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The Effect of Particle Size Distribution on some Properties of Gypsum
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Gypsum is one of the important construction materials in Iraq in plastering surfaces and gypsum board , the ability of gypsum to give a comfortable an aesthetic ambiance as a construction material increase the need of gypsum , The particle size , total surface area and particle size distribution were factors affecting plaster properties used for construction properties . In this study gypsum paste was used with different mixing ratios of particle size and studied the physical properties of these types of pastes named (standard consistency ,setting time ,density) and compressive strength . The results showed that the water to gypsum ratio increased with increasing the fineness of the gypsum to (0.75%) and the setting time to the maximum allowed according to the Iraqi standard (25 minute) when the distribution of particle size between (600-75) microns . Thus ,superplasticizer was used in more fine paste types .There is a direct relationship between setting time and the water to gypsum ratio ,but the setting time decreasing with increasing the fineness of the gypsum when the distribution of particle size between (300-75) microns. There is also a direct relationship between density and gypsum fineness . In terms of compressive resistance , it increases slightly when the particle size distribution is between (900-75) μm and increases significantly (40-42)% relatively to the reference paste with particle size distribution (300-75) μm and superplasticizer additive .Compression strength is also affected by the water to gypsum ratio ,there is an inverse relationship between them.

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Publication Date
Tue Mar 30 2021
Journal Name
Journal Of Economics And Administrative Sciences
Using Iterative Reweighting Algorithm and Genetic Algorithm to Calculate The Estimation of The Parameters Of The Maximum Likelihood of The Skew Normal Distribution
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Excessive skewness which occurs sometimes in the data is represented as an obstacle against normal distribution. So, recent studies have witnessed activity in studying the skew-normal distribution (SND) that matches the skewness data which is regarded as a special case of the normal distribution with additional skewness parameter (α), which gives more flexibility to the normal distribution. When estimating the parameters of (SND), we face the problem of the non-linear equation and by using the method of Maximum Likelihood estimation (ML) their solutions will be inaccurate and unreliable. To solve this problem, two methods can be used that are: the genetic algorithm (GA) and the iterative reweighting algorithm (IR) based on the M

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Publication Date
Tue May 16 2023
Journal Name
Journal Of Engineering
The Effect of Spatial Organization on the Sustainability of the Neighborhood Unit in the Residential Environment
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Contemporary residential neighborhoods suffer from weak sustainability of urban residential environments as a result of the adoption of inefficient spatial organization at the neighborhood unit level. This resulted negative characteristics which affected the achievement of sustainable development plans for the residential environment that constitute the majority of the urban fabric of cities.

The physical affordances ,within the vocabulary of recent times,overcame the spiritual ones and affected the residential environment. Accordingly,the concept of space changed in contemporary residential areas through the dominance of the physical aspect (mass) on the symbolic aspect (space).The modern technology occupied an important level b

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Publication Date
Sun Mar 21 2021
Journal Name
Periodicals Of Engineering And Natural Sciences (pen)
Estimation of the reliability system in model of stress- strength according to distribution of inverse Rayleigh
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Publication Date
Thu Dec 01 2022
Journal Name
Case Studies In Construction Materials
Experimental study of temperature effect on the mechanical tensile fatigue of hydrated lime modified asphalt concrete and case application for the analysis of climatic effect on constructed pavement
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Previous experimental studies have suggested that hot mixed asphalt (HMA) concrete using hydrated lime (HL) to partially replace the conventional limestone dust filler at 2.5% by the total weight of all aggregates showed an optimum improvement on several key mechanical properties, fatigue life span and moisture susceptibility. However, so far, the knowledge of the thermal response of the modified asphalt concrete and thermal influence on the durability of the pavement constructed are still relatively limited but important to inform pavement design. This paper, at first, reports an experimental study of the tensile fatigue life of HMA concrete mixes designed for wearing layer application. Tests were conducted under three different temperatur

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Publication Date
Sun Jun 12 2011
Journal Name
Baghdad Science Journal
Annealing Effect on the phase Transformation in
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This work describes the effect of temperature on the phase transformation of titanium dioxide (TiO2) prepared using metal organic precursors as starting materials. X-ray diffraction (XRD) was used to investigate the structural properties of TiO2 gels calcined at different temperatures (300, 500, 700) ?C. the results showed that the samples have typical peaks of TiO2 polycrystalline brookite nanopowders after calcined at (300 ?C), which confirmed by (111), (121), (200), (012), (131), (220), (040), (231), (132) and (232) diffraction peaks. Also, XRD diffraction spectra showed the presence of crystallites of anatase with low proportion of rutile phase where calcined at (500 ?C), while rutile phase domains at (700 ?C). The crystallite size of

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Publication Date
Tue Mar 12 2024
Journal Name
Semiconductor Physics, Quantum Electronics And Optoelectronics
Numerical study of single-layer and interlayer grating polarizers based on metasurface structures for quantum key distribution systems
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Polarization is an important property of light, which refers to the direction of electric field oscillations. Polarization modulation plays an essential role for polarization encoding quantum key distribution (QKD). Polarization is used to encode photons in the QKD systems. In this work, visible-range polarizers with optimal dimensions based on resonance grating waveguides have been numerically designed and investigated using the COMSOL Multiphysics Software. Two structures have been designed, namely a singlelayer metasurface grating (SLMG) polarizer and an interlayer metasurface grating (ILMG) polarizer. Both structures have demonstrated high extinction ratios, ~1.8·103 and 8.68·104 , and the bandwidths equal to 45 and 55 nm for th

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Publication Date
Sun Jun 05 2016
Journal Name
Baghdad Science Journal
Effect of Lactobacillus salivarius supernatant against growth and biofilm formation of some pathogenic microorganisms
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The Inhbititory effect of cocentrated and non-cocentrated supernatant of the probiotic Lactobacillus salivarius against growth of some potential pathogenic microorganisms which included Pseudomonas eruginosa, Klebsiella spp, Escherichia coli and Candida albicans. The results were diffusion assay revealed that concentrated and non-concentrated supernatant had inhitory effect against pathogenic bacteria with inhibition zone renged between 13-17mm while inhibition effect of concentrated supernatant against C.albicans was inhibition zone 8mm. On the other hand, the effect of these suprnatant against biofilm formation of the tested microorganisms was studied. The result showed that the concentrated supernatant had inhibitory effect on biofil

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Publication Date
Sun Jan 13 2019
Journal Name
Iraqi Journal Of Physics
The effect of short range correlation on the inelastic C2 and C4 form factors of 18O nucleus
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The effect of short range correlations on the inelastic Coulomb form factors for excited +2 states (1.982, 3.919, 5.250 and 8.210MeV) and +4 states (3.553, 7.114, 8.960 and 10.310 MeV) in O18 is analyzed. This effect (which depends on the correlation parameterβ) is inserted into the ground state charge density distribution through the Jastrow type correlation function. The single particle harmonic oscillator wave function is used with an oscillator size parameter .b The parameters β and b are adjusted for each excited state separately so as to reproduce the experimental root mean square charge radius of .18O The nucleusO18 is considered as an inert core of C12 with two protons and four neutrons distributed over 212521211sdp−− activ

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Publication Date
Thu Jan 01 2015
Journal Name
Egyptian Journal Of Aquatic Research
Ecological factors affecting the distribution of the zooplankton community in the Tigris River at Baghdad region, Iraq
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Publication Date
Sun Sep 30 2001
Journal Name
Iraqi Journal Of Chemical And Petroleum Engineering
The Effect of MFI of High-Density Polyethylene on the Mathematical Modeling of Tensile Characteristic
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