The paper discusses the results of a field study carried out in four cities in Mexico: Hermosillo, Mexicali, Merida and Colima, during the warmest seasons of 2006-2007. The survey is according to the adaptive approac...The paper discusses the results of a field study carried out in four cities in Mexico: Hermosillo, Mexicali, Merida and Colima, during the warmest seasons of 2006-2007. The survey is according to the adaptive approach of thermal comfort. The cities' climates are hot dry, hot sub-humid and hot humid. The respondents were inhabitants of low cost housings without air conditioning. The research was performed during warm seasons and according to ISO 10551. The measurements were processed by the common method of linear regression and also by alternative methods, useful for asymmetric climates. Individuals declared comfort at very high temperatures, either high or low humidity, therefore, the resulting neutral temperatures are higher than 30 ℃, except in Colima (28.8 ℃). The upper limits of comfort ranges achieved temperatures up to 35 ℃. The results suggest how great is the capacity of humans to adapt to conditions as extreme as those measured in the study.展开更多
Our analysis of fog and haze observations from the surface weather stations in China in recent 50 years (from 196l to 2011) shows that the number of fog days has experienced two-stage variations, with an increasing ...Our analysis of fog and haze observations from the surface weather stations in China in recent 50 years (from 196l to 2011) shows that the number of fog days has experienced two-stage variations, with an increasing trend before 1980 and a decreasing trend after 1990. Especially, an obvious decreasing trend after 1990 can be clearly seen, which is consistent with the decreas- ing trend of the surface relative humidity. However, the number of haze days has demonstrated an increasing trend. As such, the role of reduction of atmospheric relative humidity in the transition process from fog into haze has been further investigated. It is estimated that the mean relative humidity of haze days is about 69%, lower than previously estimated, which implies that it is more difficult for the haze particles to transform into fog drops. This is possibly one of the major environmental factors leading to the reduction of number of fog days. The threshold of the relative humidity for transition from fog into haze is about 82%, also lower than previously estimated. Thus, the reduction of the surface relative humidity in China mainly due to the in- crease of the surface temperature and the saturation specific humidity may exert an obvious impact on the environmental con- ditions for the formations of fog and haze. In addition, our investigation of the relationship between haze and visibility reveals that with the increase of haze days, the visibility has declined markedly. Since 1961, the mean visibility has dropped from 4-10 to 2-4 kin, about a half of the previous horizontal distance of visibility.展开更多
Climate is an important factor that affects the livability of a region.The climate suitability of a region’s environment for human settlement profoundly affects the regional socio-economic development and the populat...Climate is an important factor that affects the livability of a region.The climate suitability of a region’s environment for human settlement profoundly affects the regional socio-economic development and the population distribution.Tibet is an area that is sensitive to climate change.Given the impact of global climate change,the climate suitability of Tibet has undergone significant changes.In this study,the temperature humidity index(THI)values for Tibet were calculated,and the relationships between the population distribution and the THI were analyzed quantitatively.In this way,the zoning standards for climate suitability in Tibet were determined such that the climate suitability could be evaluated.The results show that the average annual temperature in the southeast of Tibet,where the population was densely distributed,was relatively high.The mean annual relative humidity showed a trend of gradually decreasing from south to north.Regions with a suitable climate,including the high suitability areas(HSAs),the moderately suitable areas(MSAs)and the low suitability areas(LSAs),accounted for only 7.90%of the total area but accommodated over 40%of the total population.The critically suitable areas(CSAs)accounted for 37.81%of the land area and 48.24%of the total population.Non-suitable areas(NSAs)were widely distributed in Tibet and accounted for 54.29%of the total area and 11.33%of the total population.The results of this study may provide a reference for guiding the reasonable distribution of population and promoting the optimization of the spatial planning in Tibet.展开更多
Organic thin film transistors(OTFTs)are normally sensitive to ambient conditions and show performance degradation in air.On the contrary,the performance of flexible 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene(C8...Organic thin film transistors(OTFTs)are normally sensitive to ambient conditions and show performance degradation in air.On the contrary,the performance of flexible 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene(C8-BTBT)OTFTs using cross-linked polymer layer,poly(4-vinyl-phenol)-4,4’-(hexafluoroisopropylidene)diphthalic anhydride(PVP-HDA),as the dielectric layer can be improved in air conditions with 40%relative humidity.Under soaking in air with 40%relative humidity,the electrical behavior,surface morphology,and contact angle of the flexible C8-BTBT OTFTs using PVP-HAD as dielectric layer with three different thicknesses were investigated.It is found that,when the devices with 375 nm-thick PVP-HDA films are placed in 40%relative humidity air conditions for 6 h,the corrected average mobility(μ)can increase from 3.2 to 5.1 cm^2 V^-1 s^-1.Furthermore,the average threshold voltage(Vth)changes from-12.4 to-9.3 V while keeping a constant ratio of I on/Ioff=10^4.These results indicate that the flexible C8-BTBT OTFTs with PVP-HDA dielectric layer exhibit interesting application prospects.展开更多
文摘The paper discusses the results of a field study carried out in four cities in Mexico: Hermosillo, Mexicali, Merida and Colima, during the warmest seasons of 2006-2007. The survey is according to the adaptive approach of thermal comfort. The cities' climates are hot dry, hot sub-humid and hot humid. The respondents were inhabitants of low cost housings without air conditioning. The research was performed during warm seasons and according to ISO 10551. The measurements were processed by the common method of linear regression and also by alternative methods, useful for asymmetric climates. Individuals declared comfort at very high temperatures, either high or low humidity, therefore, the resulting neutral temperatures are higher than 30 ℃, except in Colima (28.8 ℃). The upper limits of comfort ranges achieved temperatures up to 35 ℃. The results suggest how great is the capacity of humans to adapt to conditions as extreme as those measured in the study.
基金supported by National Key Basic Research Program of China(Grant Nos.2012CB417205 and 2013CB430202)the National Natural Science Foundation of China(Grant No.41130960)National Science and Technology Support Program of China(Grant No.2009BAC51B02)
文摘Our analysis of fog and haze observations from the surface weather stations in China in recent 50 years (from 196l to 2011) shows that the number of fog days has experienced two-stage variations, with an increasing trend before 1980 and a decreasing trend after 1990. Especially, an obvious decreasing trend after 1990 can be clearly seen, which is consistent with the decreas- ing trend of the surface relative humidity. However, the number of haze days has demonstrated an increasing trend. As such, the role of reduction of atmospheric relative humidity in the transition process from fog into haze has been further investigated. It is estimated that the mean relative humidity of haze days is about 69%, lower than previously estimated, which implies that it is more difficult for the haze particles to transform into fog drops. This is possibly one of the major environmental factors leading to the reduction of number of fog days. The threshold of the relative humidity for transition from fog into haze is about 82%, also lower than previously estimated. Thus, the reduction of the surface relative humidity in China mainly due to the in- crease of the surface temperature and the saturation specific humidity may exert an obvious impact on the environmental con- ditions for the formations of fog and haze. In addition, our investigation of the relationship between haze and visibility reveals that with the increase of haze days, the visibility has declined markedly. Since 1961, the mean visibility has dropped from 4-10 to 2-4 kin, about a half of the previous horizontal distance of visibility.
基金The Second Tibetan Plateau Scientific Expedition and Research Program(2019QZKK1006)The Strategic Priority Research Program of Chinese Academy of Sciences(XDA20010201,XDA20010203)+1 种基金The National Natural Science Foundation of China(41901086,41901260)The Beijing Natural Science Foundation(5204033)。
文摘Climate is an important factor that affects the livability of a region.The climate suitability of a region’s environment for human settlement profoundly affects the regional socio-economic development and the population distribution.Tibet is an area that is sensitive to climate change.Given the impact of global climate change,the climate suitability of Tibet has undergone significant changes.In this study,the temperature humidity index(THI)values for Tibet were calculated,and the relationships between the population distribution and the THI were analyzed quantitatively.In this way,the zoning standards for climate suitability in Tibet were determined such that the climate suitability could be evaluated.The results show that the average annual temperature in the southeast of Tibet,where the population was densely distributed,was relatively high.The mean annual relative humidity showed a trend of gradually decreasing from south to north.Regions with a suitable climate,including the high suitability areas(HSAs),the moderately suitable areas(MSAs)and the low suitability areas(LSAs),accounted for only 7.90%of the total area but accommodated over 40%of the total population.The critically suitable areas(CSAs)accounted for 37.81%of the land area and 48.24%of the total population.Non-suitable areas(NSAs)were widely distributed in Tibet and accounted for 54.29%of the total area and 11.33%of the total population.The results of this study may provide a reference for guiding the reasonable distribution of population and promoting the optimization of the spatial planning in Tibet.
基金supported by the National Key Research and Development Program of China(2017YFA0206600)the National Natural Science Foundation of China(51673214)。
文摘Organic thin film transistors(OTFTs)are normally sensitive to ambient conditions and show performance degradation in air.On the contrary,the performance of flexible 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene(C8-BTBT)OTFTs using cross-linked polymer layer,poly(4-vinyl-phenol)-4,4’-(hexafluoroisopropylidene)diphthalic anhydride(PVP-HDA),as the dielectric layer can be improved in air conditions with 40%relative humidity.Under soaking in air with 40%relative humidity,the electrical behavior,surface morphology,and contact angle of the flexible C8-BTBT OTFTs using PVP-HAD as dielectric layer with three different thicknesses were investigated.It is found that,when the devices with 375 nm-thick PVP-HDA films are placed in 40%relative humidity air conditions for 6 h,the corrected average mobility(μ)can increase from 3.2 to 5.1 cm^2 V^-1 s^-1.Furthermore,the average threshold voltage(Vth)changes from-12.4 to-9.3 V while keeping a constant ratio of I on/Ioff=10^4.These results indicate that the flexible C8-BTBT OTFTs with PVP-HDA dielectric layer exhibit interesting application prospects.