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Träfflista för sökning "WFRF:(Halder Amitava) "

Sökning: WFRF:(Halder Amitava)

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1.
  • Alametsä, Jarmo, et al. (författare)
  • Age-related circulatory responses to whole body cooling: observations by ballistocardiographic EMFi sensors
  • 2014
  • Ingår i: Ambience14 & 10I3M, Scientific conference for Smart and functional textiles, Well-Being, Thermal comfort in clothing, Design, Thermal Manikins and Modelling,Tampere Hall, Tampere, Finland,2014-09-07 - 2014-09-09. - : Tampere University of Technology. ; 1
  • 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.
  • Alametsä, Jarmo, et al. (författare)
  • Age‐related circulatory responses to whole body cooling: observations by heart rate variability
  • 2015
  • Ingår i: Finnish Journal of eHealth and eWelfare. - 1798-0798. ; 7:2-3, s. 57-64
  • 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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3.
  • Arias, Silvia, et al. (författare)
  • An experiment on ascending evacuation on a long, stationary escalator
  • 2016
  • Ingår i: Interflam’16, 14th International Conference and Exhibition on Fire Science and Engineering, London, UK, 4- 6th July 2016,London, United Kingdom,2016-07-04 - 2016-07-06.
  • Konferensbidrag (övrigt vetenskapligt)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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4.
  • Delin, Mattias, et al. (författare)
  • Ascending evacuation - Walking speed in stairs as a function of height
  • 2015
  • Ingår i: International symposium on Human Behaviour in Fire, 2015,Cambridge, United Kingdom,2015-09-28 - 2015-09-30. - : Interscience Communications. ; , s. 155-160
  • Konferensbidrag (refereegranskat)abstract
    • During ascending evacuation in long stairs, there is reason to believe that factors such as fatigue, and change in human behaviour will influence the possibility of satisfactory evacuation and affect the ascending walking speed. Based on these assumption, a 2-year research project was initiated at Lund University. This paper gives a brief description of the project and highlight some initial findings according ascending walking speed and effects of fatigue.
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5.
  • Delin, Mattias, et al. (författare)
  • Ascending stair evacuation : walking speed as a function of height
  • 2017
  • Ingår i: Fire and Materials. - : John Wiley and Sons Inc.. - 0308-0501 .- 1099-1018. ; 41:5, s. 514-534
  • Tidskriftsartikel (refereegranskat)abstract
    • There is reason to believe that factors such as physical exertion and behavioural changes will influence the ascending walking speed and ultimately the possibility of satisfactory evacuation. To study these effects, a 2-year research project was initiated with the focus on effects of physical exertion on walking speeds, physiological performance and behaviours during long ascending evacuations. Two sets of experiments on human performance during ascending long stairs, with a height of 48 and 109 m, were performed. The results include aspects such as walking speeds, physical exertion (oxygen consumption, heart rates and electromyography data), perceived exertion and behavioural changes, showing that physical work capacity affects walking speeds in case of long ascending evacuation and should be considered while using long ascending evacuation. Analysis of both walking and vertical speeds is recommended because it provides additional insights on the impact of stair configuration on vertical displacement and the importance of not using the same value for walking speed for different stairs because the design of the stairs has an impact. The novel datasets presented in this paper are deemed to provide useful information for fire safety engineers both for assisting fire safety design as well as the calibration of evacuation modelling tools.
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7.
  • Gao, Chuansi, et al. (författare)
  • Halk- och fallolyckor, friktionskrav och balansförmåga
  • 2013
  • Rapport (övrigt vetenskapligt)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.
  • Gao, Chuansi, et al. (författare)
  • Using a walkway with adjustable inclination to measure and assess slip and fall risks
  • 2014
  • Ingår i: CIB W099 International Health and Safety Conference on Achieving Sustainable Construction Health and Safety,Lund, Sweden,2014-06-02. - : Lund University. ; , s. 118-124
  • Konferensbidrag (refereegranskat)abstract
    • Fall is the most common cause of serious work related accidents. Falls and related injuries not only cause suffering for individuals, but also means a high economic burden to industries and society. The objective of the study was to use a walkway with in-built force plate, adjustable inclination and surface to assess how risks of slips and falls vary due to inclination and friction of the walkway surface. A walkway was designed with adjustable slopes between 0 to 30 degrees. Subject walking tests were performed on dry and wet steel sheet surfaces in two walking directions (uphill and downhill) at three inclination angles (0, 5 and 10 degrees). 3D ground reaction forces while walking were recorded using the force plate. Required coefficient of friction (RCOF) was derived to determine slip and fall risks. The main finding of this study is that the RCOF during heel strike when walking downwards on the steel plate surface increases linearly as the inclination increases. The results contribute to the understanding of slipping and falling mechanisms and the prevention of slipping and falling accidents. When ramps or sloped surfaces are used in workplaces, slip resistance between footwear and the sloped surfaces should be improved.
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10.
  • Gao, Chuansi, et al. (författare)
  • Validation of standard ASTM F2732 and comparison with ISO 11079 with respect to comfort temperature ratings for cold protective clothing
  • 2015
  • Ingår i: Applied Ergonomics. - : Elsevier. - 1872-9126. ; 46:Online 17 July 2014, s. 44-53
  • Tidskriftsartikel (refereegranskat)abstract
    • American standard ASTM F2732 estimates the lowest environmental temperature for thermal comfort for cold weather protective clothing. International standard ISO 11079 serves the same purpose but expresses cold stress in terms of required clothing insulation for a given cold climate. The objective of this study was to validate and compare the temperature ratings using human subject tests at two levels of metabolic rates (2 and 4 MET corresponding to 116.4 and 232.8 W/m(2)). Nine young and healthy male subjects participated in the cold exposure at 3.4 and -30.6 °C. The results showed that both standards predict similar temperature ratings for an intrinsic clothing insulation of 1.89 clo and for 2 MET activity. The predicted temperature rating for 2 MET activity is consistent with test subjects' thermophysiological responses, perceived thermal sensation and thermal comfort. For 4 MET activity, however, the whole body responses were on the cold side, particularly the responses of the extremities. ASTM F2732 is also limited due to its omission and simplification of three climatic variables (air velocity, radiant temperature and relative humidity) and exposure time in the cold which are of practical importance.
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