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Träfflista för sökning "WFRF:(Gao Chuansi) ;pers:(Petersson Jakob)"

Sökning: WFRF:(Gao Chuansi) > Petersson Jakob

  • Resultat 1-7 av 7
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  • Halder, Amitava, et al. (författare)
  • Comparison of different clothing area factor (fcl) calculations based on picture analysis in Adobe Photoshop : To calculate the intrinsic insulation (Icl)
  • 2019
  • Konferensbidrag (refereegranskat)abstract
    • Introduction: Clothing area factor (fcl) is an indicator of the increase in surface area relative to the nude body for calculation of heat loss from the clothed body to the environment. The aim was to calculate and compare the fcl values from two equations by the photographic method.Method: Thirty-five modern western indoor clothing sets (19 male and 16 female) were tested on a thermal manikin Tore. In order to calculate fcl , front and side views of nude and dressed manikin were photographed against bright background. During analysis in Adobe Photoshop, colour information was discarded by selecting Grey scale mode. Then Curve was adjusted under Image to increase the manikin contrast against the background. The surrounding objects were eliminated by selecting black manikin silhouette, inversing the selection and deleting background residues. In the Histogram, Brightness and Contrast were adjusted to minimum and maximum levels, respectively. Then the black silhouette was selected with Magic wand tool and pixel number was recorded followed by deselecting the whole picture, percentile of pixels was taken, when cursor was left at level 100. The fcl-s were calculated based on both pixels and percentile by two equations and the comparison was made: f_cl=(〖Front〗_clothed+〖Side〗_clothed)/(〖Front〗_nude+〖Side〗_nude ) f_cl=(〖Front〗_clothed/〖Front〗_nude +〖Side〗_clothed/〖Side〗_nude )/2Results: The calculated fcl means (SDs) for Eq. 1 found similar for both pixels and percentile 1.17 (0.07), while those values for Eq. 2 appeared 1.19 (0.07) and 1.18 (0.07), respectively. The fcl means (SDs) differences equation wise for pixels and percentiles were 1.04 (0.57) % and 1.09 (0.57) %, respectively. The calculated basic means (SDs) insulation (Icl) did not differ when using the respective pixels and percentile fcl values.Conclusions: Two equations provided the fcl values with a small difference based on either pixels or percentile of picture and did not affect the calculated intrinsic clothing insulation, Icl.
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  • Halder, Amitava, et al. (författare)
  • Predicted Heat Strain (PHS) model and the sweat loss in an extremely hot climate
  • 2019
  • Konferensbidrag (refereegranskat)abstract
    • Introduction: The aim was to study if the evaporative water loss can be predicted enough accurately for hydration recommendations by ISO 7933 – Predicted Heat Strain (PHS) model during a student laboratory exercise in an extremely hot environment.Method: Twelve young healthy students (8 males and 4 females), unacclimatized to heat, were exposed in a climatic chamber at 50˚C, 30% relative humidity and 0.4 m·s-1 air velocity for 45 minutes. They had a mean (SD) age of 25.1 (2.6) years, height 175.6 (6.9) cm, weight 72.3 (11.0) kg, VO2max 54.9 (6.5) mL·min-1·kg-1, and HRmax 194 (6) bpm. The men and women performed bicycling for 6-minutes at workloads of 150 and 100 Watts (W), when the metabolic rates (M) calculated found 363 and 290 W·m-2, respectively. Moreover, the students did step test at 60 steps·min-1 for 5-minutes with estimated M being 215 W·m-2. They were standing most of the time (34 min) (M = 80 W·m-2). Time weighted average M for males and females were 133 and 123 W·m-2, respectively, for the whole exposure duration. Clothing insulation, Icl = 0.4 clo and moisture permeability index, im = 0.42 were input to PHS model simulation. The actual water loss by evaporation was determined by subject’s dressed body weight difference before and after exposure.Results: The actual mean (SD) total water evaporated was 461.3 (176.7) g. The predicted total water loss was 427.4 (39.2) g by the PHS model. There was no significant (p = .514) difference between the actual and the predicted water loss. However, the original estimation of evaporative sweat was found only 270.1 g.Conclusions: These results suggest that it is challenging to predict the water loss in continuous extreme heat exposure at 50˚C using ISO 7933 – PHS model. It should be used cautiously to predict the dehydration, and plan for drinking in extremely hot climates.
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  • Lundgren Kownacki, Karin, et al. (författare)
  • Does a building renovation improve the indoor thermal comfort? : A thermal environment evaluation before and after renovation
  • 2019
  • Konferensbidrag (refereegranskat)abstract
    • A sustainable renovation results in both a good indoor environment and high-energy efficiency. However, contemporary renovations often focus on energy and environmental performance, leaving out other aspects, such as the thermal comfort. The aim of the ongoing study is to compare the results of an extensive thermal environment evaluation before and after major renovation of ten typical 1970’s rental apartments in multi-family buildings located in Southern Sweden. The data collected is comprehensive and includes measurements of air temperature, relative humidity (RH), air velocity, plane radiant and globe temperature, draught rate, turbulence intensity, operative temperature, PMV/PPD indices and thermal sensation (thermal comfort evaluation) using a LumaSense INNOVA 1221 Thermal Comfort data logger. MSR Temp/RH data logger sensors were also placed at four different heights. The outside weather data and individual factors such as clothing, activity, gender, age were also collected. Measurements were taken in the living room of each apartment for 2 hours during three winter seasons: one measurement session before and two after renovation resulting in 30 measurements in total. The preliminary results from the first two winter seasons for draught rate, PMV/PPD, RH and radiant temperature all showed slight improvements after renovation. Further, the study results show that the individual perceived thermal comfort does not always agree with the measured and calculated thermal comfort. The data is currently under analysis and final results will be presented.
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  • Petersson, Jakob, et al. (författare)
  • Is There a Need to Integrate Human Thermal Models with Weather Forecasts to Predict Thermal Stress?
  • 2019
  • Ingår i: International Journal of Environmental Research and Public Health. - : MDPI AG. - 1660-4601. ; 16:22
  • Tidskriftsartikel (refereegranskat)abstract
    • More and more people will experience thermal stress in the future as the global temperature is increasing at an alarming rate and the risk for extreme weather events is growing. The increased exposure to extreme weather events poses a challenge for societies around the world. This literature review investigates the feasibility of making advanced human thermal models in connection with meteorological data publicly available for more versatile practices and a wider population. By providing society and individuals with personalized heat and cold stress warnings, coping advice and educational purposes, the risks of thermal stress can effectively be reduced. One interesting approach is to use weather station data as input for the wet bulb globe temperature heat stress index, human heat balance models, and wind chill index to assess heat and cold stress. This review explores the advantages and challenges of this approach for the ongoing EU project ClimApp where more advanced models may provide society with warnings on an individual basis for different thermal environments such as tropical heat or polar cold. The biggest challenges identified are properly assessing mean radiant temperature, microclimate weather data availability, integration and continuity of different thermal models, and further model validation for vulnerable groups
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  • Resultat 1-7 av 7

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