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- Wahlström, Jens, 1979-
(författare)
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Towards a simulation methodology for prediction of airborne wear particles from disc brakes
- 2009
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- During braking, both the rotor and the pads in disc brakes are worn. Since disc brakes are not sealed, some of the wear particles generated can become airborne. Several studies have found an association between adverse health effects and the concentration of particles in the atmosphere, so it is of interest to improve our knowledge of the airborne wear particles generated by disc brakes. However, in field tests it is difficult to distinguish these particles from others in the surrounding environment, so it may be preferable to use laboratory test stands and/or simulation models to study the amount of airborne wear particles generated. This thesis deals with a simulation methodology for prediction of airborne wear particles from disc brakes and three experimental methods for testing disc brake materials with focus on airborne wear particles. The four appended papers discuss the possibility to both measure and predict the number and size distribution of airborne wear particles that originate from the pad to rotor contact. The objective is to develop a simulation methodology that predicts the number and size distribution of airborne wear particles from disc brakes. Paper A describes how a modified pin-on-disc machine was used to study airborne wear particles originating from different disc brake materials. The results indicate that the test setup can be used to measure and rank the number concentration and size distribution of the airborne wear particles generated. Paper B describes a disc brake assembly test stand for measurements of airborne wear particles from disc brakes. The results indicate that the test setup can be used to measure the number concentration and size distribution of airborne wear particles generated from disc brake materials. The results also indicate a promising ability to rank different pad/rotor material combinations with respect to the number concentration of airborne wear particles. Paper C compares measurements made in passenger car field tests with measurements made in a disc brake assembly test stand and in a pin-on-disc machine. A promising correlation between the three different test methods is found. Paper D presents a simulation methodology for predicting the number and size distribution of airborne wear particles using finite element analysis (FEA). The simulated number distribution is compared with experimental measurements at component level. The result indicates that the proposed methodology may be used to predict the number concentration and size distribution of airborne particles generated in the pad-to-rotor contact.
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| 2. |
- Wahlström Edling, Cecilia, 1959-
(författare)
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Besvär i rörelseorganen hos musiklärare och deras syn på musikelevers hälsa : visioner och verklighet på kollisionskurs
- 2017
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The overall aim of the licentiate thesis was to reach a better understanding of music teachers' health, with focus on musculoskeletal disorders, and music teachers' view on young music students' health, from a gender perspective.A cross-sectional study was directed to music teachers employed at a municipality music- and culture school, in order to investigate the relationship between physical workload and work-related disorders among music teachers. Out of 61 music teachers 47 agreed to participate. The study group was divided into two groups depending on if they had an asymmetric or symmetric upper extremity and back playing posture. Musculoskeletal disorders were frequent among the music teachers. Women music teachers reported significantly more musculoskeletal disorders than their male collegues and music teachers with asymmetric work posture had significantly higher amount of musculoskeletal disorders than those who had a symmetric playing posture.A qualitative interview study with semi-structured interviews with 18 music teachers were conducted to explore music teachers' experiences of health and gender among young music students. An interview guide was used, with topic areas concerning experiences and perceptions of positive health aspects and health problems among young music students, taking part in music education. The interviews were analysed with qualitative content analysis according to Graneheim and Lundman. The analysis resulted in an overarching theme "Visions and reality in contradiction" and three categories: "Music making to feel good", "Pressure on girls, acceptance for boys" and "Blame on the individual".Music teachers at music- and culture schools seem to be at high risk of developing musculoskeletal disorders, especially music teachers playing an instrument that requires an asymmetric playing position. Young musicians' teachers need a better knowledge in the field of prevention of music students' health problems and physiotherapists and ergonomists may assist and collaborate in this. A gender perspective in music medicine research may contribute to a better understanding of musicians' health.
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| 3. |
- Alemani, Mattia, et al.
(författare)
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ON THE INFLUENCE OF CAR BRAKE SYSTEM PARAMETERS ON PARTICULATE MATTER EMISSIONS
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The influence of car brake system parameters on particulate matter emissions was investigated using a pin-on-disc tribometer. Samples from a low-steel friction material and a cast iron disc were tested for different sliding velocities, nominal contact pressures and frictional powers. Disc temperatures were also measured. Their impact on total concentration, size distribution, particle coefficient and transition temperature was analysed. Results show that frictional power is the most significant brake system parameter. However, temperature, as a response parameter, is the most influential, inducing a shift towards the ultrafine particulate fraction and raising emissions. A transition temperature, independent of the system parameters, was identified.
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| 4. |
- Alemani, Mattia
(författare)
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Particle emissions from car brakes : The influence of contact conditions on the pad-to-rotor interface
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Due to their adverse health effects emissions have been regulated for over three decades. Brake wear particulate matter is the most important non-exhaust source, however current knowledge is mainly limited to observational studies. This thesis aims to investigate relations between the brake system contact conditions and the related emissions on a model scale; validate the results on a component level; and understand to what extent they are significant on a full-scale.Paper A investigates the influence of nominal contact pressure on a model scale. Results show that higher pressure corresponds to higher emissionsPaper B investigates the influence of the nominal contact pressure, for different friction materials, on a model scale. A temperature threshold, responsible for a relevant emission increase, is identified.Paper C investigates particle characteristics and wear mechanisms for different nominal contact pressures, on a model scale. Results show an enhanced tribo-layer at higher pressure levels.Paper D investigates the influence of brake system conditions on emissions, on a model scale. Results show that frictional power is the most important parameter. A transition temperature independent of the contact condition is identified.Paper E investigates similarities occurring on a component scale and a model scale in terms of emissions. Results show a promising correlation, and the possibility of using a pin-on-disc tribometer for R&D activities.Paper F investigates analogies occurring on a component scale and a model scale, in terms of friction performance, fictional surface and chemical composition. Results show similar phenomena occurring for the two test stands.Paper G analyses real brake system working conditions in a urban environment defining, by means of an inertia dyno bench, the related emissions. Results reveal emission factors compliant to EURO6 and EURO2 regulations, in terms of number and mass, respectively.
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| 5. |
- Barker, Dean, 1977, et al.
(författare)
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Jacob and Martin: Developing digital technology competence in physical education teacher education
- 2016
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Ingår i: Digital Technologies and Learning in Physical Education. - Abingdon, Oxon ; New York, NY : Routledge, 2016. | : Routledge. - 9781315670164 - 9781138947283 - 9781138947290 ; , s. 231-246
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This chapter provides an illustration of how digital technologies (DTs) are experienced by Physical Education Teacher Education (PETE) students. The illustration is based on the reflections of two students at the University of Gothenburg, Sweden. The students received an assignment that involved demonstrating how a specific DT could be implemented. Three perspectives of the practitioners' experiences are provided. A Deweyan perspective shows how the students and their situations are transformed by DTs. A Foucauldian perspective focuses on the regulating aspects of technology. An applied Information Technology perspective demonstrates how DTs become part of the social practices of physical education. © 2017 Ashley Casey, Victoria A. Goodyear and Kathleen M. Armour. All rights reserved.
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| 6. |
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| 7. |
- Carlsson, Daniel, 1982-
(författare)
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Effects of cold and hand-arm vibration on the peripheral neurosensory and vascular system : an occupational perspective
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background In Swedish working life, exposure to cold and exposure to hand-arm vibration (HAV) are two common health hazards. Health effects of HAV in the neurosensory, vascular and musculoskeletal systems are collectively denoted hand-arm vibration syndrome (HAVS), and have been thoroughly studied. Effects of cold exposure in terms of effects on the peripheral neurosensory and vascular system are on the contrary limited, especially in an occupational setting. Effects of cold exposure or cold injury have not previously been assessed with quantitative sensory testing (QST). Commonly reported symptoms after exposure to HAV and after cold injuries, includes cold sensitivity and sensation of cold. Cold sensitivity can also occur without previous exposure to vibration or cold and may have a major impact on quality of life. Other possible risk factors for cold sensitivity need to be assessed. Sensation of cold hands could theoretically imply an early manifestation of damage to the neurosensory or vascular system, and therefore be of importance to enable early detection of vascular and neurosensory HAVS. The purpose of this thesis was to increase the knowledge about health effects from cold and HAV on the peripheral neurosensory and vascular system, with an occupational perspective. The aims were: first, to identify and evaluate health effects and sequelae in the peripheral neurosensory and vascular system due to cold injury and cold exposure; second, to investigate if sensation of cold hands is a predictor for future onset of Raynaud's phenomenon or paresthesia; and third, to identify possible risk factors associated with cold sensitivity.Methods A case series on 15 military conscripts with local cold injuries in the hands or feet, involving QST and symptom descriptions, was conducted to investigate the hypothesis that cold injuries can result in similar neurosensory and vascular impairments as in HAVS. To assess health effects of cold exposure, a cohort study on 54 military conscripts in cold winter military training, with cold exposure assessments, was conducted. Possible health effects were assessed after 14 months of military training, containing considerable cold exposure, by means of QST, Finger systolic blood pressure after local cooling (FSBP) and a questionnaire. To investigate if sensation of cold hands is a predictor for vascular or neurosensory HAVS we investigated a cohort of 178 employees at a manufacturing company where HAV was a common exposure. The cohort was followed during 21 years and both vibration exposure and health outcomes were assessed regularly. Questionnaire items were used to assess sensations of cold hands as well as signs of Raynaud’s phenomenon and paresthesia. To identify risk factors for cold sensitivity a case-control study was conducted involving 997iiiparticipants from the general population in northern Sweden. The study was cross-sectional and explored possible risk factors for cold sensitivity.Results Cold injuries and cold exposure were associated with reduced sensibility in QST and increase severity and prevalence of neurosensory and vascular symptoms. Our results did not show any impairment in peripheral blood flow due to cold exposure, detectable by FSBP. The risk of developing Raynaud's phenomenon was increased for workers previously reporting sensation of cold hands (OR 6.3, 95% CI 2.3-17.0). No increased risk for paresthesia in relation to a sensation of cold hands was observed. The identified risk factors for cold sensitivity were frostbite in the hands, rheumatic disease, nerve injury in upper extremities or neck, migraine and vascular disease. When analysing women and men separately, women’s risk factors were frostbite in the hands, rheumatic disease, migraine and cold exposure. Men’s risk factors were frostbite in the hands, vibration exposure and nerve injury in upper extremities or neck. BMI > 25 was a protective factor for both men and women.Conclusion Cold injury and cold exposure are associated with impairments in the neurosensory system, detectable by QST. Symptoms such as sensation of cold hands and white fingers indicate vascular involvement, even though no vascular impairments due to cold exposure could be detected by objective measurements. A sensation of cold hands is a risk factor for development of Raynaud´s phenomenon, but not for paresthesia. At the individual level, reporting cold hands does not appear to be useful information when considering the possibility of a future development of Raynaud’s phenomenon. Frostbite in the hands is a risk factor for cold sensitivity among both women and men. For women rheumatic disease, migraine and cold exposure are also independent risk factors, and for men, exposure to HAV. Being overweight is a protective factor for both women and men.
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| 8. |
- Eklöf, Mats, et al.
(författare)
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Workplace intervention for improved risk perception and preventive activity among workers : using hand-held vibrating machines: a pilot study
- 2023
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This article presents a pilot study of a 1-h workplace educational intervention implemented among ten construction workers who were highly exposed to hand–arm vibration. The intervention combined risk communication and normative expert advice intended to reinforce preventive behaviour related to vibration, noise, and biomechanical loads. Data for this study comprised intervention notes and interview data from interventionists, and pre- and post-intervention interview data from participating workers.The results suggested that the intervention was sensitive to disturbances and should be directed only to motivated workers possessing sufficient self-efficacy, and only in circumstances in which exposure may be controlled on the local workplace level and by locally implemented measures. Unless these conditions are present, the studied intervention may fail to influence preventive behaviour, and may instead cause cognitive dissonance and frustration among participants and interventionists.
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| 9. |
- Eliasson, Kristina, 1979-
(författare)
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Occupational health services in the prevention of musculoskeletal disorders : Processes, tools and organizational aspects
- 2017
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Work-related musculoskeletal disorders are associated with high costs and it is essential to prevent them. Occupational Health Services(OHS) provide expert services regarding work environment, health and rehabilitation of work related disorders. Risk assessments of the work environment can be an initial step for preventive measures, and ergonomists can be assigned by clients to assess exposures in the work environment. For such assignments different tools can be used. The aim of this thesis was to explore prerequisites, processes and practices of OHS consultants in Sweden within the domain of primary prevention of work-related musculoskeletal disorders. This was explored through the work of ergonomists in their role of assessing ergonomics risks. The research methodology was both quantitative and qualitative. Data collection includes a web questionnaire, semi-structured interviews and inter- and intra-observer reliability tests. The results shows that ergonomics risk assessments were most commonly initiated reactively and a systematic work methodology for the risk assessment process was often lacking. Swedish ergonomists used only a few standardized tools for risk assessment. The Ergonomics provision from the Swedish Work Environment Authority, AFS-98, was widely used, but other observation-based tools were used far less often. Ergonomics risks were often assessed solely by means of observation, based on ergonomists’ knowledge and experience. The results also pointed to that that the reliability was not acceptable when risk assessment was performed without any standardized tool. Furthermore, the results point to that support from the OHS organizations is an important prerequisite for ergonomists to work with primary prevention. Further, opportunities for specialization within a specific industry sector seem to facilitate ergonomic interventions. It is also important to have close relationships with clients and to make them aware about ergonomists competence. Conclusively, this thesis identifies a numbers of areas in which OHS must develop to improve primary preventive services regarding work environment.
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| 10. |
- Ericsson, Pernilla, et al.
(författare)
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Reliability testing of two ergonomic risk assessment tools
- 2012
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- INTRODUCTIONQuick Exposure Check (QEC¹) and Rapid Upper Limb Assessment (RULA²) are two ergonomic risk assessment tools that have been designed to be useful for ergonomists assessing musculoskeletal risk factors in upper extremities at workplaces.AIMThe aim was to describe the variation between and within ergonomists assessments using QEC and RULA, and to compare the two tools regarding within-observer agreement.SUBJECTS & METHODSTwenty ergonomists observed five different work tasks twice with three weeks in between, watching video clips. They made ergonomic risk assessments using both QEC and RULA.The observed work tasks were: Window replacement, nailing a wooden pallet, toilet cleaning, instrumentation in an operating theatre, and sorting post.For the statistical analyses, percent agreement and kappa value was used.RESULTSThere was a variation in assessments between the ergonomists in all positions and movements both when using QEC and RULA, except from assessing armposition when observing window replacement using QEC, where all ergonomists assessed the same position (figure 1).The ergonomists had higher percent agreement between observation one and two using QEC compared with RULA (table 1).CONCLUSIONThere was a variation when assessing positions and movements in different worktasks both between ergonomists and within the same ergonomist using both QEC and RULA. However the agreement between two observations within observers was higher for QEC.
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