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61.
This paper investigates the performance of a spectral amplitude coding (SAC)–OCDMA system design utilizing subcarrier multiplexing techniques for use in the popular fiber-wireless (Fi-Wi) technology. Zero cross correlation code is employed because of its ability to eliminate phase induced intensity noise (PIIN) and the simplicity of using a direct detection technique at the receiving end. The performances are evaluated theoretically to derive the signal-to-noise ratio and results are presented in terms of bit error rates (BER). Results are analyzed to investigate the effect of code weight and variable data rates on the system performance. To validate the results, simulative analysis is also done using Optisys version 6.0. We demonstrated that the ZCC code performed better compared to other code for a BER floor of 10−9 with larger cardinality of subscribers. Results obviously indicate that system performance can be improved with larger code weight. In addition, the choice of lower bit rate is observed to perform better and more suitable for application in this hybrid Fi-Wi network. 相似文献
62.
Muthafar F. Al-Hilli Sean LiKassim S. Kassim 《Journal of magnetism and magnetic materials》2012,324(5):873-879
A series of Sm-doped Li-Ni ferrites with formula of (Li0.5Fe0.5)0.4Ni0.6SmyFe2−yO4, where 0.0≤y≤0.1 were prepared by double sintering ceramic technique. The structure was characterized by X-ray diffraction, which has confirmed the formation of single-phase spinel structure. The samarium concentration dependence of lattice parameters obeys Vegard's law. The octahedral site radii increased with Sm content while the tetrahedral site radii decreased. Deviation from the ideal crystal structure (Δ) is found to decrease with Sm substitution, and the hopping length on the octahedral site is found to increase with Sm content. Hall measurement confirmed p-type conductivity behavior for Sm-doped ferrite and the main charge transport mechanism is hopping of halls between Ni2+ and Ni3+. Sintering at 1300 °C resulted in low resistivity ferrite, which was found to increase with Sm content. Resistivity is governed by both charge carrier mobility and carrier concentration. It decreases with frequency, and this behavior with frequency is discussed according to Koop's theorem. The dielectric constant is found to decrease more rapidly at low frequencies than at higher frequencies while the dielectric constant increases with Sm content. The decrease in ε″ with frequency agrees with Deby's type relaxation process. Maximum in ε″ is observed when the hopping frequency is equal to the external electric field frequency. The variation in tan δ with frequency shows a similar nature to that of ε″ with frequency. The magnetization under applied magnetic field for the samples exhibits a clear hysteretic behavior. The scanning electron microscope (SEM) studies showed that the domain walls may tend to be trapped (pinned) by non-magnetic inclusions, precipitates and voids. The saturation magnetization (MS) increases with the sintering temperature, while the coercivity (HCi) is found to decrease. 相似文献
63.
An analysis is performed to study the heat transfer characteristics of steady two-dimensional boundary layer flow past a moving permeable flat plate in a nanofluid. The effects of uniform suction and injection on the flow field and heat transfer characteristics are numerically studied by using an implicit finite difference method. It is found that dual solutions exist when the plate and the free stream move in the opposite directions. The results indicate that suction delays the boundary layer separation, while injection accelerates it. 相似文献
64.
An analysis is carried out for the steady two-dimensional flow of a micropolar fluid over a shrinking sheet in its own plane.
The shrinking velocity is assumed to vary linearly with the distance from a fixed point on the sheet. The features of the
flow and heat transfer characteristics are analyzed and discussed. It is found that the solution exists only if adequate suction
through the permeable sheet is introduced. Moreover, stronger suction is necessary for the solution to exist for a micropolar
fluid compared to a classical Newtonian fluid. Dual solutions are obtained for certain suction and material parameters. 相似文献
65.
Norhasnida Zawawi Pei Juin Chong Nurul Nadhirah Mohd Tom Nurkhairina Solehah Saiful Anuar Salma Malihah Mohammad Norra Ismail Arif Zaidi Jusoh 《Molecules (Basel, Switzerland)》2021,26(15)
Honey is a well-known natural sweetener and is rich in natural antioxidants that prevent the occurrence of oxidative stress, which is responsible for many human diseases. Some of the biochemical compounds in honey that contribute to this property are vitamins and phenolic compounds such as phenolic acids and flavonoids. However, the extent to which these molecules contribute towards the antioxidant capacity in vitro is inconsistently reported, especially with the different analytical methods used, as well as other extrinsic factors that influence these molecules’ availability. Therefore, by reviewing recently published works correlating the vitamin, total phenolic, and flavonoid content in honey with its antioxidant activities in vitro, this paper will establish a relationship between these parameters. Based on the literature, vitamins do not contribute to honey’s antioxidant capacity; however, the content of phenolic acids and flavonoids has an impact on honey’s antioxidant activity. 相似文献
66.
The flow induced by an impermeable flat surface executing orthogonal stretching and orthogonal shearing in a rotating fluid system is investigated. Both the stretching and shearing are linear in the coordinates. An exact similarity reduction of the Navier–Stokes equations gives rise to a pair of nonlinearly-coupled ordinary differential equations governed by three parameters. In this study we set one parameter and analyze the problem which leads to flow for an impermeable surface with shearing and stretching due to velocity u along the x-axis of equal strength a while the shearing and stretching due to velocity v along the y-axis of equal strength b. These solutions depend on two parameters—a Coriolis (rotation) parameter \(\sigma = \Omega /a\) and a stretching/shearing ratio \(\lambda =b/a\). A symmetry in solutions is found for \(\lambda = 1\). The exact solution for \(\sigma = 0\) and the asymptotic behavior of solutions for \(|\sigma | \rightarrow \infty\) are determined and compared with numerical results. Oscillatory solutions are found whose strength increases with increasing values of \(|\sigma |\). It is shown that these solutions tend to the well-known Ekman solution as \(|\sigma | \rightarrow \infty\). 相似文献
67.
The steady laminar boundary layer flow and heat transfer from a warm, laminar liquid flow to a melting surface moving parallel
to a constant free stream is studied in this paper. The continuity, momentum and energy equations, which are coupled nonlinear
partial differential equations are reduced to a set of two nonlinear ordinary differential equations, before being solved
numerically using the Runge–Kutta–Fehlberg method. Results for the skin friction coefficient, local Nusselt number, velocity
profiles as well as temperature profiles are presented for different values of the governing parameters. Effects of the melting
parameter, moving parameter and Prandtl number on the flow and heat transfer characteristics are thoroughly examined. It is
found that the problem admits dual solutions. 相似文献
68.
Anuar Ishak Roslinda Nazar Ioan Pop 《Nonlinear Analysis: Real World Applications》2009,10(5):2909-2913
The unsteady laminar boundary layer flow over a continuously stretching permeable surface is investigated. The unsteadiness in the flow and temperature fields is caused by the time-dependence of the stretching velocity and the surface temperature. Effects of the unsteadiness parameter, suction/injection parameter and Prandtl number on the heat transfer characteristics are thoroughly examined. 相似文献
69.
Jun Yuan Chan Aminuddin Bin Ahmad Kayani Mohd Anuar Md Ali Chee Kuang Kok Muhamad Ramdzan Buyong Susan Ling Ling Hoe Marini Marzuki Alan Soo‐Beng Khoo Sharath Sriram Kostya Ostrikov 《Electrophoresis》2019,40(20):2728-2735
This paper presents the development and experimental analysis of a curved microelectrode platform for the DEP deformation of breast cancer cells (MDA‐MB‐231). The platform is composed of arrays of curved DEP microelectrodes which are patterned onto a glass slide and samples containing MDA‐MB‐231 cells are pipetted onto the platform's surface. Finite element method is utilised to characterise the electric field gradient and DEP field. The performance of the system is assessed with MDA‐MB‐231 cells in a low conductivity 1% DMEM suspending medium. We applied sinusoidal wave AC potential at peak to peak voltages of 2, 5, and 10 Vpp at both 10 kHz and 50 MHz. We observed cell blebbing and cell shrinkage and analyzed the percentage of shrinkage of the cells. The experiments demonstrated higher percentage of cell shrinkage when cells are exposed to higher frequency and peak to peak voltage electric field. 相似文献
70.
Abu Bakar Mohamad Hafizi Azmi Mohamad Nurul Shariff Khairul Anuar Tan Joo Shun 《Applied biochemistry and biotechnology》2019,188(1):241-259
Applied Biochemistry and Biotechnology - Withaferin A (WA), a bioactive constituent derived from Withania somnifera plant, has been shown to exhibit many qualifying properties in attenuating... 相似文献