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The Convective Instability of BEK Family of Non-Newtonian Rotating Boundary-Layer Flows
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The BEK family of flows have many important practical applications such as centrifugal pumps, steam turbines, turbo-machinery and rotor-stator devices. The Bödewadt, Ekman and von Kármán flows are particular cases within this family. The convective instability of the BEK family of rotating boundary-layer flows has been considered for generalised Newtonian fluids, power-law and Carreau fluids. A linear stability analysis is conducted using a Chebyshev collocation method in order to investigate the effect of shear-thinning and shear-thickening fluids for generalised Newtonian fluids on the convective Type I (inviscid crossflow) and Type II (viscous streamline curvature) modes of instability. The results reveal that shear-thinning power-law fluids have a universal stabilising effect across the entire BEK family of flows. However, the convective instability characteristics for the shear-thinning and shear-thickening Carreau fluids are affected by the value of the relaxation parameter k. The results reveal that Shear-thinning Carreau fluids have a small destabilising effect, while shear -thickening fluids have a slight stabilising effect on the Type I and Type II mode for the BEK family of flows when k =100. On the other hand, shear-thinning and shear-thickening Carreau fluids are found to have stabilising and destabilising effect, respectively for optimal relaxation value ko. The results are presented in terms of neutral curves and growth rates. Furthermore, an energy analysis is presented to gain insight into the underlying physical mechanisms behind the stabilising effects of generalized Newtonian fluids. In conclusion, the use of shear-thinning power-law and Carreau fluids with optimal value ko can be recommended to reduce skin-friction drag in enclosed rotor-stator devices for the entire BEK family of flows.

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Publication Date
Fri Mar 31 2017
Journal Name
Journal Of Engineering
Free Vibration Analysis of Laminated Composite plates with General Elastic Boundary Supports
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In this investigation, Rayleigh–Ritz method is used to calculate the natural frequencies of rectangular isotropic and laminated symmetric and anti-symmetric cross and angle ply composite plate with general elastic supports along its edges. Each of the admissible functions here is composed of a trigonometric function and an arbitrary continuous function that is introduced to ensure the sufficient smoothness of the so-called residual displacement function at the edges. Perhaps more importantly, this study has developed a general approach for deriving a complete set of admissible functions that can be applied to various boundary conditions. Several numerical examples are studied to demonstrate the accuracy and convergence of the current s

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Publication Date
Fri Aug 01 2025
Journal Name
Iop Conference Series: Earth And Environmental Science
Influence of Solar and Geomagnetic Activity on the Ionospheric Sporadic-E Layer Over Baghdad
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Abstract<p>This study examines the monthly mean diurnal variations of the ionospheric sporadic E (Es) layer’s critical frequency (<italic>foEs</italic>) and virtual height (<italic>h′Es</italic>) above Baghdad city (latitude 33.3˚N, longitude 44.4˚E) during Solar Cycle 22 (1988–1995). The analysis examines their correlation with solar activity, represented by sunspot numbers, and geomagnetic disturbances, particularly during the descending phase of the cycle. The findings revealed that <italic>foEs</italic> values were the highest during the solar maximum years (1989–1991), aligning with increased sunspot numbers and geomagnetic activity due to coronal mas</p> ... Show More
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Publication Date
Wed Feb 20 2019
Journal Name
Iraqi Journal Of Physics
The influence of CdCl2 layer and annealing process on the structural and electrical properties of CdTe films
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A polycrystalline CdTefilms have been prepared by thermal evaporation technique on glass substrate at room temperature. The films thickness was about700±50 nm. Some of these films were annealed at 573 K for different duration times (60, 120 and 180 minutes), and other CdTe films followed by a layer of CdCl2 which has been deposited on them, and then the prepared CdTe films with CdCl2 layer have been annealed for the same conditions. The structures of CdTe films without and with CdCl2 layer have been investigated by X-ray diffraction. The as prepared and annealed films without and with CdCl2 layer were polycrystalline structure with preferred orientation at (111) plane. The better structural pr

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Publication Date
Sun Nov 01 2020
Journal Name
Applied Surface Science
Sol-gel derived ITO-based bi-layer and tri-layer thin film coatings for organic solar cells applications
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Publication Date
Thu May 06 2010
Journal Name
Dirasat, Pure Sciences
A Study of the Effects of the Solar Cycle 22, on the Critical Frequencies of F1 Layer over Baghdad
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This paper aims to study the effects of the long term solar activity on the critical frequencies of ionospheric F1 layer over Baghdad city, during the solar cycle 22, within (1988- 1995). It is found that the critical frequency of this layer is closely related to the sunspots number during the years of the solar cycle 22, at a middle latitude region of the world. The study discussed the effect of sunspot numbers and solar events on the electron densities of F1 layer, which is the most important ionospheric parameter.

Publication Date
Fri Jan 01 2016
Journal Name
Journal Of The Electrochemical Society
Electrochemical Incineration of Oxalic Acid at Manganese Dioxide Rotating Cylinder Anode: Role of Operative Parameters in the Presence of NaCl
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A detailed experimental study was devoted to the anodic oxidation of oxalic acid using manganese dioxide rotating cylinder anode with the objective to evaluate in a systematic way the effect on the oxalic acid oxidation process of several relevant parameters, including the presence of sodium chloride, the current density (J), the rotation speed, the temperature, and the initial concentration of oxalic acid. Thin manganese dioxide film on graphite substrate has been prepared by electrochemical oxidation from MnSO4-H2SO4 electrolyte. The morphology of this electrode was investigated by XRD, SEM, EDS and AFM techniques. The results show that a firm γ-structure of MnO2 film on graphite rod can be obtained successfully. The results indicate tha

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Publication Date
Fri Mar 23 2018
Journal Name
Entropy
Methods and Challenges in Shot Boundary Detection: A Review
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Publication Date
Sun Jul 02 2017
Journal Name
Journal Of Educational And Psychological Researches
The rights of non-Muslims in the Islamic state
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The Islamic religion is a religion of tolerance and is pleased with worship and other legislation and the idea of peace is an authentic and profound idea related to the call for coexistence with all religions. The Prophet (PBUH) was keen to organize his relations with non-Muslims on the basis of cohabitation, On the basis of love and intolerance, God Almighty says: "If your Lord wants to make people one nation and they are still backward." Surah Hud: 118 Islam has taken care of the people and made them tolerant brothers who sympathize with their different beliefs. Which means that everyone has the right to live, believe and believe what he sees right and have the freedom to perform the acts of worship and beliefs he deems correct. The di

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Publication Date
Sun Sep 04 2011
Journal Name
Baghdad Science Journal
Production of Slime Layer by Staphylococcus epidermidisIsolated From Corneal Infection
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A total of 37 Staphylococcus epidermidis isolates, isolated from corneal scraping of patients with bacterial keratitis and 20 isolates from healthy eyes (as control) (all isolates, isolated from, Ibn Al- Haietham eye hospital / Baghdad), were tested for slime production, 52.63% of all isolates were positive-slime production (23 isolates from patients and 7 isolates from controls). It was found that positive-slime producing S. epidermidis were exhibited a high resistance to antibiotics as compared to negative-slime producing isolates.

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Publication Date
Mon Jul 01 2019
Journal Name
Journal Of Physics: Conference Series
Cu (In, Ga) Se2 an absorber layer of photovoltaic devices
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CIGS nanoink has synthesized from molecular precursors of CuCl, InCl3, GaCl3 and Se metal heat up 240 °C for a half hour in N2-atmosphere to form CIGS nanoink, and then deposited onto substrates of soda-lime glass (SLG). This work focused on CIGS nanocrystals, indicates their synthesis and applications in photovoltaic devices (PVs) as an active light absorber layers. in this work, using spin-coating to deposit CIGS layers (75 mg/ml and 500 nm thickness), without selenization at high temperatures, were obtained up to 1.398 % power conversion efficiency (PCE) at AM 1.5 solar illumination. Structural formations of CIGS chalcopyrite structure were studied by using x ray diffraction XRD. The morphology and composition of CIGS were studied using

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