Numerical Modeling of Ferrofluid Convective Behavior Within an Enclosure Under the Influence of a Magnetic Field

Mohammed Algarni 한국자기학회 2024 Journal of Magnetics Vol.29 No.1

With the goal of improving the performance of cooling systems of magnetic sensors, the effects of adding nanoparticles and employing ferrohydrodynamics (FHD) are studied with numerical simulations. To produce ferrohydrodynamics, a wire near the hot surface is used to produce a varying Kelvin force. To better describe the magnetic force, a ferrofluid consisting of iron oxide and water is used. In the velocity and temperature equations, new terms are added to represent ferrohydrodynamics and buoyancy. To apply such complex physics, the control volume finite element method (CVFEM) is applied, and the equations are written in vorticity form to help remove pressure terms. This modeling approach is validated against previously published work and the results show good agreement. An improvement of 11.65 % in the convection rate is achieved by adding nanoparticles. Considering a higher buoyancy force results in a 118.92 % increase in the Nusselt number Nu. As MnF increases up to 2 × 10³, Nu increases by about 81.88 % at the lowest Rayleigh number Ra. The influence of ferrohydrodynamics on Nu declines as the gravity force increases. The hot surface becomes cooler by about 10 % and 37.5 % when MnF and Ra are increased.

An Efficient Technique for Non-Uniformity Correction of Infrared Video Sequences with Histogram Matching

Abbass Mohammed Y.,Sadic Nevein,Ashiba Huda I.,Hassan Emad S.,El-Dolil Sami,Soliman Naglaa F.,Algarni Abeer D.,Alabdulkreem Eatedal A.,Algarni Fatimah,El-Banby Ghada M.,Abdel-Rahman Mohamed R.,Aldosar 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.5

Infrared (IR) image sequences are acquired with certain types of cameras. These cameras give the sequence of images according to the heat distribution. With time, some deterioration of the quality of the sequence occurs due the thermal noise eff ect generated in the camera. This thermal noise eff ect leads to some sort of non-uniformity in the obtained image sequence. Hence, it is necessary to perform some sort of non-uniformity correction in the video sequence according to the fi rst frame. This type of non-uniformity correction is scene-based. This paper introduces a scene-based non-uniformity correction technique that depends mainly on histogram matching. The noise eff ect on each frame in the sequence leads to some drift in the histogram of that frame. Hence, the proposed technique depends on the histogram matching concept to correct the histogram of each frame in the sequence based on the histogram of the fi rst frame that is free from the thermal noise eff ect. Diff erent image quality metrics including entropy, contrast, edge intensity, average gradient, and correlation with the fi rst frame are adopted to assess the quality of the obtained frames after adjustment. It is required in the frames to be corrected to reduce entropy, edge intensity and average gradient as these metrics are increased with the presence of thermal noise eff ect on all pixels represented as much details and unnecessary information. In addition, the contrast of the video sequences should be increased to determine objects in a better way. The correlation of the corrected frames with the fi rst one should be increased to reduce the noise eff ect. Simulation results reveal enhanced quality of the obtained video sequences after processing with the proposed technique.

Fabrication, characterization, TD-DFT, optical and electrical properties of poly (aniline-co-para nitroaniline)/ZrO2 composite for solar cell applications

Alaa Attar,Rima D. Alharthy,Mohammed Zwawi,Mohammed Algarni,Faisal Albatati,Mohamed Bassyouni,Mohamed Helmy Abdel-Aziz,Mohamed Shafick Zoromba,A.F. Al-Hossainy 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.109 No.-

A novel ZrO2-(aniline (AN) and p-nitroaniline (PNAn)) copolymer hybrid nanocomposite [An + PNAn/ZrO2]NC as a powder was synthesized and prepared as a thin film using the Sol-Gel spin coating tool. Optical energy bandgaps calculated by Tauc’s equation are 2.307 eV and 1.711 eV for the[An + PNAn]BD as a blend and [An + PNAn/ZrO2]NC films, respectively. Whereas the bandgaps calculatedby DFT (DMol3) are 2.396 eV and 1.696 eV for the [An + PNAn]BD and [An + PNAn/ZrO2]NC films, respectively. The blend and hybrid nanocomposite films exhibit non-ohmic current-voltage (I–V) behavior. Atlow temperatures, the conduction mechanism in [An + PNAn]BD is Schottky emission, but the Poole–Frenkel effect is prominent in ZrO2-doped films at high temperatures. The simulated values for the opticalproperties produced by CATSTEP in DFT are in good agreement with the experimental results. The photovoltaicbehavior of the solar cell was investigated. The fill factor ranged from 18.59 to 51.82 %, and thepower conversion efficiency ranged from 4.275 to 7.125 % at illumination intensities of 60 and 240 mW/cm2, respectively. The computed negative values of EHOMO and ELUMO energies revealed the product stabilityas isolated molecules matrix. The values of the optical energy gap indicate that the products are insemiconductors range.

Effect of perlite powder on properties of structural lightweight concrete with perlite aggregate

Gongxing Yan,Mohammed Zuhear Al-Mulali,Amirhossein Madadi,Ibrahim Albaijan,H. Elhosiny Ali,H. Algarni,Binh Nguyen Le,Hamid Assilzadeh 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.84 No.3

A high-performance reactive powder concrete (RPC) has been readied alongside river sand, with 1.25 mm particle size when under the condition of 80C steam curing. As a heat and sound insulation, expanded perlite aggregate (EPA) provides economic advantages in building. Concrete containing EPA is examined in terms of cement types (CEM II 32.5R and CEM I 42.5R), doses (0, 2%, 4% and 6%) as well as replacement rates in this research study. The compressive and density of concrete were used in the testing. At the end of the 28-day period, destructive and nondestructive tests were performed on cube specimens of 150 mm150 mm150 mm. The concrete density is not decreased with the addition of more perlite (from 45 to 60 percent), since the enlarged perlite has a very low barrier to crushing. To get a homogenous and fluid concrete mix, longer mixing times for all the mix components are necessary due to the higher amount of perlite. As a result, it is not suggested to use greater volumes of this aggregate in RPC. In the presence of de-icing salt, the lightweight RPC exhibits excellent freeze-thaw resistance (mass is less than 0.2 kg/m2). The addition of perlite strengthens the aggregate-matrix contact, but there is no apparent ITZ. An increased compressive strength was seen in concretes containing expanded perlite powder and steel fibers with good performance.

Study on the strengthening mechanisms of Cu/CNT nano-composites

Long, Xiang,Bai, Yuanli,Algarni, Mohammed,Choi, Youngsik,Chen, Quanfang Elsevier 2015 Materials science & engineering. properties, micro Vol.645 No.-

<P><B>Abstract</B></P> <P>Recent experimental studies by Chen et al. showed that copper (Cu) matrix reinforced by a small amount of carbon nanotubes (CNT, about 4% volume fraction) will increase material strength by about 300% while sacrificing some material ductility. The strengthening mechanisms of Cu/CNT nano-composites were firstly studied numerically using 2D axial symmetric unit cell finite element (FE) models in Ls-Dyna, which consist of both copper matrix and CNTs. The simulation results were verified by existing experimental data. A round of parametric studies was performed to investigate the effects of several modeling parameters in the FE simulations. These parameters include the volume fraction of CNTs, aspect ratio of CNTs, size of hardening zone, and the “equivalent” hardened plastic strain in the hardened zone. Two main strengthening mechanisms are found that affect CNTs reinforcement prediction. The first one is the load-bearing effect resulting from boundary condition imposed in the models. The CNTs significantly affect the plastic flow of copper around CNTs during plastic deformation, which is one important reinforcement mechanism because of high aspect ratio ( H / D ) of CNTs. The second strengthening mechanism is found to be the hardened zone of Cu matrix around CNTs, which is introduced by manufacturing processes and/or the Orowan effect. The Orowan effect plays a key role in reinforcement especially in the nano-scale, which results in a very small inter-particle spacing. The Orowan effect was also studied using analytical methods. Both analytical solution and unit cell FE modeling well correlated with the experimental results for various Cu/CNT composites with different CNT outside diameters.</P>

Small scale computational vibration of double-walled CNTs: Estimation of nonlocal shell model

Asghar, Sehar,Khadimallah, Mohamed Amine,Naeem, Muhammad N.,Ghamkhar, Madiha,Khedher, Khaled Mohamed,Hussain, Muzamal,Bouzgarrou, Souhail Mohamed,Ali, Zainab,Iqbal, Zafar,Mahmoud, S.R.,Algarni, Ali,Ta Techno-Press 2020 Advances in concrete construction Vol.10 No.4

In this paper, vibration characteristics of double-walled carbon nanotubes (CNTs) is studied based upon nonlocal elastic shell theory. The significance of small scale is being perceived by developing nonlocal Love shell model. The wave propagation approach has been utilized to frame the governing equations as eigen value system. The influence of nonlocal parameter subjected to diverse end supports has been overtly analyzed. An appropriate selection of material properties and nonlocal parameter has been considered. The influence of changing mechanical parameter Poisson's ratio has been investigated in detail. The dominance of boundary conditions via nonlocal parameter is shown graphically. The results generated furnish the evidence regarding applicability of nonlocal shell model and also verified by earlier published literature.