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

Wed Sep 29 2021

Journal Name

College Of Islamic Sciences

Almzna given in the consolation of the Prophet)) for women- an objective stu

Muzna the benevolent

the consolation of the Prophet

his aunt Safiya

the crop of patience in their chests

صلاح ناجي

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My research deals with the positions that the Prophet (PBUH) distressed. And condolences to those who lost her father and other problems and calamities that impede the life of women, has been given to the Lord of men, and good qualities, to strike the nation's finest proverbs in ensuring lost and lost of women and children, to be shown to us humanity in its finest form, and the best analyzed, and I hope God help And guidance and Rashad

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Publication Date

Sun Dec 07 2014

Journal Name

Baghdad Science Journal

Synthesis, Characterization and Stability Study of V(IV), Zr(IV), Rh(III), Pd(II), Cd(II) and Hg(II) Complexes with Pyrazol Derivative

In this work lactone (1) was prepared from the reaction of p-nitro phenyl hydrazine with ethylacetoacetate

which upon treatment with benzoyl chloride afforded the lactame (2). The reaction of (2) with 2-amino phenol produced a new Schiff base (L) in good yield. Complexes of V(IV)

Zr(IV)

Rh(III)

Pd(II)

Cd(II) and Hg(II) with the new Schiff base (L) have been prepared. The compounds (1

2) were characterized by FT-IR and UV spectroscopy

as well as characterizing ligand (L) by the same techniques with elemental analysis (C.H.N) and (1H-NMR). The prepared complexes were identified and their structural geometries were suggested by using elemental analysis (C.H.N)

flame atomic absorption technique

FT-IR and UV-Vis spectroscopy

in addition to magnetic susceptibility and conductivity measurements. Metal to ligand [M:L] ratio was obtained for all complexes in ethanol using molar ratio method

which gave comparable results with those obtained for the solid complexes. As well as the appa

Sinan M.

Enaam M.

Maysoon A

Sarab M

...Show More Authors

In this work lactone (1) was prepared from the reaction of p-nitro phenyl hydrazine with ethylacetoacetate, which upon treatment with benzoyl chloride afforded the lactame (2). The reaction of (2) with 2-amino phenol produced a new Schiff base (L) in good yield. Complexes of V(IV), Zr(IV), Rh(III), Pd(II), Cd(II) and Hg(II) with the new Schiff base (L) have been prepared. The compounds (1, 2) were characterized by FT-IR and UV spectroscopy, as well as characterizing ligand (L) by the same techniques with elemental analysis (C.H.N) and (1H-NMR). The prepared complexes were identified and their structural geometries were suggested by using elemental analysis (C.H.N), flame atomic absorption technique, FT-IR and UV-Vis spectroscopy, in additio

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Publication Date

Wed Oct 07 2020

Journal Name

Journal Of Interdisciplinary Mathematics

Discrete an SIS model with immigrants and treatment

Epidemic model

Difference equations

Stability.

Shalan R.N.

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In this paper, a discrete SIS epidemic model with immigrant and treatment effects is proposed. Stability analysis of the endemic equilibria and disease-free is presented. Numerical simulations are conformed the theoretical results, and it is illustrated how the immigrants, as well as treatment effects, change current model behavior

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Publication Date

Thu Jul 24 2025

Journal Name

Journal Of Studies And Researches Of Sport Education

The effect of using the educational bag on the level of learning some offensive skills with the epee weapon

The effect of using the educational bag on the level of learning some offensive skills with the epee weaponDr. Lamia Hassan Al-Diwan

D. Fatima Abdel-Maliki

Dr. Kholoud Laith Abdel Karim2005 Technical and technological development has been increasing day after day and has included all areas of life

including the educational process

which has benefited from technologies such as (computer

video

and pictorial models) in introducing them as tools to aid the learning process. Educational packages have proven their effectiveness in education as they prepare learners with different areas of experience. Sensory audio-visual

through which the learner acquires different educational experiences through interaction

practice

participation

and communication with the data of the surrounding environment through the diversity of knowledge sources that suit his inclinations and needs. The research aimed to prepare an educational bag to teach some offensive skills in the epee weapon. And to find out the effect of using the proposed educational bag on the level of learning some offensive skills in the epee weapon. We hypothesized that the proposed educational package has a positive impact on the level of learning some offensive skills with the epee weapon. There were statistically significant differences in testing the level of learning some offensive skills with the epee weapon between the post-tests of the experimental and control groups

and in favor of the experimental group. The researchers used the experimental method to suit the nature of solving the research problem

and the research sample was chosen intentionally from the girls’ fencing club players (beginners) in the governorate. Basra for the year 2005. The number of players was (16)

which represented the entire study population. The experiment was conducted in the sports hall of the South Oil Sports Club in Basra. We concluded that the educational package has a positive impact on the level of learning some offensive skills in the epee weapon. There were statistically significant differences in the learning level test for some offensive skills in the epee weapon between the experimental group and the control group in the post-tests and in favor of the experimental group. We recommended the necessity of using the proposed educational curriculum to learn some offensive skills in the epee weapon in fencing lessons or in sports clubs. Adopting modern techniques in training

teaching or teaching fencing skills and searching for new methods. Conducting similar studies on other skills or different samples.Keywords: educational bag

offensive skills with an epee weapon

fencing game. Teaching methods. Basra Girl Sports ClubLamya Hassan Aldewan [email protected] of Basra - College of Education and Sports Scienceshttps://orcid.org/0000-0003-0377-6915 Keywords educational bag

offensive skills with an epee weapon

fencing game. Teaching methods. Basra Girl Sports Club

‏Lamyaa

Fatima

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Publication Date

Wed Apr 01 2015

Journal Name

Mathematical Methods In The Applied Sciences

An inverse problem of finding the time-dependent diffusion coefficient from an integral condition

Mohammed S.

Daniel

Mansur I.

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Publication Date

Thu Dec 31 2020

Journal Name

Journal Of Accounting And Financial Studies ( Jafs )

Electronic payment methods used for salary resettlement and its impact on improving the mental image of customers: an applied study of the opinions of a sample of (private) commercial banks 'customers contracting with the Ministry of Higher Education and Scientific Research to localize employees' salaries

electronic banking (concept

media

and forms)

localization of salaries (the concept and its reasons for transferring money)

the mental image of customers

م.م. فاضل عباس

م.م. سندس علي

م.م. محمد حسن

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The research seeks to identify the contemporary events that face the use of electronic payment methods to localize the salaries of state employees and its impact in enhancing the mental image of customers, and to achieve this purpose from the fact that a questionnaire was designed and distributed to an optional sample of (31) individual customers (employees) dealing With the researched private banks, it has been analyzed and reached a number of conclusions and recommendations, the most prominent of which is the lack of modernity of electronic payment methods by customers, which is reflected in the mental image of customers and the achievement of their satisfaction, in the Emiratization project for salaries needs an advanced leade

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Publication Date

Fri Oct 01 2021

Journal Name

Journal Of Engineering

Experimental Study of Natural Convection in a Closed Cavity (Static Type Domestic Fridge)

Domestic refrigerator

close cavity

Refrigeration

Natural convection

cavity

Maryem Kanaan

Munther Abdullah

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This work provides an analysis of the thermal flow and behavior of the (load-free) refrigerator compartment. The main goal was to compare the thermal behavior inside the refrigerator cavity to the freezer door (home refrigerator) effect and install a fan on the freezer door while neglecting the heat transmitted by thermal radiation. Moreover, the velocity distribution, temperature, and velocity path lines are theoretically studied. This was observed without affecting the shelves inside the cabinet and the egg and butter places on the refrigerator door as they were removed and the aluminum door replaced with a glass door. This study aims to expand our knowledge about the temperature and flow fields of this refrigerator mo

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Publication Date

Thu Mar 01 2018

Journal Name

Nauchforum

THE PROBLEM OF TRANSLATING METAPHOR IN AN ARTISTIC TEXT (ON THE MATERIAL OF RUSSIAN AND ARABIC LANGUAGES)

The notion of metaphor

the types of metaphor in Russian

the types of metaphor in Arabic

Yusra Akram

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THE PROBLEM OF TRANSLATING METAPHOR IN AN ARTISTIC TEXT (ON THE MATERIAL OF RUSSIAN AND ARABIC LANGUAGES)

Publication Date

Thu Jul 24 2025

Journal Name

Journal Mustansiriyah Of Sports Science

The effect of using Daniel's model for people with two types of brain control (left and right) to learn the skill of the Cartwheel in artistic gymnastics for second-stage students

Daniel's model

two patterns of brain control

the Cartwheel.

Ayad

Murtada,

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The research problem focused through the researcher's experience in the gymnastics game and the lack of use of educational models that give the student an important role in the educational process, so it became necessary to identify the type of prevailing style for students, and the need for diversity in the use of educational models based on scientific theories, including the Daniel Document model. Based on three theories of learning, which are structural, behavioral, and meaningful learning. The research aimed to identify the effect of using the Daniel model for people with two types of brain control (left and right) to learn the skill of the Cartwheel in artistic gymnastics for students of the second stage. The researcher used the experi

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Publication Date

Sun Apr 04 2010

Journal Name

Journal Of Educational And Psychological Researches

Effective an instructional in program in the development of some of the moral values on the children of kindergarten

instructional in program

the development of some of the moral values on

the children of kindergarten

سميرة موسى البدري

تغريد مكي باقر آل عيسى

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The research aims to
1 – The discloser of the level of moral values in the children of kindergarten.
2 - Building an educational program designed to develop moral values on the children of kindergarten.

3 - Knowing the impact of the program in the development of moral values in children
Purposive sample was selected consisted of 40 children and a child aged 5-6 years and to achieve objectives of the research promising measure of the moral values kindergarten has been applied to the children of the two groups was based on pre and post test

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