Recently, environmental noise has arisen from various sources, such as those from exhaust mufflers of combustion engines found in cars, trucks, or power generators, which produce significant noise during their operation. Controlling the radiated noise from these mufflers is a major factor in improving acoustic comfort and minimizing the impact on the surrounding communities. Numerous research has been presented for this reason by modification of the internal structure of the exhaust muffler. The main objective of this work is to reduce the noise level emitted from exhaust mufflers. This can be achieved by adjusting structure parameters to attenuate the surrounding environment's radiated noise. Analysis of pressure-wave propagation has been done by building 3D models using COMSOL Multiphysics software. Different entities were conducted to investigate the influence of muffler shells and plate thicknesses on acoustic performance through the frequency domain to obtain better attenuation. SPL over a frequency band is presented, describing how the sound intensity varies at different frequencies within a given bandwidth. The results showed that increasing the muffler shell thickness improved the TL; this particularly causes a double value at a range above 1.2 kHz, where there are two distinct peaks at 1.3 kHz and 2.8 kHz. Additionally, it was found that increasing the muffler plate thickness reduces the TL whole range and moves the curve peak to higher frequencies. This is because the pressure pulses that stimulate the shell plates would exert a more distinct influence on plates characterized by a reduced thickness, and the muffler structure thickness is correlated with its increased stiffness, resulting in an elevation of the frequency for this eigenmode
Background: Any child with Down's syndrome does not develop in the same manner as normal child. Therefore, the child should not be viewed as being like everyone else. Developmental enamel defects in primary teeth have been found at least twice as frequently in disabled children as in control children. Down's syndrome consumed protein more than the recommended daily allowance compared to other disabled groups. Therefore, the aim of this study was to investigate developmental defects of enamel and their relations to nutrient intake among Down's syndrome children in comparison to normal children. Materials and Methods: A sample consisted of fifty institutionalized Down's syndrome children (study group) and 50 normal children (control group)
... Show MoreThe study aimed to identify the level of health awareness and health education among mothers zones, urban and rural areas as well as to identify the differences between them and to achieve this study was conducted on a sample of (121) or been Akhittarhn randomly, aged (20 - 43 years) and applied them to a questionnaire to measure the health awareness, which formed from a group of paragraphs, and after the collection of data was treated using the statistical software (SAS), where research showed many of the results are:
1/ Reached the age group ranging between (20-30 years), the highest rate for the present, where was (40.51%), while in the countryside matched by age group (31-40 years old) in terms of (54.76%)./ It turns out that the
Objective: To assess the functional outcome, time to union, shoulder pain, blood loss, operative time, iatrogenic radial nerve injury, hospitalization, and infection. Methodology: It is a prospective randomized study on 30 patients with mid-shaft humerus fracture according to AO classification (1.2A1, 2, 3 and 1,2B) with functioning radial nerve. They were randomly dividing into two groups. Group A were treated by a closed antegrade interlocking nail, and group B treated by open reduction and locked compression plate fixation. The follow-up was up to 6 months, including time to union, shoulder pain, intraoperative blood loss, operative time and iatrogenic radial nerve injury. Functional outcome was assessed by quick DASH score. Resu
... Show MoreIn this work, some of new 2-benzylidenehydrazinecarbothioamide derivatives have been prepared by condensation of thiosemicarbazide and different substituted aromatic benzaldehydes in presence of glacial acetic acid to give compounds (1-6), these compounds have characterized by its physical properties and spectroscopic methods. This work also included theoretical study to prove the ability of these compounds as corrosion inhibitors; The program package of Gaussian 09W with its graphical user interface GaussView 5.0 had used for this purpose; the methods of Density Functional Theory (DFT) with basis set of 6-311G (d,p) / hybrid function of B3LYP and semiempirical method of PM3 have been used, the study included theoretical simulation
... Show Moren this research, some thermophysical properties of ethylene glycol with water (H2O) and two solvent mixtures dimethylformamide/ water (DMF + H2O) were studied. The densities (ρ) and viscosities (η) of ethylene glycol in water and a mixed solvent dimethylformamide (DMF + H2O) were determined at 298.15 K, t and a range of concentrations from 0.1 to1.0 molar. The ρ and η values were subsequently used to calculate the thermodynamics of mixing including the apparent molar volume (ϕv), partial molar volume (ϕvo) at infinite dilution. The solute-solute interaction is presented by Sv results from the equation ∅_v=ϕ_v^o+S_v √m. The values of viscosity (B) coefficients and Falkenhagen coefficient(A) of the Jone-Dole equation and Gibbs free
... Show MoreThe H-Point Standard Addition Method (H-PSAM) has been applied for spectrophotometric simultaneous determination of Cimetidine and Erythromycin ethylsuccinate using Bromothymol Blue (BTB) as a chromogenic complexing agent in a buffer solution at pH 5.5.
Objective: to assess the awareness and knowledge of our medical students regarding dose levels of imaging procedures and radiation safety issues, and to conclude how the curriculum of clinical radiology in the college medical program impacts such knowledge.
Subjects and methods: this is a cross-sectional study conducted among 150 medical students in Alkindy College of Medicine between January 2021 to July 2021, regardless of their age or gender. The study included six grades according to the year 2020-2021. A questionnaire consisting of 12 multiple-choice questions was conducted via an online survey using Google Forms. The questions were divided into two parts
... Show MoreHydrogen productions were achieved by irradiating ethanol ic aqueous solutions (20%. v/v) containing mixtures of the ligand 2,4- dimethoxybcnzylidene-2-hydroxy aniline (HL) or one of i ts complexes (ML2) wi th the following divalent ions: fVbl (II), Fc(IT), Co(II). Ni( rt ), Cu(H) and Zn (11), as photosensi1izers, methyl viol ogen (MY.:-) as electron acceptor. ethylene diamine  
... Show MoreSix transition metal complexes of Cr (III), Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) were prepared using 1,2-bis -(4-Amino-2,3-dimethyl-1- phenyl-pyrazolinyl)-diimino ethane(L) as ligand. These complexes were characterized by elemental analysis, magnetic susceptibility, UV/VIS and FT-IR spectroscopy. These data showed that the solid complexes of Mn(II), Co(II), Zn(II) were tetrahedral geometry, and Cr(III) was octahedral while the symmetry around Ni(II) and Cu(II) ions with the new ligand were square planar of the formula [ML]Cl2 , M=Ni(II) and Cu(II).
A simple method for the determina
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