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Absorption Coefficient of a Double-Layer Inhomogeneous Micro-perforated Panel Backed with Multiple Cavity Depths
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Double-layer micro-perforated panels (MPPs) have been studied extensively as sound absorption systems to increase the absorption performance of single-layer MPPs. However, existing proposed models indicate that there is still room for improvement regarding the frequency bands of absorption for the double-layer MPP. This study presents a double-layer MPP formed with two single MPPs with inhomogeneous perforation backed by multiple cavities of varying depths. The theoretical formulation is developed using the electrical equivalent circuit method to calculate the absorption coefficient under a normal incident sound. The simulation results show that the proposed model can produce absorption coefficient with wider absorption bandwidth compared with the conventional double- and even triple-layer MPPs. The bandwidth can be increased to higher frequency by decreasing the cavity depth behind a sub-MPP with small hole diameter and a high perforation ratio, and to lower frequency by increasing the cavity depth behind a sub-MPP with large hole diameter and a small perforation ratio. The experimental data, measured by impedance tube, are in good agreement with the predicted results.

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Publication Date
Wed Mar 30 2022
Journal Name
Journal Of Economics And Administrative Sciences
Using Quadratic Form Ratio Multiple Test to Estimate Linear Regression Model Parameters in Big Data with Application: Child Labor in Iraq
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              The current paper proposes a new estimator for the linear regression model parameters under Big Data circumstances.  From the diversity of Big Data variables comes many challenges that  can be interesting to the  researchers who try their best to find new and novel methods to estimate the parameters of linear regression model. Data has been collected by Central Statistical Organization IRAQ, and the child labor in Iraq has been chosen as data. Child labor is the most vital phenomena that both society and education are suffering from and it affects the future of our next generation. Two methods have been selected to estimate the parameter

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Publication Date
Thu Nov 01 2018
Journal Name
Journal Of Economics And Administrative Sciences
Comparison of Estimates Nonparametric In Multiple Regression Analysis Function (Gamma ,Beta)
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The use of non-parametric models and subsequent estimation methods requires that many of the initial conditions that must be met to represent those models of society under study are appropriate, prompting researchers to look for more flexible models, which are represented by non-parametric models                  

          In this study, the most important and most widespread estimations of the estimation of the nonlinear regression function were investigated using Nadaraya-Watson and Regression Local Ploynomial, which are one of the types of non-linear

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Publication Date
Sun Mar 01 2020
Journal Name
Iop Conference Series: Materials Science And Engineering
The Behavior of Scouring Around Multiple Bridge Piers Having Different Shapes
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Abstract<p>In this research, a numerical simulation was conducted to study the behavior of the scouring pattern and the effect of spacing between bridge piers at specified hydraulic conditions such as velocity, depth of flow, and the sediment effective diameter. Moreover, the cross-section shape of piers and their effect on the scouring depth around bridge piers was studied, using Computational Fluid Dynamics (CFD), ANSYS (Fluent) software. A comparison of the simulation results obtained with previous laboratory investigations was done to verify the validity of the numerical model. Generally, the scour pattern using the CFD software gave good agreement with the experimental study. A reversed pro</p> ... Show More
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Publication Date
Sat Jan 01 2022
Journal Name
Journal Of The Mechanical Behavior Of Materials
Performance of reinforced concrete non-prismatic beams having multiple openings configurations
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Abstract<p>This experimental study demonstrates the gable-reinforced concrete beams’ behavior with several number of openings (six and eight) and posts’ inclination, aimed to find the strength reduction in this type of beam. The major results found are: for the openings extending over similar beam length it is better to increase the number of posts (openings), <italic>i.e.</italic>, increasing opening number led to decrease in opening area, which allows us to transmit stresses and act as lever arms between the upper and the lower chords. Also, findings revealed that the inclined posts have larger loading at the mid-point relative to vertical ones. For gables with vertical posts hav</p> ... Show More
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Publication Date
Mon Feb 06 2023
Journal Name
Journal Of The College Of Basic Education
Identifying the multiple intelligences of Iraqi EFL Instructors at college level
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Teachers should have acceptable ratios of multiple intelligences. Knowing their most dominate intelligence, teachers will be capable of understanding and considering the multiple intelligences of their students. Accordingly, they will be able to use Gardner’s theory as an effective approach of teaching for all kinds of learners and not limited to a specific type of students especially those who have high ratios of verbal-linguistic and logic-mathematical intelligences

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Publication Date
Sat Jan 01 2011
Journal Name
Iraqi Journal Of Physics
Monte Carlo Simulation for Bremsstrahlung Buildup Factor Produced by Absorption of Y-91 Beta Rays
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This paper presents the first data for bremsstrahlung buildup factor (BBUF) produced by the complete absorption of Y-91 beta particles in different materials via the Monte Carlo simulation method. The bremsstrahlung buildup factors were computed for different thicknesses of water, concrete, aluminum, tin and lead. A single relation between the bremsstrahlung buildup factor BBUF with both the atomic number Z and thickness X of the shielding material has been suggested.

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Publication Date
Tue Mar 12 2019
Journal Name
Lubricants
Absorption Wavebands for Discriminating Oxidation Time of Engine Oil as Detected by FT-IR Spectroscopy
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Fourier Transform-Infrared (FT-IR) spectroscopy was used to analyze gasoline engine oil (SAE 5W20) samples that were exposed to seven different oxidation times (0 h, 24 h, 48 h, 72 h, 96 h, 120 h, and 144 h) to determine the best wavenumbers and wavenumber ranges for the discrimination of the oxidation times. The thermal oxidation process generated oil samples with varying total base number (TBN) levels. Each wavenumber (400–3900 cm−1) and wavenumber ranges identified from the literature and this study were statistically analyzed to determine which wavenumbers and wavenumber ranges could discriminate among all oxidation times. Linear regression was used with the best wavenumbers and wavenumber ranges to predict oxidation time.

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Publication Date
Fri Dec 15 2023
Journal Name
Iraqi Journal Of Laser
In vitro Investigation the Antifungal and 940 nm Diode Laser Effects on Inhibition of Candida Albicans Isolated from Oral Cavity
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Background: Candida albicans is a prevalent commensal that can cause severe health problems in humans. One such condition that frequently returns after treatment is oral candidiasis. Aim: the goal of this research is to evaluate the efficiency of 940 nm as a fungicidal on the growth of Candida albicans in vitro. Material and Methods: In vitro samples (fungal swabs) were taken from the oral cavity of 75 patients suffering from oral thrush. Following the process of isolating and identifying Albicans. The samples are divided into four groups:(Group 1): Suspension of C. albicans was put in a solution of saline as a control group. (Group 2): Suspension of C. albicans that had been treated wit

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Publication Date
Fri Dec 15 2023
Journal Name
Iraqi Journal Of Laser
In vitro Investigation the Antifungal and 940 nm Diode Laser Effects on Inhibition of Candida Albicans Isolated from Oral Cavity
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Background: Candida albicans is a prevalent commensal that can cause severe health problems in humans. One such condition that frequently returns after treatment is oral candidiasis. Aim: the goal of this research is to evaluate the efficiency of 940 nm as a fungicidal on the growth of Candida albicans in vitro. Material and Methods: In vitro samples (fungal swabs) were taken from the oral cavity of 75 patients suffering from oral thrush. Following the process of isolating and identifying Albicans. The samples are divided into four groups:(Group 1): Suspension of C. albicans was put in a solution of saline as a control group. (Group 2): Suspension of C. albicans that had been treated with nystatin. (Group 3): Suspension of C. albica

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Publication Date
Fri Mar 20 2020
Journal Name
International Journal Of Dental Hygiene
A randomized double‐blind clinical trial to evaluate the efficacy of chlorhexidine, antioxidant, and hyaluronic acid mouthwashes in the management of biofilm‐induced gingivitis
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Abstract<sec><title>Objectives

To investigate the antiplaque and antigingivitis efficacy in addition to evaluating side effects and subjects’ perceptions of three commercially available mouthwashes.

Methods

This study was a double‐blind, parallel, and short‐term trial. A total of 75 dental students with biofilm‐induced gingivitis were included in the final analysis of the current study. Clinical parameters (plaque index and bleeding on probing) and the staining effect were measured at baseline and after 7 days. In addition, a VAS‐based assessment questionnaire was completed by the participants.

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