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Fulltext Chemical reaction and variable viscosity effect on mixed heat and mass transfer convection for Hiemenz flow over a porous wedge with heat radiation

Kandasamy, R., Azme, Hashim, I., Ismoen, M.

ASM Science Journal, 2008;2(1):23-33.
MyJurnal

The effect of chemical reaction and variable viscosity on mixed convection heat and mass transfer for Hiemenz flow over a porous wedge plate was studied in the presence of heat radiation. The wall of the wedge was embedded in a uniform Darcian porous medium to allow for possible fluid wall suction or injection and had a power-law variation of both the wall temperature and concentration. The fluid was assumed to be viscous and incompressible. Numerical calculations were carried out for different values of dimensionless parameters and an analysis of the results obtained showed that the flow field was influenced appreciably by the buoyancy ratio between species, thermal diffusion and suction/injection at wall surface. The effects of these major parameters on the transport behaviours were investigated methodically and typical results illustrated to reveal the tendency of the solutions. Representative results are presented for the velocity, temperature, and concentration distributions. Comparisons with previously published works were performed and excellent agreement between the results were obtained. It is predicted that this research might prove to be useful for study of the movement of oil or gas and water through the reservoir of an oil or gas field, in the migration of underground water, in filtration, and water purification processes.
Fulltext Natural convection in a differentially heated square enclosure with a solid polygon

Roslan R, Saleh H, Hashim I

ScientificWorldJournal, 2014;2014:617492.
PMID: 24991643 DOI: 10.1155/2014/617492

The aim of the present numerical study is to analyze the conjugate natural convection heat transfer in a differentially heated square enclosure containing a conductive polygon object. The left wall is heated and the right wall is cooled, while the horizontal walls are kept adiabatic. The COMSOL Multiphysics software is applied to solve the dimensionless governing equations. The governing parameters considered are the polygon type, 3 ≤ N ≤ ∞, the horizontal position, 0.25 ≤ X 0 ≤ 0.75, the polygon size, 0 ≤ A ≤ π/16, the thermal conductivity ratio, 0.1 ≤ K r ≤ 10.0, and the Rayleigh number, 10(3) ≤ Ra ≤ 10(6). The critical size of the solid polygon was found exists at low conductivities. The heat transfer rate increases with the increase of the size of the solid polygon, until it reaches its maximum value. Here, the size of the solid polygon is reaches its critical value. Further, beyond this critical size of the solid polygon, will decrease the heat transfer rate.
Fulltext Conjugate heat transfer in Rayleigh-Bénard convection in a square enclosure

Saleh H, Hashim I

ScientificWorldJournal, 2014;2014:786102.
PMID: 24971390 DOI: 10.1155/2014/786102

Conjugate natural convection-conduction heat transfer in a square enclosure with a finite wall thickness is studied numerically in the present paper. The governing parameters considered are the Rayleigh number (5 × 10(3) ≤ Ra ≤ 10(6)), the wall-to-fluid thermal conductivity ratio (0.5 ≤ Kr ≤ 10), and the ratio of wall thickness to its height (0.2 ≤ D ≤ 0.4). The staggered grid arrangement together with MAC method was employed to solve the governing equations. It is found that the fluid flow and the heat transfer can be controlled by the thickness of the bottom wall, the thermal conductivity ratio, and the Rayleigh number.
Bochdalek diaphragmatic hernia presenting with acute gastric dilatation

Quah BS, Hashim I, Simpson H

J Pediatr Surg, 1999 Mar;34(3):512-4.
PMID: 10211672

Congenital diaphragmatic hernia through the foramen of Bochdalek may present after infancy. A 21/2-year-old Malay girl presented with acute respiratory distress. Chest examination showed reduced chest expansion and decreased breath sounds on the left side. Chest radiograph showed a large "cyst" in the left chest, which was thought to be a lung cyst under tension. Tube thoracostomy resulted in clinical improvement. Results of a barium study showed that the cyst perforated by the thoracostomy tube was the stomach, which had herniated through a Bochdalek diaphragmatic defect. Surgical repair of the diaphragmatic defect and closure of the perforated stomach was performed successfully. Congenital diaphragmatic hernia should be included in the differential diagnosis of respiratory distress in young children. Nasogastric tube placement must be considered as an early diagnostic or therapeutic intervention when the diagnosis is suspected.
Lung abscess: an unusual presentation of congenital tracheoesophageal fistula without atresia

Quah BS, Indudharan R, Hashim I, Simpson H

J Pediatr Surg, 1998 Dec;33(12):1817-9.
PMID: 9869060

Tracheoesophageal fistula (TEF) without atresia is rare and usually presents with symptoms from birth. In this report, a 9-year-old boy presented with productive cough of 4 month's duration and was shown to have a right lung abscess seen on chest radiograph. His parents denied earlier respiratory symptoms or illnesses. Rigid bronchoscopy showed a fistulous opening of about 1 mm in diameter in the posterior wall of the trachea about 16 cm from the upper incisor teeth. Cannulation with a ureteral catheter demonstrated that the fistulous opening communicated with the esophageal lumen. The tracheoesophageal fistula was 1 cm long and was divided through a right supraclavicular incision. The postoperative period was uneventful, and the patient was discharged on the third postoperative day. This case demonstrated that TEF should be considered in any patient presenting with chronic respiratory problems even after a prolonged symptom-free period.
Fulltext Extension of Operational Matrix Technique for the Solution of Nonlinear System of Caputo Fractional Differential Equations Subjected to Integral Type Boundary Constrains

Khalil H, Khalil M, Hashim I, Agarwal P

Entropy (Basel), 2021 Sep 02;23(9).
PMID: 34573779 DOI: 10.3390/e23091154

We extend the operational matrices technique to design a spectral solution of nonlinear fractional differential equations (FDEs). The derivative is considered in the Caputo sense. The coupled system of two FDEs is considered, subjected to more generalized integral type conditions. The basis of our approach is the most simple orthogonal polynomials. Several new matrices are derived that have strong applications in the development of computational scheme. The scheme presented in this article is able to convert nonlinear coupled system of FDEs to an equivalent S-lvester type algebraic equation. The solution of the algebraic structure is constructed by converting the system into a complex Schur form. After conversion, the solution of the resultant triangular system is obtained and transformed back to construct the solution of algebraic structure. The solution of the matrix equation is used to construct the solution of the related nonlinear system of FDEs. The convergence of the proposed method is investigated analytically and verified experimentally through a wide variety of test problems.
Fulltext Natural Convection Flow of a Nanofluid in an Inclined Square Enclosure Partially Filled with a Porous Medium

Alsabery AI, Chamkha AJ, Saleh H, Hashim I

Sci Rep, 2017 05 24;7(1):2357.
PMID: 28539585 DOI: 10.1038/s41598-017-02241-x

This work analyses free convection flow of a nanofluid in an inclined square enclosure consisting of a porous layer and a nanofluid layer using the finite difference methodology. Sinusoidal temperature boundary conditions are imposed on the two opposing vertical walls. Nanofluids with water as base and Ag or Cu or Al2O3 or TiO2 nanoparticles are considered for the problem. The related parameters of this study are the Darcy number, nanoparticle volume fraction, phase deviation, amplitude ratio, porous layer thickness and the inclination angle of the cavity. A comparison with previously published work is performed and the results are in good agreement. Detailed numerical data for the fluid flow and thermal distributions inside the square enclosure, and the Nusselt numbers are presented. The obtained results show that the heat transfer is considerably affected by the porous layer increment. Several nanoparticles depicted a diversity improvement on the convection heat transfer.
Natural convection of [Formula: see text]-water nanofluid in a non-Darcian wavy porous cavity under the local thermal non-equilibrium condition

Alsabery AI, Tayebi T, Chamkha AJ, Hashim I

Sci Rep, 2020 Oct 22;10(1):18048.
PMID: 33093608 DOI: 10.1038/s41598-020-75095-5

This study investigates thermal natural convective heat transfer in a nanofluid filled-non-Darcian porous and wavy-walled domain under the local thermal non-equilibrium condition. The considered cavity has corrugated and cold vertical walls and insulated horizontal walls except the heated part positioned at the bottom wall. The transport equations in their non-dimensional model are numerically solved based on the Galerkin finite-element discretization technique. The dimensionless governing parameters of the present work are the nanoparticle in volume concentration, the Darcy number, number of undulations, modified heat conductivity ratio, dimensionless heated part length, and location. Comparisons with other published theoretical and experimental results show good agreement with the present outcomes. The findings indicate that the heater length, its position, and the waves number on the side vertical walls as well as the nanoparticles concentration can be the control parameters for free convective motion and heat transport within the wavy cavity.
Fulltext Entropy Generation Analysis and Natural Convection in a Nanofluid-Filled Square Cavity with a Concentric Solid Insert and Different Temperature Distributions

Alsabery AI, Ishak MS, Chamkha AJ, Hashim I

Entropy (Basel), 2018 May 03;20(5).
PMID: 33265426 DOI: 10.3390/e20050336

The problem of entropy generation analysis and natural convection in a nanofluid square cavity with a concentric solid insert and different temperature distributions is studied numerically by the finite difference method. An isothermal heater is placed on the bottom wall while isothermal cold sources are distributed along the top and side walls of the square cavity. The remainder of these walls are kept adiabatic. Water-based nanofluids with Al 2 O 3 nanoparticles are chosen for the investigation. The governing dimensionless parameters of this study are the nanoparticles volume fraction ( 0 ≤ ϕ ≤ 0.09 ), Rayleigh number ( 10 3 ≤ R a ≤ 10 6 ) , thermal conductivity ratio ( 0.44 ≤ K r ≤ 23.8 ) and length of the inner solid ( 0 ≤ D ≤ 0.7 ). Comparisons with previously experimental and numerical published works verify a very good agreement with the proposed numerical method. Numerical results are presented graphically in the form of streamlines, isotherms and local entropy generation as well as the local and average Nusselt numbers. The obtained results indicate that the thermal conductivity ratio and the inner solid size are excellent control parameters for an optimization of heat transfer and Bejan number within the fully heated and partially cooled square cavity.
Fulltext Entropy production and mixed convection within trapezoidal cavity having nanofluids and localised solid cylinder

Ishak MS, Alsabery AI, Hashim I, Chamkha AJ

Sci Rep, 2021 Jul 19;11(1):14700.
PMID: 34282226 DOI: 10.1038/s41598-021-94238-w

The entropy production and mixed convection within a trapezoidal nanofluid-filled cavity having a localised solid cylinder is numerically examined using the finite element technique. The top horizontal surface moving at a uniform velocity is kept at a cold temperature, while the bottom horizontal surface is thermally activated. The remaining surfaces are maintained adiabatic. Water-based nanofluids ([Formula: see text] nanoparticles) are used in this study, and the Boussinesq approximation applies. The influence of the Reynolds number, Richardson number, nanoparticles volume fraction, dimensionless radius and location of the solid cylinder on the streamlines, isotherms and isentropic are examined. The results show that the solid cylinder's size and location are significant control parameters for optimising the heat transfer and the Bejan number inside the trapezoidal cavity. Furthermore, the maximum average Nusselt numbers are obtained for high R values, where the average Nusselt number is increased by 30% when R is raised from 0 to 0.25.
Fulltext Dynamic behavior and stabilization of brain cell reconstitution after stroke under the proliferation and differentiation processes for stem cells

Alqarni AJ, Rambely AS, Alharbi SA, Hashim I

Math Biosci Eng, 2021 07 19;18(5):6288-6304.
PMID: 34517534 DOI: 10.3934/mbe.2021314

Stem cells play a critical role in regulatory operations, overseeing tissue regeneration and tissue homeostasis. In this paper, a mathematical model is proposed and analyzed to study the impact of stem cell transplantation on the dynamical behavior of stroke therapy, which is assumed to be based on transplanting dead brain cells following a stroke. We transform the method of using hierarchical cell systems into a method of using different compartment variables by using ordinary differential equations, each of which elucidates a well-defined differentiation stage along with the effect of mature cells in improving the brain function after a stroke. Stem cells, progenitor cells, and the impacts of the stem cells transplanted on brain cells are among the variables considered. The model is studied analytically and solved numerically using the fourth-order Runge-Kutta method. We analyze the structure of equilibria, the ability of neural stem cells to proliferate and differentiate, and the stability properties of equilibria for stem cell transplantation. The model is considered to be stable after transplantation if the stem cells and progenitor cells differentiate into mature nerve cells in the brain. The results of the model analysis and simulation facilitate the identification of various biologically probable parameter sets that can explain the optimal time for stem cell replacement of damaged brain cells. Associating the classified parameter sets with recent experimental and clinical findings contributes to a better understanding of therapeutic mechanisms that promote the reconstitution of brain cells after an ischemic stroke.
Fulltext MHD convective heat transfer in a discretely heated square cavity with conductive inner block using two-phase nanofluid model

Alsabery AI, Sheremet MA, Chamkha AJ, Hashim I

Sci Rep, 2018 May 09;8(1):7410.
PMID: 29743641 DOI: 10.1038/s41598-018-25749-2

The problem of steady, laminar natural convection in a discretely heated and cooled square cavity filled by an alumina/water nanofluid with a centered heat-conducting solid block under the effects of inclined uniform magnetic field, Brownian diffusion and thermophoresis is studied numerically by using the finite difference method. Isothermal heaters and coolers are placed along the vertical walls and the bottom horizontal wall, while the upper horizontal wall is kept adiabatic. Water-based nanofluids with alumina nanoparticles are chosen for investigation. The governing parameters of this study are the Rayleigh number (103 ≤ Ra ≤ 106), the Hartmann number (0 ≤ Ha ≤ 50), thermal conductivity ratio (0.28 ≤ k w ≤ 16), centered solid block size (0.1 ≤ D ≤ 0.7) and the nanoparticles volume fraction (0 ≤ ϕ ≤ 0.04). The developed computational code is validated comprehensively using the grid independency test and numerical and experimental data of other authors. The obtained results reveal that the effects of the thermal conductivity ratio, centered solid block size and the nanoparticles volume fraction are non-linear for the heat transfer rate. Therefore, it is possible to find optimal parameters for the heat transfer enhancement in dependence on the considered system. Moreover, high values of the Rayleigh number and nanoparticles volume fraction characterize homogeneous distributions of nanoparticles inside the cavity. High concentration of nanoparticles can be found near the centered solid block where thermal plumes from the local heaters interact.
Fulltext Energy and Entropy Production of Nanofluid within an Annulus Partly Saturated by a Porous Region

Raizah ZAS, Alsabery AI, Aly AM, Hashim I

Entropy (Basel), 2021 Sep 22;23(10).
PMID: 34681961 DOI: 10.3390/e23101237

The flow and heat transfer fields from a nanofluid within a horizontal annulus partly saturated with a porous region are examined by the Galerkin weighted residual finite element technique scheme. The inner and the outer circular boundaries have hot and cold temperatures, respectively. Impacts of the wide ranges of the Darcy number, porosity, dimensionless length of the porous layer, and nanoparticle volume fractions on the streamlines, isotherms, and isentropic distributions are investigated. The primary outcomes revealed that the stream function value is powered by increasing the Darcy parameter and porosity and reduced by growing the porous region's area. The Bejan number and the average temperature are reduced by the increase in Da, porosity ε, and nanoparticles volume fractions ϕ. The heat transfer through the nanofluid-porous layer was determined to be the best toward high rates of Darcy number, porosity, and volume fraction of nanofluid. Further, the local velocity and local temperature in the interface surface between nanofluid-porous layers obtain high values at the smallest area from the porous region (D=0.4), and in contrast, the local heat transfer takes the lower value.
Fulltext MHD mixed convection and heatlines approach of nanofluids in rectangular wavy enclosures with multiple solid fins

Azizul FM, Alsabery AI, Hashim I, Roslan R, Saleh H

Sci Rep, 2023 Jun 14;13(1):9660.
PMID: 37316564 DOI: 10.1038/s41598-023-36297-9

Two dimensional wavy walls rectangular cavity with inclined magnetohydrodynamic has been examined in mixed convection configurations. Triple fins arranged in the upwards ladder were filled within alumina nanoliquid in the cavity. Vertical sinusoidal walls were heated, and the other side was kept cold while both horizontal walls were kept adiabatic. All walls were motionless except the top cavity that was driven to the right. The diversified range of control parameter in Richardson number, Hartmann number, number of undulations, length of the cavity has been performed in this study. The analysis was simulated using finite element method by employing the governing equation formula, and the results were delineated in the form of streamlines, isotherms, heatlines, and comparisons on several relationships between the local velocity in the y-axis line of 0.6, local and average Nusselt number along the heated surface and dimensionless average temperature. The findings revealed that high concentration nanofluids boost the rate of heat transfer without the need to apply any magnetic field. Results found that the best heat mechanisms are natural convection with significant-high Richardson number as well as constructing two waves on the vertical walls in the cavity.
Fulltext Spectral technique with convergence analysis for solving one and two-dimensional mixed Volterra-Fredholm integral equation

Amin AZ, Amin AK, Abdelkawy MA, Alluhaybi AA, Hashim I

PLoS One, 2023;18(5):e0283746.
PMID: 37235577 DOI: 10.1371/journal.pone.0283746

A numerical approach based on shifted Jacobi-Gauss collocation method for solving mixed Volterra-Fredholm integral equations is introduced. The novel technique with shifted Jacobi-Gauss nodes is applied to reduce the mixed Volterra-Fredholm integral equations to a system of algebraic equations that has an easy solved. The present algorithm is extended to solve the one and two-dimensional mixed Volterra-Fredholm integral equations. Convergence analysis for the present method is discussed and confirmed the exponential convergence of the spectral algorithm. Various numerical examples are approached to demonstrate the powerful and accuracy of the technique.
Factors Influencing Malaysian Men's Perceptions of Gender Equity in Family Planning

Endut N, Bagheri R, Azmawati AA, Hashim I, Selamat NH, Mohajer L

Malays Fam Physician, 2020;15(3):43-53.
PMID: 33329862

INTRODUCTION: Various factors influence men's perceptions regarding gender equity in family planning (FP). Identifying these factors can contribute to a deeper understanding of the roles that men play in family planning and ultimately leads to women's reproductive health outcomes.
OBJECTIVES: This paper aims to investigate factors influencing Malaysian men's perceptions of gender equity in family planning. To achieve this, the effects of sociodemographic characteristics (age, education, and marital status), masculine traits, and attitudes towards domestic violence are investigated.
METHODOLOGY: This is a cross-sectional study undertaken by administrating questionnaires to a sample of 168 men in Malaysia. The data are analyzed by applying partial least squares-structural equation modeling (PLS-SEM) and by using WarpPLS 6.0.
RESULTS: The results confirmed the significant effects of masculine traits and attitudes supporting domestic violence on perceived gender equity in family planning. In other words, the results showed that men's masculine traits and attitudes supporting domestic violence negatively influenced gender equity in family planning. The hypothesized effects of sociodemographic characteristics on perceived gender equity in family planning could not be verified.
CONCLUSIONS: This study suggests some practical implications for local authorities to implement interventions that take a gender transformative approach to reduce men's masculine traits and improve their attitudes towards domestic violence to enhance gender equity in family planning.
Fulltext Numerical Investigation of Mixed Convection and Entropy Generation in a Wavy-Walled Cavity Filled with Nanofluid and Involving a Rotating Cylinder

Alsabery AI, Ismael MA, Chamkha AJ, Hashim I

Entropy (Basel), 2018 Sep 03;20(9).
PMID: 33265753 DOI: 10.3390/e20090664

This numerical study considers the mixed convection and the inherent entropy generated in Al 2 O 3 -water nanofluid filling a cavity containing a rotating conductive cylinder. The vertical walls of the cavity are wavy and are cooled isothermally. The horizontal walls are thermally insulated, except for a heat source segment located at the bottom wall. The dimensionless governing equations subject to the selected boundary conditions are solved numerically using the Galerkin finite-element method. The study is accomplished by inspecting different ranges of the physical and geometrical parameters, namely, the Rayleigh number ( 10 3 ≤ R a ≤ 10 6 ), angular rotational velocity ( 0 ≤ Ω ≤ 750 ), number of undulations ( 0 ≤ N ≤ 4 ), volume fraction of Al 2 O 3 nanoparticles ( 0 ≤ ϕ ≤ 0.04 ), and the length of the heat source ( 0.2 ≤ H ≤ 0.8 ) . The results show that the rotation of the cylinder boosts the rate of heat exchange when the Rayleigh number is less than 5 × 10 5 . The number of undulations affects the average Nusselt number for a still cylinder. The rate of heat exchange increases with the volume fraction of the Al 2 O 3 nanoparticles and the length of the heater segment.
Fulltext Control and switching synchronization of fractional order chaotic systems using active control technique

Radwan AG, Moaddy K, Salama KN, Momani S, Hashim I

J Adv Res, 2014 Jan;5(1):125-32.
PMID: 25685479 DOI: 10.1016/j.jare.2013.01.003

This paper discusses the continuous effect of the fractional order parameter of the Lü system where the system response starts stable, passing by chaotic behavior then reaching periodic response as the fractional-order increases. In addition, this paper presents the concept of synchronization of different fractional order chaotic systems using active control technique. Four different synchronization cases are introduced based on the switching parameters. Also, the static and dynamic synchronizations can be obtained when the switching parameters are functions of time. The nonstandard finite difference method is used for the numerical solution of the fractional order master and slave systems. Many numeric simulations are presented to validate the concept for different fractional order parameters.
Fulltext Fractional Multi-Step Differential Transformed Method for Approximating a Fractional Stochastic SIS Epidemic Model with Imperfect Vaccination

Abuasad S, Yildirim A, Hashim I, Abdul Karim SA, Gómez-Aguilar JF

Int J Environ Res Public Health, 2019 03 18;16(6).
PMID: 30889889 DOI: 10.3390/ijerph16060973

In this paper, we applied a fractional multi-step differential transformed method, which is a generalization of the multi-step differential transformed method, to find approximate solutions to one of the most important epidemiology and mathematical ecology, fractional stochastic SIS epidemic model with imperfect vaccination, subject to appropriate initial conditions. The fractional derivatives are described in the Caputo sense. Numerical results coupled with graphical representations indicate that the proposed method is robust and precise which can give new interpretations for various types of dynamical systems.
Optically stimulated Al2O3:C luminescence dosimeters for teletherapy: Hp(10) performance evaluation

Hashim S, Musa Y, Ghoshal SK, Ahmad NE, Hashim IH, Yusop M, et al.

Appl Radiat Isot, 2018 May;135:7-11.
PMID: 29353759 DOI: 10.1016/j.apradiso.2018.01.010

The performance of optically stimulated luminescence dosimeters (OSLDs, Al2O3:C) was evaluated in terms of the operational quantity of HP(10) in Co-60 external beam teletherapy unit. The reproducibility, signal depletion, and dose linearity of each dosimeter was investigated. For ten repeated readouts, each dosimeter exposed to 50mSv was found to be reproducible below 1.9 ± 3% from the mean value, indicating good reader stability. Meanwhile, an average signal reduction of 0.5% per readout was found. The dose response revealed a good linearity within the dose range of 5-50mSv having nearly perfect regression line with R2 equals 0.9992. The accuracy of the measured doses were evaluated in terms of operational quantity HP(10), wherein the trumpet curve method was used respecting the 1990 International Commission on Radiological Protection (ICRP) standard. The accuracy of the overall measurements from all dosimeters was discerned to be within the trumpet curve and devoid of outlier. It is established that the achieved OSL Al2O3:C dosimeters are greatly reliable for equivalent dose assessment.

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