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Wideband sound absorption of a double-layer microperforated panel with inhomogeneous perforation
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Micro-perforated panel (MPP) absorber is increasingly gaining popularity as an alternative sound absorber in buildings compared to the well-known synthetic porous materials. A single MPP has a typical feature of a Helmholtz resonator with a high amplitude of absorption but a narrow absorption frequency bandwidth. To improve the bandwidth, a single MPP can be cascaded with another single MPP to form a double-layer MPP. This paper proposes the introduction of inhomogeneous perforation in the double-layer MPP system (DL-iMPP) to enhance the absorption bandwidth of a double-layer MPP. Mathematical models are proposed using the equivalent electrical circuit model and are validated with experiments with good agreement. It is revealed that the DL-iMPP produces a wider half-absorption bandwidth compared to the conventional homogeneous double-layer MPP. The absorption bandwidth to higher frequencies can be effectively controlled by reducing the air cavity between the iMPPs and to the lower frequencies by increasing the back cavity depth at the second layer.

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Publication Date
Thu May 31 2018
On the Use of 6th-Order Tunable Complementary Metal-Oxide-Semiconductor Varactor based Filter in Ultra-Wideband Low Noise Amplifier
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Background:

The plethora of the emerged radio frequency applications makes the frequency spectrum crowded by many applications and hence the ability to detect specific application’s frequency without distortion is a difficult task to achieve.

Objective:

The goal is to achieve a method to mitigate the highest interferer power in the frequency spectrum in order to eliminate the distortion.

Method:

This paper presents the application of the proposed tunable 6th-order notch filter on Ultra-Wideband (UWB) Complementary Metal-Oxide-Semiconductor (CMOS) Low Noise

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Publication Date
Wed Jan 01 2025
Journal Name
Route Educational And Social Science Journal
DREAMS SOUND DIFFERENT IN THE WOODS: JAMES LAPINE AND STEPHEN SONDHEIM’S DRAMATI
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Publication Date
Tue Dec 15 2020
Journal Name
Al-academy
Sound Structure and Attraction Effectiveness in Graphic Design Field: منير جباري علي
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      What concerns the research is employing the modern technology  in a compatible way, because it has multiplied  with the visual  working functions and has grown  in a special way with the development of the digital graphic design field  which represents a crystallization  product according  to  investigation and experimentation mechanism within the field of the scientific research  in the design field and development of the skills of the first designing worker, who always seeks to find working and functional structures in order to produce a design  with a clear meaning by utilizing the technological  abilities including the acoustic tech

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Publication Date
Sat Mar 05 2022
Journal Name
Mathematical Methods In The Applied Sciences
Double‐diffusive convection on peristaltic flow of hyperbolic tangent nanofluid in non‐uniform channel with induced magnetic field
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Consequence of thermal and concentration convection on peristaltic pumping of hyperbolic tangent nanofluid in a non‐uniform channel and induced magnetic field is discussed in this article. The brief mathematical modeling, along with induced magnetic field, of hyperbolic tangent nanofluid is given. The governing equations are reduced to dimensionless form by using appropriate transformations. Exact solutions are calculated for temperature, nanoparticle volume fraction, and concentration. Numerical technique is manipulated to solve the highly non‐linear differential equations. The roll of different variables is graphically analyzed in terms of concentration, temperature, volume fraction of nanoparticles, axial induced magnetic fie

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Publication Date
Sat Dec 11 2021
Journal Name
Engineering, Technology & Applied Science Research
The Influence of Base Layer Thickness in Flexible Pavements
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Flexible pavement design and analysis were carried out in the past with semi-experimental methods, using elastic characteristics of pavement layers. Due to the complex interferences between various layers and their time consumption, the traditional pavement analysis, and design methods were replaced with fast and powerful methods including the Finite Element Method (FEM) and the Discrete Element Method (DEM). FEM requires less computational power and is more appropriate for continuous environments. In this study, flexible pavement consisting of 5 layers (surface, binder, base, subbase, and subgrade) had been analyzed using FEM. The ABAQUS (6.14-2) software had been utilized to investigate the influence of the base layer depth on ver

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Publication Date
Thu May 06 2010
Journal Name
Dirasat, Pure Sciences
A Study of the Effects of the Solar Cycle 22, on the Critical Frequencies of F1 Layer over Baghdad
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This paper aims to study the effects of the long term solar activity on the critical frequencies of ionospheric F1 layer over Baghdad city, during the solar cycle 22, within (1988- 1995). It is found that the critical frequency of this layer is closely related to the sunspots number during the years of the solar cycle 22, at a middle latitude region of the world. The study discussed the effect of sunspot numbers and solar events on the electron densities of F1 layer, which is the most important ionospheric parameter.

Publication Date
Tue Aug 16 2022
Journal Name
Heat Transfer
Experimental study on thermo‐hydraulic performance of metal foam twisted tape in a double pipe heat exchanger
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Abstract<p>A recent study compared experimentally the hydraulic and thermal activity of twisted tape inserts for two types, metal foam twisted tape (MFTT) and traditional twisted tape (TTT), in a double pipe heat exchanger. The investigation goal of the innovatively designed MFTT is to enhance the heat transfer process, which provides a higher thermal enhancement factor over those of TTT under the same conditions. Heat transfer activity in terms of Nusselt number (<italic>Nu</italic>) and Nusselt number ratio (<italic>Nu</italic>/<italic>Nu</italic><sub>o</sub>) as the heat exchanger equipped with the proposed MFTT and TTT inserts with various tape‐twist ratios (<i></i></p> ... Show More
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Publication Date
Sat Feb 27 2021
Journal Name
Journal Of Engineering
Design and Simulation of a controller for Double Fed Induction Generator turbine Utilized Solar Up Draft Tower
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This paper introduces a complete design and simulation of a controller for the double fed induction generator (DFIG) turbine. The work also included the solar updraft tower (SUT) design to supply Al-Mahmoudia hospital in Baghdad/Iraq. The design includes the daily average load estimation, annual solar irradiance and, temperature monitoring, and logging.

According to the data obtained from the Ministry of Science and Technology, Baghdad has low wind speed. Therefore, the (SUT) has been designed to generate electrical power depending on the difference between the external and internal air temperature. The temperature difference will generate a suitable airspeed to drive the wind turbine, connected to the proposed (DFIG) generators

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Publication Date
Wed Dec 03 2025
Journal Name
Journal Of Baghdad College Of Dentistry
Shear bond strength of endodontic sealers to dentin with and without smear layer and gutta percha (An in vitro study)
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Background: The bond strength of root canal sealers to dentin and gutta-percha seems to be an important property for maintaining the stability of root canal filling, which potentially influences both leakage and root strength. The objective of this, in vitro, study was to evaluate the shear bond strength of three different endodontic sealers (Gutta-Flow, AH Plus, Apexit Plus) to dentin, in the presence and absence of the smear layer and gutta percha. Material and Methods: After slicing off the occlusal 2mm of 60 extracted human maxillary premolar teeth, the exposed dentin served as the tested surfaces; the teeth were fixed with cold cure acrylic, and were divided into two groups according to the smear layer presence, group A without smear

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Publication Date
Sun Dec 16 2018
Journal Name
Al-academy
The Eloquence of the Sound in the Production of Mental Image in the Feature Film
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