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

Sun Apr 01 2018

Journal Name

Journal Of Educational And Psychological Researches

The effectiveness of Barman model in acquiring the historical concepts among fourth-grade literary students

As the model of Barman

the acquisition of historical concepts

fourth-grade literary students

Shakir Jassim Mohammed

Sarah Sami Abbas A- Wardi

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The researcher attempts to examine Barman model in acquiring the historical concepts among fourth-grade students at literary classrooms. To this end, the researcher held the null hypothesis, there is no significant difference between the experimental groups who was taught based on Barman model and the control group that taught based on the traditional method in acquiring the historical concepts on the post-test. To testify the effectiveness of Barman model, the researcher administered a questionnaire included (60) items on bunch of female-students who were selected from al-khamaeal preparatory school in al-hurriyah district in Baghdad. The author utilized different statistical tools to analyze the collected data. &

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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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(31)

(21)

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

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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

Tue Sep 01 2009

Journal Name

Journal Of Economics And Administrative Sciences

Comparison of estimation methods for regression model parametersIn the case of the problem of linear multiplicity and abnormal values

نزار مصطفى

غفران اسماعيل

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A simulation study is used to examine the robustness of some estimators on a multiple linear regression model with problems of multicollinearity and non-normal errors, the Ordinary least Squares (LS) ,Ridge Regression, Ridge Least Absolute Value (RLAV), Weighted Ridge (WRID), MM and a robust ridge regression estimator MM estimator, which denoted as RMM this is the modification of the Ridge regression by incorporating robust MM estimator . finialy, we show that RMM is the best among the other estimators

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Publication Date

Fri Jul 01 2016

Journal Name

Journal Of Engineering

An Adaptive Multi-Objective Particle Swarm Optimization Algorithm for Multi-Robot Path Planning

multi-robot system

path planning

multi-objective approaches

adaptive multi-objective particle swarm optimization

danger zones.

Nizar Hadi

Jaafer Ahmed

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This paper discusses an optimal path planning algorithm based on an Adaptive Multi-Objective Particle Swarm Optimization Algorithm (AMOPSO) for two case studies. First case, single robot wants to reach a goal in the static environment that contain two obstacles and two danger source. The second one, is improving the ability for five robots to reach the shortest way. The proposed algorithm solves the optimization problems for the first case by finding the minimum distance from initial to goal position and also ensuring that the generated path has a maximum distance from the danger zones. And for the second case, finding the shortest path for every robot and without any collision between them with the shortest time. In ord

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Publication Date

Sun Jun 12 2011

Journal Name

Baghdad Science Journal

Study The effect of central ion to the dithene complexes on spectral shifting of saturable absorber band

dithine complexes

passive Q-switch NIR lasers

saturable absorber

Ashwaq .A

Afrah.A

Morooj.A

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In this work dithine complexes prepared from dithiol benzil ligand and central ion to the Ni,Pd,Pt, element the ligand and complexes have been investigated using FTIR spectrophotometer and uv-vis-NIR spectral reigns show higher intensity represents the ?-?* transition in the chromopher cycle .These absorption which appear in visible and near IR spectral regions ,According to the complexes of one group ,the spectral shifting due to the change of central ion has been found to be related to atomic number of central ion .This shifting is increased while decreasing the central ion atom number These complexes have been implemented in Nd+2:YAG cavity because each posses resonant absorption band near Nd+2:YAG, Nd+2:Glass emitting at (106

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Publication Date

Wed Sep 10 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

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

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

...Show More Authors

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

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

...Show More Authors

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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