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 Oct 07 2012

Journal Name

Journal Of Educational And Psychological Researches

The effect of music therapy in lowering high blood pressure in patients with diseases of sugar

The music therapy

lowering high blood pressure

patients with diseases of sugar

Nuha Hamed Taher

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Faces of the individual in his life many stressful events, which includes expertise undesirable, and events may involve a lot of sources of tension and the risk factors and threats in all areas of life, and this would make the stressful events play a role in the genesis of many diseases physical.

The high blood pressure is one of the most Actual manifestations of mental stress in the present scale physical disorders which may frequently in men relative to women, which may be caused by spasms in the blood vessels.

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Publication Date

Fri Jul 01 2016

Journal Name

Al–bahith Al–a'alami

Manufacturing the Functions and Responsibilities of the Press Photo: The Photo of the Child Elian as a Model

Manufacturing

the Functions

Responsibilities

the Press Photo

the Child Elian

هدى

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The theory of the psychologist’s Piaget states that man passes through four stages; other says that mankind passes through five. At each stage, human learn new characteristics, values, skills, and cultures from different environment that differ from one society to another. Therefore, the cultures of societies vary according to the diversity of the environments. These environments also vary depending on the circumstances surrounding them, e.g., in war environment, the individual learns what he does not learn from living in safe environment. As the environment changes, the communicative message also changes. This message is subject to person, groups, organizations and parties and directed to a diverse audience in its orientations and bel

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Publication Date

Mon Oct 31 2022

Journal Name

International Journal Of Intelligent Engineering And Systems

Robot Path Planning in Unknown Environments with Multi-Objectives Using an Improved COOT Optimization Algorithm

Jafaar Ahmed

Dheyaa Jasim

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(15)

(4)

Publication Date

Sun Mar 01 2020

Journal Name

Computer Networks

An improved multi-objective evolutionary algorithm for detecting communities in complex networks with graphlet measure

Dhuha Abdulhadi

Siti Zaiton Mohd

Roselina

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(8)

(5)

Publication Date

Fri Jul 29 2022

Journal Name

Journal For Vascular Ultrasound

A Comparative Study of the Right and Left Carotid Arteries in Relation to Age for Patients With Diabetes and Hypertension

Introduction: Age

hypertension

and diabetes can cause significant alterations in arterial structure and function

including changes in lumen diameter (LD)

intimal-medial thickness (IMT)

flow velocities

and arterial compliance. These are also considered risk markers of atherosclerosis and cerebrovascular disease. A difference between right and left carotid artery blood flow and IMT has been reported by some researchers

and a difference in the incidence of nonlacunar stroke has been reported between the right and left brain hemispheres. The aim of this study was to determine whether there are differences between the right and left common carotid arteries and internal carotid arteries in patients with hypertension and diabetes for 2 age groups. Methods: We studied 250 patients with both diabetes and hypertension. Patients were divided into 2 age groups with the old age group being 56 to 75 years and the young age group 35 to 55 years. The bilateral common carotid and internal carotid arteries were evaluated with B-mode ultrasound and Doppler examinations. The LD and IMT were measured for both common carotid arteries

and spectral waveform parameters and indices were recorded for both internal carotid arteries. Results: The difference in LD between the left and right common carotid arteries for the old age group was 11.64% and for the young age group was 6.42%

with significant P values of <.05 for both age groups. The difference in IMT between the left and right common carotid arteries was 18.27% in the old age group compared with 15.38% in the young age group

with significant P values of <.05. There was a difference in peak systolic velocity between the left and right internal carotid arteries of 4.85% in the old age group which was not significant

compared with 14.28% in the young age group with a significant P value <.05

whereas the difference in end-diastolic velocity between the left and right internal carotid arteries was not significant for both age groups. Differences between the right and left internal carotid arteries for resistive index

pulsatility index

and pressure gradient were significant only in the young age group. Conclusion: We found significant differences between the right and left common carotid and internal carotid arteries in patients with diabetes and hypertension which were more prominent in the young age group. Values for common carotid IMT and LD were significantly higher in the left common carotid artery versus the right common carotid artery in both age groups. Differences between the 2 carotid sides may be attributed to anatomic variations in the common carotid artery origins which lead to differences in stress between the 2 sides

Ahmed Abduljabar

Samar I.

Anmar Z

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Introduction:

Age, hypertension, and diabetes can cause significant alterations in arterial structure and function, including changes in lumen diameter (LD), intimal-medial thickness (IMT), flow velocities, and arterial compliance. These are also considered risk markers of atherosclerosis and cerebrovascular disease. A difference between right and left carotid artery blood flow and IMT has been reported by some researchers, and a difference in the incidence of nonlacunar stroke has been reported between the right and left brain hemispheres. The aim of this study was to determine whether there are differences between the right and left common carotid arteries and internal carotid arteries in patient

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(7)

(5)

Publication Date

Fri Jun 30 2023

Journal Name

Journal Of The College Of Islamic Sciences

The translated text is a second launch of the text (Al-Kharja Al-Muwashah Al- Andalusian as an example

The text

the translation

the Andalusian kharaj

the muwashshah

the singular

siham saib

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Literary translation is one of the most difficult types of translation ,because it conveys feelings that differ from one person to another, and since the language constitutes an obstacle to understanding the Andalusian excerpts, the translators resorted to translating it, and this was a second start to the text, different from its first start, is said from the tongue of the Al-washah , The muwashshah is a poetic art that appeared in Andalusia after the Arabs entered it ,characterized by special system It differs from the traditional Arabic poem, as it has a beginning represented in the beginning of the muwashshah and several equal parts ending with differentrhymes.

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Publication Date

Thu Jan 08 2026

Journal Name

Heat Transfer

Numerical Analysis of Mixed Convection in Vented Curved Cavity With a Metal Foam Layer

Luma F.

Raed G.

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ABSTRACT<p>Heat transfer applications usually contemplated day‐to‐day are primarily spotlighted on mixed convection, such as solar collector heating arrangements, electronic cooling, and drying processes. Enhancing convection heat transmission in such appliances can be achieved by inserting porous media, inflow loci, and/or line geometry. In the present paper, convection heat transmission inside a vented curved cavity () with an inserted metal foam layer ( PPI and 0.9% porosity) saturated with water was accomplished. The bottom cavity wall was discretely heated at a constant hot temperature, and the curved wall was kept at a constant cold temperature. Governing equations comprising cont</p> ... Show More

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Publication Date

Thu May 14 2026

Journal Name

Al–bahith Al–a'alami

Employment of Body Language in Television Advertising An Analytical Study of Al-Hayat TV Commercials (The Egyptian Series as a Model)

Body Language

Television Ads

Al-Hayat TV

Commercials

the Egyptian Series

Huda

Zina Abdul Hadi

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Whatever the designers of the advertisement in choosing the text and spoken phrases, those phrases cannot give or convey the full meaning to the recipient only if this spoken and written language is reinforced with another language based on the signals, movements, and symbols that are displayed using the body or other artistic elements of the advertisement such as pictures, colors, music, effects, and other elements used in the artistic construction of television advertising. All these artistic elements contribute to the completion of the advertising idea and make it ready to be displayed to the public.

Scientists and researchers, in the field of psychology, have relied a lot on this language (body language). And some of them put

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Publication Date

Wed Dec 01 2010

Journal Name

Journal Of Economics And Administrative Sciences

Openness Management by Figures as a Model of Integrity and Transparency

Sa’ad

Mustafa muneer

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Competitive advantage is a substantial strategic objective for organizations. It requires high levels in the quality of products and services provided to customers, continuous improvement of costing , care for creativity and innovative employees, and speed unique to the marketing and financial engineering, and business re-engineering processes. The situation in this area, requires actors to attract and develop human resources, including help in proper implementation of the strategic tasks that targeted by those institutions. According to the opinions and viewpoints of management scholars, the competitive advantage resource is the most important issue for organizations in the third millennium, which can be a

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Publication Date

Tue Aug 15 2023

Journal Name

Journal Of Economics And Administrative Sciences

Inclusive leadership in the General Secretariat for the Council of Ministers - An analytical research

Inclusive leadership

the General Secretariat for the Council of Ministers

Openness

Availability

Ali

Salma

Zaid

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The current research aims to evaluate the level of inclusive leadership within the General Secretariat for the Council of Ministers, and its role in achieving integration in work through the need to improve relationships between different administrative levels, facilitate participation, expression of opinions, and belonging to the organization. In order to achieve the research objective, the descriptive analytical statistical method was chosen using the SPSS V.25 programs, with various statistical methods and measures, including mean, standard deviation, variance coefficient, relative importance, and simple regression, through a questionnaire tool for data collection. The research community included the leadership in the sample of resear

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