A V-shaped nylon net fence installed in 1990 on top of the Mogao Grottoes is shown to be effectively resisting aeolian sand damage to the grottoes. The structure guides and causes deposition of sand from westerly wind...A V-shaped nylon net fence installed in 1990 on top of the Mogao Grottoes is shown to be effectively resisting aeolian sand damage to the grottoes. The structure guides and causes deposition of sand from westerly wind （the primary hard wind）, but to some extent hinders the inverse function of easterly wind carrying sand away from the grottoes toward Mount Mingsha. The gobi side by the fence experiences higher wind speed, so that on which are easily formed undercutting pits, and the deposited sands on it generally form double-peak structures due to abundant sand sources. If the earth surface characteristics in gobi areas by both sides of the fence are quite varied, the erosion and deposition features of the accumulating sand section are similar in different seasons; however, if the earth surface characteristics are similar, the features become irregular in different seasons. Sand depositions with long slope feet are formed along the south and north sides of V-shaped nylon net fence. Disrupted by strong westerly wind and northwesterly wind, sand accumulations by north of the fence are in form of single peaks. Although the operation duration of the V-shaped nylon net fence has exceeded its design life （10 years）, our observations indicate that it is still effective in reducing wind-driven sand damages to the Mogao Grottoes, so it should not be withdrawn.展开更多
Moisture adsorption-desorption tests (MATs) were conducted on simulated mural plaster specimens under different air temperatures (ATs) and relative humidity (RH) to investigate the possible effect of seasonal alterati...Moisture adsorption-desorption tests (MATs) were conducted on simulated mural plaster specimens under different air temperatures (ATs) and relative humidity (RH) to investigate the possible effect of seasonal alteration and visitors’ breath on the deterioration of Mogao Grottoes, Dunhuang, China. Saturated salt solutions were used to maintain a constant RH, and plant growth cabinets were used to maintain a constant or varying temperature in the simulation test. The weight of specimen was periodically measured to determine the adsorbed or desorbed moisture. Test data illustrate that the desorption process is far quicker than the adsorption one, indicating that it is possible to inhibit the disadvantage effect from visitors, such as shortening the staying time in caves. In case of high humidity, an accumulated moisture adsorption was found to correspond to the varying temperature. On the other hand, in case of low humidity, accumulated moisture desorption corresponded. Test data imply that opening caves more often to visitors in humid seasons should be avoided so as to prevent continuous wetting of wall paintings.展开更多
基金supported jointly by the National Science and Technology Support Program (2012BAC08B07)the Natural Science Foundation of China (Nos. 2009BAC54B01-1 and 40930741)the Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX2-EW-313)
文摘A V-shaped nylon net fence installed in 1990 on top of the Mogao Grottoes is shown to be effectively resisting aeolian sand damage to the grottoes. The structure guides and causes deposition of sand from westerly wind （the primary hard wind）, but to some extent hinders the inverse function of easterly wind carrying sand away from the grottoes toward Mount Mingsha. The gobi side by the fence experiences higher wind speed, so that on which are easily formed undercutting pits, and the deposited sands on it generally form double-peak structures due to abundant sand sources. If the earth surface characteristics in gobi areas by both sides of the fence are quite varied, the erosion and deposition features of the accumulating sand section are similar in different seasons; however, if the earth surface characteristics are similar, the features become irregular in different seasons. Sand depositions with long slope feet are formed along the south and north sides of V-shaped nylon net fence. Disrupted by strong westerly wind and northwesterly wind, sand accumulations by north of the fence are in form of single peaks. Although the operation duration of the V-shaped nylon net fence has exceeded its design life （10 years）, our observations indicate that it is still effective in reducing wind-driven sand damages to the Mogao Grottoes, so it should not be withdrawn.
基金Project supported by the National Key Technology R&D Program during the 11th Five-Year Plan of China (No. 2006BAK30B02)the China National Engineering Research Center for Conservation of Ancient Wall Paintings Program (No. 200806)
文摘Moisture adsorption-desorption tests (MATs) were conducted on simulated mural plaster specimens under different air temperatures (ATs) and relative humidity (RH) to investigate the possible effect of seasonal alteration and visitors’ breath on the deterioration of Mogao Grottoes, Dunhuang, China. Saturated salt solutions were used to maintain a constant RH, and plant growth cabinets were used to maintain a constant or varying temperature in the simulation test. The weight of specimen was periodically measured to determine the adsorbed or desorbed moisture. Test data illustrate that the desorption process is far quicker than the adsorption one, indicating that it is possible to inhibit the disadvantage effect from visitors, such as shortening the staying time in caves. In case of high humidity, an accumulated moisture adsorption was found to correspond to the varying temperature. On the other hand, in case of low humidity, accumulated moisture desorption corresponded. Test data imply that opening caves more often to visitors in humid seasons should be avoided so as to prevent continuous wetting of wall paintings.
