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Numerical Study of Heat Transfer Enhancement in Heat Exchanger Using AL2O3 Nanofluids
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In this study, the flow and heat transfer characteristics of Al2O3-water nanofluids for a range of the Reynolds number of 3000, 4500, 6000 and 7500 with a range of volume concentration of 1%, 2%, 3% and 4% are studied numerically. The test rig consists of cold liquid loop, hot liquid loop and the test section which is counter flow double pipe heat exchanger with 1m length. The inner tube is made of smooth copper with diameter of 15mm. The outer tube is made of smooth copper with diameter of 50mm. The hot liquid flows through the outer tube and the cold liquid (or nanofluid) flow through the inner tube. The boundary condition of this study is thermally insulated the outer wall with uniform velocity at (0.2, 0.3, 0.4 and 0.5 m/s) at the cold loop and constant velocity at (0.5 m/s) at the hot loop.

The results show that the heat transfer coefficient and Nusselt number increased by increasing Reynolds number and particle concentration. Numerical results indicate that the maximum enhancement in Nusselt number and heat transfer coefficient were 9.5% and 13.5% respectively at Reynolds number of 7100 and particles volume fraction of 4%. Results of nanofluids also showed a good agreement with the available empirical correlation at particles volume fractions of 1%, 2% and 3%, but at volume fractions of 4% a slight deviation is obtained.

 

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Publication Date
Mon Feb 13 2023
Journal Name
Journal Of Educational And Psychological Researches
The Level of Mental Alertness and Its Relationship to Academic Self-Efficacy among Northern Border University Students
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Abstract

This study aims at investigating the relationship between mindfulness and academic self-efficacy among Northern Border University students. To achieve this objective, the researcher adopted the correlative survey method for (97) students. For data collection, the researcher developed a mindfulness scale consisting of (42) items divided into seven topics, each one consisting of six items. The researcher developed an academic self-efficacy scale consisting of (20) items, adopting a five-point Likert scale. The results showed that there is a high level of mindfulness among students at the level of the seven units which formed the mindfulness scale; the conscious thinking unit showed the highest mean value o

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Publication Date
Tue Sep 11 2018
Journal Name
Iraqi Journal Of Physics
An experimental cross-section measurement of 10B(n,α)7Li reaction on counting alpha particles track density
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The present work determines the particle size based only on the number of tracks detected in a cluster created by a hot particle on the CR-39 solid state nuclear track detector and depending on the exposure time. The mathematical model of the cross section developed here gives the relationship between alpha particle emitting from the (n, α) reaction and the number of tracks created and distribution of tracks created on the surface of the track detector. In an experiment performed during this work, disc of boron compound (boric acid or sodium tetraborate) of different weights were prepared and exposed to thermal neutron from the source. Chemical etching is processes of path formation in the detector, during which a suitable etching solut

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Publication Date
Mon Mar 15 2021
Journal Name
Journal Of Baghdad College Of Dentistry
Comparison between the mesiodistal crown dimensions of second primary molar with stainless steel crowns from different companies
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Background: Due to the variations in tooth anatomy and size among different populations, this study aimed to compare the mesiodistal width of primary second molars in Iraqi children with the mesiodistal width of stainless-steel crowns from different companies. Materials and Methods: This cross-sectional study was conducted on 220 intact maxillary and mandibular primary second molars selected from boys and girls’ Iraqi children aged 8-9 years collected from different primary schools in Baghdad city. The mesiodistal dimensions of the selected teeth and the available maxillary and mandibular stainless-steel crowns from three different companies were measured by using a 3-D scanner, and then the whole measurements were calculated usin

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Publication Date
Thu Sep 13 2018
Journal Name
Baghdad Science Journal
Assessment of Radiological Air Contamination for Selected Places at Al-Tuwaitha Nuclear Site during Winter and Spring
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This study presents the results of atmospheric particulates sampling using high volume air sampler for selected places at Al Tuwaitha nuclear site. The collected samples were analyzed for gross alpha /beta radioactivity using Ludlum model 3030 and measurement particles activity in Al Tuwaitha nuclear site and the surrounding areas for the period from 28/12/2016 to 13/4/2017.The measurement of activity concentrations ranged from (0.42±0.03 to 4.18±0.13) Bq/m3 for alpha particles and from(0.93±0.06 to 9.21±0.26) Bq/m3for beta particles. The activity concentration of nuclides inversely proportional with air temperature and wind speed while humidity is directly proportional with it. Highest value of activity concentration has been found at(

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Publication Date
Wed Apr 11 2012
Journal Name
Diyala Journal For Pure Sciences
Synthesis and Characterization of 3-(4-Antipyrene azo)-4-amino benzoic acid Complexes with Selected Metal Ions
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Coupling reaction of 4-amino antipyrene with 4-amino benzoic acid gave bidentate azo ligand. The prepared ligand was identified by Microelemental Analysis, 1HNMR, FT-IR and UV-Vis spectroscopic techniques. Treatment of the prepared ligand with the following metal ions (CoII, NiII, CuII and ZnII) in aqueous ethanol with a 1:2 M:L ratio and at optimum pH, yielded a series of neutral complexes of the general formula [M(L)2]Cl2 . The prepared complexes were characterized using flame atomic absorption, (C.H.N) Analysis, FT-IR and UV-Vis spectroscopic methods as well as magnetic susceptibility and conductivity measurements. Chloride ion content was also evaluated by (Mohr method). The nature of the complexes formed were studied following the mol

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Publication Date
Tue Jun 21 2022
Journal Name
Peerj Computer Science
Performance evaluation of frequency division duplex (FDD) massive multiple input multiple output (MIMO) under different correlation models
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Massive multiple-input multiple-output (massive-MIMO) is considered as the key technology to meet the huge demands of data rates in the future wireless communications networks. However, for massive-MIMO systems to realize their maximum potential gain, sufficiently accurate downlink (DL) channel state information (CSI) with low overhead to meet the short coherence time (CT) is required. Therefore, this article aims to overcome the technical challenge of DL CSI estimation in a frequency-division-duplex (FDD) massive-MIMO with short CT considering five different physical correlation models. To this end, the statistical structure of the massive-MIMO channel, which is captured by the physical correlation is exploited to find sufficiently

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Publication Date
Tue Dec 01 2020
Journal Name
Journal Of Economics And Administrative Sciences
Joint audit and its impact on the market value of firms listed on the Iraq Stock Exchange
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The research aims to investigate the possibility of joint auditing in improving the market value of Iraqi companies listed on the Iraq Stock Exchange. The sample was represented by 10 Iraqi companies listed in the Iraq market for the period from 2014-2017 (2 years before implementation and 2 years after implementation) and the research was based on the idea that joint auditing enhances investor confidence and raises their level of security as a result of providing quality and reliable reports, and thus This indicates good news in the market that reflects on the performance of stocks and the market value of companies that adopt joint auditing. The results of the analysis indicate an improvement in the market value, but this improv

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Publication Date
Wed Feb 22 2023
Journal Name
Iraqi Journal Of Science
New Pd and Pt Complexes of Guanine –Azo Dye: Structural, Spectroscopic, Dyeing Performance and Antibacterial Activity Studies
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Four new complexes of Pd(II), Pt(II) and Pt(IV) with DMSO solution of the ligand 8-[(4-nitrophenyl)azo]guanine (L) have been synthesized. Reaction of the ligand with Pd(II) at different pH gave two new complexes, at pH=8, a complex of the formula [Pd(L)2]Cl2.DMSO (1) was formed, while at pH=4.5,the complex[Pd(L)3]Cl2.DMSO (2) was obtained. Meanwhile, the reaction of the ligand with Pt(II) and Pt(IV) revealed new complexes with the formulas[Pt(L)2]Cl2.DMSO (3)and [Pt(L)3]Cl4.DMSO (4) at pH 7.5 and 6 respectively.
All the preparations were performed after fixing the optimum pH and concentration. The effect of time on the stability of these complexes was checked. The stoichiometry of the complexes was determined by the mole ratio and Job

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Publication Date
Thu Apr 21 2022
Journal Name
Journal Of Ecological Engineering
Simultaneous Adsorption of Ternary Antibiotics (Levofloxacin, Meropenem, and Tetracycline) by SunFlower Husk Coated with Copper Oxide Nanoparticles
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In this study, a new adsorbent derived from sunflower husk powder and coated in CuO nanoparticles (CSFH) was investigated to evaluate the simultaneous adsorption of Levofloxacin (LEV), Meropenem (MER), and Tetracycline (TEC) from an aqueous solution. Significant improvements in the adsorption capacity of the sunflower husk were identified after the powder particles had been coated in CuO nanoparticles. Kinetic data were correlated using a pseudo-second-order model, and was successful for the three antibiotics. Moreover, high compatibility was identified between the LEV, MER, and TEC, isotherm data, and the Langmuir model, which produced a better fit to suit the isotherm curves. In addition, the spontaneous and exothermic nature of the adso

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Publication Date
Fri Nov 01 2019
Journal Name
Journal Of Environmental Quality
Effects of Conservation Practices on Soil Quality Compared with a Corn–Soybean Rotation on a Claypan Soil
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Restoration of degraded lands by adoption of recommended conservation management practices can rehabilitate watersheds and lead to improving soil and water quality. The objective was to evaluate the effects of grass buffers (GBs), biomass crops (BCs), grass waterways (GWWs), agroforestry buffers (ABs), landscape positions, and distance from tree base for AB treatment on soil quality compared with row crop (RC) (corn [Zea mays L.]–soybean [Glycine max (L.) Merr.] rotation) on claypan soils. Soil samples were taken from 10‐cm‐depth increments from the soil surface to 30 cm for GB, BC, GWW, and RC with three replicates. Soil samples were collected from

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