This paper investigates the influence of temperature and wind conditions on ventilation of the air cavity beneath the roofing in a full-scale pitched wooden roof construction.The potential for condensation in the air ...This paper investigates the influence of temperature and wind conditions on ventilation of the air cavity beneath the roofing in a full-scale pitched wooden roof construction.The potential for condensation in the air cavity is studied.The relevant roof construction is equipped with 81 thermocouples and four air velocity measurement devices.A weather station at the site records outdoor temperature and wind conditions.Five periods between 2016 and 2018 are investigated.The findings show distinct periods of below-ambient temperature and positive condensation potential in the ventilated air cavity of the roof.A relation between low wind speed and positive condensation potential is shown.Difference in size of periods with below-ambient temperature and periods with positive condensation potential implies that the materials in the roof regulate the humidity in the air cavity.Large negative peaks in the condensation potential indicate dry-out of the construction.展开更多
Proper orthogonal decomposition （POD） is an effective statistical technique for data reduction and feature extraction of the random field including the wind field. This paper introduces the theory of the POD and ill...Proper orthogonal decomposition （POD） is an effective statistical technique for data reduction and feature extraction of the random field including the wind field. This paper introduces the theory of the POD and illustrates engineering of structures. Using the POD technique, it is shown that wind pressure data can be accurately reconstructed with a limited number of modes using the wind pressure data from wind tunnel test. Comparing the reconstructed values by POD with the original measured values from the wind tunnel test both in the time and frequency domains, it is concluded that the proper orthogonal decomposition（POD） is an efficient and practical technique for deriving the random wind pressure field from limited known data as shown in the pitched roof example in this paper.展开更多
文摘This paper investigates the influence of temperature and wind conditions on ventilation of the air cavity beneath the roofing in a full-scale pitched wooden roof construction.The potential for condensation in the air cavity is studied.The relevant roof construction is equipped with 81 thermocouples and four air velocity measurement devices.A weather station at the site records outdoor temperature and wind conditions.Five periods between 2016 and 2018 are investigated.The findings show distinct periods of below-ambient temperature and positive condensation potential in the ventilated air cavity of the roof.A relation between low wind speed and positive condensation potential is shown.Difference in size of periods with below-ambient temperature and periods with positive condensation potential implies that the materials in the roof regulate the humidity in the air cavity.Large negative peaks in the condensation potential indicate dry-out of the construction.
基金Acknowledgements The authors are grateful for the support of this research by the Committee of National Science Foundation of China （50908077） and Foundation of Heilongjiang Province Educational Committee （11551368）.
文摘Proper orthogonal decomposition （POD） is an effective statistical technique for data reduction and feature extraction of the random field including the wind field. This paper introduces the theory of the POD and illustrates engineering of structures. Using the POD technique, it is shown that wind pressure data can be accurately reconstructed with a limited number of modes using the wind pressure data from wind tunnel test. Comparing the reconstructed values by POD with the original measured values from the wind tunnel test both in the time and frequency domains, it is concluded that the proper orthogonal decomposition（POD） is an efficient and practical technique for deriving the random wind pressure field from limited known data as shown in the pitched roof example in this paper.
