Theoretical model of absorption coefficient of an inhomogeneous MPP absorber with multi-cavity depths

Ali Ibrahim Mosa; Azma Putra; Roszaidi Ramlan; Iwan Prasetiyo; Al-Ameri Esraa

doi:10.1016/j.apacoust.2018.11.002

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Publication Date

Fri Mar 01 2019

Journal Name

Applied Acoustics

Volume

146

DOI

10.1016/j.apacoust.2018.11.002

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Theoretical model of absorption coefficient of an inhomogeneous MPP absorber with multi-cavity depths

Micro-perforated panel (MPP) absorber has been known as an alternative absorber to classical porous material given its facile installation

long durability

environmental friendliness and attractive appearance. Extensive studies of MPP absorber proposing the improvement of its absorption frequency bandwidth have been published. This study presents a MPP absorber introduced with inhomogeneous perforations and with multi-cavity depths. The MPP is divided into two sub-area

where each area has different hole diameter

perforation ratio and a separated backed cavity depth. The acoustic impedance is modelled using electrical equivalent circuit and the absorption coefficient is calculated under normal-incidence of sound. It is found that the inhomogeneous MPP can have good bandwidth of absorption by designing the sub-MPP of smaller perforation ratio with large hole diameter and the one having the larger perforation ratio with smaller hole diameter. The absorption bandwidth can be conveniently controlled by adjusting the cavity depth of each sub-MPP. The results from the experimental work show good agreement with the theoretical model.

Ali Ibrahim Mosa

Azma Putra

Roszaidi Ramlan

Iwan Prasetiyo

Al-Ameri Esraa

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Publication Date

Sat Sep 01 2018

Journal Name

Polyhedron

Novel dichloro (bis {2-[1-(4-methylphenyl)-1H-1, 2, 3-triazol-4-yl-κN3] pyridine-κN}) metal (II) coordination compounds of seven transition metals (Mn, Fe, Co, Ni, Cu, Zn and Cd)

The 1

3-dipolar cycloaddition “click” reaction between an azide and an alkyne to give a 1

2

3-triazole was reported by Huisgen in 1961 [1]. In 2002 the Copper(I)-catalyzed Azide-Alkyne Cycloaddition (CuAAC) to prepare a 1

2

3-triazole was reported [2]

[3]. The existence of relatively basic nitrogen atoms in the 1

2

3-triazole rings

and the possibility of introducing additional donor groups in the substituents (Fig. 1)

made the CuAAC “click” reaction an attractive method to prepare differently substituted 1

2

3-triazoles. These compounds have been used as ligands to coordinate to various metal ions that display a range of applications such as in electrochemical and photochemical studies

in supramolecular chemistry

magnetism

metal-ion sensing and catalysis [4]. The reasons for the success of the “click” reaction

is that it is easy to carry out and is widely applicable. It is not affected by a variety of functional groups

and can be carried out with a variety of Cu(I) catalysts and solvents

including aqueous conditions. The Cu(I) catalysts overcome the high activation energy barrier of the non-catalyzed Huisgen reaction by changing the mechanism of the reaction. A large variety of copper catalysts can be used for the CuAAC reaction

on condition that the maximum concentration of Cu(I) species is generated during the reaction. The pre-catalyst can be a Cu(II) salt (usually CuSO4) together with a reducing agent (often sodium ascorbate) or a Cu(I) compound in the presence of a base or amine ligand and a reducing agent to prevent oxidation to Cu(II). Some strong oxidising cupric salts or complexes such as Cu(OAc)2 also work. The solvent is very flexible from organic to aqueous

with the most commonly used combination water + an alcohol (t-BuOH

MeOH or EtOH). The key role of the solvent or solvent mixture is to solubilize the substrates and Cu(I) catalyst in order to ensure rapid reactions. Such aqueous conditions are very useful for biochemical conjugations

as well as for organic syntheses. We recently reported on the synthesis of a series of differently substituted 1

2

3-triazole chromophores

the substituted 2-(1-phenyl-1H-1

2

3-triazol-4-yl)pyridine ligands [5]

see Fig. 2 middle

with substituents R = H (L1)

CH3 (L2)

OCH3 (L3)

COOH

F

Cl

CN

CF3

O(CH2)3CH3 and N(CH3)2. These versatile ligands were found to coordinate to various first row transition metals

such as manganese

cobalt and nickel [6]. Here we extend the series to include more first row transition metal(II) coordination compounds

iron

copper and zinc

as well as a second row transition metal(II) coordination compound

cadmium

containing the 2-(1-(4-methyl-phenyl)-1H-1

2

3-triazol-1-yl)pyridine chromophore (Fig. 2 right with R = CH3). This series of seven novel coordination compounds is the first series of pyridyl-triazole based transition metal coordination compounds where seven different transition metals are coordinated to the same 1

2

3-triazole chromophore

namely 2-(1-(4-methyl-phenyl)-1H-1

2

3-triazol-1-yl)pyridine.

Kinaan M

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Publication Date

Thu Jan 04 2024

Journal Name

Journal Of Accounting And Financial Studies ( Jafs )

Creative accounting practices for supply contracts and the role of internal audit in reducing them: An exploratory study on a sample of industrial companies in Iraq

Creative accounting

Contract

Internal ouditor

The general company of industrial

Huda Shakir Mahmood

Dr. Muhammad Hazem Ismail AL- Ghazali

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Abstract:

The internal control is the tool through which it is possible to verify and ensure the implementation of tasks in accordance with the established plans and programs and to evaluate the level of performance that is implemented within the different companies.

A guarantee from the supplier with the absence of a specialized technical committee that follows up the stages of implementing the contract and disbursing all amounts of financial dues to the supplier before completing the implementation of the contract and overlooking the non-implementation of some clauses of the contract by the committee in charge of

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Publication Date

Wed Sep 30 2020

Journal Name

Journal Of Accounting And Financial Studies ( Jafs )

The Impact of Earnings Quality using the Sustainability model (Persistence) and predictability in the Continuity of the Banks: بحث تطبيقي في عينة من المصارف التجارية المدرجة في سوق العراق للاوراق المالية

Earnings Quality

Persistence

Predictability

continuity of the Banks

financial failure

ثائر كامل

ا.م.د. وفاء عبدالامير

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The research aims to measure the extent of the impact of Earnings quality in the continuity of the company for a sample of private commercial banks listed on the Iraq Stock Exchange. The research sample included (15) of the listed commercial banks that continue to issue their financial statements for the period from (2009-2018).The research relied on three main models of measurement and on four steps. The first step is to measure the Persistence (Earnings Quality) by Depending the sustainability model. While the second step included measuring the Predictability of accounting profits by deriving the square root of the disparity of the estimation error from the first model Persistence (Earnings Quality), and the third step included

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Publication Date

Thu Mar 01 2012

Journal Name

Journal Of Economics And Administrative Sciences

Analysis of the relationship between the degree of economic freedom and foreign trade of selected developing countries for the period (1990-2005) *

ايمان عبد

سردار عثمان

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Is a high degree of economic freedom an important part in the development of the economies of developing countries in the last decade of the twentieth century and the beginning of the twentieth century and the atheist. This is because a test subject (deltoid analysis of the relationship between the degree of economic freedom and foreign trade of selected developing countries for the period
( 1990 -2005) to determine the degree of economic freedom in foreign trade promotion in Singapore and Turkey. The research recommends a number of recommendations, the most important is the responsibility of the Ministry of Planning in Iraq that is providing the necessary data for the Fraser Institute, the aim of increasing cooperation

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Publication Date

Fri Jan 01 2021

Journal Name

Journal Of Accounting And Financial Studies ( Jafs )

Measuring the relationship between the skills required for the labor market and the employment of graduates of community colleges in KSA: An applied study on a sample of faculty members at KKU

Skills required for the labor market

Skills of graduates

Employment of graduates

أحمد أحمد

محمد عبد الكريم

عبد الرحيم بن سعيد محمد آل سلطان

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This study has aimed to measure the relationship between the skills required for the labor market and the employment of graduates of community colleges at King Khalid University. For gathering the required data, a questionnaire has been designed and distributed to the faculty members of community colleges at King Khalid University in a random sample method. The chosen sample size has covered (123) individuals. Questionnaire forms have been distributed and retrieved from (117) participants. Therefore, the estimated response has reached 95 % of the total sample size. The results of the study have shown that there is not any significant relationship between the skills which the graduates acquire and the requirements of employmen

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Publication Date

Mon Jan 01 2024

Journal Name

Journal Of The College Of Languages (jcl)

Individualism and the Symbolic Language of Imagination (Pablo Neruda as an Example)

Romanticism

Imagination

Individualism

Pablo Neruda

The dialectical relationships

Athraa

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Pablo Neruda's artistic distinctiveness can be considered in two ideas or attitudes of romanticism. First, the imagination, which is the result of conduct and spirituality, and second, the individualism, which is a collection of mysterious mysteries from the texts of individuality based on philosophical sonnets. His collection of poems points out the ethereality and indescribability of life, employing the reality of life at the level of human perception in a symbolic language. In other words, Pablo Neruda recreates the meanings in poetry through the three ideas of reduction, interpretation, and analysis. "What is the essential connection between individualism and the symbolic language of Pablo Neruda's imagination and What are the reason

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Publication Date

Sun Sep 30 2018

Journal Name

الجامعة المستنصرية كلية الإدارة و الاقتصاد

The possibility of adoption of hybrid cloud computing in Iraqi universities : an analytical study using technology acceptance model

Cloud Computing

Hybrid Cloud Computing

HCC's Features and Services

Technology Acceptance Model

Structural Equation Modeling

Iraqi Universities

salah aldeen

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الناصر، عامر عبد الرزاق عبد المحسن والكبيسي، صلاح الدين عواد كريم. 2018. إمكانية تبني الحوسبة السحابية الهجينة في الجامعات العراقية : دراسة تحليلية باستخدام أنموذج القبول التكنولوجي. مجلة الإدا

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Publication Date

Thu Oct 01 2015

Journal Name

Journal Of Educational And Psychological Researches

The Attitudes of School Teachers and Principals at Regular Government Basic Schools toward Inclusion of Disabled Students in Ajloun Governorate

The Attitudes of School Teachers and Principals

Mohammad Ahmad,Sh Alomari

Buthainah Elias Uwais

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This study aimed to identify the attitudes of school teachers and principals at basic government schools in Ajloun governorate towards the inclusion of disabled students at basic schools, and investigate how they will accept the merger. To achieve the purpose of this study, a questionnaire containing 35 items was administered to school teachers and principals to measure their attitudes toward the inclusion of disabled students in regular schools. The sample of this study consisted of 43 male teachers and (74) female teachers and principals. The frequency, normal distribution, arithmetic means and t-test were used to analyze the data of present study. The findings showed that there

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Publication Date

Sat Jan 01 2022

Journal Name

Materials Today: Proceedings

Experimental and theoretical investigations of seepage reduction through zoned earth dam material with special core

Zaid N.

Basim Sh.

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(15)

(10)

Publication Date

Sun Jul 03 2016

Journal Name

Journal Of Educational And Psychological Researches

The Impact of the Constructive Scientific Stations Strategy on Achievement and Mind Habits for The Fourth Scientific students in biology

The Impact of the Constructive Scientific

tariq Kamel Dawood

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The study aimed at ideutifying the impact of scieutific skills in strategy and liabits of mind amony stueuts in tenth grade . The study demanded to choose a sampie that coutaiun (42) student of the fourth grade of the secondary school who were dirided into tow groups , the first is experimental studied according to scieutific skill strategy , and the other controlling , studied according to the usualway . An achievement test has been taken that adopted staudard for mind skills as research tools that are applid after ascertaining sincerity proved at the end of the experiment .The study has reached to the conclusion that there are statistically significant differnces in farour of the experiment group in both

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