The thermal response of hedges alters the urban climate, resulting in energy and comfort affectations that impact city dwellers, so the aim of this study is to analyze the energy fluxes of urban horizontal coverage, e...The thermal response of hedges alters the urban climate, resulting in energy and comfort affectations that impact city dwellers, so the aim of this study is to analyze the energy fluxes of urban horizontal coverage, especially expanded polystyrene waterproofed with elastomeric paint in the city of Mexicali, Baja California, located northwest of Mexico. The experiment was realized on summer of 2011 and 2012 by using four components radiometric sensor, eddy covariance equipment, which was possible to analyze the behavior and intensities of heat fluxes using the model Q＊ = QE ＋ QG ＋ QH ＋ QF ＋ QD. The results show that in both campaigns the sensible heat flux exceeds the net radiation, in 2011 the net radiation was 31.41 W/mE and sensible heat flux of 74.9 W/m2, in 2012 resulted 43.46 W/m2 and 87.32 W/mE, respectively. This additional heat flux is attributed to the thermal influence of the air conditioning units, which changes the energy balance model to Q＊ = QH ＋ QF ＋ QD. With the results arise the need for experimentation on a larger scale in which it is possible to model the flow in housing development. The knowledge of the energy balance model will help to propose materials that minimize the thermal impact to the city of Mexicali.展开更多
This study assessed the applicability of chitin nanocrystals prepared by 2,2,6,6-Tetramethyl-1-Piperidine-1-oxyl radical(TEMPO)-mediated oxidation in traditional papermaking coating color systems.The𝛼-chitin n...This study assessed the applicability of chitin nanocrystals prepared by 2,2,6,6-Tetramethyl-1-Piperidine-1-oxyl radical(TEMPO)-mediated oxidation in traditional papermaking coating color systems.The𝛼-chitin nanocrystals(CTNCs)with different carboxyl content,size,and morphology were prepared from crab shells by alkali pretreatment and TEMPO-mediated oxidation in the water at pH 10,and then the ratio of CTNCs to latex was applied to traditional coating color system to replace part of latex.The results showed that when the amount of NaClO added as co-oxidant in the oxidation was 15.0 mmol/g of chitin,the carboxyl content of alkali-pretreated CTNCs was up to 0.76 mmol/g.The amount of carboxyl groups presented a linear relation with the degree of individualization of nanocrystals and dispersion.When the ratio of latex to CTNCs was 90꞉10,the water retention value of the coating was 92%lower than that of the pure latex system,and the rheological property was better.The relationship between the addition amount of CTNCs and the surface strength and the coverage of coating layers were also studied,and results showed that when the ratio of latex to CTNCs was 95꞉5,the surface strength was the highest of 1.45 m/s,and the coverage of coating layers rate reached the highest of 78%.展开更多
文摘The thermal response of hedges alters the urban climate, resulting in energy and comfort affectations that impact city dwellers, so the aim of this study is to analyze the energy fluxes of urban horizontal coverage, especially expanded polystyrene waterproofed with elastomeric paint in the city of Mexicali, Baja California, located northwest of Mexico. The experiment was realized on summer of 2011 and 2012 by using four components radiometric sensor, eddy covariance equipment, which was possible to analyze the behavior and intensities of heat fluxes using the model Q＊ = QE ＋ QG ＋ QH ＋ QF ＋ QD. The results show that in both campaigns the sensible heat flux exceeds the net radiation, in 2011 the net radiation was 31.41 W/mE and sensible heat flux of 74.9 W/m2, in 2012 resulted 43.46 W/m2 and 87.32 W/mE, respectively. This additional heat flux is attributed to the thermal influence of the air conditioning units, which changes the energy balance model to Q＊ = QH ＋ QF ＋ QD. With the results arise the need for experimentation on a larger scale in which it is possible to model the flow in housing development. The knowledge of the energy balance model will help to propose materials that minimize the thermal impact to the city of Mexicali.
基金support for this work from National Natural Science Foundation of China(No.31370583).
文摘This study assessed the applicability of chitin nanocrystals prepared by 2,2,6,6-Tetramethyl-1-Piperidine-1-oxyl radical(TEMPO)-mediated oxidation in traditional papermaking coating color systems.The𝛼-chitin nanocrystals(CTNCs)with different carboxyl content,size,and morphology were prepared from crab shells by alkali pretreatment and TEMPO-mediated oxidation in the water at pH 10,and then the ratio of CTNCs to latex was applied to traditional coating color system to replace part of latex.The results showed that when the amount of NaClO added as co-oxidant in the oxidation was 15.0 mmol/g of chitin,the carboxyl content of alkali-pretreated CTNCs was up to 0.76 mmol/g.The amount of carboxyl groups presented a linear relation with the degree of individualization of nanocrystals and dispersion.When the ratio of latex to CTNCs was 90꞉10,the water retention value of the coating was 92%lower than that of the pure latex system,and the rheological property was better.The relationship between the addition amount of CTNCs and the surface strength and the coverage of coating layers were also studied,and results showed that when the ratio of latex to CTNCs was 95꞉5,the surface strength was the highest of 1.45 m/s,and the coverage of coating layers rate reached the highest of 78%.
