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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
Tue May 16 2023
Journal Name
Journal Of Engineering
Experimental Study For a Laminar Natural Convection Heat Transfer From an Isothermal Heated Square Plate With and Without Circular Hole
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An experimental investigation of natural convection heat transfer from an isothermal horizontal,vertical and inclined heated square flat plates with and without circular hole, were carried out in two cases, perforated plates without an impermeable adiabatic hole "open core" and perforated plates with an impermeable adiabatic hole "closed core" by adiabatic plug. The experiments covered the laminar region with a range of Rayleih number of (1.11x106 ≤RaLo≤4.39x106 ), at Prandtle number (Pr=0.7). Practical experiments have been done with variable inclination angles from horizon (Ф=0o ,45o,90o,135oand 180o),facing upward (0o≤Ф<90o), and downward (90o
≤Ф<180o). The results showed that the temperature gradient increases whi

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Publication Date
Sun Nov 01 2020
Journal Name
The International Journal Of Oral &amp; Maxillofacial Implants
Early Failure Rate and Associated Risk Factors for Dental Implants Placed With and Without Maxillary Sinus Augmentation: A Retrospective Study
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Publication Date
Fri Feb 28 2025
Journal Name
Bmc Psychology
Delving into the Elements Impacting Treatment Acceptance among patients with Substance Use Disorder using Health Belief Model: a qualitative study
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Publication Date
Thu May 29 2025
Journal Name
Bmc Public Health
Coping skills and associated sociodemographic, clinical, and psychological factors among women with breast cancer in Iraq: a cross-sectional study”
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Background: Coping skills play a vital role in managing the physical and psychological effects of breast cancer (BC). Despite improvements in early detection and treatment, Breast cancer survivors continue to face long-term challenges after diagnosis. Therefore, this study aims to evaluate the coping skills employed by breast cancer women in Iraq and to identify the sociodemographic, clinical, and psychological factors associated with these coping skills. Methods: A cross-sectional study was conducted among 244 breast cancer women in The Medical City Teaching Oncology Hospital, Baghdad, Iraq, from August 2023 to October 2023, coping skills and psychological factors were assessed using the BRIEF COPE-28, and Hospital Anxiety Depression scale

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Publication Date
Sun Feb 22 2026
Journal Name
Al-fatih Journal
Development of explosive power training with weights in a way the ups and downs and its impact on the improvement of some variables Albyukinmetekih and technical performance of the skill of a leap forward on your hands vaulting modern
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Publication Date
Sat Mar 30 2019
Journal Name
Iraqi Journal Of Chemical And Petroleum Engineering
Removal of Manganese Ions (Mn2+) from a Simulated Wastewater by Electrocoagulation/ Electroflotation Technologies with Stainless Steel Mesh Electrodes: Process Optimization Based on Taguchi Approach
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This study depicts the removal of Manganese ions (Mn2+) from simulated wastewater by combined electrocoagulation/ electroflotation technologies. The effects of initial Mn concentration, current density (C.D.), electrolysis time, and different mesh numbers of stainless steel screen electrodes were investigated in a batch cell by adopting Taguchi experimental design to explore the optimum conditions for maximum removal efficiency of Mn. The results of multiple regression and signal to noise ratio (S/N) showed that the optimum conditions were Mn initial concentration of 100 ppm, C.D. of 4 mA/cm2, time of 120 min, and mesh no. of 30 (wire/inch). Also, the relative significance of each factor was attained by the analysis

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Publication Date
Tue Oct 01 2019
Journal Name
Karbala Journal Of Physical Education Sciences
Effect of use a designed device to develop some biochemical variables for rear vault dismount with one-half twist on parallel bars in gymnastics
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The research included five sections containing the first section on the introduction o research and its importance and was addressed to the importance of the game of gymnastic and skilled parallel bars effectiveness and the importance of biochemical variables, either the research problem that there is a difference in learning this skill and difficulty in learning may be one of the most important reasons are falling and injury Has a negative impact on the performance and lack of sense of movement of is one of the obstacles in the completion of the skill and the goal of research to design a device that helps in the development of biochemical changes to skill of rear vault dismount with one-half twist on parallel bars in gymnastics . And the n

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Publication Date
Tue Jun 03 2014
Journal Name
Heat Transfer - Asian Research
CFD Simulation of Heat Transfer Augmentation in a Circular Tube fitted with Alternative Axis Twisted Tape in Laminar Flow under the Constant Heat Flux
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Publication Date
Sat Mar 30 2019
Journal Name
Iraqi Journal Of Chemical And Petroleum Engineering
Removal of Manganese Ions (Mn2+) from a Simulated Wastewater by Electrocoagulation/ Electroflotation Technologies with Stainless Steel Mesh Electrodes: Process Optimization Based on Taguchi Approach
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This study depicts the removal of Manganese ions (Mn2+) from simulated wastewater by combined electrocoagulation/ electroflotation technologies. The effects of initial Mn concentration, current density (C.D.), electrolysis time, and different mesh numbers of stainless steel screen electrodes were investigated in a batch cell by adopting Taguchi experimental design to explore the optimum conditions for maximum removal efficiency of Mn. The results of multiple regression and signal to noise ratio (S/N) showed that the optimum conditions were Mn initial concentration of 100 ppm, C.D. of 4 mA/cm2, time of 120 min, and mesh no. of 30 (wire/inch). Also, the relative significance of each factor was attained by the analysis of variance (ANO

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Publication Date
Sun May 22 2022
Journal Name
International Journal Of Early Childhood Special Education
A training program based on integrating futuristic thinking skills with classroom interaction patterns and its effect on the academic self- efficacy of mathematics teachers
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The research aims to identify the effect of the training program that is based on integrating futuristic thinking skills with classroom interaction patterns on mathematics teachers in order to provide their students with creative solution skills. The research sample consisted of 31teachers (15 teachers for the experimental group and 16 for the control groups). The researcher developed a measure for the academic self-efficacy consisting of (39) items. Its validity, reliability, coefficient of difficulty and discriminatory power were estimated. To analyze the findings, the researcher adopted the Mann-Whitney (U) test and the effect size, and the findings were as follows: There is a statistically significant difference at the significance leve

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