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 research, titanium dioxide nanoparticles (TiO2 NPs) were prepared through the sol-gel process at an acidic medium (pH3).TiO2 nanoparticles were prepared from titanium trichloride (TiCl3) as a precursor with Ammonium hydroxide (NH4OH) with 1:3 ratio at 50 °C. The resulting gel was dried at 70 °C to obtain the Nanocrystalline powder. The powder from the drying process was treated thermally at temperatures 500 °C and 700 °C. The crystalline structure, surface morphology, and particle size were studied by using X-ray diffraction (XRD), Atomic Force Microscopy (AFM), and Scanning Electron Microscope (SEM). The results showed (anatase) phase of titanium dioxide with the average grain size
... Show MoreBackground: Antimicrobial prescribing patterns have an important role in the emergence of resistance, and community pharmacists have a substantial influence on this issue. Objective: To assess community pharmacists' behaviors and attitudes toward antimicrobial dispensing, determine their proportions and categories, and examine the underlying rationales for this practice. Methods: A descriptive cross-sectional survey of community pharmacists in Iraq was conducted from June to August 2023, using a self-administered validated questionnaire. The attitudes, practices, and motivations driving the distribution of antimicrobials without a prescription (AWP) were explored in three areas. Results: A sizable proportion (61.6%) of respondents rejected
... Show MoreThe present work reports the performance of three types of polyethersulfone (PES) membrane in the removal of highly polluting and toxic lead Pb2+ and cadmium Cd2+ ions from a single salt. This study investigated the effect of operating variables, including pH, types of PES membrane, and feed concentration, on the separation process. The transport parameters and mass transfer coefficient (k) of the membranes were estimated using the combined film theory-solution-diffusion (CFSD), combined film theory-Spiegler-Kedem (CFSK), and combined film theory-finely-porous (CFFP) membrane transport models. Various parameters were used to estimate the enrichment factors, concentration polarization modulus, and Péclet number. The pH values signif
... Show MoreAW Ali T, Journal of the Faculty of Medicine, 2016 - Cited by 1
The bandwidth requirements of telecommunication network users increased rapidly during the last decades. Optical access technologies must provide the bandwidth demand for each user. The passive optical access networks (PONs) support a maximum data rate of 100 Gbps by using the Orthogonal Frequency Division Multiplexing (OFDM) technique in the optical access network. In this paper, the optical broadband access networks with many techniques from Time Division Multiplexing Passive Optical Networks (TDM PON) to Orthogonal Frequency Division Multiplex Passive Optical Networks (OFDM PON) are presented. The architectures, advantages, disadvantages, and main parameters of these optical access networks are discussed and reported which have many ad
... Show MoreThe concept of transitional justice is newly emerging, as it was mainly associated with addressing issues of serious breaches and abuses of human rights during conflicts and situations resulting from violence and the use of force in societies that are in the process of democratization, as transitional justice aims primarily to restore civil peace and rebuild institutions The state needs multidimensional justice: a judicial system that achieves the rule of law, corrective restoration of the wounds of the past, and a distributive characteristic of the redistribution of wealth.
OpenStreetMap (OSM), recognised for its current and readily accessible spatial database, frequently serves regions lacking precise data at the necessary granularity. Global collaboration among OSM contributors presents challenges to data quality and uniformity, exacerbated by the sheer volume of input and indistinct data annotation protocols. This study presents a methodological improvement in the spatial accuracy of OSM datasets centred over Baghdad, Iraq, utilising data derived from OSM services and satellite imagery. An analytical focus was placed on two geometric correction methods: a two-dimensional polynomial affine transformation and a two-dimensional polynomial conformal transformation. The former involves twelve coefficients for ad
... Show MoreDavid Hare (b.1947) is one of the most critically acclaimed, contemporary British dramatists. A playwright, director and filmmaker, he has written more than thirty plays for the stage and seven original screen plays for cinema and TV (Susan Emerling, p.1). He began his dramatic career in the late sixties. Along with such dramatists as Howard Brenton and Trevor Griffiths, he writes in the aftermath of the "Angry Young Men" tradition of John Osborne. It is a well-known fact that the element of anger continued in the drama of the 1960s and became even more radicalized after the social, cultural and political unrests of 1968 by the dramatists of the "second wave" to whom Hare belongs (John Russell Taylor, p.14). Setting his plays in a variet
... Show MoreThe present study aims at analyzing the polysemy of the English preposition in from the cognitive linguistic (CL) point of view using Evans' and Tyler's approach (2003). The perplexity faced by Iraqi second language learners (L2) due to the multi-usages of this preposition has motivated the researcher to conduct this study. Seventy-six second year university students participated in this experimental study. The data of the pre-test and post-test were analyzed by SPSS statistical editor. The results have shown the following: First, a progress of more than (0.05≤) has been detected as far as students' understanding of the multiple usages of the preposition in is concerned. Second, the results of the questionnaire have s
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