scholarly journals Physical Welding Factors for Reclassified Welding Positions in Shipbuilding Assembly Process Based on Muscle Activity Measured by Surface Electromyography

2021 ◽  
Vol 9 (11) ◽  
pp. 1211
Author(s):  
So-Yeon Baek ◽  
Jong-Ho Nam
Keyword(s):  
Muscle Activity ◽  
Important Determinant ◽  
Complex Structure ◽  
Welding Process ◽  
Assessment Method ◽  
Important Variable ◽  
Shipbuilding Industry ◽  
Working Posture ◽  
Working Postures ◽  
Physiological Assessment

Welding, a key technology in the shipbuilding industry, is mostly performed by hand, owing to the complex structure and shape of production blocks. This manual welding requires a variety of working postures, which have become an important determinant of the worker’s workload and, consequently, assembly man-hours. Currently, major shipyards calculate welding man-hours by reflecting the welding factor, which is defined as the working time consumed in the welding process. A set of welding factors is known to be based on the accumulated experience in shipyards, whereas the verification or derivation process for these factors is not disclosed or available. This study proposed a method for quantitatively calculating work difficulty for welding positions based on the working posture in a process where the posture acts as an important variable. Standard welding positions reflecting the actual welding work at shipyards were established. A physiological assessment method was used to propose the physical welding factor by analyzing the measured muscle activity. The validity of the proposed method was verified by comparing the results of a musculoskeletal simulation package and shipyard welding factors. The proposed method can be readily applied to other fields in which workers’ physical activities are involved.

scholarly journals Posture in dentists: Sitting vs. standing positions during dentistry work - an EMG study

2016 ◽  
Vol 144 (3-4) ◽  
pp. 181-187 ◽  
Author(s):  
Natasa Pejcic ◽  
Milica Djuric-Jovicic ◽  
Nadica Miljkovic ◽  
Dejan Popovic ◽  
Vanja Petrovic
Keyword(s):  
Muscle Activity ◽  
Standing Position ◽  
The Body ◽  
Working Posture ◽  
Working Postures ◽  
Significant Difference ◽  
Splenius Capitis ◽  
Muscle Groups ◽  
The Right ◽  
Electromyography Signals

Introduction. Adequate working posture is important for overall health. Inappropriate posture may increase fatigue, decrease efficiency, and eventually lead to injuries. Objective. The purpose was to examine posture positions used during dentistry work. Methods. In order to quantify different posture positions, we recorded muscle activity and positions of body segments. The position (inclination) data of the back was used to assess two postures: sitting and standing during standard dental interventions. Results. During standard interventions, whether sitting or standing, a tilt of less than 20 degrees was most prevalent in the forward and lateral flexion directions. Amplitude of electromyography signals corresponding to the level of muscle activity were higher in sitting compared with the electromyography in standing position for all muscle groups on the left and right side of the body. Significant difference between muscle activity in two working postures was evident in splenius capitis muscle on the left (p = 0.032), on the right side of the body (p = 0.049) and in muscle activity of mastoid muscle on the left side (p = 0.029). Conclusion. These findings show that risk for increased fatigue and possible injures can be reduced by combining the sitting and standing occupational postures.

Integrative physiological assessment of cerebral hemodynamics and metabolism in acute ischemic stroke

2021 ◽  
pp. 0271678X2110337
Author(s):  
Jui-Lin Fan ◽  
Ricardo C Nogueira ◽  
Patrice Brassard ◽  
Caroline A Rickards ◽  
Matthew Page ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Acute Ischemic Stroke ◽  
Cerebral Autoregulation ◽  
Cerebral Perfusion ◽  
Prognostic Markers ◽  
Important Determinant ◽  
Stroke Care ◽  
Contentious Issue ◽  
Ischemic Tissue ◽  
Physiological Assessment

Restoring perfusion to ischemic tissue is the primary goal of acute ischemic stroke care, yet only a small portion of patients receive reperfusion treatment. Since blood pressure (BP) is an important determinant of cerebral perfusion, effective BP management could facilitate reperfusion. But how BP should be managed in very early phase of ischemic stroke remains a contentious issue, due to the lack of clear evidence. Given the complex relationship between BP and cerebral blood flow (CBF)—termed cerebral autoregulation (CA)—bedside monitoring of cerebral perfusion and oxygenation could help guide BP management, thereby improve stroke patient outcome. The aim of INFOMATAS is to ‘ identify novel therapeutic targets for treatment and management in acute ischemic stroke’. In this review, we identify novel physiological parameters which could be used to guide BP management in acute stroke, and explore methodologies for monitoring them at the bedside. We outline the challenges in translating these potential prognostic markers into clinical use.

scholarly journals Influence of design of dentist’s chairs on body posture for dentists with different working experience

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
F. Huppert ◽  
W. Betz ◽  
C. Maurer-Grubinger ◽  
F. Holzgreve ◽  
L. Fraeulin ◽  
...  
Keyword(s):  
Work Experience ◽  
Dental Treatment ◽  
Subjective Assessment ◽  
Body Posture ◽  
Control Group ◽  
Sitting Position ◽  
Ergonomic Design ◽  
Sitting Posture ◽  
Working Posture ◽  
Working Postures

Abstract Background Musculoskeletal disorders (MSD) are a common health problem among dentists. Dental treatment is mainly performed in a sitting position. The aim of the study was to quantify the effect of different ergonomic chairs on the sitting position. In addition, it was tested if the sitting position of experienced workers is different from a non-dental group. Methods A total of 59 (28 m/31f) subjects, divided into two dentist groups according to their work experience (students and dentists (9 m/11f) < 10 years, dentists (9 m/10f) ≥ 10 years) and a control group (10 m/10f) were measured. A three-dimensional back scanner captured the bare back of all subjects sitting on six dentist’s chairs of different design. Initially, inter-group comparisons per chair, firstly in the habitual and secondly in the working postures, were carried out. Furthermore, inter-chair comparison was conducted for the habitual as well as for the working postures of all subjects and for each group. Finally, a comparison between the habitual sitting posture and the working posture for each respective chair (intra-chair comparison) was conducted (for all subjects and for each group). In addition, a subjective assessment of each chair was made. For the statistical analysis, non-parametric tests were conducted and the level of significance was set at 5%. Results When comparing the three subject groups, all chairs caused a more pronounced spinal kyphosis in experienced dentists. In both conditions (habitual and working postures), a symmetrical sitting position was assumed on each chair. The inter-chair comparisons showed no differences regarding the ergonomic design of the chairs. The significances found in the inter-chair comparisons were all within the measurementerror and could, therefore, be classified as clinically irrelevant. The intra-chair comparison (habitual sitting position vs. working sitting position) illustrated position-related changes in the sagittal, but not in the transverse, plane. These changes were only position-related (forward leaned working posture) and were not influenced by the ergonomic sitting design of the respective chair. There are no differences between the groups in the subjective assessment of each chair. Conclusions Regardless of the group or the dental experience, the ergonomic design of the dentist’s chair had only a marginal influence on the upper body posture in both the habitual and working sitting postures. Consequently, the focus of the dentist’s chair, in order to minimize MSD, should concentrate on adopting a symmetrical sitting posture rather than on its ergonomic design.

Risk Factors and their Interactions in VDT Workstation Systems

1996 ◽  
Vol 40 (13) ◽  
pp. 637-641 ◽  
Author(s):  
Hongzheng Lu ◽  
Fereydoun Aghazadeh
Keyword(s):  
Risk Factors ◽  
Physical Symptoms ◽  
Computer Users ◽  
Research Model ◽  
Factors Associated ◽  
Work Posture ◽  
Design Variables ◽  
Working Posture ◽  
Workstation Design ◽  
Working Postures

This study examined important risk factors and their interactions associated with physical symptoms reported by VDT users. A research model was developed. A survey was designed and conducted among 88 computer users. The results show that risk factors associated with various physical symptoms are different. Screen glare, awkward working posture, and fatigue are important factors related to physical symptoms. Psychosocial factors significantly interact with other variables, such as demographics variables, and contribute to awkward work posture and psychological stress. Workstation design variables significantly affect working postures.

Fatigue Behaviour of Friction Stir Welded Steel Joints

2014 ◽  
Vol 891-892 ◽  
pp. 1488-1493 ◽  
Author(s):  
José Azevedo ◽  
Virgínia Infante ◽  
Luisa Quintino ◽  
Jorge dos Santos
Keyword(s):  
Base Material ◽  
Welding Process ◽  
Steel Structures ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Welded Steel ◽  
Shipbuilding Industry ◽  
Friction Stir ◽  
Steel Joints

The development and application of friction stir welding (FSW) technology in steel structures in the shipbuilding industry provide an effective tool of achieving superior joint integrity especially where reliability and damage tolerance are of major concerns. Since the shipbuilding components are inevitably subjected to dynamic or cyclic stresses in services, the fatigue properties of the friction stir welded joints must be properly evaluated to ensure the safety and longevity. This research intends to fulfill a clear knowledge gap that exists nowadays and, as such, it is dedicated to the study of welded steel shipbuilding joints in GL-A36 steel, with 4 mm thick. The fatigue resistance of base material and four plates in as-welded condition (using several different parameters, tools and pre-welding conditions) were investigated. The joints culminate globally with defect-free welds, from which tensile, microhardness, and fatigue analyses were performed. The fatigue tests were carried out with a constant amplitude loading, a stress ratio of R=0.1 and frequency between 100 and 120 Hz. The experimental results show the quality of the welding process applied to steel GL-A36 which is reflected in the mechanical properties of joints tested.

Experimental Analysis of Repair Welding Alternatives for Shipbuilding DH36 Plates

2020 ◽  
Vol 64 (04) ◽  
pp. 384-391
Author(s):  
Tetyana Gurova ◽  
Segen F. Estefen ◽  
Anatoli Leontiev ◽  
Plinio T. Barbosa ◽  
Valentin Zhukov ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Best Practice ◽  
Welding Process ◽  
Offshore Structures ◽  
Residual Stress Distribution ◽  
Shipbuilding Industry ◽  
Repair Welding ◽  
Ship Construction ◽  
Repair Techniques

Repair by welding is widely used in the shipbuilding industry during ship construction. The effect of the residual stress distribution induced by the welding process on the ship structure is important for the repair effectiveness. This article presents an experimental study of the residual stress distribution induced by repair welding in the plates that are typically used in ships and offshore structures. Different repair techniques are evaluated to identify the best practice associated with residual stress values. Recommendations for repair welding are discussed, and modifications to the present practice are proposed.

Working Posture Assessment in a Small and Medium Industry (SMI): Automotive Repair Facility

2015 ◽  
Vol 761 ◽  
pp. 664-667
Author(s):  
M.S. Syed Mohamed ◽  
Muhammad Nur Hakam Basiri
Keyword(s):  
Risk Factors ◽  
Injury Risk ◽  
Work Related ◽  
Working Posture ◽  
Working Postures ◽  
Repair Facility ◽  
Automotive Repair ◽  
Small And Medium Industry ◽  
Ergonomic Risk Factors ◽  
Ergonomic Risk

In automotive repair facilities worldwide, technicians are exposed to various ergonomic risk factors such as excessive exertions, awkward and static postures. The exposure of several ergonomic risk factors can lead to work related musculoskeletal complaints. This study was set out to examine working postures encountered by automotive service technicians in a small medium industry automotive workshop. A total of 240 observations (n=240) were made, and five types of working positions were identified, namely the “Underneath Vehicle” (vehicle on floor),“Side of Vehicle” (vehicle on floor), “Under the Hood”, “Side of Vehicle” (vehicle on lift), and “Underneath Vehicle” (vehicle on lift). Two positions, which were the “Underneath Vehicle” (vehicle on floor), and the “Side of Vehicle” (vehicle on floor) recorded 69 and 60 occurrences respectively. These two positions posed a significant ergonomic injury risk since the upper limbs, shoulders, spinal flexion combined with static holding were present in those two positions.

A Simplified Transient Thermal Analysis of Resistance Spot Welding Process

2010 ◽  
Vol 154-155 ◽  
pp. 443-446
Author(s):  
Zhi Gang Hou ◽  
Jun Zhao ◽  
Li Qiang Xu ◽  
Zhong Guo
Keyword(s):  
Resistance Spot Welding ◽  
Spot Welding ◽  
Complex Structure ◽  
Welding Process ◽  
Temperature Dependent ◽  
Resistance Spot ◽  
Whole Process ◽  
History Of ◽  
Transient Thermal

In order to theoretically simulate the welding process of complex structure with large quantities of welding spots, a simplified method for analyzing a single spot welding should be developed firstly. In this paper, a 2D axisymmetric model of thermoelectric Finite Element Method (FEM) is developed to analyze the transient thermal behavior of Resistance Spot Welding (RSW) process using ANSYS. The determination of the contact resistance at the faying surface is moderately simplified to reduce the calculating time, while the temperature dependent material properties, phase change and convectional boundary conditions are taken into account for the improvement of the calculated accuracy. The thermal history of the whole process and temperature distributions for any position in the weldment is obtained through the analysis. The model can also predict the weld nugget size and the width of the Heat Affected Zone (HAZ).

scholarly journals Investigation into the Musculoskeletal Disorders Prevalence and Postural Assessment among Barbers in Sari-2016

2018 ◽  
Author(s):  
Siavash Etemadinezhad ◽  
Fateme Ranjbar ◽  
Jamshid Yazdani Charati
Keyword(s):  
Musculoskeletal Disorders ◽  
Work Experience ◽  
Assessment Method ◽  
Entire Body ◽  
Chi Square ◽  
Work Related ◽  
Body Regions ◽  
Working Postures ◽  
The Mean ◽  
Rapid Entire Body Assessment

Background and purpose: Work-related musculoskeletal disorders usually entangle back spines, neck and upper limbs. Working as a barber paves the ground for probable high prevalence of musculoskeletal disorders. This study was designed to evaluate the working postures of sari male barbers by Rapid Entire Body Assessment method and determining the prevalence of musculoskeletal disorders using NORDIC questionnaire.Methods: In the present research, 108 Sari barbers working conditions were evaluated using Rapid Entire Body Assessment (REBA) tool, and the data on the prevalence of musculoskeletal disorders was collected using Nordic questionnaire. Microsoft Excel and SPSS were then applied to analyze the data. Quantitative variables were analyzed using the descriptive statistical methods including mean and standard deviation. Chi-square test and ordinal regression have also been applied to analyze the relationship between different variables and musculoskeletal disorders' prevalence.Results: The mean age the participants was 33.11±8.2 and the mean of work experience was 12±3.7 years. According to the results of the Nordic questionnaire, during 12 past months, 78% of the studied subjects have discovered pain and discomfort at least in one of their 9 body regions. Complaints of musculoskeletal pains in the wrist were also most prevalent (72.1%), followed by the neck (49%) and elbow pains (46.2%). Through REBA Method, the highest frequency of corrective measures was at level 2 (73.9%).Conclusion: The results of the present study indicated that the evaluated subjects working postures required correction. Also, it was found essential to train barbers in what way to identify the biomechanical and ergonomic risk factors and correct working postures.

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