchical structure constructed on the fiber surface and the synergetic effects of CB and PDA contributed to the high light absorbance (>95%), superhydrophilicity, and high energy conversion efficiency. The one-way fluidic PDA/CB@PP photothermal based solar steam evaporator demonstrated a high evaporation rate of 1.68 kg m-2h−1 with a solar steam efficiency of 91.5%. Moreover, the PDA/CB@PP fabric shows remarkable salt resistance when purifying seawater because of the water channel preserved by the hydrophilic porous structure of the fabric which could provide sustained water supply. Besides, the PDA/CB@PP fabric possesses excellent purification capability to wastewaters contaminated by heavy-metal and chemical dyes. This study provides insights into the design and development of low-cost, scalable, highly stable, and efficient solar steam generators for seawater desalination and wastewater purification.
Fall on the same level is the leading cause of non-fatal injuries in construction workers; however, identifying loss of balance events associated with specific unsafe surface conditions in a timely ...manner remain challenging. The objective of the current study was to develop a novel method to detect and classify loss of balance events that could lead to falls on the same level by using foot plantar pressure distributions data captured from wearable insole pressure sensors. Ten healthy volunteers participated in experimental trials, simulating four major loss of balance events (e.g., slip, trip, unexpected step-down, and twisted ankle) to collect foot plantar pressure distributions data. Supervised machine learning algorithms were used to learn the unique foot plantar pressure patterns, and then to automatically detect loss of balance events. We compared classification performance by varying window sizes, feature groups and types of classifiers, and the best classification accuracy (97.1%) was achieved when using the Random Forest classifier with all feature groups and a window size of 0.32 s. This study is important to researchers and site managers because it uses foot plantar pressure distribution data to objectively distinguish various potential loss of balance events associated with specific unsafe surface conditions. The proposed approach can allow practitioners to proactively conduct automated fall risk monitoring to minimize the risk of falls on the same level on sites.
•Laboratory simulated loss of balance events are conducted.•The proposed approach uses wearable insole pressure sensors.•Supervised machine learning algorithms were used to learn foot plantar pressure data.•Random forest classifier had the best classification performance.•This approach can serve as an automated fall risk monitoring tool.
By adopting a systematic literature and science mapping review, this paper aims to explore the impact of artificial intelligence (AI) on organizational justice and project performance. A total of 47 ...bibliographic records from the Scopus database were analyzed. The results revealed the annual publication trends of research articles and relevant peer-reviewed journals in the studied domain. It was found that while AI technology has made significant progress in several fields, its application areas in project management and organizational justice are still relatively low. Moreover, it objectively discussed the co-occurrence analysis of keywords, co-authors, countries/regions, and documents in the fields, revealing the current research topics. The main research topics include the (1) AI’s influence on organizational justice, decision analysis, and digital transformation, (2) fostering organizational justice and AI’s role in enhancing project performance, and (3) improving organizational performance approaches. Furthermore, this paper proposed research gaps and future research directions, including (1) advancing business intelligence strategies, (2) unlocking AI technology potential on organizational justice and project performance, (3) the adaption of cultural, diversity, environmental, and social factors, (4) the impact of AI on complex and challenging leadership styles, and (5) developing a comprehensive understanding of the agile framework. The findings of this paper could contribute to a better understanding of how AI shapes project/construction management and organizational justice, providing practical solutions for innovative development for researchers and policymakers.
•Physical exertion scales such as Borg-20 are not good surrogate for physical fatigue.•Physiological measures weakly correlated to fatigue compared to previous studies.•Multimodal physiological ...monitoring is better for accurate fatigue monitoring.
Physical fatigue has been recognized as a serious health and safety risk among construction workers. As a result, numerous studies have endeavored to monitor/predict it using physiological measures. While the results are promising, their methodologies seem inappropriate. First, many studies utilized inappropriate benchmarking methods for physical fatigue monitoring. Importantly, a few of them utilized physical exertion scales as a surrogate for physical fatigue benchmarking. Second, many of them collected data in highly structured tasks in controlled environments. To assess these potential flaws, this research monitored fourteen construction workers' fatigue onsite by gathering physiological measures and fatigue data simultaneously. The results show that while the physical exertion scale was on average moderately correlated with a valid physical fatigue scale (average correlation coefficient 0.65), correlation coefficients varied widely among workers with the lowest of 0.05 and the highest of 0.89. This variation could be attributed to numerous factors including nature of the task, pacing and breaks during work, and individual factors. This might suggest that the physical exertion scale cannot serve as a good surrogate for physical fatigue. Additionally, the results found that workers’ physiological measures were weakly correlated to fatigue than previous laboratory studies. Overall, this study contributes to the body of knowledge by highlighting the methodological issues in the previous studies related to physical fatigue monitoring using physiological measures and the need to re-evaluate the usefulness of the measures, entailing appropriate methods. More importantly, the current study has challenged the status quo for monitoring/predicting fatigue using physiological measures.
Significant developments in digital technologies can potentially provide managers and engineers with the ability to improve the quality of the construction industry. Acknowledging the current and ...future use of digital technologies in construction quality management (CQM), we address the following research question: What developments in digital technologies can be used to improve quality in the construction industry? In addressing this research question, a systematic review approach is used to examine the studies that have been used for the management of quality in the construction industry. This review indicates that there is a need for digital technology-based quality management to be: (1) enhance defect management for concealed work, (2) enhance pre-construction defects prevention as well as post-completion product function testing, and (3) research on construction compliance inspection as a direction. We suggest that future research focus on quality culture development, advanced data analytics, and behavioral quality assessment.
•Digital technologies for construction quality management are an emerging application field.•Quality defect identification and dimensional deviation on concrete and reinforcement inspection were most studied.•Numerous studies focused on the evaluation and measurement of apparent quality but lack attention to concealed works.•Lack of research on workers' operation onsite for automatically compliance check during the construction process.
PDF
