The thermal front in the oceanic system is believed to have a significant effect on biological activity.During an era of climate change,changes in heat regulation between the atmosphere and oceanic interior can alter ...The thermal front in the oceanic system is believed to have a significant effect on biological activity.During an era of climate change,changes in heat regulation between the atmosphere and oceanic interior can alter the characteristics of this important feature.Using the simulation results of the 3D Regional Ocean Modelling System(ROMS),we identified the location of thermal fronts and determined their dynamic variability in the area between the southern Andaman Sea and northern Malacca Strait.The Single Image Edge Detection(SIED)algorithm was used to detect the thermal front from model-derived temperature.Results show that a thermal front occurred every year from 2002 to 2012 with the temperature gradient at the location of the front was 0.3°C/km.Compared to the years affected by El Ni?o and negative Indian Ocean Dipole(IOD),the normal years(e.g.,May 2003)show the presence of the thermal front at every selected depth(10,25,50,and 75 m),whereas El Ni?o and negative IOD during 2010 show the presence of the thermal front only at depth of 75 m due to greater warming,leading to the thermocline deepening and enhanced stratification.During May 2003,the thermal front was separated by cooler SST in the southern Andaman Sea and warmer SST in the northern Malacca Strait.The higher SST in the northern Malacca Strait was believed due to the besieged Malacca Strait,which trapped the heat and make it difficult to release while higher chlorophyll a in Malacca Strait is due to the freshwater conduit from nearby rivers(Klang,Langat,Perak,and Selangor).Furthermore,compared to the southern Andaman Sea,the chlorophyll a in the northern Malacca Strait is easier to reach the surface area due to the shallower thermocline,which allows nutrients in the area to reach the surface faster.展开更多
This study investigated the temperature field and thawing depth of wide embankment for expressway in permafrost regions based on numerical analysis by using finite element method(FEM).According to specific embankment ...This study investigated the temperature field and thawing depth of wide embankment for expressway in permafrost regions based on numerical analysis by using finite element method(FEM).According to specific embankment section of Qinghai-Tibet highway,computational region for numerical analysis was defined.And numerical model was developed through FEM software named as ABAQUS and was verified by field observed data.The effects by width and height of embankment on the thermal regime of computational region were analyzed based on FEM modeling.Numerical analysis showed that embankment construction has serious disturbance on the thermal stability of ground permafrost showing as annual average ground temperature and the maximum thawing depth keeps increasing with service time increasing.And larger embankment width leads to poorer thermal stability and more serious uneven temperature field of embankment.Raising embankment height can improve the thermal stability; however,the improvement is restricted for wide embankment and it cannot change the degradation trend of thermal stability with service life increasing.Thus,to construct expressway with wide embankment in permafrost regions of Qinghai-Tibet Plateau,effective measures need to be considered to improve the thermal stability of underlying permafrost.展开更多
To investigate the thermal stability of ceramic-matrix composites,three kinds of C/C−ZrC−SiC composites with different Zr/Si molar ratios were synthesized by reactive melt infiltration.Employing region labeling method...To investigate the thermal stability of ceramic-matrix composites,three kinds of C/C−ZrC−SiC composites with different Zr/Si molar ratios were synthesized by reactive melt infiltration.Employing region labeling method,the high-temperature thermal stability of the composites was systematically studied by changing the temperature and holding time of thermal treatment.Results show that the mass loss rate of low Si composites has a growth trend with increasing temperature,and a crystal transformation from β-SiC toα-SiC occurs in the composites.In the calibrated area,SiC phase experiences Ostwald ripening and volume change with location migration,while ZrC phase experiences a re-sintering process with diffusion.Moreover,it is found that increasing temperature has a more obvious effect on the thermal stability than extending holding time,which is mainly attributed to the faster diffusion rate of atoms.展开更多
We present a directional region control （DRC） model of thermal diffusion fractal growth with active heat diffusion in three-dimensional space. This model can be applied to predict the space body heat fractal growth ...We present a directional region control （DRC） model of thermal diffusion fractal growth with active heat diffusion in three-dimensional space. This model can be applied to predict the space body heat fractal growth and study its directional region control. When the nonlinear interference term and the inner heat source term are generalized functions, the relationship between the particle aggregation probability and the interference terms can be obtained using the norm theory. We can then predict the aggregation form of particles in different regions. When the nonlinear interference terms in the model are expressed as a trigonometric function and its composite function, our simulations show that the DRC method of thermal fractal diffusion is effective and has reference value for the directional control of actual fractal growth systems.展开更多
The balcony is responsible to a series of effects on the environmental behavior of a building,mainly in relation of thermal comfort and air distribution to their indoor spaces.Currently a very common practice in sever...The balcony is responsible to a series of effects on the environmental behavior of a building,mainly in relation of thermal comfort and air distribution to their indoor spaces.Currently a very common practice in several metropolitan areas is the closing with retractable glass panels in balcony openings.This work analyzed the effects of glazed balconies upon thermal comfort in a hot tropical region.Environmental parameters were carried out in a flat alternating the conditions of retractable glass panels to balconies.Thermal simulations were performed considering closing or not the glass door that divides the balcony room;the building material used on the balcony sill;and the use of curtains or shading devices.The results show the maximum mean hourly temperatures recorded on the balcony during the period when the retractable glass panels were closed,reaching peaks between 31.7 and 39.2°C,above the comfort range recommended by ASHRAE 55.All situations simulated show the thermal discomfort prevails in the use of the closed glass panels reaching DhTD of 94.55°C/day.Thus,this practice of using most of the closed retractable glass panels in the balconies presents disadvantages and inefficiencies especially in hot and humid tropical climate regions.展开更多
基金the Higher Education Ministry research grant,under the Long-Term Research Grant Scheme(No.LRGS/1/2020/UMT/01/1/2)the Universiti Malaysia Terengganu Scholarship(BUMT)。
文摘The thermal front in the oceanic system is believed to have a significant effect on biological activity.During an era of climate change,changes in heat regulation between the atmosphere and oceanic interior can alter the characteristics of this important feature.Using the simulation results of the 3D Regional Ocean Modelling System(ROMS),we identified the location of thermal fronts and determined their dynamic variability in the area between the southern Andaman Sea and northern Malacca Strait.The Single Image Edge Detection(SIED)algorithm was used to detect the thermal front from model-derived temperature.Results show that a thermal front occurred every year from 2002 to 2012 with the temperature gradient at the location of the front was 0.3°C/km.Compared to the years affected by El Ni?o and negative Indian Ocean Dipole(IOD),the normal years(e.g.,May 2003)show the presence of the thermal front at every selected depth(10,25,50,and 75 m),whereas El Ni?o and negative IOD during 2010 show the presence of the thermal front only at depth of 75 m due to greater warming,leading to the thermocline deepening and enhanced stratification.During May 2003,the thermal front was separated by cooler SST in the southern Andaman Sea and warmer SST in the northern Malacca Strait.The higher SST in the northern Malacca Strait was believed due to the besieged Malacca Strait,which trapped the heat and make it difficult to release while higher chlorophyll a in Malacca Strait is due to the freshwater conduit from nearby rivers(Klang,Langat,Perak,and Selangor).Furthermore,compared to the southern Andaman Sea,the chlorophyll a in the northern Malacca Strait is easier to reach the surface area due to the shallower thermocline,which allows nutrients in the area to reach the surface faster.
基金Project(2014BAG05B04)supported by the National Science and Technology Support Program,ChinaProject(51378006)supported by the National Natural Science Foundation of ChinaProject(2242015R30027)supported by the Excellent Young Teacher Program of Southeast University,China
文摘This study investigated the temperature field and thawing depth of wide embankment for expressway in permafrost regions based on numerical analysis by using finite element method(FEM).According to specific embankment section of Qinghai-Tibet highway,computational region for numerical analysis was defined.And numerical model was developed through FEM software named as ABAQUS and was verified by field observed data.The effects by width and height of embankment on the thermal regime of computational region were analyzed based on FEM modeling.Numerical analysis showed that embankment construction has serious disturbance on the thermal stability of ground permafrost showing as annual average ground temperature and the maximum thawing depth keeps increasing with service time increasing.And larger embankment width leads to poorer thermal stability and more serious uneven temperature field of embankment.Raising embankment height can improve the thermal stability; however,the improvement is restricted for wide embankment and it cannot change the degradation trend of thermal stability with service life increasing.Thus,to construct expressway with wide embankment in permafrost regions of Qinghai-Tibet Plateau,effective measures need to be considered to improve the thermal stability of underlying permafrost.
基金supported by the National Natural Science Foundation of China(No.U19A2099)the CAS Key Laboratory of Carbon Materials,China(No.KLCMKFJJ2005)the Fund of Aerospace Research Institute of Material and Processing Technology,China(No.6142906200108).
文摘To investigate the thermal stability of ceramic-matrix composites,three kinds of C/C−ZrC−SiC composites with different Zr/Si molar ratios were synthesized by reactive melt infiltration.Employing region labeling method,the high-temperature thermal stability of the composites was systematically studied by changing the temperature and holding time of thermal treatment.Results show that the mass loss rate of low Si composites has a growth trend with increasing temperature,and a crystal transformation from β-SiC toα-SiC occurs in the composites.In the calibrated area,SiC phase experiences Ostwald ripening and volume change with location migration,while ZrC phase experiences a re-sintering process with diffusion.Moreover,it is found that increasing temperature has a more obvious effect on the thermal stability than extending holding time,which is mainly attributed to the faster diffusion rate of atoms.
基金supported by the National Natural Science Foundation of China(Grant Nos.61273088,61473173,and 61473174)
文摘We present a directional region control （DRC） model of thermal diffusion fractal growth with active heat diffusion in three-dimensional space. This model can be applied to predict the space body heat fractal growth and study its directional region control. When the nonlinear interference term and the inner heat source term are generalized functions, the relationship between the particle aggregation probability and the interference terms can be obtained using the norm theory. We can then predict the aggregation form of particles in different regions. When the nonlinear interference terms in the model are expressed as a trigonometric function and its composite function, our simulations show that the DRC method of thermal fractal diffusion is effective and has reference value for the directional control of actual fractal growth systems.
文摘The balcony is responsible to a series of effects on the environmental behavior of a building,mainly in relation of thermal comfort and air distribution to their indoor spaces.Currently a very common practice in several metropolitan areas is the closing with retractable glass panels in balcony openings.This work analyzed the effects of glazed balconies upon thermal comfort in a hot tropical region.Environmental parameters were carried out in a flat alternating the conditions of retractable glass panels to balconies.Thermal simulations were performed considering closing or not the glass door that divides the balcony room;the building material used on the balcony sill;and the use of curtains or shading devices.The results show the maximum mean hourly temperatures recorded on the balcony during the period when the retractable glass panels were closed,reaching peaks between 31.7 and 39.2°C,above the comfort range recommended by ASHRAE 55.All situations simulated show the thermal discomfort prevails in the use of the closed glass panels reaching DhTD of 94.55°C/day.Thus,this practice of using most of the closed retractable glass panels in the balconies presents disadvantages and inefficiencies especially in hot and humid tropical climate regions.
