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Sökning: WFRF:(Holmér Ingvar) > Wang Faming > Engelska

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11.
  • Wang, Faming, et al. (författare)
  • A Study on Evaporative Resistances of Two Skins Designed for Thermal Manikin Tore under Different Environmental Conditions
  • 2009
  • Ingår i: Textile Bioengineering And Informatics Symposium Proceedings, Vols 1 And 2. - 1942-3438. ; , s. 211-215
  • Konferensbidrag (refereegranskat)abstract
    • A cotton skin and Gore-Tex skin were designed for thermal manikin "Tore" to simulate different sweating styles (wet cotton skin inside and Gore-Tex outside to simulate sweating style of thermal manikin "Walter", and Gore-Tex skin inside with wet cotton skin outside to simulate sweating style of thermal manikins "Newton". The evaporative resistances of two skin combinations with clothing ensembles were compared at two different environmental conditions. In addition, the total evaporative resistance of clothing ensemble was calculated by both heat loss method (option 1) and mass loss method (option 2) according to ASTM F 2370. We found that the effect of different sweating mechanisms on clothing evaporative resistance should be considered. The results showed that the total evaporative resistances obtained by option 2 were more accurate than values by option 1 under an isothermal condition. It was also found that total evaporative resistance differences between two skin combinations with clothing ensembles decreased with increasing clothing ensemble layer. In a non-isothermal condition, the total evaporative resistance calculated by option 1 was more accurate than value obtained by option 2, which was due to lower ambient temperature and condensation between each adjacent layer.
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12.
  • Wang, Faming, et al. (författare)
  • A Study on Evaporative Resistances of Two Skins Designed for Thermal Manikin Tore under Different Environmental Conditions
  • 2009
  • Ingår i: Journal of Fiber Bioengineering and Informatics. - : Textile Bioengineering and Informatics Society. - 1940-8676 .- 2617-8699. ; 1:4, s. 301-305
  • Tidskriftsartikel (populärvet., debatt m.m.)abstract
    • A cotton skin and a waterproof but permeable Gore-Tex skin were designed for the thermal manikin “Tore” to simulate different sweating styles (the wet cotton skin inside and Gore-Tex skin outside to simulate the sweating style of thermal manikin “Walter”, and Gore-Tex skin inside with wet cotton skin outside to simulate the sweating style of thermal manikins “Newton”). The evaporative resistances of two skin combinations with clothing ensembles were compared at different environmental conditions. In addition, the total evaporative resistance of clothing ensemble was calculated by both the heat loss method (option 1) and the mass loss method (option 2) according to ASTM F 2370. We found that the effect of different sweating mechanisms on the clothing evaporative resistance should be considered. The results showed that the total evaporative resistances calculated by option 2 were more accurate than values in option 1 under the isothermal condition. It was also found that differences of the total evaporative resistance between two skin combinations with clothing ensembles decreased with the increasing clothing ensemble layer. In a non-isothermal condition, the total evaporative resistance calculated by option 1 was more accurate than the value obtained in option 2, which was due to the lower ambient temperature and condensations between each adjacent layer.
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13.
  • Wang, Faming, et al. (författare)
  • Can the PHS model (ISO7933) predict reasonable thermophysiological responses while wearing protective clothing in hot environments?
  • 2011
  • Ingår i: Physiological Measurement. - : IOP Publishing. - 0967-3334 .- 1361-6579. ; 32:2, s. 239-249
  • Tidskriftsartikel (populärvet., debatt m.m.)abstract
    • In this paper, the prediction accuracy of the PHS (predicted heat strain) model on human physiological responses while wearing protective clothing ensembles was examined. Six human subjects (aged 29 ± 3 years) underwent three experimental trials in three different protective garments (clothing thermal insulation Icl ranges from 0.63 to 2.01 clo) in two hot environments (40 °C, relative humidities: 30% and 45%). The observed and predicted mean skin temperature, core body temperature and sweat rate were presented and statistically compared. A significant difference was found in the metabolic rate between FIRE (firefighting clothing) and HV (high visibility clothing) or MIL (military clothing) (p < 0.001). Also, the development of heart rate demonstrated the significant effects of the exposure time and clothing ensembles. In addition, the predicted evaporation rate during HV, MIL and FIRE was much lower than the experimental values. Hence, the current PHS model is not applicable for protective clothing with intrinsic thermal insulations above 1.0 clo. The results showed that the PHS model generated unreliable predictions on body core temperature when human subjects wore thick protective clothing such as firefighting clothing (Icl > 1.0 clo). The predicted mean skin temperatures in three clothing ensembles HV, MIL and FIRE were also outside the expected limits. Thus, there is a need for further extension for the clothing insulation validation range of the PHS model. It is recommended that the PHS model should be amended and validated by individual algorithms, physical or physiological parameters, and further subject studies.
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14.
  • Wang, Faming, et al. (författare)
  • Determination of Clothing Evaporative Resistance on a Sweating Thermal Manikin in an Isothermal Condition: Heat Loss Method or Mass Loss Method?
  • 2011
  • Ingår i: Annals of Occupational Hygiene. - : Oxford University Press (OUP). - 1475-3162. ; 55, s. 775-783
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper addresses selection between two calculation options, i.e heat loss option and mass loss option, for thermal manikin measurements on clothing evaporative resistance conducted in an isothermal condition (Tmanikin = Ta = Tr). Five vocational clothing ensembles with a thermal insulation range of 1.05–2.58 clo were selected and measured on a sweating thermal manikin ‘Tore’. The reasons why the isothermal heat loss method generates a higher evaporative resistance than that of the mass loss method were thoroughly investigated. In addition, an indirect approach was applied to determine the amount of evaporative heat energy taken from the environment. It was found that clothing evaporative resistance values by the heat loss option were 11.2–37.1% greater than those based on the mass loss option. The percentage of evaporative heat loss taken from the environment (He,env) for all test scenarios ranged from 10.9 to 23.8%. The real evaporative cooling efficiency ranged from 0.762 to 0.891, respectively. Furthermore, it is evident that the evaporative heat loss difference introduced by those two options was equal to the heat energy taken from the environment. In order to eliminate the combined effects of dry heat transfer, condensation, and heat pipe on clothing evaporative resistance, it is suggested that manikin measurements on the determination of clothing evaporative resistance should be performed in an isothermal condition. Moreover, the mass loss method should be applied to calculate clothing evaporative resistance. The isothermal heat loss method would appear to overestimate heat stress and thus should be corrected before use.
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15.
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16.
  • Wang, Faming, et al. (författare)
  • Development and Validation of an Empirical Equation to Predict Sweating Skin Surface Temperature for Thermal Manikins
  • 2010
  • Ingår i: Textile Bioengineering and Informatics Symposium Proceedings. - 1942-3438. ; 1-3, s. 1213-1218
  • Konferensbidrag (refereegranskat)abstract
    • Thermal manikins are useful tools to study the clothing comfort and environmental ergonomics. The simulation of sweating can be achieved by putting a highly wicking stretchable knit fabric “skin” on top of the manikin. However, the addition of such a fabric skin makes it is difficult to accurately measure the skin surface temperature. Moreover, it takes considerable amount of time to measure the fabric skin surface temperature for each test. At present the attachment of temperature sensors to the wet fabric skin is still a challenge. The distance of the sensors to the fabric skin could significantly influence the temperature and relative humidity values of the wet skin surface. Hence, we conducted an intensive skin study on a dry thermal manikin to investigate the relationships among the nude manikin surface temperature, heat losses and the fabric skin surface temperature. An empirical equation was developed and validated on the thermal manikin "Tore" at Lund University. The empirical equation at ambient temperature 34 oC is Tsk =34.00- 0.0103HL. This equation can be used to enhance the prediction accuracy on the sweating skin surface temperature and the calculation of clothing evaporative resistance.
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17.
  • Wang, Faming, et al. (författare)
  • Development and validation of an empirical equation to predict wet fabric skin surface temperature of thermal manikins
  • 2010
  • Ingår i: Journal of Fiber Bioengineering and Informatics. - : Textile Bioengineering and Informatics Society. - 1940-8676 .- 2617-8699. ; 3:1, s. 9-15
  • Tidskriftsartikel (refereegranskat)abstract
    • Thermal manikins are useful tools to study clothing comfort and environmental ergonomics. The simulation of sweating can be achieved by putting a highly wicking stretchable knit fabric “skin” on top of the manikin. However, the addition of such a fabric skin makes it difficult to accurately measure the skin surface temperature. Moreover, it takes considerable amount of time to measure the fabric skin surface temperature at each test. At present the attachment of temperature sensors to the wet fabric skin is still a challenge. The distance of the sensors to the fabric skin could significantly influence the temperature and relative humidity values of the wet skin surface. Hence, we conducted an intensive skin study on a dry thermal manikin to investigate the relationships among the nude manikin surface temperature, heat losses and the fabric skin surface temperature. An empirical equation was developed and validated on the thermal manikin „Tore‟ at Lund University. The empirical equation at an ambient temperature 34.0 ºC is Tsk =34.00-0.0103HL. This equation can be used to enhance the prediction accuracy of wet fabric skin surface temperature and the calculation of clothing evaporative resistance.
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18.
  • Wang, Faming, et al. (författare)
  • Development and validity of a universal empirical equation to predict skin surface temperature on thermal manikins
  • 2010
  • Ingår i: Journal of Thermal Biology. - : Elsevier BV. - 0306-4565. ; 35:4, s. 197-203
  • Tidskriftsartikel (populärvet., debatt m.m.)abstract
    • Clothing evaporative resistance is an important input in thermal comfort models. Thermal manikin tests give the most accurate and reliable evaporative resistance values for clothing. The calculation methods of clothing evaporative resistance require the sweating skin surface temperature (i.e., options 1 and 2). However, prevailing calculation methods of clothing evaporative resistance (i.e., options 3 and 4) are based on the controlled nude manikin surface temperature due to the sensory measurement difficulty. In order to overcome the difficulty of attaching temperature sensors to the wet skin surface and to enhance the calculation accuracy on evaporative resistance, we conducted an intensive skin study on a thermal manikin ‘Tore’. The relationship among the nude manikin surface temperature, the total heat loss and the wet skin surface temperature in three ambient conditions was investigated. A universal empirical equation to predict the wet skin surface temperature of a sweating thermal manikin was developed and validated on the manikin dressed in six different clothing ensembles. The skin surface temperature prediction equation in an ambient temperature range between 25.0 and 34.0 °C is Tsk=34.0–0.0132HL. It is demonstrated that the universal empirical equation is a good alternative to predicting the wet skin surface temperature and facilitates calculating the evaporative resistance of permeable clothing ensembles. Further studies on the validation of the empirical equation on different thermal manikins are needed however.
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19.
  • Wang, Faming, et al. (författare)
  • Development of Empirical Equations to Predict Sweating Skin Surface Temperature for Thermal Manikins in Warm Environments.
  • 2010
  • Ingår i: ; , s. 1-5
  • Konferensbidrag (refereegranskat)abstract
    • Clothing evaporative resistance is one of the most important parameters for clothing comfort. The clothing evaporation resistance can be measured on a sweating guarded hotplate, a sweating thermal manikin or a human subject. The sweating thermal manikin gives the most accurate value on evaporative resistance of the whole garment ensemble compared to the other two methods. The determination of clothing evaporative resistance on a thermal manikin requires sweating simulation. This can be achieved by either a pre-wetted fabric skin on top of the manikin (TORE), or a waterproof but permeable Gore-tex skin filled with water inside. The addition of a fabric skin can introduce a temperature difference between the manikin surface and the sweating skin surface. However, calculations on clothing evaporative resistance have often been based on the thermal manikin surface temperature. A previous study showed that the temperature differences can cause an error up to 35.9 % on the clothing evaporative resistance. In order to reduce such an error, an empirical equation to predict the skin surface temperature might be helpful. In this study, a cotton knit fabric skin and a Gore-tex skin were used to simulate two types of sweating. The cotton fabric skin was rinsed with tap water and centrifuged in a washing machine for 4 seconds to ensure no water drip. A Gore-tex skin was put on top of the pre-wetted cotton skin on a dry heated thermal manikin ‘Tore’ in order to simulate senseless sweating, similar to thermal manikins ‘Coppelius’ and ‘Walter’. Another simulation involved the pre-wetted fabric skin covered on top of the Gore-tex skin in order to simulate sensible sweating. This type of sweating simulation can be widely found on many thermal manikins worldwide, e.g. ‘Newton’. Six temperature sensors (Sensirion Inc, Switzerland) were attached on six sites of the skin outer surface by white thread rings to record the skin surface temperature. Twelve skin tests for each skin combination were performed at three different ambient temperatures: 34, 25 and 20 oC. Two empirical equations to predict the skin surface temperature were developed based on the mean manikin surface temperature, mean fabric skin surface temperature and the total heat loss. The prediction equations for the senseless sweating and sensible sweating on the thermal manikin ‘Tore’ were Tsk=34.0-0.0146HL and Tsk=34.0-0.0190HL, respectively. Further study should validate these two empirical equations, however.
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20.
  • Wang, Faming, et al. (författare)
  • Does PHS Model Predict Acceptable Skin and Core Temperatures While Wearing Protective Clothing.
  • 2010
  • Ingår i: ; , s. 1-5
  • Konferensbidrag (refereegranskat)abstract
    • Mathematical modeling is very important when experimental settings with human subjects are restricted to thermal limits necessary to protect the individual. The predicted heat strain (PHS) model has been published AS ISO 7933 for about six years. It describes a method for predicting the sweat rate and internal core temperature that the human body will develop in response to the working conditions. The PHS model was developed based on thousands of laboratory and field experiments collected from eight European laboratories. However, most of the laboratory and field tests were performed on human subjects with light clothing ensembles (0.38±0.34 clo < Icl < 0.77±0.18 clo). The prediction of physiological responses while human wearing highly insulating protective clothing might be weak. In order to check the prediction accuracy of current PHS model while using protective clothing, we conducted totally series of human subject tests at a simulated hot environment. The results of 18 tests involving the high visibility (HV), military (MIL) and firefighting (FIRE) clothing are reported here. Six human subjects were asked to walk on a treadmill at 4.5 km/h at 40 oC for 70 min. Two humidity levels were chosen: 2 kPa (RH = 27 %) and 3 kPa (RH = 41 %) depending on the garment. The rectal temperature, skin temperature, heart rate and metabolic rate were measured. The clothing and the subjects were weighed before and after the exposure in order to calculate the sweat and evaporation rate. The observed and predicted rectal temperatures and mean skin temperatures were compared. The PHS model failed to predict the final rectal temperature in FIRE and the predicted estimate was 1.83 oC higher than the observed value after 63-min exposure. The predicted curve showed a much deeper linear increase during the whole exercise. None of the predicted mean skin temperatures during the three testing scenarios were accurately predicted. The PHS model was consistently providing conservative mean skin temperature evaluations. The predicted curve in HV and MIL showed a much shallower increase during the early portion of the exposure and plateaued at temperatures lower than ever achieved by the subjects. The observed sweat rates were 556±110 g/h in HV, 717±200 g/h in MIL, and 834±274 g/h in FIRE. There was no significant difference between the predicted total sweat values and the experimental data (P=0.073). In summary, the PHS model produce prediction of core temperature which has an unacceptable error when human wore thick protective clothing. The weak prediction on the mean skin temperature in HV and MIL was in agreement with the empirical prediction equation in the source codes has the poorest and lowest correlation when a clothed human subject exercised at the humidity level above 2 kPa. It is therefore recommended that the PHS model should be amended to development and validated by manipulation of individual algorithms or physical (or physiological) parameters.
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  • Resultat 11-20 av 31

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