| 1. |
- 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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| 2. |
- 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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| 3. |
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| 4. |
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| 5. |
- Bröde, Peter, et al.
(författare)
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Assessment of Thermal Discomfort when Wearing Bicycle Helmets – A Modelling Framework
- 2015
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Ingår i: International Cycling Safety Conference 2015.
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Konferensbidrag (refereegranskat)abstract
- Excessive sweating is a major ergonomic concern in bicycle helmet use and low wearing rates are suspected to originate, at least partly, from impaired thermal comfort due to accumulated sweat increasing skin wettedness at the head region. As a development from COST Action TU1101 WG4, we introduce a modelling framework for assessing the thermal comfort of bicy-cle helmet use. We predicted local sweat rate (LSR) at the head region as ratio to gross sweat rate (GSR) of the whole body and also based on sudomotor sensitivity (SUD), which relates the change in LSR to the change in body core temperature (ΔTre). We coupled those local models with models of thermoregulation predicting ΔTre and GSR, thus modelling head sweating in re-sponse to the characteristics of the thermal environment, clothing, level of activity, and expo-sure duration. We then validated the predictions of several local models (SUD, LSR/GSR) com-bined with different whole-body models against head sweat rates measured in the laboratory. Eventually, we developed thermal comfort criteria from head LSR by relating skin wettedness to the thermal properties of bicycle helmets. We discuss the potential of this approach as well as needs for further research.
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| 6. |
- Bröde, Peter, et al.
(författare)
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Deriving the operational procedure for the Universal Thermal Climate Index (UTCI)
- 2012
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Ingår i: International Journal of Biometeorology. - : Springer Science and Business Media LLC. - 1432-1254 .- 0020-7128. ; 56:3, s. 481-494
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Tidskriftsartikel (refereegranskat)abstract
- The Universal Thermal Climate Index (UTCI) aimed for a one-dimensional quantity adequately reflecting the human physiological reaction to the multi-dimensionally defined actual outdoor thermal environment. The human reaction was simulated by the UTCI-Fiala multi-node model of human thermoregulation, which was integrated with an adaptive clothing model. Following the concept of an equivalent temperature, UTCI for a given combination of wind speed, radiation, humidity and air temperature was defined as the air temperature of the reference environment, which according to the model produces an equivalent dynamic physiological response. Operationalising this concept involved (1) the definition of a reference environment with 50% relative humidity (but vapour pressure capped at 20 hPa), with calm air and radiant temperature equalling air temperature and (2) the development of a one-dimensional representation of the multivariate model output at different exposure times. The latter was achieved by principal component analyses showing that the linear combination of 7 parameters of thermophysiological strain (core, mean and facial skin temperatures, sweat production, skin wettedness, skin blood flow, shivering) after 30 and 120 min exposure time accounted for two-thirds of the total variation in the multi-dimensional dynamic physiological response. The operational procedure was completed by a scale categorising UTCI equivalent temperature values in terms of thermal stress, and by providing simplified routines for fast but sufficiently accurate calculation, which included look-up tables of pre-calculated UTCI values for a grid of all relevant combinations of climate parameters and polynomial regression equations predicting UTCI over the same grid. The analyses of the sensitivity of UTCI to humidity, radiation and wind speed showed plausible reactions in the heat as well as in the cold, and indicate that UTCI may in this regard be universally useable in the major areas of research and application in human biometeorology.
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| 7. |
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| 8. |
- Bröde, Peter, et al.
(författare)
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Einfluss der unteren Schichten von Schutzbekleidung auf die Erwärmung durch Infrarotstrahlung
- 2008
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Ingår i: Produkt- und Produktions-Ergonomie : Aufgaben für Entwickler und Planer : Bericht zum 54. Kongress der Gesellschaft für Arbeitswissenschaft vom 9. - 11. April 2008 - Aufgaben für Entwickler und Planer : Bericht zum 54. Kongress der Gesellschaft für Arbeitswissenschaft vom 9. - 11. April 2008. - 9783936804065 ; , s. 239-242
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Konferensbidrag (refereegranskat)abstract
- Mit einer Thermopuppe wurde die Erwärmung durch langwellige Wärmestrahlung beim Tragen von Schutzkleidung erfasst, wobei Material und Anzahl der Schichten der Unterbekleidung variiert wurden. Die Unterbekleidung minderte die durch Strahlungs-Absorption hervorgerufene Erwärmung. Die dabei beobachtete hohe negative Korrelation mit der thermischen Isolation zeigt Möglichkeiten zur Berücksichtigung von Effekt modifizierenden Eigenschaften wie Materialdichte oder -dicke bei der Modellierung auf.
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| 9. |
- Bröde, Peter, et al.
(författare)
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Heat gain from thermal radiation through protective clothing with different insulation, reflectivity and vapour permeability
- 2010
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Ingår i: International Journal of Occupational Safety and Ergonomics. - 2376-9130. ; 16:2, s. 231-244
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Tidskriftsartikel (refereegranskat)abstract
- The heat transferred through protective clothing under long wave radiation compared to a reference condition without radiant stress was determined in thermal manikin experiments. The influence of clothing insulation and reflectivity, and the interaction with wind and wet underclothing were considered. Garments with different outer materials and colours and additionally an aluminised reflective suit were combined with different number and types of dry and pre-wetted underwear layers. Under radiant stress, whole body heat loss decreased, i.e., heat gain occurred compared to the reference. This heat gain increased with radiation intensity, and decreased with air velocity and clothing insulation. Except for the reflective outer layer that showed only minimal heat gain over the whole range of radiation intensities, the influence of the outer garments’ material and colour was small with dry clothing. Wetting the underclothing for simulating sweat accumulation, however, caused differing effects with higher heat gain in less permeable garments.
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| 10. |
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