| 1. |
- Alametsä, Jarmo, et al.
(författare)
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Age-related circulatory responses to whole body cooling: observations by ballistocardiographic EMFi sensors
- 2014
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Ingår i: Proceedings of Ambience 14&10i3m : Scientific Conference for Smart and Functional Textiles, Well-Being, Thermal Comfort in Clothing, Design, Thermal Manikins and Modellin, 7-9 September 2014, Tampere, Finland - Scientific Conference for Smart and Functional Textiles, Well-Being, Thermal Comfort in Clothing, Design, Thermal Manikins and Modellin, 7-9 September 2014, Tampere, Finland. - 2342-4540. - 9789521532696 ; 1
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Konferensbidrag (refereegranskat)abstract
- The purpose was to study age related changes in circulatory system via Ballistocardiography (BCG) by utilizing Electromechanical Film (EMFi) sensors by gradually changing the ambient temperature from a thermoneutral area to cold direction. ECG and BCG were recorded from a young person (23 years) and from an older person (78 years), both males. During the tests, brachium blood pressure (BP) and pulse signals were recorded from neck and ankle (with EMFi sensor strips). Thermal camera images were taken in order to find out temperature changes in whole body and limbs. Temporal durations and amplitudes of seat BCG:s components (systolic and diastolic) as well as from pulse signals from neck and ankle were calculated. Aortic pulse wave velocity (PWV) was obtained by utilizing the time between ECG’s R wave and maximum value of the ankle pulse signal. In both persons, the ankle pulse amplitude decreased when propagating to cold direction and increased in young person when returning to warmer ambient temperature. With young and old BCG:s systolic and diastolic temporal complexes remained stable, but systolic amplitudes increased in the older person (AHI 1.02 – 2.87, AIJ 0.7 – 2.66) as well as diastolic amplitudes (old; AKL 0.47 – 2.37). In the older person, PWV increased when moving to colder side. BP increased with a young person (from 95/64 to 132/75 mmHg), and with older person (from 125/68 to 176/101 mmHg) having a prominent rise in diastolic values during the cooling. The neck pulse wave amplitude AOP rise was modest with the younger person and had variation with the older person. Older person had also more intensive shivering compared to younger one. With the older person, the limbs stayed cold in thermal images when returning from cold to thermoneutral area. The present preliminary observations indicated clear age-related differences in the circulatory response to a mild whole-body thermal challenge.
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| 2. |
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| 3. |
- Gao, Chuansi, et al.
(författare)
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Cooling vests with phase change material packs: the effects of temperature gradient, mass, and covering area
- 2010
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Ingår i: Ergonomics. - : Informa UK Limited. - 0014-0139 .- 1366-5847. ; 53:5, s. 716-723
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Tidskriftsartikel (refereegranskat)abstract
- Phase change material (PCM) absorbs or releases latent heat when it changes phases, making thermal-regulated clothing possible. The objective of this study was to quantify the relationships between PCM cooling rate and temperature gradient, mass, and covering area on a thermal manikin in a climatic chamber. Three melting temperatures (24, 28, 32 °C) of the PCMs, different mass, covering areas, and two manikin temperatures (34 and 38 °C) were used. The results showed that the cooling rate of the PCM vests tested is positively correlated with the temperature gradient between the thermal manikin and the melting temperature of the PCMs. The required temperature gradient is suggested to be greater than 6 °C when PCM vests are used in hot climates. With the same temperature gradient, the cooling rate is mainly determined by the covering area. The duration of the cooling effect is dependent on PCM mass and the latent heat
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| 4. |
- Gao, Chuansi, et al.
(författare)
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Cooling vests with phase change materials: the effects of melting temperature on heat strain alleviation in an extremely hot environment
- 2011
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6327 .- 1439-6319. ; 111:6, s. 1207-1216
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Tidskriftsartikel (refereegranskat)abstract
- A previous study by the authors using a heated thermal manikin showed that the cooling rates of phase change material (PCM) are dependent on temperature gradient, mass, and covering area. The objective of this study was to investigate if the cooling effects of the temperature gradient observed on a thermal manikin could be validated on human subjects in extreme heat. The subjects wore cooling vests with PCMs at two melting temperatures (24 and 28°C) and fire-fighting clothing and equipment, thus forming three test groups (vest24, vest28 and control group without the vest). They walked on a treadmill at a speed of 5 km/h in a climatic chamber (air temperature = 55°C, relative humidity = 30%, vapour pressure = 4,725 Pa, and air velocity = 0.4 m/s). The results showed that the PCM vest with a lower melting temperature (24°C) has a stronger cooling effect on the torso and mean skin temperatures than that with a higher melting temperature (28°C). Both PCM vests mitigate peak core temperature increase during the resting recovery period. The two PCM vests tested, however, had no significant effect on the alleviation of core temperature increase during exercise in the heat. To study the possibility of effective cooling of core temperature, cooling garments with PCMs at even lower melting temperatures (e.g. 15°C) and a larger covering area should be investigated.
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| 5. |
- Gao, Chuansi, et al.
(författare)
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Fashion and function: challenges faced by textiles incorporated with phase change materials
- 2014
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Ingår i: [Host publication title missing]. - 2342-4540.
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Konferensbidrag (refereegranskat)abstract
- Designers focus on fashion and appearance, whereas safety and protection engineers and physiologists emphasize functions in terms of developing functional and protective clothing. Phase change materials (PCMs) have been used in textiles and clothing to achieve cooling or warming function. The objective of this paper was to compare effectiveness of PCM cooling or warming determined by critical factors. Cooling or warming effectiveness and duration were directly dependent on physical activity level (body heat production), PCM mass and temperature gradient between the skin temperature and PCM phase change temperature. Given these factors, textiles and clothing incorporated with PCMs may be lightweight, well-designed, smart and fashionable, but are insufficiently functional when the amount of the PCM and latent heat are small relative to the body heat production and duration of activities. It is therefore challenging by incorporating PCMs into textiles and clothing to achieve desirable light weight, fashion, thermal comfort and effective alleviation of body heat strain unless the critical factors are taken into account.
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| 6. |
- Gao, Chuansi, et al.
(författare)
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Halk- och fallolyckor, friktionskrav och balansförmåga
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Syftet med detta projekt var att studera samspelet mellan friktion, balansförmåga och halkrisker, samt att ta fram designrekommendationer för friktionskrav och halksäkrare skor och underlag. Sex studier har utförts innefattande friktionsmätningar av skor på olika underlag och temperaturer, studier av stående balans och gång på ramp med justerbar lutning samt fokusgruppintervjuer. Resultaten visar att vid arbete i rumstemperatur på våta klinkergolv bör skosulor av polyuretan användas då de ger högre friktion, utomhus på isigt underlag bör skor med gummi eller latexsulor användas. Oavsett skosulans material och mönster hade alla testade skor utom de dubbade mycket låg friktion på is med vatten. Mjukare material på skosulor bör användas i kyla. Stående tester på plan eller lutande balansplatta med två ytmaterial, takpapp och halt underlag, visade att mer friktion utnyttjades då underlaget lutades. Både underlagets lutning och friktion påverkade balansförmågan. Alla förändringar var tydligare för det hala underlaget, låg friktion är en riskfaktor för att tappa balansen, inte bara vid gång utan också vid stående arbete. Intervjuerstudien visade att upplevda halkrisker var relaterade till hala och lutande underlag och/eller våta eller snöiga skor. Kriterier för en halkfri vintersko var flexibilitet, komfort, multifunktionalitet, ergonomiskt design, individuell anpassning, stabilitet och gångsäkerhet samt anpassning till arbetssituation. Samband mellan friktionskrav och halkrisk på en ramp med olika lutningsvinklar och ytmaterial visade att ju högre lutningsvinkel, dess högre halkrisk och högre friktionskrav vid gång nedåt på både torr och våt stålplåt. Vått underlag och högre grad av lutning bör undvikas. Ett linjärt förhållande har identifierats mellan friktionskrav och lutningsvinkel, där friktionskrav för olika lutningsvinklar kan förutsägas. Ny kunskap om prevention av halk- och fallolyckor, utformning av halksäkrare skor och arbetsplatser har erhållits i projektet.
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| 9. |
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| 10. |
- Gao, Chuansi, et al.
(författare)
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Personal cooling with phase change materials to improve thermal comfort from a heat wave perspective
- 2012
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Ingår i: Indoor Air. - : Hindawi Limited. - 0905-6947. ; 22:6, s. 523-530
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Tidskriftsartikel (refereegranskat)abstract
- Abstract in UndeterminedAbstract The impact of heat waves arising from climate change on human health is predicted to be profound. It is important to be prepared with various preventive measures for such impacts on society. The objective of this study was to investigate whether personal cooling with phase change materials (PCM) could improve thermal comfort in simulated office work at 34°C. Cooling vests with PCM were measured on a thermal manikin before studies on human subjects. Eight male subjects participated in the study in a climatic chamber (T(a) = 34°C, RH = 60%, and ν(a) = 0.4 m/s). Results showed that the cooling effect on the manikin torso was 29.1 W/m(2) in the isothermal condition. The results on the manikin using a constant heating power mode reflect directly the local cooling effect on subjects. The results on the subjects showed that the torso skin temperature decreased by about 2-3°C and remained at 33.3°C. Both whole body and torso thermal sensations were improved. The findings indicate that the personal cooling with PCM can be used as an option to improve thermal comfort for office workers without air conditioning and may be used for vulnerable groups, such as elderly people, when confronted with heat waves. PRACTICAL IMPLICATIONS: Wearable personal cooling integrated with phase change materials has the advantage of cooling human body's micro-environment in contrast to stationary personalized cooling and entire room or building cooling, thus providing greater mobility and helping to save energy. In places where air conditioning is not usually used, this personal cooling method can be used as a preventive measure when confronted with heat waves for office workers, vulnerable populations such as the elderly and disabled people, people with chronic diseases, and for use at home.
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