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Experimental Investigation of Turbulent Cross-flow in a Staggered Tube Bundle with Wavy Cylinders
Morad Belharizi,Tayeb Yahiaoui,Azzeddine Khorsi,Omar Ladjedel,Lahouari Adjlout,OndřejŠikula 한국유체기계학회 2022 International journal of fluid machinery and syste Vol.15 No.3
This paper presents the results of an investigation on the effects of wavy cylindrical tubes on the turbulent cross-flow in a staggered tube bundle arrangement with transverse and longitudinal pitch-to-diameter ratios of 3.8 and 2.1, respectively. Two models of staggered tube bundles equipped with wavy cylinders are tested; the Model-A having a wavelength ratio ( /Dm= 2) corresponding to a wave steepness (a/ = 0.1) and the Model-B having ( /Dm= 1) corresponding to (a/ = 0.2).Experimental measurements were performed using a subsonic wind tunnel to study and compare the flow characteristics of the new configuration of cylindrical tubes with that of a similar arrangement with smooth cylinders for Reynolds numbers ranging from 0.5 104 to 2 104 based on the mean tube diameter and the free stream velocity. Experimental results show that the circumferential minimum pressure coefficients for wavy tube bundles are greater than at the bundle with smooth cylinders. As a result, the lift forces of wavy tube bundles are suppressed and a significant drag reduction is observed up to 20% for both wavy models. This continuous reduction of the drag force becomes larger with the increase of Reynolds number.
Quadratic magnetoelectric effect of barium titanatecobalt ferrite (0-3) ceramic composite
Morad Etier,Hesham Almomani 한양대학교 세라믹연구소 2020 Journal of Ceramic Processing Research Vol.21 No.5
In this research, the quadratic magnetoelectric effect for different compositions of barium titanate cobalt ferrite ceramiccomposites has been reported. Structural analysis was firstly demonstrated using different techniques e.g. x-ray diffraction andscanning electron microscopy, then both the first and the second order magnetoelectric effects were measured and analyzed. It was shown that the magnetic, ferroelectric and magnetoelectric properties of the ceramic composites depend mainly on theweight percentage of the constituents. Sample of 50% weight of barium titanate gave the highest longitudinal and traversemagnetostriction. The maximum induced magnetization as a function of electric field was observed for the sample contains50% weight of barium titanate with a second order magnetoelectric coupling coefficient value γ333 = 20 × 10-18 s/V. This valueis considered to be the first estimated quadratic magnetoelectric effect value for a composite material.
Hamad, Morad Kh. Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.8
We used the GEANT4 Monte Carlo MC Toolkit to simulate carbon ion beams incident on water, tissue, and bone, taking into account nuclear fragmentation reactions. Upon increasing the energy of the primary beam, the position of the Bragg-Peak transfers to a location deeper inside the phantom. For different materials, the peak is located at a shallower depth along the beam direction and becomes sharper with increasing electron density NZ. Subsequently, the generated depth dose of the Bragg curve is then benchmarked with experimental data from GSI in Germany. The results exhibit a reasonable correlation with GSI experimental data with an accuracy of between 0.02 and 0.08 cm, thus establishing the basis to adopt MC in heavy-ion treatment planning. The Kolmogorov-Smirnov K-S test further ascertained from a statistical point of view that the simulation data matched the experimentally measured data very well. The two-dimensional isodose contours at the entrance were compared to those around the peak position and in the tail region beyond the peak, showing that bone produces more dose, in comparison to both water and tissue, due to secondary doses. In the water, the results show that the maximum energy deposited per fragment is mainly attributed to secondary carbon ions, followed by secondary boron and beryllium. Furthermore, the number of protons produced is the highest, thus making the maximum contribution to the total dose deposition in the tail region. Finally, the associated spectra of neutrons and photons were analyzed. The mean neutron energy value was found to be 16.29 MeV, and 1.03 MeV for the secondary gamma. However, the neutron dose was found to be negligible as compared to the total dose due to their longer range.
ON THE CLASS OF TRANSMUTED-G DISTRIBUTIONS
AHMAD, MORAD,AL-AQTASH, RAID,AKINSETE, ALFRED The Korean Society for Computational and Applied M 2022 Journal of applied mathematics & informatics Vol.40 No.5-6
In this article, we compare the reliability and the hazard function between a baseline distribution and the corresponding transmuted-G distribution. Some examples based on existing transmuted-G distributions in literature are used. Three tests of parameter significance are utilized to test the importance of a transmuted-G distribution over the baseline distribution, and real data is used in an application of the inference about the importance of transmuted-G distributions.
S. Z. Moussavi,Sh. Javadi,M. Alasvandi,E. Morad 보안공학연구지원센터 2014 International Journal of Control and Automation Vol.7 No.12
Intelligent control that can be used learning ability and human experiences, is widely used in industrial application such as motors speed control. This paper presents Proportional-Integral-Derivative Controller (PID controller) based on Adaptive Neuro-Fuzzy Inference System (ANFIS) for Permanent Magnet Direct Current (PMDC) motor. ANFIS provides combination of artificial neural network and fuzzy inference systems therefore ANFIS uses advantages of them simultaneously. The proposed PID controller Coefficients are determined by ANFIS. The proposed controller based system is compared with Internal Model Control (IMC) PID controller based system. The Comparison shows that proposed controller improves characteristics in different conditions such as no load, increasing reference speed, applied load and noisy load. Proposed controller based system can improve system performance by smaller fuzzy rule set.
Peripheral Defocus and Myopia Management: A Mini-Review
Nir Erdinest(Nir Erdinest ),Naomi London(Naomi London ),Itay Lavy(Itay Lavy ),David Berkow(David Berkow ),David Landau(David Landau ),Yair Morad(Yair Morad ),Nadav Levinger(Nadav Levinger ) 대한안과학회 2023 Korean Journal of Ophthalmology Vol.37 No.1
Myopia is the most common refractive error in the world, and its’ prevalence continually increases. The potential pathological and visual complications of progressive myopia have inspired researchers to study the sources of myopia, axial elongation, and explore modalities to arrest progression. Considerable attention has been given over the past few years to the myopia risk factor known as hyperopic peripheral blur, the focus of this review. The primary theories currently believed to be the cause of myopia, the parameters considered to contribute and influence the effect of peripheral blur, such as the surface retinal area or depth of blur will be discussed. The currently available optical devices designed to provide peripheral myopic defocus will be discussed, including bifocal and progressive addition ophthalmic lenses, peripheral defocus single vision ophthalmic lenses, orthokeratology lenses, and bifocal or multifocal center distance soft lenses, as well as their effectivity as mentioned in the literature to date.
서방제재가 러시아 금융시장에 미친 영향: SVAR 분석
민지영,Morad Bali 한국외국어대학교(글로벌캠퍼스) 동유럽발칸연구소 2023 동유럽발칸연구 Vol.47 No.4
After the outbreak of the Ukraine crisis in 2014, Russia began to face economic sanctions from the West. Over time, Western sanctions have gradually expanded to various sectors such as individuals, institutions, industry, and trade. Western sanctions are expected to enlarge and prolong due to the outbreak of the Russo-U.S. war in 2022. Experts assessed those Western sanctions act as a risk factor for the Russian financial market, including increasing instability in the Russian financial market. In fact, Russian financial indicators fluctuated when new sanctions were introduced. Against this background, this study focused on the impact of Western sanctions on the Russian financial market. This study is significantly different from existing studies in that it isolates the direct impact of Western sanctions through the SVAR model using an index developed to quantitatively measure Western sanctions between 2014 and 2019. As a result of the analysis, the impact of Western sanctions was found to be very minimal. This is because the sanctions index was limited to EU sanctions, and the speed of expansion of sanctions during that period was relatively slow. The Russian financial market was found to have been more affected by factors indicating economic downturn such as an increase in the exchange rate and a decline in oil prices during that period.