| 1. |
- Glimne, Susanne, et al.
(författare)
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Headaches in combination with visual ability, eye- and musculoskeletal strain in connection with visually demanding work tasks
- 2022
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Konferensbidrag (refereegranskat)abstract
- Suboptimal visual ergonomics (i.e., the interaction between our vision, the light, the visual object, and the influence of other factors which impairs visibility) in work environment such as glare can cause headache in combination with eyestrain, visual ability, and musculoskeletal strain. Symptoms constituted to the syndrome of eyestrain has been well described among computer workers (see for example Han et al., 2013; Portello et al., 2012; Bhanderi et al., 2008; Mocci et al., 2001; Sanchez-Roman et al., 1996). However, research has not focused on investigating the presence of headaches associated with eye-related and musculoskeletal disorders among employees and visual related environmental factors.The purpose of presented research was to study the presence of headaches in combination with visual ability, eye- and musculoskeletal strain, and work ability in connection with visually demanding work. Trained assessors recruited study participants primarily from their regular clients in the OHS field. Evaluators were instructed to recruit participants with a variety of characteristics to ensure highly variable data, such as different work tasks, age, and gender. The participants mean age was 48.3 years (±10.3); 66% were women.A visual ergonomics risk assessment method (VERAM, Heiden et al. 2019; Zetterberg et al. 2017) was used to compile the participated workers subjective grading of headache, eye- and musculoskeletal strain using a questionnaire (n=430). At the same time, an evaluation of the visual environment was carried out, which established if there was a risk of glare associated with the implementation of work task (e.g., computer work and other related work such as industry, healthcare, and shipping industry). The frequency of headaches was divided into three categories; (1) no headache, (2) headache occasionally, and (3) headache a few times per week/almost every day. The measurements regarding evaluation of the visual environment used a photometer, an instrument which was available and that the assessors could use, usually a Hagner ScreenMaster or Hagner S1 / S2 / S3.About 65% of the workers reported headaches occasionally, a few times/week or almost every day. Among the workers with headaches reported about 29% of them that they experienced the headaches a few times/week or almost every day.Out of the workers with headaches reported 37% a severity of the headaches of more than 3 (on a scale of 1-10) and 5 % reported a severity of more than 6. About 40% of the workers also stated that the headaches affected their working ability. The headaches were mainly located around the eyes, forehead, or temples (70%) and came in the afternoon (69%). About 75% of the workers also reported that the headache disappeared or were reduced when they were off work for one night or over the weekend. The data collection showed that visual- related symptoms increased the higher the estimated headaches was.The musculoskeletal strain increased when the headache increased. When workers reported a high frequency of headaches 95% of them reported neck strain, 86% shoulder strain, 73% upper back strain, and 61% were reported arm strain.Moreover, only 8.2% of the workers rated their visual ability as bad or very bad, but at the same time, about 60% reported dim vision, 14% diplopia, and 59% problems changing focus at some time.Dividing the data into workers with experienced or unexperienced headaches this study has shown that there was a significant presence of headaches in combination with visual related symptoms regarding experienced photophobia (p=0.011), eye pain (p=0.015), diplopia (p=0.029), and arm strain (p=0.006). Further, the statistical analysis showed that there was a tendency of combination regarding headaches and visual ability (p=0.070).Dividing the data into workers with experienced or unexperienced headaches, our study showed that the frequency of headache increased due to high luminance levels within the visual field (p=0.044).This study concludes presence of headaches in combination with eye- and musculoskeletal strain performing work task such as computer work. Further, the presence of headaches is due to visual ability induced by high luminance levels within the visual field.
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| 2. |
- Hemphälä, Hillevi, et al.
(författare)
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Objective risk assessment of glare and subjective rating of the frequency of glare ‐ a visual ergonomics risk assessment, VERAM
- 2022
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Konferensbidrag (refereegranskat)abstract
- Insufficient lighting conditions and glare from luminaires in the visual environment can affect our visual ability and cause eyestrain, headache, and musculoskeletal strain. Knave et al. found that the frequency of reported glare was associated with more eyestrain. In this study a subjectively rated frequency of glare was compared to an objectively rated risk for glare made by trained assessors.A visual ergonomics risk assessment method (VERAM) was used to gather data at workplaces, mainly computer workstations (n=420). Trained assessors (ergonomists) measured the luminance ratio and assessed the risk for glare (objective risk for glare) divided into three categories high risk (red), low risk (yellow) and no risk (green).Workers rated the frequency of experienced glare at their workplaces (subjective assessment of glare) via questionnaires. The frequency of subjective strain was divided into three categories; no, never; occasionally; a few times a week/almost always.Workers rated the frequency of glare present more seldom than the trained assessors rated the presence for risk for glare, at the same workplaces. One factor behind this might be individuals’ ability to evaluate the visual environment such as risk for glare. A trained assessor can easier evaluate any risks in the visual environment.When the objective risk for glare was assessed to be high (red) or low (yellow) the percentage of individuals reporting strain, such as eyestrain and musculoskeletal strain, increased for most symptoms compared to when there was no risk (green). An objective risk assessment for glare needs to be performed together with a subjective rating of the frequency of glare to find the individuals with problems.
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| 3. |
- Hemphälä, Hillevi, et al.
(författare)
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Risks in the visual environment such as glare, illuminance, and luminance ratio - risk assessments made with visual ergonomics risk assessment method - VERAM - a descriptive paper
- 2021
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Ingår i: Proceedings of the Conference CIE 2021 : September 27 - 29, 2021 hosted by the CIE National Committee (NC) Malaysia online - September 27 - 29, 2021 hosted by the CIE National Committee (NC) Malaysia online. - 9783902842299
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Konferensbidrag (refereegranskat)abstract
- The visual environment has an impact on subjective strain and headaches. A visual ergonomics risk assessment method, VERAM, was used on 217 workplaces, and consists of both of a subjective questionnaire and an objective risk assessment, the objective risks are presented in this paper. The risk for daylight was assessed to be yellow (risk) or red (high risk) at 53% of the workplaces and the risk for glare was yellow or red at 66%. The assessment of the lighting design showed a yellow or red risk at 44% of the workplaces and the illuminance was assessed to be insufficient at 49% of the workplaces. Flicker or TLM (temporal light modulation) was assessed to be a problem among 33%. These results show that the design of the visual environment is in most cases not performed in a satisfying way. To increase wellbeing, health and performance a good visual environment is essential.
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| 4. |
- Hemphälä, Hillevi, et al.
(författare)
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Visual Symptoms and Risk Assessment Using Visual Ergonomics Risk Assessment Method (VERAM)
- 2021
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Ingår i: Proceedings of the 21st Congress of the International Ergonomics Association (IEA 2021) - Volume II : Inclusive Design - Inclusive Design. - Cham : Springer International Publishing. - 2367-3389 .- 2367-3370. - 9783030746049 ; 220, s. 729-735, s. 729-735
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Konferensbidrag (refereegranskat)abstract
- A visual environment impaired by e.g. glare can cause eyestrain, visual symptoms and musculoskeletal strain. A Visual Ergonomics Risk Assessment Method (VERAM) consisting of both a subjective questionnaire and an objective risk assessment, have been used at 217 workplaces, mainly computer work. VERAM can be used to examine and prevent deficiencies and increase wellbeing as well as detecting risks in the visual work environment and suggest measures that can be used to reduce the risks. The questionnaire showed that eyestrain, visual symptoms and musculoskeletal strain are common among Swedish workers. The overall risk assessments for glare and amount of illuminance on work surface are divided into three categories, green – no risk, yellow – risk, and red – high risk. Risk of glare and insufficient illuminance was present at 66% and 49% of the assessed workplaces, respectively. When the risk of glare and illuminance levels was rated as red, the frequency of the subjective strain was higher.
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| 5. |
- Balachandramurthi, Arun Ramanathan, 1989-
(författare)
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Towards understanding the fatigue behaviour of Alloy 718 manufactured by Powder Bed Fusion processes
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Additive Manufacturing (AM) is a disruptive modern manufacturing process in which parts are manufactured in a layer-wise fashion. Among the metal AM processes, Powder Bed Fusion (PBF) technology — comprised of Electron Beam Powder Bed Fusion (EB-PBF) and Laser Beam Powder Bed Fusion (LB-PBF) —has opened up a design space that was formerly unavailable with conventionalmanufacturing processes. PBF processes offer several advantages; however, thesuitability of these processes to replace the conventional processes must be investigatedin detail. Therefore, understanding the AM process – post-processing –microstructure – property relationships is crucial for the manufacturing of high performance components. In this regard, only limited work has been done towards understanding the fatigue behaviour of PBF Alloy 718. The aim of this work, therefore, is to understand how the fatigue behaviour of PBF Alloy 718 is affected by its microstructure. Besides, the influence of the rough as-built surface is also investigated. In general, the <100> fibre texture along the build direction that resulted from PBF processing of Alloy 718 led to anisotropy in Young's modulus. Consequently,the fatigue performance under controlled amplitudes of strain was anisotropic such that the low-modulus direction had longer fatigue life and vice versa. This texture-induced elasticity-dependent anisotropic strain-life behaviour couldbe normalized by the pseudo-elastic stress vs fatigue life approach.Inclusions and defects had a detrimental effect on fatigue performance. Numerousfactors, such as their geometry, volume fraction, and distribution, determinedthe effect on fatigue behaviour. Hot Isostatic Pressing (HIP) eliminated most defect sand led to an improvement in fatigue performance. However, HIP did not alter the inclusions, which acted as crack initiation sites and reduced fatigue life. The rough as-built surface, which had numerous notch-like crack initiation sites, deteriorated fatigue performance; however, it lowered the scatter in fatigue life. Machining off the as-built surface improved fatigue life but increased the scatter.
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| 6. |
- Joshi, Shrikant V., 1960-, et al.
(författare)
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New Generation Ceramic Coatings for High-Temperature Applications by Liquid Feedstock Plasma Spraying : Defense, Security, Aerospace and Energy Applications
- 2020
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Ingår i: Handbook of Advanced Ceramics and Composites. - Cham : Springer. - 9783319732558 ; , s. 1-42
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Plasma spraying with liquid feedstock offers an exciting opportunity to obtain coatings with characteristics that are vastly different from those produced using conventional spray-grade powders. The two extensively investigated variants of this technique are suspension plasma spraying (SPS), which utilizes a suspension of fine powders in an appropriate medium, and solution precursor plasma spraying (SPPS), which involves use of a suitable solution precursor that can form the desired particles in situ. The advent of axial injection plasma spray systems in recent times has also eliminated concerns regarding low deposition rates/efficiencies associated with liquid feedstock. The 10–100 μm size particles that constitute conventional spray powders lead to individual splats that are more than an order of magnitude larger compared to those resulting from the fine (approximately 100 nm–2 μm in size) particles already present in suspensions in SPS or formed in situ in SPPS. The distinct characteristics of the resulting coatings are directly attributable to the above very dissimilar splats (“building blocks” for coatings) responsible for their formation. This chapter discusses the salient features associated with SPS and SPPS processing, highlights their versatility for depositing a vast range of ceramic coatings with diverse functional attributes, and discusses their utility, particularly for high-temperature applications through some illustrative examples. A further extension of liquid feedstock plasma processing to enable use of hybrid powder-liquid combinations for plasma spraying is also discussed. This presents a novel approach to explore new material combinations, create various function-dependent coating architectures with multi-scale features, and enable convenient realization of layered, composite, and graded coatings as demonstrated through specific examples.
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| 7. |
- Kumara, Chamara
(författare)
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Microstructure Modelling of Additive Manufacturing of Alloy 718
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In recent years, additive manufacturing (AM) of Alloy 718 has received increasing interest in the field of manufacturing engineering because of its attractive features compared with those of conventional manufacturing methods. Nevertheless, owing to the inherent nature of the process, the build material is exposed to complex thermal conditions that affect the microstructure. In addition, the post heattreatments applied to the built component further cause microstructural changes. Thus, obtaining the desired microstructure that gives the desired properties is still a challenging task. Therefore, understanding the microstructure formation during the build and subsequent post-heat treatment is important and is the objective of this thesis work.To this end, a computational modelling approach was used that combines multiphase-field modelling with transformation kinetics modelling. Two different AM processes, laser metal powder directed energy deposition (LM-PDED) and electron beam powder bed fusion (EB-PBF), were considered in this study.Based on the modelling work, it was observed that solidification conditions (thermal gradients and cooling rates) that occur during the AM process have an impact on the as-solidified microstructure in Alloy 718 and the resultant Laves phase formation. With an increase in cooling rate, the Laves phase volume fraction becomes lower and the morphology tends to become discrete particles,which is important for resisting the formation of liquation cracks in Alloy 718. It was also found that the precipitates formed during the solidification process did not undergo any significant change during subsequent thermal cycles associated with the deposition of subsequent layers, given that the deposition of the subsequent layer does not increase the global temperature of the build to> 600 °C. If the global temperature increases above 600 °C, then phase changes are expected, depending on the temperature value. In the case of the EB-PBF process, the high build temperature maintained in the build chamber resulted in an ‘‘in situ’’ heat treatment, which had a homogenisation effect on the as-solidified microstructure because of the smaller dendrite spacing and relatively low Lavesphase size. In the case of the LM-PDED, the microsegregation of composition observed in the as-built microstructure was shown to change the equilibrium conditions and precipitation kinetics of Alloy 718. As a result, excess precipitationof γ'/γ″ and δ was observed in the interdendritic region compared with the dendrite core, depending on the type of heat treatment used.In addition, modelling was performed to evaluate the elastic properties of EB-PBF Alloy 718. To this end, crystallographic orientation data gathered from EBSD data and single-crystal elastic constants were used. The prediction showed good agreement with published literature data. The hatch (bulk) region of the EB-PBF samples showed significant anisotropic elastic properties because of the strong crystallographic texture observed in the microstructure. The lowest Young’s modulus was observed along the build direction. Normal to the build direction, the elastic properties were shown to be isotropic. Overall, the elastic behaviour of the hatch region was similar to that of a transversely isotropic case
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| 8. |
- Chen, Ying, et al.
(författare)
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Measurements of elastic modulus and fracture toughness of an air plasma sprayed thermal barrier coating using micro-cantilever bending
- 2019
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Ingår i: Surface & Coatings Technology. - : Elsevier BV. - 0257-8972 .- 1879-3347. ; 374, s. 12-20
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Tidskriftsartikel (refereegranskat)abstract
- The elastic modulus and fracture toughness of an air plasma sprayed thermal barrier coating (APS TBC) were measured using the micro-cantilever bending technique. The micro-cantilevers were machined by a focused ion beam with their central arms either parallel or normal to the bond coat/topcoat interface. Such orientations allowed direct measurements of both the in-plane and out-of-plane elastic moduli as well as mode I fracture toughness by bending. The calculated elastic modulus along the in-plane and out-of-plane direction is 144 GPa and 110 GPa, respectively, suggesting that the APS TBC is elastically anisotropic at microscale. The derived mode I fracture toughness along the plane parallel to the interface is 0.40 MPam. This relatively low toughness reflects the weak fracture resistance of the highly-flawed APS for short cracks at microscale. The measurements in this study can be incorporated into micromechanical life time prediction models of the APS TBCs. © 2019 Elsevier B.V.
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| 9. |
- Heiden, Marina, 1974-, et al.
(författare)
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Validity of a computer-based risk assessment method for visual ergonomics
- 2019
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Ingår i: International Journal of Industrial Ergonomics. - : Elsevier BV. - 0169-8141 .- 1872-8219. ; 72, s. 180-187
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Tidskriftsartikel (refereegranskat)abstract
- ObjectiveTo describe the development of a computer-based risk assessment method for visual ergonomics, and assess its face validity, content validity, and internal consistency.MethodsThe risk assessment method contained a questionnaire for the worker, an evaluation form for the evaluator, a section of follow-up questions based on the worker's responses, and a section for recommended changes, including an overall risk assessment with respect to daylight, lighting, illuminance, glare, flicker, work space, work object and work postures, respectively. Forty-eight trained evaluators used the method to perform 224 workplace evaluations. Content validity of the method was assessed by the completeness and distribution of responses, and internal consistency was assessed by Cronbach's alpha, Spearman's rank correlation between items and indices, and exploratory factor analysis.ResultsThe proportion of missing values in items was generally low (questionnaire: 0–2.3%; evaluation form: 1.4–4.1%). In the questionnaire, items about double vision, migraine and corrective lenses had limited information content. Cronbach's alpha and item-index correlations for the indices frequency of eyestrain, intensity of eyestrain, visual symptoms, lighting conditions, frequency of musculoskeletal discomfort and intensity of musculoskeletal discomfort were satisfactory. Based on the factor analysis, suggestions for improving some of the indices were made.ConclusionOur findings suggest that this computer-based method is a valid instrument for assessing risks in the visual work environment. By incorporating subjective ratings by the worker as well as objective measurements of the work environment, it provides a good basis for recommendations with respect to daylight, lighting, work surfaces/material, and work object.Relevance to industryVisual environment factors, such as glare, can cause eyestrain, headache and musculoskeletal discomfort. This method satisfies the need of a valid tool for determining risks associated with the visual work environment. It contains both worker's ratings and objective measurements, and is designed to be used in different types of work.
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| 10. |
- Joshi, Shrikant V., 1960-, et al.
(författare)
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Advanced Coatings by Thermal Spray Processes
- 2019
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Ingår i: Technologies. - : MDPI. - 2227-7080. ; 7:4, s. 1-14
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Tidskriftsartikel (refereegranskat)abstract
- Coatings are pivotal in combating problems of premature component degradation in aggressive industrial environments and constitute a strategic area for continued development. Thermal spray (TS) coatings offer distinct advantages by combining versatility, cost-effectiveness, and the ability to coat complex geometries without constraints of other in-chamber processes. Consequently, TS techniques like high-velocity oxy-fuel (HVOF) and atmospheric plasma spray (APS) are industrially well-accepted. However, they have reached limits of their capabilities while expectations from coatings progressively increase in pursuit of enhanced efficiency and productivity. Two emerging TS variants, namely high-velocity air-fuel (HVAF) and liquid feedstock thermal spraying, offer attractive pathways to realize high-performance surfaces superior to those hitherto achievable. Supersonic HVAF spraying provides highly adherent coatings with negligible porosity and its low processing temperature also ensures insignificant thermal ‘damage’ (oxidation, decarburization, etc.) to the starting material. On the other hand, liquid feedstock derived TS coatings, deposited using suspensions of fine particles (100 nm–5 µm) or solution precursors, permits the production of coatings with novel microstructures and diverse application-specific architectures. The possibility of hybrid processing, combining liquid and powder feedstock, provides further opportunities to fine tune the properties of functional surfaces. These new approaches are discussed along with some illustrative examples.
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