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 w

In this study, the effect of ceramic coating on the performance and gases emission on diesel engine was investigated. A four-stroke, direct injected, single cylinder, diesel engine was tested at constant speed and at different load conditions without coating. Then, the inlet and exhaust valves faces were coated by about 500µm with ceramic materials. Ceramic layers were made of YttriaStabilized Zirconia (YSZ), and NiCrAl as a bond coat. The coating technique adapted in this work is the flame spray method. The engine with valves ceramiccoated research was tested for the same operation conditions of the engine (without coating). The results indicate a reduction in both fuel consumption by about 7.6% and particulate emissions by about (13

The research deals with a new type of high-performance concrete with improved physical properties, which was prepared by using metal additives minutes (Metakaolin) and by studing their impact on the properties of mortar and concrete high-performance through destructive and non destructive tests. This type of concrete is used broadly in public buildings and in other structures . The research involved a number of experiments such as finding the activity index of burned at a temperature of 750 º C according to the standard ( ASTM C-311/03), as well as casting models for the cubic mortar mixtures and concrete containers at different rates of metakaolin ranging between (5% - 20%) as an added part to the cement mix to get a high- compressive

Orthogonal polynomials and their moments serve as pivotal elements across various fields. Discrete Krawtchouk polynomials (DKraPs) are considered a versatile family of orthogonal polynomials and are widely used in different fields such as probability theory, signal processing, digital communications, and image processing. Various recurrence algorithms have been proposed so far to address the challenge of numerical instability for large values of orders and signal sizes. The computation of DKraP coefficients was typically computed using sequential algorithms, which are computationally extensive for large order values and polynomial sizes. To this end, this paper introduces a computationally efficient solution that utilizes the parall

Abstract

The research aims to shed light on the extent to which the practices of performance management in achieving organizational excellence in one of the formations and the Ministry of Finance (GCT). The importance of the selection of these organizations is that they occupies a large and exceptional importance in the national economy through income redistribution add it to cover a large part of the state budget revenues, these organizations possess functionally diverse cadre of them pregnant initial certification and other senior and he fairly stable To meet this target, and on the basis of the data search exploratory researcher built model hypothesis for the search included variable impressionist and

The family found itself confused any of the methods of dealing (Control - democracy) follow to reach the best level in education, what was favorite yesterday about a father dealing with his children control which showed generations characterized by high levels of self-esteem and decision-making, today rejected and opposed it. As some believe that a sense of control generates a negative represented by fear and frustration.
Find the goal of preparing the current scale of the father control when junior high students.
To achieve this goal, has been preparing a tool to measure the father control after that, the researcher extract the validity and reliability of the scale, and then applied to a sample of 500 students from junior high sch

Titanium dioxide nanorods have been prepared by sol-gel template
method. The structural and surface morphology of the TiO₂ nanorods was
investigated by X-ray diffraction (XRD) and atomic force microscopy
(AFM), it was found that the nanorods produced were anatase TiO₂ phase.
The photocatalytic activity of the TiO2 nanorods was evaluated by the
photo degradation of methyl orange (MO). The relatively higher
degradation efficiency for MO (D%=78.2) was obtained after 6h of exposed
to UV irradiation.