Optimization of Graphene concentration in optoelectronic properties has been studied which leads to progressive stability based on Graphene-CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub&g...Optimization of Graphene concentration in optoelectronic properties has been studied which leads to progressive stability based on Graphene-CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> employing nanoparticles perovskites solar cells in this work. CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> wafer-based hetero-junction solar cells were developed under atmospheric conditions using Graphite as a hole transport layer (HTL) and TiO<sub>2</sub> as an electron transport layer (ETL). In particular a considerable enhancement in power conversion efficiency (PCE < 0.01%) has been realized using optimum Graphene concentration (0.05 g/ml). The charge injection rate is radically faster for the particular Graphene composition than the pristine perovskites, which exposes ephemeral absorption in near to UV range. Graphene incorporation increased the average crystallite size and reduced the band gap 1.32 eV in the visible range. The expensive metals such as Ag and Au have been replaced by simple ITO, which tremendously reduces the fabrication cost of the PSCs. The fabricated devices were exposed to high conservation stability without cell encapsulation ambient condition for 150 days to show excellent stability.展开更多
The combined effect of conduction-convection-radiation on natural convec- tion flow of an optically thick Newtonian fluid with gray radiant properties, confined in a porous media square cavity with Darcy-Brinkman-Forc...The combined effect of conduction-convection-radiation on natural convec- tion flow of an optically thick Newtonian fluid with gray radiant properties, confined in a porous media square cavity with Darcy-Brinkman-Forchheimer drag is studied numeri- cally. For a gray fluid, Rosseland diffusion approximation is considered. It is assumed that （i） the temperature of the left vertical wall varies linearly with height, （ii） the right vertical and top walls are at a lower temperature, and （iii） the bottom wall is uniformly-heated. The governing equations are solved using the alternate direct implicit method together with the successive over relaxation technique. The investigation of the effect of governing parameters, namely, the Forschheimer resistance （F）, the temperature difference （A）, and the Plank number （Rd）, on the flow pattern and heat transfer characteristics is carried out. It can be seen that the reduction of flow and heat transfer occur as the Forschheimer resistance is increased. On the other hand, both the flow strength and heat transfer in- crease as the temperature ratio A is increased.展开更多
In this article, the problem of mixed convection boundary layer flow of viscous fluid along a heated vertical plate is examined. In the analysis radiative component of heat flux emulates the surface temperature. Appro...In this article, the problem of mixed convection boundary layer flow of viscous fluid along a heated vertical plate is examined. In the analysis radiative component of heat flux emulates the surface temperature. Appropriate set of variables are embraced here which reduces the governing boundary layer equations into dimensionless form. Subsequently, a group of continuous transformation is applied on the dimensionless equations in order to obtain the parabolic partial differential equations for the regimes where modified Richardson number, Ri*, is 1) small i.e. when Ri* 1, 2) large i.e. when Ri* 1, and 3) covers all its values i.e. when 0 ≤ Ri* ≤ ∞. The system of equation for the corresponding regimes are thus integrated numerically via straightforward finite difference method along with Gaussian elimination technique. Its worth mentioning that results obtained here are valid particularly for the liquid metals for which Pr 1. Moreover, the numerical results are demonstrated graphically by showing the effects of important physical parameters, namely, the modified Richardson number (or mixed convection parameter), Ri*, surface radiation parameter, R, and Prandtl number, Pr, in terms of local skin friction and local Nusselt number coefficients. In addition, comprehensive interpretation of thermal energy distributions is also given in terms of heatlines which is termed as good tool to visualize the flow patterns.展开更多
Available data have been analyzed to assess impacts of global warming induced sea level rise on loss of soil and land resources and their implications on food security of Bangladesh. Scientists believe that because of...Available data have been analyzed to assess impacts of global warming induced sea level rise on loss of soil and land resources and their implications on food security of Bangladesh. Scientists believe that because of sea level rise coastal zone of Bangladesh has already experienced noticeable impacts especially in terms of area of inundation and erosion, saline intrusion, loss of soil and land, loss of crop production in addition to migration of people from vulnerable areas. The loss of land mass and degradation of soil and land resources will adversely affect national food production and thereby food security. Sea level rise impacts are really high for Bangladesh, though the country plays insignificant role in green house gas emission. Development and implementation of adaptation policies and taking initiatives to realize those policies are the right ways to respond to sea level rise impacts in Bangladesh.展开更多
文摘Optimization of Graphene concentration in optoelectronic properties has been studied which leads to progressive stability based on Graphene-CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> employing nanoparticles perovskites solar cells in this work. CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> wafer-based hetero-junction solar cells were developed under atmospheric conditions using Graphite as a hole transport layer (HTL) and TiO<sub>2</sub> as an electron transport layer (ETL). In particular a considerable enhancement in power conversion efficiency (PCE < 0.01%) has been realized using optimum Graphene concentration (0.05 g/ml). The charge injection rate is radically faster for the particular Graphene composition than the pristine perovskites, which exposes ephemeral absorption in near to UV range. Graphene incorporation increased the average crystallite size and reduced the band gap 1.32 eV in the visible range. The expensive metals such as Ag and Au have been replaced by simple ITO, which tremendously reduces the fabrication cost of the PSCs. The fabricated devices were exposed to high conservation stability without cell encapsulation ambient condition for 150 days to show excellent stability.
文摘The combined effect of conduction-convection-radiation on natural convec- tion flow of an optically thick Newtonian fluid with gray radiant properties, confined in a porous media square cavity with Darcy-Brinkman-Forchheimer drag is studied numeri- cally. For a gray fluid, Rosseland diffusion approximation is considered. It is assumed that （i） the temperature of the left vertical wall varies linearly with height, （ii） the right vertical and top walls are at a lower temperature, and （iii） the bottom wall is uniformly-heated. The governing equations are solved using the alternate direct implicit method together with the successive over relaxation technique. The investigation of the effect of governing parameters, namely, the Forschheimer resistance （F）, the temperature difference （A）, and the Plank number （Rd）, on the flow pattern and heat transfer characteristics is carried out. It can be seen that the reduction of flow and heat transfer occur as the Forschheimer resistance is increased. On the other hand, both the flow strength and heat transfer in- crease as the temperature ratio A is increased.
文摘In this article, the problem of mixed convection boundary layer flow of viscous fluid along a heated vertical plate is examined. In the analysis radiative component of heat flux emulates the surface temperature. Appropriate set of variables are embraced here which reduces the governing boundary layer equations into dimensionless form. Subsequently, a group of continuous transformation is applied on the dimensionless equations in order to obtain the parabolic partial differential equations for the regimes where modified Richardson number, Ri*, is 1) small i.e. when Ri* 1, 2) large i.e. when Ri* 1, and 3) covers all its values i.e. when 0 ≤ Ri* ≤ ∞. The system of equation for the corresponding regimes are thus integrated numerically via straightforward finite difference method along with Gaussian elimination technique. Its worth mentioning that results obtained here are valid particularly for the liquid metals for which Pr 1. Moreover, the numerical results are demonstrated graphically by showing the effects of important physical parameters, namely, the modified Richardson number (or mixed convection parameter), Ri*, surface radiation parameter, R, and Prandtl number, Pr, in terms of local skin friction and local Nusselt number coefficients. In addition, comprehensive interpretation of thermal energy distributions is also given in terms of heatlines which is termed as good tool to visualize the flow patterns.
文摘Available data have been analyzed to assess impacts of global warming induced sea level rise on loss of soil and land resources and their implications on food security of Bangladesh. Scientists believe that because of sea level rise coastal zone of Bangladesh has already experienced noticeable impacts especially in terms of area of inundation and erosion, saline intrusion, loss of soil and land, loss of crop production in addition to migration of people from vulnerable areas. The loss of land mass and degradation of soil and land resources will adversely affect national food production and thereby food security. Sea level rise impacts are really high for Bangladesh, though the country plays insignificant role in green house gas emission. Development and implementation of adaptation policies and taking initiatives to realize those policies are the right ways to respond to sea level rise impacts in Bangladesh.
基金the Damien Foundation Belgiumfor their unconditional and continuous supportThis publication was made possible through the support provided by the United States Agency for International Development (USAID) under the terms of Award No.GHS-A-00-03-0004500
