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.
Background: Multiple sclerosis (MS) prevalence in Iraq is 11.73/100,000 it causes disability in younger adults. Expanded Disability Status Scale (EDSS) can monitor MS disability while Visually Evoked Potentials (VEP) serves as a marker of myelination.
Objectives: To explore the relationship between EDSS and VEPs in multiple sclerosis patients.
Patients and Methods: A cross-sectional study was conducted in Ghazi Al- Hariri Hospital from first of Nov 2021 till the end of Jan 2022. Fifty patients with multiple sclerosis were compared to 50 healthy individuals. EDSS Data were collected using a structured questionnaire, P100 latency were measured using VEP. The Correlation was u
... Show MoreThe primary components of successful engineering projects are time, cost, and quality. The use of the ring footing ensures the presence of these elements. This investigation aims to find the optimum number of geogrid reinforcement layers under ring footing subjected to inclined loading. For this purpose, experimental models were used. The parameters were studied to find the optimum geogrid layers number, including the optimum geogrid layers spacing and the optimum geogrid layers number. The optimum geogrid layers spacing value is 0.5B. And as the load inclination angle increased, the tilting and the tilting improvement percent for the load inclination angles (5°,10°,15°) are (40%,28%, and 5%) respectively. The reduction percent o
... Show MoreThe primary components of successful engineering projects are time, cost, and quality. The use of the ring footing ensures the presence of these elements. This investigation aims to find the optimum number of geogrid reinforcement layers under ring footing subjected to inclined loading. For this purpose, experimental models were used. The parameters were studied to find the optimum geogrid layers number, including the optimum geogrid layers spacing and the optimum geogrid layers number. The optimum geogrid layers spacing value is 0.5B. And as the load inclination angle increased, the tilting and the tilting improvement percent for the load inclination angles (5°,10°,15°) are (40%,28%, and 5%) respectively. The reduction percent of the
... Show MoreBackground: Assessment is an important part of the learning cascade in education. Students realize it as an influential motivator to direct and guide their learning. The method of assessment determines the way the students reach high levels of learning. It has been documented that one of factor affecting students’ choice of learning approach is the way how assessment is being performed. Many methods of assessment namely multiple choice questions, essay questions and others are mainly used to assess basic science knowledge in undergraduate education. Objectives: The aim of this study is to compare multiple choice questions (MCQ) and essay questions (EQ) (record the success and failure rate of multiple choice questions (MCQ) and essay qu
... Show MoreBackground: Paediatric-onset multiple sclerosis (MS) has been a focus of great interest in recent years. The prognostic factors in early onset of MS have been evaluated in few studies with various methodologic approaches, and the discussion about the existence of clinical courses different from that of adult-onset MS is still open.
Background: Multiple myeloma is characterized by clonal expansion and accumulation of abnormal plasma cells in the bone marrow compartment. This study was conducted to determine the frequency and hematological presentation of multiple myeloma in Nanakaly Hospital in Erbil city.
patients and Methods: This descriptive retrospective study was carried out at Nanakaly Hospital over a period of six years from January 2007 to August 2012. A total of 109 patients who were diagnosed with multiple myeloma all were included to analyze the clinical and laboratory profiles. All patients were selected based on preset diagnostic criteria by the WHO.
Results: The study showed a male: female ratio of 1:1.1, the mean age of male patients was 57.8 ye
This paper describes the digital chaotic signal with ship map design. The robust digital implementation eliminates the variation tolerance and electronics noise problems common in analog chaotic circuits. Generation of good non-repeatable and nonpredictable random sequences is of increasing importance in security applications. The use of 1-D chaotic signal to mask useful information and to mask it unrecognizable by the receiver is a field of research in full expansion. The piece-wise 1-D map such as ship map is used for this paper. The main advantages of chaos are the increased security of the transmission and ease of generation of a great number of distinct sequences. As consequence, the number of users in the systems can be increased. Rec
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