An integrated ergonomic risk assessment framework based on fuzzy logic and IVSF-AHP for optimising ergonomic risks in a mixed-model assembly line.

This study proposes a systematic approach to address ergonomic factors, including physical, environmental and psychosocial aspects, in solving assembly line balancing problems. A three-stage framework is developed, starting with determining weights for ergonomic risk assessment methods using the interval-valued spherical fuzzy analytical hierarchy process. In the second stage, a fuzzy logic model for integrated ergonomic risk assessment is constructed based on these weights, and the integrated ergonomic risk score is determined. In the third stage, a mathematical model is formulated to minimise the cycle time while balancing the ergonomic risk level. A case study conducted in a wire harness factory validated the effectiveness of the proposed approach, showing a 10-11% improvement in line efficiency and a 12-25% enhancement in ergonomic risk balancing performance. These findings underscore the potential benefits of implementing this approach, which can significantly improve occupational safety and overall performance.

This article presents a practical and systematic approach for enhancing ergonomic conditions in assembly lines. The proposed approach aims to balance the ergonomic risk level while minimising the cycle time by considering physical, environmental and psychosocial risk factors. A case study conducted in a wire harness factory demonstrated significant improvements in balancing ergonomic risks, highlighting the real-world applicability of this research.

The Ergonomic Behaviors Evaluation Tool (EBET) based on social cognitive theory for the assembly line workers: development and psychometric assessment.

BACKGROUND: Ergonomic behaviors play a crucial role in preventing work-related musculoskeletal disorders (WMSDs). To measure these behaviors, this research aimed to develop and evaluate an ergonomic behaviors tool (EBET) based on the Social Cognitive Theory (SCT) among women workers on assembly lines (WwAL). METHODS: The study was conducted from December 2022 to January 2023 with a focus on the psychometric assessment of EBET. Initially, a literature review and interviews were carried out to identify crucial concepts and primary items. The questionnaire's validity was evaluated using the Content Validity Ratio (CVR) and the Content Validity Index (CVI). To determine the domains of the tool, construct validity was examined by administering the items to 270 eligible women. The reliability of the tool was assessed using McDonald's Omega coefficient. RESULTS: From a total of 67 primary items, 50 were confirmed. The study demonstrated good validity with CVR = 0.92 and CVI = 0.97, along with reliable results indicated by McDonald's Omega coefficient of 0.74. The exploratory factor analysis (EFA) revealed ten distinct dimensions: outcome expectations, outcome expectancies, normative beliefs, perceived barriers, social support, observational learning, reinforcement, behavioral skills, self-efficacy, and intention. Together, these dimensions accounted for 66.25% of the variance in the data. Additionally, the confirmatory factor analysis results supported the presence of these ten constructs and demonstrated a satisfactory fit. CONCLUSIONS: EBET is a dependable and valid instrument for evaluating the ergonomic behaviors of workers, utilizing the principles of SCT. Researchers can employ EBET to gather data and implement suitable training interventions to enhance ergonomic behavior among WwAL. However, it is crucial to recognize that EBET may not encompass all facets of ergonomic behaviors. Therefore, it is imperative for future research to prioritize the evaluation of EBET's suitability among diverse worker populations and to consider additional dimensions of ergonomics to ensure its wider applicability and effectiveness.

Solution approach using heuristic and artificial neural networks methods in assembly line balancing problems: A case study in the lighting industry.

Assembly line efficiency is one of the most important parameters that determine the overall efficiency of a manufacturing company. The production of a product under optimum conditions is ensured by a balanced assembly. With a balanced assembly line, machinery, material and labour costs are reduced. Within the scope of this research, real data about the daily production capacity and assembly line efficiency of a company producing Emergency Luminaire were taken, the same assembly line was balanced with 4 different Heuristic ALB methods and the results were compared. According to the results obtained, a high line efficiency of 93.955% was achieved using the Hoffman, Comsoal and Moodie&Young (M&Y) methods, and 84.414% was achieved with the Ranked Positional Weight (RPW) method. As a result of this, it was observed that the daily production capacity increased from 250 units to 375 units. As a result of the study, it was revealed that the efficiency of the existing assembly line and accordingly the daily production capacity increased. In addition, the study results of this assembly line were taught to an artificial neural network model for training purposes, and the work station results of the operations of a different assembly line were obtained with 99.940 accuracy. In this context, it has been revealed that the artificial neural networks method can be used in addition to the use of the heuristic method in the solution of ALB problems.

Investigating product innovation pathway from a modular standpoint: A case study of large aircraft assembly line.

Product innovation is a robust approach for enterprises to acquire and maintain a competitive edge. In order to support the development of enterprise product innovation, it is essential to establish an innovation pathway. Grounded in a modular perspective and considering the product innovation process, this study segments the process into product demand analysis, product module partitioning, product innovation opportunity recognition, and product innovation design. Consequently, an integrated product innovation pathway is constructed by incorporating relevant innovation theories and methodologies, encompassing the innovation process, theory, and methods. The feasibility and efficacy of this research are validated through a case study of a large aircraft assembly line, indicating that this approach effectively bolsters product innovation development and holds practical significance.

Predictive factors of ergonomic behaviors based on social cognitive theory among women workers on assembly lines: application of Bayesian networks.

BACKGROUND: This study focuses on identifying the key factors associated with ergonomic behaviors (ERBE) among women workers on assembly lines (WwAL) to prevent musculoskeletal disorders (MSDs) caused by repetitive motions and unfavorable body postures. To achieve this objective, this study employed Bayesian networks (BN) analysis based on social cognitive theory (SCT). METHODS: A cross-sectional study was conducted to examine the predictive factors of ERBE among 250 WwAL from six different industries located in Neyshabur, a city in northeastern Iran. The study used a two-stage cluster sampling method for participant selection and self-report questionnaires to collect data on demographic characteristics, variables associated with SCT, ERBE, and the standard Nordic questionnaire. The collected data were analyzed using Netica and SPSS version 21, which involved statistical analyses such as independent t-tests, Pearson correlation, and ANOVA tests at a significance level of p < 0.05. BN analysis was conducted to identify the important factors that impact ERBE. RESULTS: The majority of individuals reported experiencing chronic pain in their back, neck, and shoulder areas. Engaging in physical activity, consuming dairy products, and attaining a higher level of education were found to be significantly associated with the adoption of ERBE p < 0.05. Among the various SCT constructs, observational learning, intention, and social support demonstrated the highest levels of sensitivity towards ERBE, with scores of 4.08, 3.82, and 3.57, respectively. However, it is worth noting that all SCT constructs exhibited a certain degree of sensitivity towards ERBE. CONCLUSIONS: The research findings demonstrate that all constructs within SCT are effective in identifying factors associated with ERBE among WwAL. The study also highlights the importance of considering education levels and variables related to healthy lifestyles when promoting ERBE in this specific population.

A novel competitive exact approach to solve assembly line balancing problems based on lexicographic order of vectors.

The assembly line balancing problem (ALBP) is an eminent NP-hard topic that is discussed in mass production systems with low diversity. Primarily, two types of ALBPs are discussed in the literature as type I, which aims to find the minimum number of workstations for a given cycle time, and type II, which assigns some tasks to a given number of workstations such that the maximum workstation load is minimized. To solve ALBPs, various exact, heuristic, and metaheuristic methods have been proposed. However, these methods lose their efficiency when handling large-size problems. Therefore, researchers have focused on proposing heuristic and metaheuristic algorithms to solve large-size problems, especially when they deal with real-life case problems in the industry. This study aims to present a novel and competitive exact method for solving ALBP type II based on the lexicographic order of vectors for feasible solutions. To evaluate the performance of the developed method, a group of highly used standard test problems in the literature is utilized, and the results are compared and discussed in detail. The computational results in this study specify that the developed solution approach performs efficiently and yields the best global solution of all the ALB test problems, which proves the proposed method's potential and its competitive advantage.

Understanding and Manipulating Assembly Line Biosynthesis by Heterologous Expression in Streptomyces.

Assembly line enzymes, including polyketide synthases and nonribosomal peptide synthetases, play central roles in the construction of complex natural products. Due to the sequential biochemistry processed in each domain, the domain architecture of the assembly line enzymes strictly correlates with the product molecule. This colinearity makes assembly line enzymes an ideal target for rational reprogramming. Although many of the past engineering attempts suffered from decreased product yield, recent advancements in the bioinformatic analysis and engineering design now provide new opportunity to work on these modular megaenzymes. This chapter describes the methods for analyzing and engineering the assembly line enzymes, including module and domain analysis needed for designing the engineering of assembly line biosynthesis, and the expression vector construction with an example of two-vector heterologous expression system in Streptomyces.

Visualizing transiently associated catalytic domains in assembly-line biosynthesis using cryo-electron microscopy.

While cryo-electron microscopy (cryo-EM) has revolutionized the structure determination of supramolecular protein complexes that are refractory to structure determination by X-ray crystallography, structure determination by cryo-EM can nonetheless be complicated by excessive conformational flexibility or structural heterogeneity resulting from weak or transient protein-protein association. Since such transient complexes are often critical for function, specialized approaches must be employed for the determination of meaningful structure-function relationships. Here, we outline examples in which transient protein-protein interactions have been visualized successfully by cryo-EM in the biosynthesis of fatty acids, polyketides, and terpenes. These studies demonstrate the utility of chemical crosslinking to stabilize transient protein-protein complexes for cryo-EM structural analysis, as well as the use of partial signal subtraction and localized reconstruction to extract useful structural information out of cryo-EM data collected from inherently dynamic systems. While these approaches do not always yield atomic resolution insights on protein-protein interactions, they nonetheless enable direct experimental observation of complexes in assembly-line biosynthesis that would otherwise be too fleeting for structural analysis.

Effect of a Simulated Heat Wave on Physiological Strain and Labour Productivity.

BACKGROUND: The aim of the study was to investigate the effect of a simulated heat-wave on the labour productivity and physiological strain experienced by workers. METHODS: Seven males were confined for ten days in controlled ambient conditions. A familiarisation day was followed by three (pre, during, and post-heat-wave) 3-day periods. During each day volunteers participated in a simulated work-shift incorporating two physical activity sessions each followed by a session of assembly line task. Conditions were hot (work: 35.4 °C; rest: 26.3 °C) during, and temperate (work: 25.4 °C; rest: 22.3 °C) pre and post the simulated heat-wave. Physiological, biological, behavioural, and subjective data were collected throughout the study. RESULTS: The simulated heat-wave undermined human capacity for work by increasing the number of mistakes committed, time spent on unplanned breaks, and the physiological strain experienced by the participants. Early adaptations were able to mitigate the observed implications on the second and third days of the heat-wave, as well as impacting positively on the post-heat-wave period. CONCLUSIONS: Here, we show for first time that a controlled simulated heat-wave increases workers' physiological strain and reduces labour productivity on the first day, but it promotes adaptations mitigating the observed implications during the subsequent days.

Nanoscale assembly line composed of dual DNA-machines enabling sensitive microRNA detection using upconversion nanoparticles probes.

DNA machines are smart artificial devices that perform well-organized DNA hybridization reactions or nanoscale mechanical movements. Herein, a nanoscale assembly line composing of dual DNA machines is meticulously designed by coupling a catalytic hairpin assembly (CHA)-based machine with a 3D DNA walker machine. Equipped with upconversion nanoparticles (UCNPs) as signal tags, the dual DNA machines-based assembly line (DDMAL) can efficiently amplify the fluorescent signal of target recognition event, enabling sensitive detection of microRNA (miRNA). In detail, once activated by target miRNA-21, the CHA machine is initiated to constantly produce a single-stranded DNA (named binding DNA) via the strand displacement reaction. The binding DNA as a trigger factor can initiate the DNA walker machine by linking a walking strand DNA with an anchor strand DNA immobilized on the surface of magnetic beads (MBs). The movement of walking strand on the surface of MBs is then driven by Mn2+-dependent DNAzyme formed through the hybridization of walking strand with a UCNPs-linked substrate strand. The DNAzyme-catalyzed cleavage of substrate strand is accompanied by the release of numerous UCNPs from MBs. By measuring the fluorescent signal of released UCNPs after the magnetic separation, target miRNA-21 can be detected by the DDMAL system in a linear range from 1.0 fM to 10 nM, with a limit of detection (LOD) of 0.62 fM (3σ). Moreover, the practicability of DDMAL system was demonstrated by using it to evaluate the expression levels of miRNA-21 in cell lines and assay miRNA-21 in human serum.

Residency Exposure to Emergency Medical Services Concepts Through Immersion, Interprofessional Collaboration and Assembly Line Education.

INTRODUCTION: The use of innovative strategies for teaching, such as flipped classroom and assembly line education, has become increasingly popular to engage learners. Residency education has been incorporating these methods to master content, develop critical skills, and improve professionalism. METHODS: We created a three-part immersion experience to teach Emergency Medical Services (EMS) concepts to emergency medicine residents. Residents participated in a mass casualty incident (MCI) in which they were tasked to triage patients and allocate resources in a hospital to treat 11 victims properly. The second portion was to manage a cardiac arrest scenario in the field with the tools our EMS colleagues had available. Lastly, they were asked to create short, high-yield lectures about topics related to EMS. RESULTS: Pre- and post-test surveys were used to assess the effectiveness of the experience in teaching residents core EMS topics. It was determined that residents not only felt more prepared for an MCI, but they also were more comfortable with their skills as a result of participating in this activity. CONCLUSION: Our study further highlights the benefits of non-traditional techniques in residency education. The use of immersion experiences was unique and overall a positive experience for learners. The techniques used in this activity allowed residents to gain confidence in more challenging topics for emergency physicians. This format could be applied to many more topics in the future as an innovative education technique.

Self-Reported Variables as Determinants of Upper Limb Musculoskeletal Symptoms in Assembly Line Workers.

BACKGROUND: Assembly lines work is frequently associated to work-related upper limb musculoskeletal disorders. The related disability and absenteeism make it important to implement efficient health surveillance systems. The main objective of this study was to identify self-reported variables that can determine work-related upper limb musculoskeletal symptoms-discomfort/pain-during a 6-month follow-up. METHODS: This was a prospective study with a 6-month follow-up period, performed in an assembly line. Upper limb musculoskeletal discomfort/pain was assessed through the presence of self-reported symptoms. Uni- and multivariate logistic regression analyses were used to evaluate which self-reported variables were associated to upper limb symptoms after 6 months at the present and to upper limbs symptoms in the past month. RESULTS: Of the 200 workers at baseline, 145 replied to the survey after 6 months. For both outcomes, "having upper limb symptoms during the previous 6 months" and "education" were possible predictors. CONCLUSION: Our results suggest that having previous upper limb symptoms was related to its maintenance after 6 months, sustaining it as a specific determinant. It can be a hypothesis that this population had mainly workers with chronic symptoms, although our results give only limited support to self-reported indicators as determinants for upper limb symptoms. Nevertheless, the development of an efficient health surveillance system for high demanding jobs should implicate self-reported indicators, but also clinical and work conditions assessment should be accounted on the future.

Adapted exercises versus general exercise recommendations on chronic low back pain in industrial workers: A randomized control pilot study.

BACKGROUND: Exercise has been demonstrated as effective for the treatment of low back pain (LBP) in workers. OBJECTIVE: The purpose of this study was to investigate whether an exercise program adapted to the characteristics of the workplace is a useful supplement to general exercise recommendations in assembly line workers with chronic LBP. METHODS: Workers were randomly assigned to intervention group-adapted exercises plus general exercise recommendations (n = 10), and control group-general exercise recommendations (n = 8). Both received 8-week exercise program through a mobile application (APP) to manage the intervention. Outcome was based on lumbar disability (Oswestry Disability Index), interference and lumbar pain intensity (Brief Pain Inventory), and kinematic parameters. RESULTS: Significant differences were obtained for the intervention group in the "pain interference" variable, in the "mood" and "enjoyment" sub-variables, as well as in "flexion angle" variable. For the control group, significant differences occurred in the "pain intensity" variable. Adapted exercise plus general recommendations seems more effective than the general recommendations for the improvement of lumbar flexion. CONCLUSIONS: An adapted exercise program for assembly line workers with chronic LBP could be an effective treatment. Future studies with a larger sample size and with an exhaustive control of the exercise adherence are required to confirm the findings of this pilot study.

A Smartphone Integrated Hand-Held Gap and Flush Measurement System for in Line Quality Control of Car Body Assembly.

This paper presents the design and the characterization of a portable laser triangulation measurement system for measuring gap and flush in the car body assembly process. Targeting Human in the Loop (HILT) operations in the manufacturing sector, and in line with the vision of human empowerment with Industry 4.0 technologies, the instrument embeds features to ease operators' activity and compensate possible misuse that could affect the robustness and the quality of data acquired. The device is based on a smartphone integrated with a miniaturized laser triangulation system installed in a cover. The device embodies additional sensors and control systems in order to guarantee operators' safety (switching on and off the laser line based on specific conditions), support operators during the measurement execution task, and optimize the image acquisition process for minimizing the uncertainty associated to the measurement. The smartphone performs on-board processing and allows Wi-Fi communication with the plant IT infrastructure. Compliance to Industry 4.0 requirements is guaranteed using OPC-UA (Open Platform Communications-Unified Architecture) communication protocol enabling the exchange of live data with the plant middleware. The smartphone provides also an advanced high-resolution color display and well proven and ergonomic human-machine interfaces, which have been fully exploited in the design. The paper introduces the system optical layout and then presents the algorithms implemented to realize the gap and flush measurement. The paper finally presents the calibration of the instrument and estimates its calibration uncertainty in laboratory conditions. Then it discusses how performance decays when the operator handles the instrument on a reference car body. Finally, it shows the analysis of uncertainty when the device is used on real car bodies of different colors in a production line. It is observed that the measurement uncertainty of the whole measurement chain (measurand + instrument + operator + uncontrolled environmental conditions) is larger than the instrument calibration uncertainty because the measurement process is affected by the operator and the variable conditions of the production line.

Evaluation of biochemical and immunological assembly line in emergency test / 中华检验医学杂志

Objective@#To explore the application value of biochemical and immunological assembly line in emergency test by comparatively analyzing the changes in sample test process and turnaround time (TAT) in emergency test before and after installation of the assembly line.@*Methods@#A retrospective study was performed with the run data of the emergency biochemical and immunodetection project in Department of Clinical Laboratory in Tongji Hospital Affiliated to Tongji University from July to September in 2017 and from July to September in 2018. (1)The changes in sample circulation mode and test process were compared in emergency test before and after installation of the assembly line.(2)The changes in TAT of sample test and distribution of time interval in emergency laboratory report were statistically analyzed before and after installation.(3)The number of samples tested between instruments and occurrence of instrument failure were statistically compared before and after installation. (4)Biosafety risk assessment was performed on the sample test process before and after installation to analyze the effects of the assembly line installation on biosafety control in emergency test.@*Results@#(1) By applying the assembly line, the sample test process was well controlled and the workload for laboratorians was eased greatly through reduction of manual work.(2) Report TAT was remarkably shortened after installation compared to that before installation; the TAT of dry biochemistry and myocardial zymogram report in emergency test was shorted from 39 min and 48 min to 34 min and 42 min respectively, with a reduction of 12.82% an 12.50% compared to those before installation; the TAT of dry biochemistry and myocardial zymogram report in inpatient emergency was shorted from 37 min and 43 min to 29 min and 35 min respectively, with a reduction of 21.61% an 18.60% compared to those before installation; distribution of report TAT was comparatively analyzed, the percentage of reports in 0-30 min and 31-45 min increased remarkably compared to that before installation, the percentage of TAT of dry biochemistry report falling into 0-45 min increased to 74.58% and 85.66% after installation from 57.91% and 78.28% before installation, respectively in emergency and inpatient emergency. (3)For the model VITROS5600, the percentage of samples tested changed from 30.29% and 69.71% before installation to 47.63% and 52.37% after installation, respectively; for the model DXI800, the percentage of samples tested changed from 28.77% and 71.23% before installation to 53.49% and 46.51% after installation, respectively. After installation, there was a tendency of balance in the number of samples tested between instruments. Instrument failure was significantly reduced: for the model VITROS5600, the frequency of instrument failure decreased from 3.5 times a month/instrument before installation to 2 times a month/instrument after installation on average; for the model DXI800, the frequency of instrument failure decreased from 2.8 times a month/instrument before installation to 1.8 times a month/instrument after installation on average.(4) Installation of the assembly line lowered the risks biosafety events in sample test process in emergency test and the two risks of accidental contact with aerosol in sample tubes before detection and accidental contact with biological specimen due to overturning and spilling during detection were reduced from a high level before installation to a low level after installation.@*Conclusion@#In emergency test, biochemical and immunological assembly line is of certain value in process improvement, reduction of workload for laboratorians, improvement of work efficiency, TAT reduction and optimization, as well as control of biosafety conditions.

A case of extensor pollicis longus (EPL) tendon rupture in an automotive assembly line worker: an ergonomic evaluation through job strain index (JSI) and musculoskeletal risk factor survey.

BACKGROUND: We report a case of extensor pollicis longus (EPL) tendon rupture caused by repetitive motions and awkward posture on hand and wrist joints. CASE PRESENTATION: A 47-year-old right-handed man who worked for 15 years in an assembly line at an automotive manufacturing company has been diagnosed with a complete tear of right EPL tendon. We investigated the patient's occupational history in detail and evaluated the tasks ergonomically through musculoskeletal risk factors survey and job strain index (JSI) using the 22 task-related videos recorded by the patient. Three out of the 12 tasks (25%) were identified as high-risk work on the hand and wrist in the musculoskeletal risk factors survey in 2016. Among the 22 tasks analyzed by JSI, 11 tasks (50%) were evaluated as probably hazardous. In addition, he used localized vibration tools in 19 (86.4%) out of 22 tasks. CONCLUSION: We concluded the patient's disease was probably caused by repetitive motion and improper posture of the hand and wrist, and the hand-arm vibration is a possible cause as well.

Assessing the brain 'on the line': An ecologically-valid assessment of the impact of repetitive assembly line work on hemodynamic response and fine motor control using fNIRS.

To investigate neural correlates of repetitive assembly tasks in ecologically-valid empirical settings, this study measured bilateral prefrontal (PFC) and motor activations when participants performed a carburetor assembly task using functional near-infrared spectroscopy (fNIRS). Participants worked for one hour at a typical (low-) pace and at an accelerated high-pace. Before and after the task, a test was conducted to assess motion stability and fine motor control. The behavioral data revealed decreased motion stability after the assembly work in both conditions, with a significantly higher reduction after the high-pace task. The fNIRS data also revealed reduced activations in bilateral prefrontal and motor regions in both conditions over time. However, the low-pace task led to significantly greater activity decreases compared with the high-pace. Activity decrease in prefrontal and motor regions within the low pace also significantly related to minimal motion stability impairment, suggesting that the brain activation decreases in this and, potentially, findings of higher alpha in past repetitive-task studies using EEG, may be a result of not fatigue but worker adaptation or increasing efficiency.

A genetic regulatory network based method for multi-objective sequencing problem in mixed-model assembly lines.

This research proposes a genetic regulatory network based sequencing method that minimizes multiple objectives including utility work costs, production rate variation costs and setup costs in mixed-model assembly lines. After constructing mathematical model of this multi-objective sequencing problem, the proposed method generates a set of genes to represent the decision variables and develops a gene regulation equation to describe decision variable interactions composed of production constraints and some validated sequencing rules. Moreover, a gene expression procedure that determines each gene's expression state based on the gene regulation equation is designed. This enables the generation of a series of problem solutions by indicating decision variable values with related gene expression states, and realizes the minimization of weighted sum of multiple objectives by applying a regulatory parameter optimization mechanism in regulation equations. The proposed genetic regulatory network based sequencing method is validated through a series of comparative experiments, and the results demonstrate its effectiveness over other methods in terms of solution quality, especially for industrial instances collected from a diesel engine assembly line.

Ergonomic interventions for prevention of work-related musculoskeletal disorders in a small manufacturing assembly line.

This study involves performing improvements in workstation specification using a three-dimensional human modeling tool and proposing well-balanced work scheduling (WBWS) to prevent work-related musculoskeletal disorders (WMSDs) in a small manufacturing plant. To analyze risk factors of WMSDs, various tasks at 10 different types of workstation were evaluated with detailed motion analysis using a customized checklist. Questionnaires were administered to 27 workers to evaluate symptoms related to WMSDs. Revised workstation specifications were suggested based on anthropometric characteristics of workers using before-after analyses as an engineering control. Additionally, WBWS was proposed as an administrative control to avoid continuous physical stress on specific body parts in repetitive tasks. A software tool for WBWS was developed for convenient and easy application. The results of the study may aid managers in applying ergonomic interventions with time and cost savings, and enhance worker satisfaction and motivation due to improvements in working conditions to prevent WMSDs.