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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
Tue Feb 11 2025
Journal Name
Al–bahith Al–a'alami
Organizational reputation: A descriptive study of concept development and measurement techniques
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The study aimed to monitor the concept of reputation in the previous literature, its relationship to mental image and identity, and to reveal recent trends in its measurement Techniques.

    The study relied on a descriptive approach using library survey and comparative analysis, and the study reached following conclusions:

     Despite the beginning of the first signs of reputation In the fifties of the last century, however, Defining and standardizing the concept with clear and specific dimensions began in the 1990s and the beginning of the third millennium. The concept of reputation refers to the stakeholders’ overall evaluation of organizations, which reflects their perceptions of

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Publication Date
Sat Dec 15 2018
Journal Name
Journal Of Baghdad College Of Dentistry
Development of Sinusitis After Sinus Floor Elevation Surgery: A Systematic Review
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Background: Maxillary sinusitis can arise after sinus floor elevation surgery and should be treated immediately to prevent further complications which included dental implants failure, graft lost, and oro-antral fistula. This is the first systematic review to assess the incidence, causes, and treatment of sinusitis after sinus lift surgery. Materials and methods: An electronic search included MEDLINE (PUBMED) data base site was carried out for articles involving development of sinusitis after sinus lift surgery from September 1997 up to April, 8, 2017. The search was done and reviewed by two independent authors. Results: The total results of electronic search were (182) abstracts and articles, the extracted articles which involved develo

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Publication Date
Fri Mar 31 2017
Journal Name
Journal Of Engineering
Aerodynamic Characteristics of a Rectangular Wing Using Non-LinearVortex Ring Method
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The aerodynamic characteristics of general three-dimensional rectangular wings are considered using non-linear interaction between two-dimensional viscous-inviscid panel method and vortex ring method. The potential flow of a two-dimensional airfoil by the pioneering Hess & Smith method was used with viscous laminar, transition and turbulent boundary layer to solve flow about complex configuration of airfoils including stalling effect. Viterna method was used to extend the aerodynamic characteristics of the specified airfoil to high angles of attacks. A modified vortex ring method was used to find the circulation values along span wise direction of the wing and then interacted with sectional circulation obtained by Kutta-Joukowsky the

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Publication Date
Fri Jul 21 2023
Journal Name
Journal Of Engineering
Design and Implementation of a Multiplier free FPGA based OFDM Transmitter
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Orthogonal Frequency Division Multiplexing (OFDM) is an efficient multi-carrier technique.The core operation in the OFDM systems is the FFT/IFFT unit that requires a large amount of hardware resources and processing delay. The developments in implementation techniques likes Field Programmable Gate Array (FPGA) technologies have made OFDM a feasible option. The goal of this paper is to design and implement an OFDM transmitter based on Altera FPGA using Quartus software. The proposed transmitter is carried out to simplify the Fourier transform calculation by using decoder instead of multipliers. After programming ALTERA DE2 FPGA kit with implemented project, several practical tests have been done starting from monitoring all the results of

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Publication Date
Sat Jan 01 2022
Journal Name
Materials Today: Proceedings
Studying the impact of condensate blockage on gas production: A review
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When the drawdown pressure amounts to a value below the dew point pressure, a minor droplet of condensate is shaped and accumulated in the close area of wellbore. As the accumulation happens, the saturation of the liquid will grow and a reduction in gas relative permeability will happen, therefore it will affect the productivity. Generally, condensate baking problem in gas wells is being deliberated and studied and numerous techniques have been suggested to solve the problem. The studying of condensate banking dynamics is essential to evaluate the productivity and behavior of the wells of the gas fields.

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Publication Date
Thu Jul 01 2021
Journal Name
Periodicals Of Engineering And Natural Sciences (pen)
A proposed encryption technique of different texts using circular link lists
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Publication Date
Tue Dec 05 2023
Journal Name
Baghdad Science Journal
Further Results on (a, d) -total Edge Irregularity Strength of Graphs
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Consider a simple graph   on vertices and edges together with a total  labeling . Then ρ is called total edge irregular labeling if there exists a one-to-one correspondence, say  defined by  for all  where  Also, the value  is said to be the edge weight of . The total edge irregularity strength of the graph G is indicated by  and is the least  for which G admits   edge irregular h-labeling.  In this article,   for some common graph families are examined. In addition, an open problem is solved affirmatively.

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Publication Date
Fri Jan 01 2021
Journal Name
Tigris And Euphrates Rivers: Their Environment From Headwaters To Mouth
Ornamental Fishes: A Looming Danger for Inland Fish Diversity of Iraq
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Publication Date
Wed May 10 2023
Journal Name
Journal Of Engineering
ANALYTICAL SOLUTION OF UNSATURATED SOIL WATER FLOW FROM A POINT SOURCE
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Water flow into unsaturated porous media is governed by the Richards’ partial differential equation expressing the mass conservation and Darcy’s laws. The Richards’ equation may be written in three forms,where the dependent variable is pressure head or moisture content, and the constitutive relationships between water content and pressure head allow for conversion of one form into the other. In the present paper, the “moisture-based" form of Richards’ equation is linearized by applying Kirchhoff’s transformation, which
combines the soil water diffusivity and soil water content. Then the similarity method is used to obtain the analytical solution of wetting front position. This exact solution is obtained by means of Lie’s

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Publication Date
Tue Sep 01 2015
Journal Name
Journal Of Engineering
Performance Enhancement of a Piezoelectric Harvester Included into an Autonomous System
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Autonomous systems are these systems which power themselves from the available ambient energies in addition to their duties. In the next few years, autonomous systems will pervade society and they will find their ways into different applications related to health, security, comfort and entertainment. Piezoelectric harvesters are possible energy converters which can be used to convert the available ambient vibration energy into electrical energy. In this contribution, an energy harvesting cantilever array with magnetic tuning including three piezoelectric bimorphs is investigated theoretically and experimentally. Other than harvester designs proposed before, this array is easy to manufacture and insensitive to manufacturi

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