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Multi-Channel Distributed DSA Networks: Connectivity and Rendezvous Tradeoffs
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In this paper, we investigate and characterize the effects of multi-channel and rendezvous protocols on the connectivity of dynamic spectrum access networks using percolation theory. In particular, we focus on the scenario where the secondary nodes have plenty of vacant channels to choose from a phenomenon which we define as channel abundance. To cope with the existence of multi-channel, we use two types of rendezvous protocols: naive ones which do not guarantee a common channel and advanced ones which do. We show that, with more channel abundance, even with the use of either type of rendezvous protocols, it becomes difficult for two nodes to agree on a common channel, thereby, potentially remaining invisible to each other. We model this invisibility as a Poisson thinning process and show that invisibility is even more pronounced with channel abundance. Following the disk graph model, we represent the multiple channels as parallel edges in a graph and build a multi-layered graph (MLG) in R2. In order to study the connectivity, we show how percolation occurs in the MLG by coupling it with a typical discrete percolation. Using a Boolean model and the MLG, we study both cases of primaries' absence and presence. For both cases, we define and characterize connectivity of the secondary network in terms of the available number of channels, deployment densities, number of simultaneous transmissions per node, and communication range. When primary users are absent, we derive the critical number of channels which maintains supercriticality of the secondary network. When primary users are present, we characterize and analyze the connectivity for all the regions: channel abundance, optimal, and channel deprivation. For each region we show the requirement and the outcome of using either type of rendezvous techniques. Moreover, we find the tradeoff between deployment-density versus rendezvous probability which results in a connected network. Our results can be used to decide on the goodness of any channel rendezvous algorithm by computing the expected resultant connectivity. They also provide a guideline for achieving connectivity using minimal resources.

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Publication Date
Thu Dec 09 2021
Journal Name
Iraqi Journal Of Pharmaceutical Sciences ( P-issn 1683 - 3597 E-issn 2521 - 3512)
Cressa cretica Pharmacognosy, and Pharmacology (A review )
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Cressa cretica (Shuwwayl) is a halophytic that belongs to Convolvulaceae, naturally grown in the Middle East including Iraq. Traditionally the plant is used as a paste for sore treatment, also it is used for fever, jaundice, and other illness. Regarding nonclinical use it is used as goat, sheep, and camel feed also as an oil source. Flavonoids including quercetin, kamepferol, apigenin, and their glycosides, phenolic acid as chlorogenic acid, and phytosterols mainly ?–sitosterol were the most important phytochemicals that were detected in this halophyte. Crude ethanolic, methanolic extracts and ethyl acetate fraction of the areal parts were used in clinical studies and demonstrated various effe

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Publication Date
Fri Mar 29 2024
Journal Name
Iraqi Journal Of Science
Pure-Hollow Modules and Pure-Lifting Modules
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   Let  be a commutative ring with identity, and  be a unitary left R-module. In this paper we, introduce and study a new class of modules called pure hollow (Pr-hollow) and pure-lifting (Pr-lifting). We give a fundamental, properties of these concept.  also, we, introduce some conditions under which the quotient and direct sum of Pr-lifting modules is Pr-lifting.

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Publication Date
Sat Dec 01 2012
Journal Name
Journal Of Economics And Administrative Sciences
Emotional Intelligence and Leadership Personality for Managers
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The purpose of this research is to analyze the relationship between the emotional intelligence and the leadership personality of the managers . the research was tested at the college of administration and economics – university of Baghdad through applying it on a sample of (67) members and units of the college. a questionnaire was used as a major tool for collecting data and information . for the purpose of researching to conclusion, the research aimed to test two main hypotheses related to the correlation coefficient and the effect correlation between the two main variable of the research, some statistical techniques such as (the mean, student deviation, percentages, correlation coefficient spearman, simple regression) were us

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Publication Date
Wed Jun 01 2022
Journal Name
Innovations
Proteolytics, Their Functional Role and Practical Applications
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RMK Al-Zaid, AT Al-Musawi, SJ Mohammad

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Publication Date
Sun Dec 05 2010
Journal Name
Baghdad Science Journal
Jordan ?-Centralizers of Prime and Semiprime Rings
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The purpose of this paper is to prove the following result: Let R be a 2-torsion free ring and T: R?R an additive mapping such that T is left (right) Jordan ?-centralizers on R. Then T is a left (right) ?-centralizer of R, if one of the following conditions hold (i) R is a semiprime ring has a commutator which is not a zero divisor . (ii) R is a non commutative prime ring . (iii) R is a commutative semiprime ring, where ? be surjective endomorphism of R . It is also proved that if T(x?y)=T(x)??(y)=?(x)?T(y) for all x, y ? R and ?-centralizers of R coincide under same condition and ?(Z(R)) = Z(R) .

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Publication Date
Wed Mar 10 2021
Journal Name
Baghdad Science Journal
Synthesis of New Amide and ThioUrease Compounds.
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The reaction of some new Schiff bases ( 2-[(2-Amino – ethylimino)-methyl]-R , 2-({2-[(R-benzylidene)-amino]-ethylimino}-methyl)-R with Benzoyl chloride or Acetyl chloride were carried out. Subsequent reactions of these products N-(2-Amino-ethyl)-N-[Chloro-(R) –methyl]-benzamide or N-(2-{?-[chloro-(R) –methyl]-amino}-ethyl)-N-[chloro-(R) –methyl]- benzamide with thiourea afforded thioureas compounds. The synthesized compounds were confirmed by their IR,UV,spectra and C.H.N. analysis.

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Publication Date
Sun Dec 30 2001
Journal Name
Iraqi Journal Of Chemical And Petroleum Engineering
Deasphaltening and Hydrodesulfurization of Basrah Vacuum Residue
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Publication Date
Fri Feb 01 2019
Journal Name
Journal Of The College Of Education For Women
Baghdadin Drinks and Foods stuff Abbasyat Ages
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Baghdadin Drinks and Foods stuff Abbasyat Ages

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Publication Date
Tue Jul 01 2014
Journal Name
Sage Open
Individual Mobility and the Sense of “Deadlock”
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Individual mobility is an outcome of the rapid changes in life; it is revealed in particular literary works within the end of the 19th century. Mobility is clearer in modern time as the individual has become physically freer in his movement. But the individual’s freedom is often conditioned by restrictions. Usually, change stimulates individuals to obtain new structure of feeling; the individual mocks or rages against institutions, or he would comply, suffering rapid personal deterioration as he faces effective stability or institutions. There is a continuous sense of “deadlock.” Sylvia Plath’s novel reflects the depression of an intellectual young woman who fails to find her right path muddled by an inconsistent, confusing

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Publication Date
Sat Mar 30 2002
Journal Name
Iraqi Journal Of Chemical And Petroleum Engineering
Preparation, Characterization, and Properties of Barium Titanate
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