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Medium access control protocol design for wireless communications and networks review
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<p><span>Medium access control (MAC) protocol design plays a crucial role to increase the performance of wireless communications and networks. The channel access mechanism is provided by MAC layer to share the medium by multiple stations. Different types of wireless networks have different design requirements such as throughput, delay, power consumption, fairness, reliability, and network density, therefore, MAC protocol for these networks must satisfy their requirements. In this work, we proposed two multiplexing methods for modern wireless networks: Massive multiple-input-multiple-output (MIMO) and power domain non-orthogonal multiple access (PD-NOMA). The first research method namely Massive MIMO uses a massive number of antenna elements to improve both spectral efficiency and energy efficiency. On the other hand, the second research method (PD-NOMA) allows multiple non-orthogonal signals to share the same orthogonal resources by allocating different power level for each station. PD-NOMA has a better spectral efficiency over the orthogonal multiple access methods. A review of previous works regarding the MAC design for different wireless networks is classified based on different categories. The main contribution of this research work is to show the importance of the MAC design with added optimal functionalities to improve the spectral and energy efficiencies of the wireless networks.</span></p>

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Publication Date
Mon Oct 01 2012
Journal Name
Iraqi Journal Of Physics
Structural and optical properties for nano GaxSb1-x films
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Alloys of GaxSb1-x system with different Ga concentration (x=0.4, 0.5, 0.6) have been prepared in evacuated quartz tubes. The structure of the alloys were examined by X-ray diffraction analysis (XRD) and found to be polycrystalline of zincblend structure with strong crystalline orientation (220). Thin films of GaxSb1-x system of about 1.0 μm thickness have been deposited by flash evaporation method on glass substrate at 473K substrate temperature (Ts) and under pressure 10-6 mbar. This study concentrated on the effect of Ga concentration (x) on some physical properties of GaxSb1-x thin films such as structural and optical properties. The structure of prepared films for various values of x was polycrystalline. The X-ray diffraction analy

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Publication Date
Fri Oct 25 2013
Journal Name
International Endodontic Journal
Fabrication and characterization of polymer composites for endodontic use
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Aim To develop a low-density polyethylene–hydroxyapatite (HA-PE) composite with properties tailored to function as a potential root canal filling material. Methodology Hydroxyapatite and polyethylene mixed with strontium oxide as a radiopacifier were extruded from a single screw extruder fitted with an appropriate die to form fibres. The composition of the composite was optimized with clinical handling and placement in the canal being the prime consideration. The fibres were characterized using infrared spectroscopy (FTIR), and their thermal properties determined using differential scanning calorimetry (DSC). The tensile strength and elastic modulus of the composite fibres and gutta-percha were compared, dry and after 1 month storage in

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Publication Date
Sat Mar 20 2021
Journal Name
Agroforestry Systems
Hydraulic lift: processes, methods, and practical implications for society
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Publication Date
Tue Oct 02 2018
Journal Name
Iraqi Journal Of Physics
Synthesis and characterization of Au nanoparticles for nanomedicine application
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Gold nanoparticles AuNPs have proven to be powerful tools in various nanomedicine applications, because of their photo-optical distinctiveness and biocompatibility. Noble metal gold nanoparticles was prepared by pulsed laser ablation method (1064-Nd: YAG with various Laser power from 200 to 800 mJ and 1 Hz frequency) in distil water. The process was characterized using UV-VIS absorption spectroscopy. Morphology and average size of nanoparticles were estimated using AFM and X-ray diffraction (XRD) analysis which show the nature of gold nanoparticles (AuNPs). Antibacterial activity of gold nanoparticles as a function of particles concentration against gram negative bacterium Escherichia coli and gram positive bacterial Staphylococcus aureu

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Publication Date
Sun Jan 01 2023
Journal Name
Journal Of Interdisciplinary Mathematics
Computations for the groups SL(2,81) and SL(2,729)
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For any group G, we define G/H (read” G mod H”) to be the set of left cosets of H in G and this set forms a group under the operation (a)(bH) = abH. The character table of rational representations study to gain the K( SL(2,81)) and K( SL(2, 729)) in this work.

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Publication Date
Mon Apr 25 2022
Journal Name
Knowledge And Information Systems
Unsupervised model for aspect categorization and implicit aspect extraction
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People’s ability to quickly convey their thoughts, or opinions, on various services or items has improved as Web 2.0 has evolved. This is to look at the public perceptions expressed in the reviews. Aspect-based sentiment analysis (ABSA) deemed to receive a set of texts (e.g., product reviews or online reviews) and identify the opinion-target (aspect) within each review. Contemporary aspect-based sentiment analysis systems, like the aspect categorization, rely predominantly on lexicon-based, or manually labelled seeds that is being incorporated into the topic models. And using either handcrafted rules or pre-labelled clues for performing implicit aspect detection. These constraints are restricted to a particular domain or language which is

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Publication Date
Wed Jul 01 2020
Journal Name
Journal Of Engineering
An Analytical Solution for the Maximum Tensile Stress and Stress Concentration Factor Investigations for Standard, Asymmetric fillets, Asymmetric Pressure Angle and Profile Shifted Helical and Spur Gears
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This research introduces a developed analytical method to determine the nominal and maximum tensile stress and investigate the stress concentration factor. The required tooth fillets parametric equations and gears dimensions have been reformulated to take into account the asymmetric fillets radiuses, asymmetric pressure angle, and profile shifting non-standard modifications. An analytical technique has been developed for the determination of tooth weakest section location for standard, asymmetric fillet radiuses, asymmetric pressure angle and profile shifted involute helical and spur gears. Moreover, an analytical equation to evaluate gear tooth-loading angle at any radial distance on the involute profile of spur and hel

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Publication Date
Fri Mar 29 2024
Journal Name
Iraqi Journal Of Science
Evaluating the Performance and Behavior of CNN, LSTM, and GRU for Classification and Prediction Tasks
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     Deep learning (DL) plays a significant role in several tasks, especially classification and prediction. Classification tasks can be efficiently achieved via convolutional neural networks (CNN) with a huge dataset, while recurrent neural networks (RNN) can perform prediction tasks due to their ability to remember time series data. In this paper, three models have been proposed to certify the evaluation track for classification and prediction tasks associated with four datasets (two for each task). These models are CNN and RNN, which include two models (Long Short Term Memory (LSTM)) and GRU (Gated Recurrent Unit). Each model is employed to work consequently over the two mentioned tasks to draw a road map of deep learning mod

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Publication Date
Wed Jan 07 2015
Journal Name
World Journal Of Experimentalbiosciences
Biofilm formation and antibiotic susceptibility for clinical and environmental isolates of Pseudomonas aeruginosa
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Pseudomonas aeruginosa is emerging opportunistic clinical pathogens. Clinical isolates of P. aeruginosaresist wide spectrum of antibiotics and form biofilm. The comparison study between clinical and environmental of P. aeruginosa in terms of biofilm formation and antibiotic resistance is very scanty. Thus, in current study microtiter plate technique was used to measure the biofilm formation by several clinical and environmental isolates. Moreover, the antibiotic susceptibility of these bacteria was evaluated by VITIK 2 techniques. The relationship between the antibiotic susceptibility and biofilm formation was evaluated for clinical and environmental isolates. Clinical and environm

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Publication Date
Mon Apr 24 2017
Journal Name
Ibn Al-haitham Journal For Pure And Applied Sciences
The Study Properties (Compressive And Tensile And Wear) For The Composite Materials Hybried
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  This study included prepared samples of epoxy reinforced by the novolac , aluminum , glass powder and epoxy reinforced by aluminum , glass powder and epoxy alone .They are used as reinforced materials of volum fraction amounting 40% .  The mechanical properties inclouded ( tensile , compressive and wear) where the wear test inclouded different applied loads (5,10,15) . From the results showed the epoxy reinforced by aluminum and glass powder has higher compressive strength (56.91) Mpa and higher tensile strength (132.2) Mpa .But the epoxy alone has higher wear rate and the epoxy reinforced by aluminum and glass powder which have higher elasticity of modulus from the tensile test (315.7) Mpa

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