| 11. |
- Alametsä, Jarmo, et al.
(författare)
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Age‐related circulatory responses to whole body cooling: observations by heart rate variability
- 2015
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Ingår i: Finnish Journal of eHealth and eWelfare. - 1798-0798. ; 7:2-3, s. 57-64
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Tidskriftsartikel (refereegranskat)abstract
- The purpose was to study potential age ‐ related changes in the circulatory system via heart rate variability (HRV) by gradually lowering ambient temperature (0.2°C/min) from thermoneutral (32 C°) towards cold (18 C°). ECG was recorded from a young (31 years) and from an older subject (78 years), both males. During the tests, brachium blood pressure (BP) was recorded. During the cooling, BP increased in both subjects (young from 95/69 to 132/75 mmHg, old from 125/68 to 176/101 mmHg), the latter exhibiting a prominent rise in diastolic values after cooling. HRV parameters increased in both subjects during the cold exposure being modest in the younger subject as compared to the older one. Also, recovery from the cold in terms of HRV was faster in the younger subject. The present preliminary observations indicate that older age is coupled with altered HRV response to a mild whole‐body skin cooling.
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| 12. |
- Aljaste, Helena, et al.
(författare)
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Better bicycle helmets for commuters – evaluation of ventilation
- 2014
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Ingår i: International Cycling Safety Conference 2014.
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Konferensbidrag (refereegranskat)abstract
- As a continuation of the work on the development of setting the requirements for ventilation of a bicycle helmet for commuters, 15 full scale helmet mock-ups were created by the students of the Estonian Academy of Arts. In order to encourage creativity for ventilation solutions the students were not restricted to consider the other properties except it was pointed out that the meaning of helmets use is protection. These 1:1 scaled mock-ups were tested at Thermal Environment Laboratory, Lund University for their heat transfer characteristics (insulation) in a wind tunnel on a thermal head manikin. The helmets were tested at the room temperature with the air velocities of 0.2, 1.6 and 6.0 m/s. The air velocities of 0.2 and 1.6 m/s were tested without a wig and 1.6 and 6.0 m/s were tested with wig to simulate the effect of hair. In addition, 4 reference helmets were tested in some conditions. Three (3) of them were one of the best, one average and one of the less well performing helmets of an earlier study, and one was a helmet commonly bought and used by an ordinary bicyclist. The helmets in new design were affected by ventilation and covered a wide range of insula-tion. The reference helmets from the earlier study stayed quite in the middle of the tested range. Thus, the new solutions could work much better or worse than available helmets. However, practically any new helmet was better than the common helmet from the shop. It was also very clear that various air velocities affected heat loss from the helmets. This means that a best solution for a commuter has to be defined by the user’s bicycling velocity. The best ventilation solutions will be chosen and the design work with considering of impact testing will be continued.
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| 13. |
- Aljaste, Helena, et al.
(författare)
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The effects of air channel construction and design elements on heat transfer characteristics of bicycle helmets for commuters
- 2015
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Ingår i: International Cycling Safety Conference 2015.
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Konferensbidrag (refereegranskat)abstract
- The earlier studies in this measurement series defined the limits and aims for design process to create better ventilating helmets [1], and tested the insulation [2] and evaporative characteristics [3] of the designed mock-ups. In addition some of the tested mock-ups were modified to study more closely the factors that were expected to improve heat transfer from the bicycle helmets. The present paper covers making a new prototype that allowed modifications of the air channels and in- and outlet openings. In total 2 new helmet design concept mock-ups were created and tested with 13 modifications in comparison with 6 selected helmets from the previous studies including the modified versions. The mock-ups were tested at the Thermal Environment Laboratory, Lund University for insulation and evaporative resistance. Dry tests for insulation were carried on at 20 °C temperature in a wind tunnel on a thermal head manikin at the chosen air velocities of 1.6 m/s on a bald head and 1.6 m/s and 6 m/s with the wig in order to simulate the effect of hair. Wet tests were carried out with textile skin on the head manikin, using the air velocity 1.6 m/s with and without the wig. As the main result it was concluded that a well ventilating helmet is characterized by less contact with the head, and proper air channels with strategically placed air inlets and outlets. Large openings worked much better than a several small ones, yet, the care has to be taken as too large openings reduce the helmet protective capabilities. The shape and other design related modifications of the air inlets and outlets had minimal effect on ventilation.
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| 14. |
- Annaheim, Simon, et al.
(författare)
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Final report of Working Group 4: Ergonomics of thermal effects. A COST Action TU1101 / HOPE collaboration
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The thermal effects related to wearing a bicycle helmet are complex and different studies have investigated single parts of this topic. A literature review was produced and published (Bogerd et al., 2015) summarizing the different findings to give a complete overview on this topic as well as to suggest new perspectives. Headgear increases head insulation and therefore is mainly problematic under warm conditions, which is the focus of that review. Helmets do not affect physiological parameters other than the local skin temperature and sweat rate. However, the head is among the most sensitive body parts related to thermal comfort, thereby directly affecting the willingness to wear headgear. Several methods have been used to study thermal aspects of headgear, which could be categorized as (i) numerical, (ii) biophysical, (iii) combined numerical and biophysical, and (iv) user trials. The application of these methods established that heat transfer mainly takes place through radiation and convection. Headgear parameters relevant to these heat transfer pathways are reviewed and suggestions are provided for improving existing headgear concepts and developing new concepts, ultimately leading to more accepted headgear. The report of working group 4 (WG4) provides information about activities undertaken during the COST Action TU1101 “Towards safer bicycling through optimization of bicycle helmets and usage” to better understand the ergonomics of thermal aspects and to work towards the tasks defined in the memorandum of understanding (COST Secretariat, 2011). Primary Task 5: Development of guidelines for thermally-optimized helmet designs Secondary Task 3: Inform impact studies on which kinds of ventilation structures are useful and which are unnecessary Secondary Task 7: Review of physiological and comfort effect of wearing bicycle helmets All the chapters listed below include important aspects contributing to the primary task 5. Modelling and simulation tools (Chapter II) are becoming more and more important in research and development of new bicycle helmets but also in the development of guidelines, directives and norms. An example for the industrial application of models is given in Chapter III. The investigation of different forms of helmet coverings provides important information about the future direction for the development of helmet designs. Completely new helmet designs and the respective thermal properties are presented in Chapter IV. This chapter shows a different approach for finding new concepts of helmet designs. In Chapter V, new project initiatives are introduced to improve thermal aspects of helmets but also to include information and communication techniques (ICT) into helmets. Finally, the tasks of WG4 are summarized in Chapter VI, conclusions are drawn and an outlook is provided regarding the future development of helmets to comply with the requests of two-wheel commuters (including e-bikes, segway and others).
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| 15. |
- Anttonen, Hannu, et al.
(författare)
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Thermal manikin measurements - exact or not?
- 2004
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Ingår i: International Journal of Occupational Safety and Ergonomics. - 2376-9130. ; 10:3, s. 291-300
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Tidskriftsartikel (refereegranskat)abstract
- According to the European prestandard ENV 342:1998, the thermal insulation of cold-protective clothing is measured with a thermal manikin. Systematic studies on the reproducibility of the values, measured with different types of clothing on the commonly used standing and walking manikins, have not been reported in the literature. Over 300 measurements were done in 8 different European laboratories. The reproducibility of the thermal insulation test results was good. The coefficient of variation was lower than 8%. The measured clothing should fit the manikin precisely, because poorly fitting clothing gave an error in the results. The correlation between parallel and serial insulation values was excellent and parallel values were about 20% lower than serial ones. The influence of ambient conditions was critical only in the case of air velocity. The reproducibility of thermal insulation test results in a single laboratory was good, and the variation was lower than 3%.
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| 16. |
- Arias, Silvia, et al.
(författare)
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An experiment on ascending evacuation on a long, stationary escalator
- 2016
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Ingår i: Interflam 2016.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Ascending evacuation is becoming more relevant with underground stations reaching increasing depths. Therefore there is need for better understanding of the effects of physical exertion during evacuation. An experiment was conducted in a 61 m long, stationary escalator in Stockholm (Sweden) in order to obtain data on walking speeds, resting and behavior, which consisted on measuring the walking speed and gathering data about the perceived exertion of test participants walking up the escalator. The walking speeds of 29 single individuals and a group of 21 individuals were obtained. The results showed that people decrease their walking speed with the height, and some of them need to take breaks along the climb. No clear influence of background participants’ variables was found on the results. In the group experiment, the slower people had an impact on the walking speed of others due to the reduced space between them at the beginning of the climb. However, the slower participants gradually move to the right hand of the escalator to allow overtaking on the left hand side, and the faster ones could move at their preferred speed. This behavior is similar that observed during regular use of escalators.
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| 17. |
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| 18. |
- Bogerd, Cornelis P., et al.
(författare)
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A review on ergonomics of headgear: Thermal effects
- 2015
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Ingår i: International Journal of Industrial Ergonomics. - : Elsevier BV. - 0169-8141. ; 45:February, s. 1-12
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Forskningsöversikt (refereegranskat)abstract
- The thermal effects related to wearing headgear are complex and different studies have investigated single parts of this topic. This review aims at summarizing the different findings to give a complete overview on this topic as well as to suggest new perspectives. Headgear increases head insulation and therefore is mainly problematic under warm conditions, which is the focus of this review. Helmets do not affect physiological parameters other than the local skin temperature and sweat rate. However, the head is among the most sensitive body parts related to thermal comfort, thereby directly affecting the willingness to wear headgear. Several methods have been used to study thermal aspects of headgear, which could be categorized as (i) numerical, (ii) biophysical, (iii) combined numerical and biophysical, and (iv) user trials. The application of these methods established that heat transfer mainly takes place through radiation and convection. Headgear parameters relevant to these heat transfer pathways, are reviewed and suggestions are provided for improving existing headgear concepts and developing new concepts, ultimately leading to more accepted headgear. Relevance to industry: This review provides a sound basis for improving existing headgear concepts. Firstly, a concise overview of headgear research related to thermal effects is given, leading to empirically based improvement suggestions and identification of research fields with a high potential. Finally, relevant research methods are described facilitating evaluation in R&D processes.
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| 19. |
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| 20. |
- Bouskill, Lisa M., et al.
(författare)
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The relationship between ventilation index and thermal insulation
- 1998
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Ingår i: Proceedings / ICCE8 the 8th International Conference on Environmental Ergonomics, 18-23 October 1998, San Diego, California, USA. - : International Conference on Environmental Ergonomics. - 0966695305
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Konferensbidrag (refereegranskat)
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