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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
Thu Jun 01 2023
Journal Name
Baghdad Science Journal
Design and construction of anair pollution detection system using a laser beam and absorption spectroscopy
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Air pollution is one of the important problems facing Iraq. Air pollution is the result of uncontrolled emissions from factories, car exhaust electric generators, and oil refineries and often reaches unacceptable limits by international standards. These pollutants can greatly affect human health and regular population activities. For this reason, there is an urgent need for effective devices to monitor the molecular concentration of air pollutants in cities and urban areas. In this research, an optical system has been built consisting of aHelium-Neonlaser,5mWand at 632.8 nm, a glass cell with a defined size, and a power meter(Gentec-E-model: uno) where a scattering of the laser beam occurs due to air pollution. Two pollutants were examin

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Publication Date
Sat Feb 12 2022
Journal Name
Engineering, Technology & Applied Science Research
The Effect of Different Curing Temperatures on the Properties of Geopolymer Reinforced with Micro Steel Fibers
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In this study, geopolymer mortar was designed in various experimental combinations employing 1% micro steel fibers and was subjected to different temperatures, according to the prior works of other researchers. The geopolymer mortar was developed using a variety of sustainable material proportions (fly ash and slag) to examine the influence of fibers on its strength. The fly ash weight percentage was 50%, 60%, and 70% by slag weight to study its effect on the geopolymer mortar's properties. The optimal ratio produced the most significant results when mixed at a 50:50 ratio of fly ash and slag with 1% micro steel fibers at curing temperature 240oC for 4 hours through two days. The compressive strength of the geopolymer mortar increas

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Publication Date
Fri Sep 01 2023
Journal Name
Iranian Journal Of Veterinary Science And Technology
Investigation of bacterial contamination with Klebsilla and E. coli in the prepucal cavity of pubertal and adult age in caprine
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Publication Date
Mon Apr 01 2024
Journal Name
Heliyon
Ground effect of an inverted double element wing diffuser on a sedan car
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Publication Date
Thu Jun 30 2016
Journal Name
Al-kindy College Medical Journal
Evaluation Of Risk Factors In Perforated Acute Appendicitis In Al-Kindy Teaching Hospital
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Background: Appendectomy is still one of the most commonly performed emergency surgical procedures worldwide.Avoiding delays in the diagnosis in these patients may play a role in reducing observed morbidity.Aim of study:To analyze the clinico-pathological profile and outcomes of patients undergoing emergency appendectomies to determine risk factors influencingcomplicaions.Type of the study: A prospective analytic studyPatients and Methods: The study involves 108 patients underwent emergency appendectomies at Al-kindy teaching hospital from April 2014 to March 2015. Appendicitis was categorized into two groups perforated andnonperforatedappendicities. A comparison between them was made in regard to Gender, Age, clinical presentation, inve

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Publication Date
Fri Aug 07 2020
Journal Name
Key Engineering Materials
Compressive Strength and Shrinkage Behavior of Concrete Produced from Portland Limestone Cement with Water Absorption Polymer Balls
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From the sustainability point of view a combination of using water absorption polymer balls in concrete mix produce from Portland limestone cement (IL) is worth to be perceived. Compressive strength and drying shrinkage behavior for the mixes of concrete prepared by Ordinary Portland Cement (O.P.C) and Portland limestone cement (IL) were investigated in this research. Water absorbent polymer balls (WAPB) are innovative module in producing building materials due to the internal curing which eliminates autogenous shrinkage, enhances the strength at early age, improve the durability, give higher compressive strength at early age, and reduce the effect of insufficient external curing. Polymer balls (WAPB) had been used in the mixes of thi

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Publication Date
Wed Nov 13 2024
Journal Name
Aip Conference Proceedings
Fibrewise micro-ideal topological spaces
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Abstract. In this study, we shall research the fibrewise micro ideal topological spaces over Ḃ, as well as the relationship between fibrewise micro ideal topological spaces over Ḃ and fibrewise micro topological spaces over Ḃ. At first present introduces a novel notion from fibrewise micro ideal topological spaces over Ḃ, and differentiates it from fibrewise micro topological spaces over Ḃ. Some fundamental characteristics from these spaces are studied. Then show discussed the fibrewise micro ideal closed and micro ideal open topologies. Many propositions relating to these ideas are offered. In the next part will study defines and investigates novel conceptions from fibrewise micro ideal topological spaces over Ḃ, particularly f

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Publication Date
Mon Sep 10 2018
Journal Name
Iraqi Journal Of Physics
Thermal conductivity and diffusion coefficient of polymer blend 80%EP/20%UPE reinforced with sand particles
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New polymer blend with enhanced properties was prepared from (80 %) epoxy resin (Ep), (20%) unsaturated polyester resin (UPE) as a matrix material. The as-obtained polymer blend was further reinforced by adding Sand particles of particle size (53 μm) with various weight fraction (5, 10, 15, 20 %). Thermal conductivity and sorption measurements are performed in order to determine diffusion coefficient in different chemical solutions (NaOH, HCl) with concentration (0.3N) after immersion for specific period of time (30 days). The obtained results demonstrate that the addition of sand powder to (80%EP/20%UPE) blend leads to an increase of thermal conductivity, with an optimum/minimum diffusion coefficient in (HCl)/(NaOH), respectively.

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Publication Date
Wed Mar 10 2021
Journal Name
Baghdad Science Journal
Simole matimatical technique in leaser cavity design and manufacturing
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In this research design was treated gap laser mathematically and practically Bashaddam model Raasi simple and new and we have found that there is a good match in the practical and theoretical results

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Publication Date
Fri Jun 25 2021
Journal Name
International Journal Of Drug Delivery Technology
Oral Cavity Microbiome as Infectious Agents: Iraqi Kocuria Rosea
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