We demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic met... more We demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low absorptivity (emissivity) at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributions to elucidate how the absorption occurs within the metasurface structure.
Fine-tuning of the temperature coefficients of capacitance and dielectric constant of magnesium o... more Fine-tuning of the temperature coefficients of capacitance and dielectric constant of magnesium orthostannate (Mg2SnO4) has been attempted by means of Sn (IV) and Zr (IV) oxide incorporation as a second phase. The additives were also employed to enhance the density and minimize or eliminate porosity at lower sintering temperatures. Phase-pure magnesium stannate powder was synthesized via conventional solid-state reaction. It
We design a dual-band absorber formed by combining two cross-shaped metallic resonators of differ... more We design a dual-band absorber formed by combining two cross-shaped metallic resonators of different sizes within a super-unit-cell arranged in mirror symmetry. Simulations indicate that absorption efficiencies greater than 99% can be achieved at two different frequencies under normal incidence. We employ a design scheme with graphene integration, which allows independent tuning of individual absorption frequencies by electrostatically changing the Fermi energy of the graphene layer. High absorbance is maintained over a wide incident angle range up to 50 degrees for both TE and TM polarizations. It thus enables a promising way to design electrically tunable absorbers, which may contribute toward the realization of frequency selective detectors for sensing applications.
ABSTRACT We will describe research conducted at Los Alamos National Laboratory towards developing... more ABSTRACT We will describe research conducted at Los Alamos National Laboratory towards developing components for controlling terahertz waves. We employ meta-materials and, particularly, meta-films, as very compact absorbers for controlling quasi-optical beams. We believe that dielectric photonic bandgap structures could replace ordinary metal waveguide devices at THz, since metal structures become extremely lossy in this frequency range. We are also acquiring new measurement equipment which will allow us to enhance capabilities of testing THz components.
ABSTRACT Steam assisted gravity drainage (SAGD) is a thermal oil recovery technique which has bee... more ABSTRACT Steam assisted gravity drainage (SAGD) is a thermal oil recovery technique which has been used mostly for Alberta's unconventional oil sands reservoirs. Roger Butler, known as the father of SAGD, was the first one to establish a theory and an analytical model for SAGD. His model is a rigorous solution and is widely referred to as a SAGD fast flow simulator. However, geomechanics, which has been shown to be a relevant part of SAGD's physics, has not been included in the model. When rock properties are influenced by geomechanical behaviour, the Butler theory is not able to capture the complete physics of the SAGD process. In such cases, the model must adopt unrealistic or high values for rock properties. In this study, a classical theory in the field of geotechnical engineering (limit equilibrium) is employed to act as the geomechanical module for SAGD's mathematical coupled simulation. The Butler/Reis model has also been improved using a model of slices for flow simulation. Methodology of combining these two models in a single coupled mathematical simulator is presented in this paper. The solver is a fast and realistic proxy and can be used as a low-order tool for history matching. The results of coupled simulations show that the model is able to predict permeability and porosity of the reservoir closer to real values than uncoupled (flow only) modelling.
2Nd International Conference on the Developments in Renewable Energy Technology, 2012
The word itself “Solar” describes that we are dealing with some renewable energy source for a hot... more The word itself “Solar” describes that we are dealing with some renewable energy source for a hot water system. A Solar Hot Water System(SHWS) has been already designed, further implementation has been done by working on its insulation at variable time, temperature and solar radiation so that there is a minimum temperature drop over night decreases. A suitable material is
By utilizing polymers it is possible to create hybrid or composite materials which maximize the b... more By utilizing polymers it is possible to create hybrid or composite materials which maximize the bactericidal properties of active agents, such as silver nanoparticles (AgNPs). The synthesis of hybrid nanofibers by the incorporation of silver nanoparticles into polymer solution via electrospinning has gained much attention due to the strong antimicrobial activity of the resulting fibers. In this work, the antibacterial activity of electrospun nanofibers functionalized with silver nanoparticles (AgNPs) has been investigated against both gram positive and gram negative bacteria. Well characterized silver nanoparticles have been synthesized and mixed to allow interaction with polymer chain to form hybrid nanofibers by electrospinning process. Thus, fibers containing AgNPs have been demonstrated using a variety of polymers including polyethyleneterephthalate (PET), polyacrylonitrile (PAN) and polystyrene. Though there are many methods of imparting biocidal properties to electrospin fiber...
We demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic met... more We demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low absorptivity (emissivity) at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributions to elucidate how the absorption occurs within the metasurface structure.
Fine-tuning of the temperature coefficients of capacitance and dielectric constant of magnesium o... more Fine-tuning of the temperature coefficients of capacitance and dielectric constant of magnesium orthostannate (Mg2SnO4) has been attempted by means of Sn (IV) and Zr (IV) oxide incorporation as a second phase. The additives were also employed to enhance the density and minimize or eliminate porosity at lower sintering temperatures. Phase-pure magnesium stannate powder was synthesized via conventional solid-state reaction. It
We design a dual-band absorber formed by combining two cross-shaped metallic resonators of differ... more We design a dual-band absorber formed by combining two cross-shaped metallic resonators of different sizes within a super-unit-cell arranged in mirror symmetry. Simulations indicate that absorption efficiencies greater than 99% can be achieved at two different frequencies under normal incidence. We employ a design scheme with graphene integration, which allows independent tuning of individual absorption frequencies by electrostatically changing the Fermi energy of the graphene layer. High absorbance is maintained over a wide incident angle range up to 50 degrees for both TE and TM polarizations. It thus enables a promising way to design electrically tunable absorbers, which may contribute toward the realization of frequency selective detectors for sensing applications.
ABSTRACT We will describe research conducted at Los Alamos National Laboratory towards developing... more ABSTRACT We will describe research conducted at Los Alamos National Laboratory towards developing components for controlling terahertz waves. We employ meta-materials and, particularly, meta-films, as very compact absorbers for controlling quasi-optical beams. We believe that dielectric photonic bandgap structures could replace ordinary metal waveguide devices at THz, since metal structures become extremely lossy in this frequency range. We are also acquiring new measurement equipment which will allow us to enhance capabilities of testing THz components.
ABSTRACT Steam assisted gravity drainage (SAGD) is a thermal oil recovery technique which has bee... more ABSTRACT Steam assisted gravity drainage (SAGD) is a thermal oil recovery technique which has been used mostly for Alberta's unconventional oil sands reservoirs. Roger Butler, known as the father of SAGD, was the first one to establish a theory and an analytical model for SAGD. His model is a rigorous solution and is widely referred to as a SAGD fast flow simulator. However, geomechanics, which has been shown to be a relevant part of SAGD's physics, has not been included in the model. When rock properties are influenced by geomechanical behaviour, the Butler theory is not able to capture the complete physics of the SAGD process. In such cases, the model must adopt unrealistic or high values for rock properties. In this study, a classical theory in the field of geotechnical engineering (limit equilibrium) is employed to act as the geomechanical module for SAGD's mathematical coupled simulation. The Butler/Reis model has also been improved using a model of slices for flow simulation. Methodology of combining these two models in a single coupled mathematical simulator is presented in this paper. The solver is a fast and realistic proxy and can be used as a low-order tool for history matching. The results of coupled simulations show that the model is able to predict permeability and porosity of the reservoir closer to real values than uncoupled (flow only) modelling.
2Nd International Conference on the Developments in Renewable Energy Technology, 2012
The word itself “Solar” describes that we are dealing with some renewable energy source for a hot... more The word itself “Solar” describes that we are dealing with some renewable energy source for a hot water system. A Solar Hot Water System(SHWS) has been already designed, further implementation has been done by working on its insulation at variable time, temperature and solar radiation so that there is a minimum temperature drop over night decreases. A suitable material is
By utilizing polymers it is possible to create hybrid or composite materials which maximize the b... more By utilizing polymers it is possible to create hybrid or composite materials which maximize the bactericidal properties of active agents, such as silver nanoparticles (AgNPs). The synthesis of hybrid nanofibers by the incorporation of silver nanoparticles into polymer solution via electrospinning has gained much attention due to the strong antimicrobial activity of the resulting fibers. In this work, the antibacterial activity of electrospun nanofibers functionalized with silver nanoparticles (AgNPs) has been investigated against both gram positive and gram negative bacteria. Well characterized silver nanoparticles have been synthesized and mixed to allow interaction with polymer chain to form hybrid nanofibers by electrospinning process. Thus, fibers containing AgNPs have been demonstrated using a variety of polymers including polyethyleneterephthalate (PET), polyacrylonitrile (PAN) and polystyrene. Though there are many methods of imparting biocidal properties to electrospin fiber...
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Papers by Abul Kalam Azad