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15
result(s) for
"Abdullah, Nooraihan"
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Tunable Transparency and Group Delay in Cavity Optomechanical Systems with Degenerate Fermi Gas
by
Ahmad Hambali, Nor Azura Malini
,
Yusoff, Fatin Nadiah
,
Zulkifli, Muhammad Afiq
in
Atoms
,
Control methods
,
Data processing
2023
We theoretically investigate the optical response and the propagation of an external probe field in a Fabry–Perot cavity, which consists of a mechanical mode of trapped, ultracold, fermionic atoms inside and simultaneously driven by an optical laser field. We investigate the electromagnetically-induced transparency due to coupling of the optical cavity field with the collective density excitations of the ultracold fermionic atoms via radiation pressure force. Moreover, we discuss the variations in the phase and group delay of the transmitted probe field with respect to effective cavity detuning as well as pumping power. It is observed that the transmitted field is lagging in this fermionic cavity optomechanical system. Our study shall provide a method to control the propagation as well as the speed of the transmitted probe field in this kind of fermionic, ultracold, atom-based, optomechanical cavity system, which might have potential applications in optical communications, signal processing and quantum information processing.
Journal Article
Clustering at the nuclear surface and symmetry energy
by
Abdullah, Nooraihan
,
Sauli, Zaliman
,
Usmani, Q N
in
Binding energy
,
Binding energy (nuclear)
,
Clustering
2011
With in the energy density functional formalism a phenomenological theory of nuclei is developed which incorporates clustering at the nuclear surface in a general form. This explains the large values of symmetry energy extracted recently at low values of nuclear matter density. It is shown that the nuclear matter binding energy per nucleon (B/A), in the neighbourhood of zero density, must approach its value at the saturation density. The parameters of the theory are mainly constrained from the binding energies and root mean square radii of 376 spherical nuclei as well as the large values of the recently extracted symmetry energy at low densities. Importance of quartic term in symmetry energy is demonstrated. It is shown that it originates due to clustering as well as due to contribution of three-nucleon interaction in the state-of-the-art equation of state of neutron matter at and below the saturation densities. It is found that clustering significantly reduces the neutron skin thickness in nuclei.
Journal Article
Symmetry Energy of Nuclear Matter at Low Densities and Clustering at the Nuclear Surface
by
Anwar, K
,
Sauli, Zaliman
,
Abdullah, Nooraihan
in
Clustering
,
Density
,
Density functional theory
2012
We present a density functional theory which connects nuclear matter equation of state, which incorporates clustering at low densities, with clustering in medium and heavy nuclei at the nuclear surface. This explains the large values of symmetry energy reported by Natowitz et al for densities < 0.01 fm−3 in addition to the binding energies and charge rms radii of 367 spherical nuclei. The present theory which is partly macroscopic competes with other high quality microscopic-macroscopic approaches. Merits of the results with clustering and no-clustering are discussed. We also make connection with realistic interactions (AV18+UIX/IL2) which have been used in ab initio calculations in s- and p-shell nuclei and neutron matter. Theory predicts new situations and regimes to be explored both theoretically and experimentally. It is demonstrated that, due to clustering, the neutron skin thickness reduces significantly.
Journal Article
Natural Heat Convection Analysis on Cylindrical Al Slug of LED
2014
This paper presents the characterization of a single chip high power LED package through simulation. Ansys version 11 was used for the simulation. The characterization of the LED package with aluminum cylindrical heat slug was carried out under natural convection condition at ambient temperature of 25°C. The junction temperature and the stress of the LED chip was assesed. The LED chip was powered with input power of 0.1 W and 1 W and the heat dissipation was assesed. Results showed that that the junction temperature and the Von Mises Stress of the single chip LED package increases with the increased input power.
Journal Article
BaxSr1-x TiO3 Different Thickness Analysis Using Sol Gel Approach
by
Retnasamy, Vithyacharan
,
Sauli, Zaliman
,
Anwar, K.
in
Barium strontium titanates
,
Deposition
,
Dynamic random access memory
2014
Barium Strontium Titanate (BST) a common topic in the microelectronic field for many devices which is mainly on dynamic random access memories (DRAM). There are many methods of preparing BaxSr1-xTiO3; barium strontium titanate. In this work, sol-gel method was used as it has some advantages like better homogeneity, lower cost, lower processing temperature and easier fabrication. BaxSr1-xTiO3 solution was deposited on the silicon substrate of 4 different thicknesses with different ratio of the concentration of Barium (Ba). The thickness of the thin film has a linear increase as the Ba content increases.
Journal Article
Physical Characterization of BST with Different (x’) Ratios
by
Retnasamy, Vithyacharan
,
Sauli, Zaliman
,
Anwar, K.
in
Atomic force microscopy
,
Atomic structure
,
Barium strontium titanates
2014
Nowdays Barium strontium titanate (BST) can be applied into many fields of engineering. Its properties attracted more researchers to research and apply it into many fields of study. In this work, sol-gel method of preparing barium strontium titanate (BST) has been used. This work was done with 4 different ratio of x with 4 different deposition layers. The main purpose of this work is to investigate the relation between the ratio of barium (Ba) with different deposition layer and the surface of the substrate. Atomic force microscopy (AFM) was used in whole work to investigate the crystalline structure and surface roughness of the BST thin films.
Journal Article
Fibrous Material Density Difference Analysis Using Light Reflectance
by
Retnasamy, Vithyacharan
,
Say, Ong Tee
,
Sauli, Zaliman
in
Electric potential
,
Lasers
,
Light (visible radiation)
2014
The objective of this work is designed and fabricated a lab module tester to differentiate the different type of printing paper quality which available commercially was done. Laser light source was used to differentiate the quality of printing paper. The concept light reflectance on surface material was used in this study. The photodiode was used as photo detector to detect the reflected light from the surface of printing paper. The laser diode and photodiode were placed in a box which the box named light box. The laser was used to emit light on the sample and the photodiode detects light intensity from the surface printing paper in the light box. Different level of intensity will have different value of voltage output. The differentiation on the different type of printing paper including of 70 g/m2, 80 g/m2 and 100 g/m2 were done respectively. The result showed that the 100 g/m2 printing paper has a higher reflected voltage output compared to 80 g/m2 and 70 g/m2 printing paper.
Journal Article
Surface Roughness and Wettability Correlation on Etched Platinum Using Reactive Ion Ecthing
by
Retnasamy, Vithyacharan
,
Yeow, Aaron Koay Terr
,
Sauli, Zaliman
in
Adhesive bonding
,
Contact angle
,
Droplets
2014
As the world of semiconductor is moving towards smaller and high-end applications, the quality of the bonding adhesion for wire bonding is very critical. Although aluminium has been the metallization of choice in integrated circuits, it can be easily oxidized during high temperature and pressure. On the other hand, Platinum metallization layer has high thermal coefficient resistance and inert to oxygen. This paper reports the correlation between surface roughness and the wettability in the form of contact angle for Platinum deposited wafer etched using Inductively Couple Plasma-Reactive Ion Etching (ICP-RIE). Surface roughness was measured using AFM while contact angle was obtained via droplet test. The results clearly suggested that both surface roughness and wettabily, calculated by its contact angle value has the same trend. Surface roughness is directly proportional to the contact angle. This indicates that surface roughness have great influence on the surface wettability. Therefore, the adhesion for wire bonding process on platinum metallization which can be used in high end applications can be controlled by its surface roughness and wettability.
Journal Article
WSS Investigation in Microfluidic FFS Channel at Re 500
by
Retnasamy, Vithyacharan
,
Taniselass, Steven
,
Sauli, Zaliman
in
Computational fluid dynamics
,
Computer simulation
,
Devices
2014
Wall shear stress (WSS) is one of the important variables in microfluidic devices. In this paper WSS distribution for a microfluidic device in Forward Facing Step (FFS) configuration has been investigated using Reynolds number 500 and step height 1μm. Numerical simulation was performed usingAnsys-CFX software with the assumption of Newtonian fluid and laminar condition. The simulation result showed that wall shear stress distribution increased after the fluid passing through the step.
Journal Article
Velocity Profile Investigation of FFS Microchannel at Re 100
by
Retnasamy, Vithyacharan
,
Taniselass, Steven
,
Sauli, Zaliman
in
Biomedical materials
,
Computational fluid dynamics
,
Cross sections
2014
Recently, microfluidics system has been widely employed in various areas for instance biomedical,pharmaceuticals and cell biological researchdue to its advantages. The flow behavior in microchannels with different cross-sections has been topic in previous studies. In this paper, numerical simulation of fluid flow in Forward Facing Step (FFS) configuration was performed to investigate velocity profile after the step. Reynolds numbers (Re) 100 with different step heights, 1μm and 3μm were used to observe trend occurs in the flow characteristics. The result illustrated an increase of velocity distribution with the increase of the step height.
Journal Article