Dennis Ling Chuan Ching

New Exact Solutions for MHD Transient Rotating Flow of a Second-Grade Fluid in a Porous Medium

The magnetohydrodynamic (MHD) and rotating flow of second-grade fluid over a suddenly moved flat plate is investigated, where the second-grade fluid saturates the porous medium. The new exact solution is derived by using the Fourier sine and Laplace transforms. Many interesting available results in the literature are obtained as limiting cases of our solution. Finally, some graphical results are presented for different values of the material constants.

Effect of Zinc Oxide Nanoparticle Sizes on Viscosity of Nanofluid for Application in Enhanced Oil Recovery

Zinc oxide (ZnO) with different nanoparticle (NP) sizes was prepared and synthesized by using the sol-gel method with organic precursor, followed by the characterization of the ZnO nanoparticle by using X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) to identify the effect of nanoparticle sizes of ZnO on the viscosity of the nanofluid. The impact of nanoparticle sizes on EOR was investigated. Results showed both viscosity and interfacial tension (IFT) increased with the nanoparticle size.

Constant Accelerated Flow for a Third-Grade Fluid in a Porous Medium and a Rotating Frame with the Homotopy Analysis Method

The homotopy analysis method (HAM) is applied to obtain the approximate analytic solution of a constant accelerated flow for a third-grade fluid in a porous medium and a rotating frame. HAM is an analytic technique which provides us with a new way to obtain series solutions of such nonlinear problems. The approximate analytic solution for constant accelerated flow is obtained by using HAM. HAM contains the auxiliary parameter , which provides us with a straightforward way to obtain the convergence region of the series solution. Graphical results are plotted and the consequences discussed. The obtained solutions clearly satisfy the governing equations and all the imposed initial and boundary conditions. Many interesting results can be obtained as the special cases of the presented analysis. The influence of the material parameters of a third-grade fluid and rotation upon the velocity field is finally deliberated.

Central Composite Design (CCD) applied for statistical optimization of glucose and sucrose binary carbon mixture in enhancing the denitrification process

The present study provides an insight into the optimization of a glucose and sucrose mixture to enhance the denitrification process. Central Composite Design was applied to design the batch experiments with the factors of glucose and sucrose measured as carbon-to-nitrogen (C:N) ratio each and the response of percentage removal of nitrate–nitrogen (NO3−–N). Results showed that the polynomial regression model of NO3−–N removal had been successfully derived, capable of describing the interactive relationships of glucose and sucrose mixture that influenced the denitrification process. Furthermore, the presence of glucose was noticed to have more consequential effect on NO3−–N removal as opposed to sucrose. The optimum carbon sources mixture to achieve complete removal of NO3−–N required lesser glucose (C:N ratio of 1.0:1.0) than sucrose (C:N ratio of 2.4:1.0). At the optimum glucose and sucrose mixture, the activated sludge showed faster acclimation towards glucose used to perform the denitrification process. Later upon the acclimation with sucrose, the glucose uptake rate by the activated sludge abated. Therefore, it is vital to optimize the added carbon sources mixture to ensure the rapid and complete removal of NO3−–N via the denitrification process.

Impact of pH on zinc oxide particle size by using sol-gel process

Zinc oxide (ZnO) nanoparticles were prepared and synthesized via sol-gel method, by using citric acid as a precursor. The annealing temperature was fixed at 600 °C. The impact of pH on the particle size was investigated. Based on the results from the Thermogravimetric Analysis (TGA), three different pH for the precursor which is 3.0, 5.0 and 1.01 were chosen followed by the characterization of the ZnO nanoparticle by using Powder X-Ray Diffraction (PXRD), Transmission Electron Microscopy (TEM) and Field Emission Scanning Electron Microscopy (FESEM). Results showed that the crystallite size estimated from PXRD increased with the pH value which was hexagonal structure for ZnO. TEM further revealed the same tendency which the Zn NPs size also increased with the alkalinity of the precursor.

Scaled down Design of a Cold and Hot Flow Model Based on a Bubbling Fluidized Bed Pilot Plant Gasifier

Bubbling fluidized bed (BFB) is a vital equipment in many applications in the energy, pharmaceuticals, and chemicals process industries due to its numerous advantages such as large heat capacity inside a bed, and rapid heat and mass transfer rate. In spite of numerous research activities, achieving high fluidization performances in BFB process is still a challenge of science. This research is being conducted to study the hydrodynamic regime of a BFB pilot plant gasifier. To this end, a lab-scale cold model was first designed based on the empirical equations and scaling laws. The scaling laws was used to scale down the Tenaga Nasional Berhad-PETRONAS (TNBR-PETRONAS) pilot plant gasifier into a small scale laboratory model. Moreover, the empirical equations were utilized to determine the critical parameters such as bed pressure drop, height of the bed, number of orifices of the distributor plate and the pitch size. Finally a lab-scale hot flow model will be designed based on the cold model geometric dimensions but under a real operating conditions as that of a pilot plant.

Numerical solutions for linear Fredholm integral equations of the second kind using 2-point half-sweep explicit group method

In this paper, performance of the 2-Point Half-Sweep Explicit Group (2-HSEG) iterative method with first order composite closed Newton-Cotes quadrature scheme for solving second kind linear Fredholm integral equations is investigated. The formulation and implementation of the method are described. Furthermore, numerical results of test problems are also presented to verify the performance of the method compared to 2-Point Full-Sweep Explicit Group (2-FSEG) method. From the numerical results obtained, it is noticeable that the 2-HSEG method is superior to 2-FSEG method, especially in terms of computational time.

A New Local Search Algorithm for Minimum Span Frequency Assignment in Mobile Communication

Recent years, the use of mobile communication has been steadily increases. An important process in mobile communication is the assignment of frequency spectrum called channel to each of the caller and receiver pair in order to communicate. This headed to some problems faced by mobile communication on how to distribute the large number of users efficiently with the limited capital of radio frequency spectrum. Zero interference between channels assigned may contributed to a high quality call service between users. In mobile communication one of the ways to solve the problem is dividing a geographical area into a number of cells in order to reuse the limited frequencies with the aim of supporting more users and also to minimize interference. Hence, a local search method is proposed in this project to solve the channel assignment problem with the minimum span of frequency and zero interference between the channels assigned.

Impact of temperature on zinc oxide particle size by using sol-gel process

Zinc oxide (ZnO) nanoparticles were prepared and synthesized via sol-gel method, by using citric acid as a precursor. The impact of annealing on the particle size was investigated. Based on the results from the Thermogravimetric Analysis (TGA), three different annealing temperature which is 500, 600 and 700 °C were chosen followed by the characterization of the ZnO nanoparticle by using Powder X-Ray Diffraction (PXRD), Transmission Electron Microscopy (TEM) and Field Emission Scanning Electron Microscopy (FESEM). Results showed that the crystallite size estimated from PXRD increased with the annealing temperature which was hexagonal structure for ZnO. TEM further revealed the same tendency which the Zn NPs size also increased with the annealing temperature.

Pseudo wave by propagation of SH-wave with sinusoidal force in saturated medium

Analytical solutions for the propagation of SH-wave with the existing sinusoidal force or pseudo wave in miscible and immiscible mediums are found. Comparison is done for the propagating SH-wave with and without sinusoidal force. Identical waves are found in both the mediums. Studies are extended to wave attenuation where sinusoidal force tends to amplify SH-wave and increase the diffusion.