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- de Alwis, Manudul Pahansen, 1980-
(författare)
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Towards consonance in working conditions, health and performance aboard high-performance marine craft
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The High-Performance Marine Craft (HPMC) is a complex man-machine system dealing with the stochastic nature of the sea. The occupants of these craft are challenged by the strenuous work environments resulting in various detrimental conditions and reducing the overall performance of the system. The sophisticated craft, designed and developed for high operational demands, are underused due to the human limitations while occupants confronting various psychophysical impairments. A balance is required between the craft and human to get the most out of the system as an ensemble. Achieving that, the knowledge is essential about the human response to the working conditions aboard HPMC which is lacking in the scientific community.In this context, a research program has been commenced to investigate working conditions aboard HPMC and the response of the craft occupants in terms of health and performance. The thesis presents the research as a holistic approach to integrate the exposure-response relationship into HPMC design and operation.An epidemiological study is designed and executed to identify and quantify the risk associated with the working conditions aboard HPMC. As the first step, two web-based questionnaire tools are developed, validated and pilot tested for cross-sectional and longitudinal investigation of health and performance in HPMC occupants. Then a sample of HPMC occupants is investigated for work-related and individual risk factors relating to their work-exposure, health and performance in a cross-sectional cohort study. The prevalence of health impairments and performance degradation is determined while estimating their association with work exposure. Following that, another sample of HPMC occupants is longitudinally examined in a prospective cohort study for their work exposure, health and performance estimating the incidence of adverse health effects and its association with the occupational exposure to shock and vibration. Finally, a method is developed for a decision support feedback system continuously updating the crew during real-time operations on the severity of expected high-intensity short-duration impacts as well as the accumulated vibration exposure aboard HPMC.The cross-sectional study shows that the prevalence of musculoskeletal pain (MSP) among HPMC occupants is comparatively high and that the exposure to severe conditions aboard semi-displacement and planing craft increases the risk of MSP. The latter also increases the risk of performance degradation. The longitudinal study indicates an incidence of MSP and performance degradation in HPMC occupants. It also suggests that the accumulation of occupational exposure to shock and vibration aboard HPMC is a factor increasing the risk of MSP incidence while quantifying the level of risk. The introduced method for real-time crew feedback is capable of capturing the exposure severity and informing it to the crew in a sufficiently short time.The research has successfully achieved the objectives. It has also highlighted the areas that need further improvements and suggested the domains that require extended investigations.
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| 2. |
- de Alwis, Pahansen, 1980-, et al.
(författare)
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Adverse health effects and reduced work ability due to vertical accelerations in high-performance marine craft personnel
- 2017
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Ingår i: Proceedings of the 16<sup>th</sup> International Ship Stability Workshop.
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Konferensbidrag (refereegranskat)abstract
- Human factors engineering is a key parameter in High-Performance Marine Craft (HPMC) design since the human tolerance to working conditions aboard, in fact, decides the operational limits. So far, the deficiency of the knowledge on how the crew is influenced by the working conditions in terms of health risk and work performance has lead the designing process to exit before incorporating the human element when determining these operational limits. Knowledge, on the relationship of the physical and perceived exposure conditions and on risk factors for health and work performance impairments, would open up possibilities for drawing the operational limits at the design stage and providing feedback to the crew during operations. This is investigated in a research program and the current study pilot test a set of High-Performance Marine Craft Personnel (HPMCP) in order to collect data on their work exposure, health and performance impairments. The study collects subjective and objective data and investigates their correlation and the potential risk factors. Although the amount of data collected is too limited to draw direct conclusions, the pilot test confirms the feasibility of the set-up and the method giving good inputs and experience to the research crew.
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| 4. |
- de Alwis, Pahansen, 1980-, et al.
(författare)
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Effect of occupational exposure to shock and vibration on health in high-performance marine craft occupants
- 2021
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Ingår i: Journal of Engineering for the Maritime Environment (Part M). - : SAGE Publications. - 1475-0902 .- 2041-3084. ; 235:2, s. 394-409
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Tidskriftsartikel (refereegranskat)abstract
- Working conditions of High-performance Marine Craft (HPMC) occupants are inherent with shock and vibration. Therefore, HPMC occupants are usually investigated believing that their psychophysical health and performance are negatively affected by exposure to these conditions. However, the association between the regular occupational vibration exposures of HPMC occupants and the deterioration of their health and performance is disputable. Therefore, a sample of HPMC occupants are investigated in a prospective cohort study by measuring perceived work exposure, health and performance via validated web-based questionnaires and physical work exposure as vibration using measurement systems installed onboard their craft. Incidence of musculoskeletal pain (MSP) during four operational seasons is determined and presented as incidence proportion (IP). Association between accumulated vibration exposure aboard HPMC and incidence of MSP is systematically assessed using multiple logistic regression models and expressed as odds ratio (OR). Moreover, the correlation between objectively and subjectively measured vibration exposures is determined using the Spearman’s rank correlation coefficient (rs). Incidence proportion of neck pain was 63.4% and that of lower back pain ranged from 12.5% to 87.5% over the four seasons. The accumulated vibration exposure was strongly associated with the incidence of MSP primarily with lower back pain. However, the association was not statistically significant. The objective and subjective vibration exposures of the craft drivers showed a statistically significant positive monotonic correlation. The study suggests that occupational exposure to shock and vibration aboard HPMC is a factor increasing the incidence of MSP. The HPMC occupants regularly experience attrition in their performance. The perceived vibration exposure of the drivers can be used to rank the exposure severity aboard HPMC in the absence of objective measurements. The current vibration exposure assessment methods are also recommended to be revised accounting for shock and vibration inherent in HPMC exposures.
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| 6. |
- de Alwis, Pahansen, 1980-, et al.
(författare)
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Exposure aboard high-performance Marine craft increases musculoskeletal pain and lowers contemporary work capacity of the occupants
- 2021
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Ingår i: Journal of Engineering for the Maritime Environment (Part M). - : SAGE Publications. - 1475-0902 .- 2041-3084. ; 235:3, s. 750-762
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Tidskriftsartikel (refereegranskat)abstract
- High-Performance Marine Craft (HPMC) occupants are currently being investigated for various psychophysical impairments degrading work performance postulating that these deteriorations are related to their occupational exposures. However, scientific evidence for this is lacking and the association of exposure conditions aboard HPMC with adverse health and performance effects is unknown. Therefore, the study estimates the prevalence of musculoskeletal pain (MSP) among HPMC occupants and the association of their work exposure with MSP and performance degradation. It also presents a criterion for evaluating the self-reported exposure severity aboard three different types of mono-hull HPMC; displacement, semi-displacement and planing, on a par with the available standard criteria for objectively measurable exposures. Furthermore, another criterion is proposed to assess the performance-degradation of HPMC occupants based on self-reported fatigue symptoms and MSP. Swedish Coast Guard HPMC occupants were surveyed for MSP, fatigue symptoms as well as for work-related and individual risk indicators using a validated web-based questionnaire. Prevalence of MSP and performance-degradation during the past 12 months were assessed and presented as a percentage of the sample. Associations of exposure conditions aboard HPMC with MSP and performance-capacity were systematically evaluated using multiple logistic regression models and expressed as odds ratio (OR). Prevalence of MSP was 72% among which lower back pain was the most prevalent (46%) followed by neck pain (29%) and shoulder pain (23%) while 29% with degraded performance. Exposure to severe conditions aboard semi-displacement craft was associated with lower back (OR = 2.3) and shoulder (OR = 2.6) pain while severe conditions aboard planing craft with neck pain (OR = 2.3) and performance-degradation (OR = 2.6). MSP is common among Swedish coast guards. Severe exposure conditions aboard HPMC are significantly associated with both MSP and performance-degradation. The spine and shoulders are the most susceptible to work-related MSP among HPMC occupants which should be targeted in work-related preventive and corrective measures.
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| 7. |
- de Alwis, Pahansen, 1980-, et al.
(författare)
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Feasibility of Using Kidney-Belt-Mounted Accelerometers for Measuring Shock and Vibration Exerted on the Lumbar Spine Region of High-Speed Marine Craft Occupants
- 2023
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Ingår i: HSMV 2023 - Proceedings of the 13th Symposium on High Speed Marine Vehicles. - : IOS Press. ; , s. 233-240, s. 233-240
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Konferensbidrag (refereegranskat)abstract
- The feasibility of using kidney-belt-mounted accelerometers for measuring the shock and vibration exposure in the lumbar spine region of high-speed marine craft occupants and evaluating them on a par with the current standards remain largely unexplored in scientific literature. To address this gap a series of laboratory and field experiments were conducted. In the laboratory experiments, two test subjects performed predefined body movements while accelerations were measured using body-mounted and kidney-belt-mounted accelerometers. Field experiments involved recording acceleration exposures of two test subjects using the kidney belt arrangement and seat-mounted accelerometers during a high-speed marine craft exercise. Results suggest that kidney-belt-mounted accelerometers effectively measure lumbar spine accelerations during basic body movements with an upright torso. However, evaluating vibration exposures measured with the kidney belt arrangement using existing international standards proved challenging in the field experiment.
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| 9. |
- de Alwis, Pahansen, 1980-, et al.
(författare)
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Monitoring and characterization of vibration and shock conditions aboard high-performance marine craft
- 2018
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Ingår i: Journal of Engineering for the Maritime Environment (Part M). - UK : Institution of Mechanical Engineers. - 1475-0902 .- 2041-3084. ; 233:4, s. 1068-1081
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Tidskriftsartikel (refereegranskat)abstract
- The stochastic environmental conditions together with craft design and operational characteristics make it difficult to predict the vibration environments aboard high-performance marine craft, particularly the risk of impact acceleration events and the shock component of the exposure often being associated with structural failure and human injuries. The different timescales and the magnitudes involved complicate the real-time analysis of vibration and shock conditions aboard these craft. The article introduces a new measure, severity index, indicating the risk of severe impact acceleration, and proposes a method for real-time feedback on the severity of impact exposure together with accumulated vibration exposure. The method analyzes the immediate 60s of vibration exposure history and computes the severity of impact exposure as for the present state based on severity index. The severity index probes the characteristic of the present acceleration stochastic process, that is, the risk of an upcoming heavy impact, and serves as an alert to the crew. The accumulated vibration exposure, important for mapping and logging the crew exposure, is determined by the ISO 2631:1997 vibration dose value. The severity due to the impact and accumulated vibration exposure is communicated to the crew every second as a color-coded indicator: green, yellow and red, representing low, medium and high, based on defined impact and dose limits. The severity index and feedback method are developed and validated by a data set of 27 three-hour simulations of a planning craft in irregular waves and verified for its feasibility in real-world applications by full-scale acceleration data recorded aboard high-speed planing craft in operation.
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