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Power Efficiency Maximization in Cognitive Radio Networks
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Cognitive radio technology is used to improve spectrum efficiency by having the cognitive radios act as secondary users to access primary frequency bands when they are not currently being used. In general conditions, cognitive secondary users are mobile nodes powered by battery and consuming power is one of the most important problem that facing cognitive networks; therefore, the power consumption is considered as a main constraint. In this paper, we study the performance of cognitive radio networks considering the sensing parameters as well as power constraint. The power constraint is integrated into the objective function named power efficiency which is a combination of the main system parameters of the cognitive network. We prove the existence of optimal combination of parameters such that the power efficiency is maximized. Then we reformulate the objective function to incorporate the throughput. According to different constraints or degree of significance, we may put proper weight to each term so that we could obtain more preferable combination of parameters. Computer simulations have given the optimal solution curve for different weights. We can draw the conclusion that if we put more emphasis on power efficiency, the transmit power is a more critical parameter, however if throughput is more important, the effect of sensing time is significant.

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Publication Date
Mon Mar 31 2014
Journal Name
Al-khwarizmi Engineering Journal
Corrosion Behavior of V2AlC and Cr2AlC Compared with SS 316L in NaOH at Four Temperatures
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Abstract

      This work involves the manufacturing of MAX phase materials include V2AlC and Cr2AlC using powder metallurgy as a new class of materials which characterized by regular crystals in lattice. Corrosion behavior of these materials was investigated by Potentiostat to estimate corrosion resistance and compared with the most resistant material represented by SS 316L. The experiments were carried out in 0.01N of NaOH solution at four temperatures in the range of 30–60oC. Polarization resistance values which calculated by Stern-Geary equation indicated that the MAX phase materials more resistant than SS 316L. Also cyclic polarization tests confirme

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Publication Date
Sat Dec 01 2018
Journal Name
Political Sciences Journal
American strategic performance towards Middle East in the era of president Trump - A future study
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Abstract The strategic performance of the United States depends on dealing with the Middle East countries and its variants on several bases and motives that enabled them to achieve American hegemony and invest its interests at the expense of the region countries. Within this performance, the administration of the United State President Donald Trump presented the Strategic Document on December 18, 2017, which focused on the principle of "America First", to determine the direction of future US strategic performance in the formulation of means of cooperation and intersections or hostility in addition to interests and threats.The future vision of the Arab region and the Middle East as a whole, this strategy is based on the fact that

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Publication Date
Tue Jan 01 2019
Journal Name
Annals Of Medicine And Surgery
The prevalence and correlation between subclinical hypothyroidism and gall stone disease in Baghdad teaching hospital
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Publication Date
Fri Feb 03 2012
Journal Name
Ibn Al-haitham Journal For Pure And Applied Science
Viscosity and Density of Chrom Alum in Aqueous Poly (Ethylene Glycol) Solution at Different Temperature
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Density data of alum chrom in water and in aqueous solution of poly (ethylene glycol) (1500) at different temperatures (288.15, 293.15, 298.15) k have been used to estimate the apparent molar volume (Vθ), limiting apparent molar volume (Vθ˚) experimental slope (Sv) and the second derivative of limiting partial molar volume [δ2 θ v° /δ T2] p .The viscosity data have been analyzed by means of Jones –Dole equation to obtain coefficient A, and Jones –Dole coefficient B, Free activation energy of activation per mole of solvent, Δμ10* solute, Δμ20* the activation enthalpy ΔH*,and entropy, ΔS*of activation of viscous flow. These results have been discussed in terms of solute –solvent interaction and making/breaking ability of so

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Publication Date
Sun Oct 01 2017
Journal Name
Journal Of Engineering
Optimization of Surface Roughness for Al-alloy in Electro-chemical Machining (ECM) using Taguchi Method
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Electro-chemical Machining is  significant  process to remove metal with using  anodic dissolution. Electro-chemical machining use to removed metal workpiece from (7025) aluminum alloy using Potassium chloride (KCl) solution .The tool used was made from copper. In this present the optimize processes input parameter use are( current, gap and electrolyte concentration) and surface roughness (Ra) as output .The experiments on electro-chemical machining with use current (30, 50, 70)A, gap (1.00, 1.25, 1.50) mm and electrolyte concentration (100, 200, 300) (g/L).  The method (ANOVA) was used to limited the large influence factors affected on surface roughness and found the current was the large influence f

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Publication Date
Fri Jan 01 2016
Journal Name
International Archives Of Medicine
The role of MRI in the diagnosis of intra articular knee derangement: A prospective study
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Publication Date
Wed Jan 01 2020
Journal Name
Energy Conversion And Management
Improved PCM melting in a thermal energy storage system of double-pipe helical-coil tube
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Publication Date
Mon Jan 01 2024
Journal Name
Corporate And Business Strategy Review
The role of entrepreneurial leadership strategy in promoting organizational sustainability: A descriptive and analytical study
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The paper aims to build a model that supports organizational sustainability by analyzing the correlations and revealing the impact between the two main variables (entrepreneurial leadership) with its dimensions of proactive outlook, risk, and creativity (Van Zyl & Mathur-Helm, 2007), and (organizational sustainability) with its economic, environmental, and societal dimensions (Hansmann et al., 2012). As well as identifying the level of awareness and informing managers in the General Company for the Automotive and Equipment Industry, of the theoretical implications and performance, and its vital importance to society and the surrounding ecological environment, and drawing attention to that and improving performance, and indicatin

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Publication Date
Wed Sep 01 2021
Journal Name
Baghdad Science Journal
Concentrations and Radiation Hazard Indices of Naturally Radioactive Materials for Flour Samples in Baghdad Markets
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In the present work, Uranium (238U), Thorium (232Th) and Potassium (40K) specific activity concentration in (Bq/kg) was measured in five different types for wheat flours that are available in the Iraqi markets. The gamma spectrometry method with an NaI (Tl) detector has been used for radiometric measurements. Calculations of radium equivalent activity, annual effective dose equivalent, external hazard index (Hex), internal hazard index (Hin), representing gamma index and gamma dose rate in all  flour samples were 17.98132 Bq/kg, 0.0100334, 0.04502, 0.04857, 0.06872, 0.125883 and 8.181244 respectively. It is found that the average of specific activity concentration of wheat flour sam

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Publication Date
Sat Sep 30 2023
Journal Name
Al–bahith Al–a'alami
The Role of Website Users in the Consumption of Notifications: A Field Study of Websites
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This research seeks to explore the impact of notifications on enhancing user engagement with websites, primarily through user subscriptions and their interaction with notifications on these websites. The significance of this study lies in its implications for crafting compelling headlines that capture users' attention, streamline their access to journalistic content, and align with the objectives and editorial policies of news websites. It sheds light on the factors influencing users' preferences for specific notifications and their engagement with content based on their individual interests, motivations, and the satisfaction derived from such interactions.
The researcher has reached several key findings, inc

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