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.
In this paper a system is designed and implemented using a Field Programmable Gate Array (FPGA) to move objects from a pick up location to a delivery location. This transportation of objects is done via a vehicle equipped with a robot arm and an FPGA. The path between the two locations is followed by recognizing a black line between them. The black line is sensed by Infrared sensors (IR) located on the front and on the back of the vehicle. The Robot was successfully implemented by programming the Field Programmable Gate Array with the designed system that was described as a state diagram and the robot operated properly.
Gender and culture are among the factors that influence the process of understanding and interpreting different types of communication, especially images. The current study, which is a part of a master’s thesis, aims at investigating the role of gender and culture in interpreting and understanding the caricatures that deal with women’s issues in Arab societies. To this end, the researchers adopted Barthes’ (1957) concepts of denotation and connotation in his theory of mythologies in addition to Langacker’s (1987) theory of (Domains). The research concludes that the female subjects have better cognitive abilities in investing the signs within the selected caricatures. The other factor the study reached to is that the respondents
... Show MoreCD40 is a type 1 transmembrane protein composed of 277 amino acids, and it belongs to the tumor necrosis factor receptor (TNFR) superfamily. It is expressed in a variety of cell types, including normal B cells, macrophages, dendritic cells, and endothelial cells, as a costimulatory molecule. This study aims to summarize the CD40 polymorphism effect and its susceptibility to immune-related disorders. The CD40 gene polymorphisms showed a significant association with different immune-related disorders and act as a risk factor for increased susceptibility to these diseases.
The absorption spectrum for three types of metal ions in different concentrations has been studying experimentally and theoretically. The examination model is by Gaius model in order to find the best fitting curve and the equation controlled with this behavior. The three metal ions are (Copper chloride Cu+2, Iron chloride Fe+3, and Cobalt chloride Co+2) with different concentrations (10-4, 10-5, 10-6, 10-7) gm/m3. The spectroscopic study included UV-visible and fluorescence spectrum for all different concentrations sample. The results refer to several peaks that appear from the absorption spectrum in the high concentration of all metal ions solution.
... Show MoreAge, hypertension, and diabetes can cause significant alterations in arterial structure and function, including changes in lumen diameter (LD), intimal-medial thickness (IMT), flow velocities, and arterial compliance. These are also considered risk markers of atherosclerosis and cerebrovascular disease. A difference between right and left carotid artery blood flow and IMT has been reported by some researchers, and a difference in the incidence of nonlacunar stroke has been reported between the right and left brain hemispheres. The aim of this study was to determine whether there are differences between the right and left common carotid arteries and internal carotid arteries in patient
Background: Economic Globalization affects work condition by increasing work stress. Chronic work stress ended with burnout syndrome.
Objectives: To estimate the prevalence of burnout syndrome and the association of job title, and violence with it among physicians in Baghdad, and to assess the burnout syndrome at patient and work levels by structured interviews.
Subjects and Methods: A cross section study was conducted on Physicians in Baghdad. Sampling was a multistage, stratified sampling to control the confounders in the design phase. A mixed qualitative and quantitative
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Absence or hypoplasia of the internal carotid artery (ICA) is a rare congenital anomaly that is mostly unilateral and highly associated with other intracranial vascular anomalies, of which saccular aneurysm is the most common. Blood flow to the circulation of the affected side is maintained by collateral pathways, some of which include the anterior communicating artery (Acom) as part of their anatomy. Therefore, temporary clipping during microsurgery on Acom aneurysms in patients with unilateral ICA anomalies could jeopardize these collaterals and place the patient at risk of ischemic damage. In this paper, we review the literature on cases with a unilaterally absent ICA associa