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Thermal performance of a flat-plate solar collector using aqueous colloidal dispersions of multi-walled carbon nanotubes with different outside diameters
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The thermal performance of a flat-plate solar collector (FPSC) using novel heat transfer fluids of aqueous colloidal dispersions of covalently functionalized multi-walled carbon nanotubes with β-Alanine (Ala-MWCNTs) has been studied. Multi-walled carbon nanotubes (MWCNTs) with outside diameters of (< 8 nm) and (20–30 nm) having specific surface areas (SSAs) of (500 m2/g) and (110 m2/g), respectively, were utilized. For each Ala-MWCNTs, waterbased nanofluids were synthesized using weight concentrations of 0.025%, 0.05%, 0.075%, and 0.1%. A MATLAB code was built and a test rig was designed and developed. Heat flux intensities of 600, 800, and 1000 W/m2; mass flow rates of 0.6, 1.0, and 1.4 kg/min; and inlet fluid temperatures of 30, 40, and 50°C were used to perform the test runs. Using water and nanofluids, the efficiency of the FPSC was found to increase with the increase in heat flux intensity and flow rate, and decrease with the increase in inlet fluid temperature. When applying nanofluids in the FPSC and as weight concentration and SSA increased, a reduction in the values of absorber plate temperature (AP) and tube wall temperature (TW) was observed down to 2.86% and 3.03%, respectively, while the FPSC’s efficiency increased up to 9.55% for 0.1-wt% Ala-MWCNTs < 8 nm at 1.4 kg/min, compared with water. Good agreement was obtained between the experimental values and MATLAB code predictions for AP, TW, and efficiency with maximum differences of 3.02%, 3.19%, and 3.26% for water, and 4.24%, 3.94%, and 12.64% for nanofluids, respectively. Consequently, the MATLAB code was judged suitable for modeling the nanofluid-based FPSC with suitable precision. It was proved that the positive effects of using nanofluids in the FPSC were higher their negative effects on pressure drop because all the calculated values of performance index (PI) were more than 1. As weight concentration and SSA increased, PI increased up to 1.095 for 0.1-wt% Ala-MWCNTs < 8 nm. Therefore, it was concluded that the nanofluids considered in this research can usefully be employed as working fluids in FPSCs for improved thermal performance, and the 0.1-wt% water-based Ala-MWCNTs < 8 nm nanofluid was fairly the distinguished one.

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Publication Date
Tue Dec 19 2023
Journal Name
Journal Of Information Systems Engineering And Management
Corporate Governance Towards Sustainability Performance Quality: A Case of Listed Firms in Malaysia
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The sustainable development according to the United Nation, listed firms throughout globally now routinely provide sustainability data. However, there is not enough information on Sustainability Performance Quality (SPQ) in the majority of emerging economies, including Malaysia. This study looks at how the SPQ of the top 100 Malaysian-listed businesses is affected by factors as connected with corporate governance (e.g., board meeting, board size, and board ethnic diversity). Utilizing 500 firm-year data, a longitudinal sample of 500 nonfinancial firms on the Bursa Malaysia for 2015-2019 is employed in this study. The findings from the analysis using the panel regression demonstrated that: ethnic diversity and board siz

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Publication Date
Thu Dec 31 2020
Journal Name
Iraqi Journal Of Market Research And Consumer Protection
SYNTHESIS OF THE NEW NAPROXEN SELECTIVE ELECTRODE BASED ON IMPRINTED POLYMER USING DIFFERENT MONOMERS AND ITS DETERMINATION AT PHARMACEUTICAL PREPARATION: SYNTHESIS OF THE NEW NAPROXEN SELECTIVE ELECTRODE BASED ON IMPRINTED POLYMER USING DIFFERENT MONOMERS AND ITS DETERMINATION AT PHARMACEUTICAL PREPARATION
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ABSTRACT

Naproxen(NPX) imprinted liquid electrodes of polymers are built using polymerization precipitation. The molecularly imprinted (MIP) and non imprinted (NIP) polymers were synthesized using NPX as a template. In the polymerization precipitation involved, styrene(STY) was used as monomer, N,N-methylenediacrylamide (N,N-MDAM) as a cross-linker and benzoyl peroxide (BPO) as an initiator. The molecularly imprinted membranes and the non-imprinted membranes were prepared using acetophenone(AOPH) and di octylphathalate(DOP)as plasticizers in PVC matrix. The slopes and detection limits of the liquid electrodes ranged from)-18.1,-17.72 (mV/decade and )4.0 x 10-

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Publication Date
Sun Sep 01 2013
Journal Name
Journal Of Economics And Administrative Sciences
Using Six-Sigma to measure the quality performance of the Department of Statistics-University of Baghdad-Case Study
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Abstract

            This research was to provide a definition of quality, dimensions and concepts, whether traditional or modern concept, as well as review the dimensions of quality in higher education and vision and mission with the overall objectives of the Statistics Department.

         After reviewing quality goals and purposes achieved as well as the mechanisms used to achieve them. and use standard Six-Sigma as one of the methodologies used in quality with the historical roots of using this methodology and methods applied and their definitions t

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Publication Date
Tue Jan 08 2019
Journal Name
Iraqi Journal Of Physics
Effect of concentrations ratios of NiO on the efficiency of solar cell for (CdO)1-x(NiO)x thin films
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CdO:NiO/Si solar cell film was fabricated via deposition of CdO:NiO in different concentrations 1%, 3%, and 5% for NiO thin films in R.T and 723K, on n-type silicon substrate with approximately 200 nm thickness using pulse laser deposition. CdO:NiO/n-Si solar cell photovoltaic properties were examined under 60 mW/cm2 intensity illumination. The highest efficiency of the solar cell is 2.4% when the NiO concentration is 0.05 at 723K.

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Publication Date
Fri Dec 01 2017
Journal Name
Al-nahrain Journal For Engineering Sciences (njes)
Investigation of the thermodynamic, kinetic and equilibrium parameters of batch biosorption of Pb (II), Cu (II), and Ni (II) from aqueous phase using low cost biosorbent
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In this study, low cost biosorbent ̶inactive biomass (IB) granules (dp=0.433mm) taken from drying beds of Al-Rustomia Wastewater Treatment Plant, Baghdad-Iraq were used for investigating the optimum conditions of Pb(II), Cu(II), and Ni(II) biosorption from aqueous solutions. Various physico-chemical parameters such as initial metal ion concentration (50 to 200 mg/l), equilibrium time (0-180 min), pH (2-9), agitation speed (50-200 rpm), particles size (0.433 mm), and adsorbent dosage (0.05-1 g/100 ml) were studied. Six mathematical models describing the biosorption equilibrium and isotherm constants were tested to find the maximum uptake capacities: Langmuir, Freundlich, Redlich–Peterson, Sips, Khan, and Toth models. The best fit to the P

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Publication Date
Sat Apr 01 2023
Journal Name
Baghdad Science Journal
A Study of a-Si:H Absorption Edge Using Dunstan’s Model
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The optical absorption data of Hydrogenated Amorphous Silicon was analyzed using a Dunstan model of optical absorption in amorphous semiconductors. This model introduces disorder into the band-band absorption through a linear exponential distribution of local energy gaps, and it accounts for both the Urbach and Tauc regions of the optical absorption edge.Compared to other models of similar bases, such as the O’Leary and Guerra models, it is simpler to understand mathematically and has a physical meaning. The optical absorption data of Jackson et al and Maurer et al were successfully interpreted using Dunstan’s model. Useful physical parameters are extracted especially the band to the band energy gap , which is the energy gap in the a

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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
Tue Aug 03 2021
Journal Name
Key Engineering Materials
Study the Behavior of Castellated Steel Column Encasing by Different Reactive Powder Concrete Thickness with Laced Reinforcement
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Castellated columns are structural members that are created by breaking a rolled column along the center-line by flame after that rejoining the equivalent halves by welding such that for better structural strength against axial loading, the total column depth is increased by around 50 percent. The implementation of these institutional members will also contribute to significant economies of material value. The main objectives of this study are to study the enhancement of the load-carrying capacity of castellated columns with encasement of the columns by Reactive Powder Concrete (RPC) and lacing reinforcement, and serviceability of the confined castellated columns. The Castellated columns with RPC and Lacing Reinforcement improve com

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Publication Date
Tue Aug 03 2021
Journal Name
Key Engineering Materials
Comparative Study of Structural Behavior for Asymmetrical Castellated (Concavely - Curved Soffit) Steel Beams with Different Strengthening Techniques
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The Asymmetrical Castellated concavely – curved soffit Steel Beams with RPC and Lacing Reinforcement improves compactness and local buckling (web and flange local buckling), vertical shear strength at gross section (web crippling and web yielding at the fillet), and net section ( net vertical shear strength proportioned between the top and bottom tees relative to their areas (Yielding)), horizontal shear strength in web post (Yielding), web post-buckling strength, overall beam flexure strength, tee Vierendeel bending moment and lateral-torsional buckling, as a result of steel section encasement. This study presents two concentrated loads test results for seven specimens Asymmetrical Castellated concavely – curved soffit Steel Be

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Publication Date
Fri Nov 26 2021
Journal Name
Nanomaterials
Solidification Enhancement in a Multi-Tube Latent Heat Storage System for Efficient and Economical Production: Effect of Number, Position and Temperature of the Tubes
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Thermal energy storage is an important component in energy units to decrease the gap between energy supply and demand. Free convection and the locations of the tubes carrying the heat-transfer fluid (HTF) have a significant influence on both the energy discharging potential and the buoyancy effect during the solidification mode. In the present study, the impact of the tube position was examined during the discharging process. Liquid-fraction evolution and energy removal rate with thermo-fluid contour profiles were used to examine the performance of the unit. Heat exchanger tubes are proposed with different numbers and positions in the unit for various cases including uniform and non-uniform tubes distribution. The results show that

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