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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
Wed Sep 01 2010
Journal Name
Al-khwarizmi Engineering Journal
Free Convection in an Inclined Concentric Annular Square Cavities Filled With Porous Medium and Heated By Non-Uniform Temperature
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A numerical study of the two-dimensional steady free convection flow in an inclined annulus between two concentric square cavities filled with a porous medium is presented in this paper for the case when the side outer walls are kept with differentially heated temperature while the horizontal outer walls and the inner walls are insulated. The heated wall is assumed to have spatial sinusoidal temperature variation about a constant mean value. The Darcy model is used and the fluid is assumed to be a standard Boussinesq fluid. For the Cartesian coordinate system, the governing equations which were used in stream function form are discretized by using the finite difference method with successive under – relaxation method (SUR) and are solv

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Publication Date
Fri Jun 05 2015
Journal Name
International Journal Of Science And Research
The Effect of Growth Medium and Nodes Number on the Acclimatization Success of Tissue Propagated Potatoes Seedlings Solanum tuberasum
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The experiment was conducted at the period from 20th Dec. 2015 to 30th Mar. 2016 to know the effect of growth medium and nodes number on the acclimatization success of tissue propagated potatoes seedlings (Burrin class) and study some plant physiological properties. The first experiment involved testing growth media: loam, peat moss, and perlite with different portions (1:1) to plant tissue propagated potato tubers, while the second experiment involved testing the nodes number where 9, 8, 7, 6, and 5 plant nodes were chosen. Results of the first experiment showed the superiority of the culture media of peat moss + perlite to other culture media by giving the higher values of shoot system studied properties: plant height, branches number, le

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Publication Date
Thu Mar 14 2019
Journal Name
Al-khwarizmi Engineering Journal
Sculptured Surface Design and Implementation by Lofting Design Method Using Cross-sectional B-Spline Curves
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This research presents a particular designing strategy for a free form of surfaces, constructed by the lofting design method. The regarded surfaces were created by sliding a B-spline curves (profile curves), in addition to describing an automatic procedure for selective identification of sampling points in reverse engineering applications using Coordinate Measurement Machine. Two models have been implemented from (Ureol material) to represent the different cases of B-spline types to clarify its scope of application. The interior data of the desired surfaces was designed by MATLAB software, which then were transformed to UG-NX9 software for connecting the sections that were designed in MATLAB program and obtaining G-code programs for the

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Publication Date
Fri Jul 21 2023
Journal Name
Journal Of Engineering
SIMULATION OF OPTIMAL SPEED CONTROL FOR A DC MOTOR USING LINEAR QUADRATIC REGULATOR (LQR)
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This paper describes DC motor speed control based on optimal Linear Quadratic Regulator (LQR) technique. Controller's objective is to maintain the speed of rotation of the motor shaft with a particular step response.The controller is modeled in MATLAB environment, the simulation results show that the proposed controller gives better performance and less settling time when compared with the traditional PID controller.

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Publication Date
Wed Mar 10 2021
Journal Name
Baghdad Science Journal
An Approximate solution for two points oundary value problem corresponding to some optimal control
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this paper presents a novel method for solving nonlinear optimal conrol problems of regular type via its equivalent two points boundary value problems using the non-classical

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Publication Date
Fri Mar 08 2024
Journal Name
Applied System Innovation
Adaptive Active Disturbance Rejection Control for Vehicle Steer-by-Wire under Communication Time Delays
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In this paper, an adaptive active disturbance rejection control is newly designed for precise angular steering position tracking of the uncertain and nonlinear SBW system with time delay communications. The proposed adaptive active disturbance rejection control comprises the following two elements: (1) An adaptive extended state observer and (2) an adaptive state error feedback controller. The adaptive extended state observer with adaptive gains is employed for estimating the unmeasured velocity, acceleration, and compound disturbance which consists of system parameter uncertainties, nonlinearities, exterior disturbances, and time delay in which the observer gains are dynamically adjusted based on the estimation error to enhance est

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Publication Date
Mon Dec 19 2022
Journal Name
Drones
Practically Robust Fixed-Time Convergent Sliding Mode Control for Underactuated Aerial Flexible JointRobots Manipulators
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The control of an aerial flexible joint robot (FJR) manipulator system with underactuation is a difficult task due to unavoidable factors, including, coupling, underactuation, nonlinearities, unmodeled uncertainties, and unpredictable external disturbances. To mitigate those issues, a new robust fixed-time sliding mode control (FxTSMC) is proposed by using a fixed-time sliding mode observer (FxTSMO) for the trajectory tracking problem of the FJR attached to the drones system. First, the underactuated FJR is comprehensively modeled and converted to a canonical model by employing two state transformations for ease of the control design. Then, based on the availability of the measured states, a cascaded FxTSMO (CFxTSMO) is constructed to estim

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Scopus (38)
Crossref (32)
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Publication Date
Wed Dec 12 2018
Journal Name
Iraqi National Journal Of Nursing Specialties
Effectiveness of Instructional Health Educational Vascular Access on Hemodialysis Patients' Knowledge at Al-Hussein Teaching Hospital in AL-Nasiriyah City.
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Objectives: The study aims: (1) To determine effectiveness of instructional health education vascular access on hemodialysis patients' knowledge, (2) To find out the association between effects of instructional health education vascular access and demographic characteristics of (age, gender and educational level). Methodology: A quasi experimental study –control study design is carried out at AL-Hussein Teaching Hospital in AL-Nasiriyah City, from 3November,2015 to 2 June, 2016. A non-probability (Purposive sample) of (80) patients with vascular access devices on maintenance hemodialysis patients divided int

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Publication Date
Sun Sep 27 2020
Journal Name
Iraqi National Journal Of Nursing Specialties
Effectiveness of an Educational Program on Patients’ Knowledge Concerning care of Vascular Access of Hemodialysis in Al-Muthana Teaching Hospitals
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Objectives:  The study aims to identify the effects of an educational program on patients’ knowledge about vascular access care and to find out the relationship between patients knowledge scores and their selected demographic variable.                                                                                  &

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Publication Date
Thu Sep 01 2016
Journal Name
Journal Of Engineering
Calculating the Transport Density Index from Some of the Productivity Indicators for Railway Lines by Using Neural Networks
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The efficiency evaluation of the railway lines performance is done through a set of indicators and criteria, the most important are transport density, the productivity of enrollee, passenger vehicle production, the productivity of freight wagon, and the productivity of locomotives. This study includes an attempt to calculate the most important of these indicators which transport density index from productivity during the four indicators, using artificial neural network technology. Two neural networks software are used in this study, (Simulnet) and (Neuframe), the results of second program has been adopted. Training results and test to the neural network data used in the study, which are obtained from the international in

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