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

Improving" Jackknife Instrumental Variable Estimation method" using A class of immun algorithm with practical application

A series of laboratory model tests has been carried out to investigate the using of pomegranate sticks mat as reinforcement to increase the bearing capacity of footing on loose sand. The influence of depth and length of pomegranate sticks layer was examined. In the present research single layer of pomegranate sticks reinforcement was used to strengthen the loose sand stratum beneath the strip footing. The dimensions of the used foundation were 4*20 cm. The reinforcement layer has been embedded at depth 2, 4 and 8 cm under surcharge stresses . Reinforcing layer with length of 8 and 16 cm were used. The final model test results indicated that the inclusion of pomegranate sticks reinforcement is very effective in improvement the loading cap

This research aims to identify the level of extension administration performance under comprehensive quality standards from the perspective of the working staff in agricultural extension at the level of the general extension body and agricultural directorates and agricultural division.this was to identify the extension administration performance under comprehensive quality standards from the perspective of vegetables growers , random sample was selected from the central region governorates Baghdad , Diyala , Babel , karbala and Al-Najaf , a random sample from the workers in the general body numbered 56 employee , sample of staff working in agricultural extension was selected at the level of agricultural directorates in proportion

Expressions for the molecular topological features of silicon carbide compounds are essential for quantitative structure-property and structure-activity interactions. Chemical Graph Theory is a subfield of computational chemistry that investigates topological indices of molecular networks that correlate well with the chemical characteristics of chemical compounds. In the modern age, topological indices are extremely important in the study of graph theory. Topological indices are critical tools for understanding the core topology of chemical structures while examining chemical substances. In this article, compute the first and second k-Banhatti index, modified first and second k-Banhatti index, first and second k-hyper Banhatti index, fir

This paper presents a fully computerized method to backup the router configuration file. The method consists of a friendly graphical interface programmed by Java programming language.

    The proposed method is compared with the two existing methods, namely: TFTP server method and Copy/Paste method. The comparison reveals that the proposed method has many advantages over the existing ones. The proposed method has been implemented on Cisco routers (series 2500, 2600 and 2800).

Allowing Iraqi companies to use multiple systems and policies leads to varying levels of disclosure and no high symmetry between report preparers and users, and that the adoption of integrated reporting can reduce information asymmetry. The theoretical side addressed the concepts of these variables, and in the practical side the binary variable (0, 1) was used. To compensate for the value of the independent variable (integrated reporting) based on the Central Bank of Iraq’s classification of banks according to the (CAMLES) index, and the dependent variable (information asymmetry) was measured through two measures (price difference, unusual return), the research community was represented by (5) Banks out of the total of banks li