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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
Wed Jan 02 2019
Journal Name
Journal Of Educational And Psychological Researches
Educational Plan for Private and Public Kindergartens
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The research aims to identify the educational plan for the private and public kindergartens. The researchers selected a sample consisted of (59) female teachers for the private kindergartens and (150) female teachers for the public kindergartens in the city of Baghdad. As for the research tool, the two researchers designed a questionnaire to measure the educational plan for the private and public kindergartens. The results   revealed that private kindergartens have educational plans that contribute considerably to classroom interaction, the public kindergartens lack for educational plans. In light of the findings of the research, the researchers recommend the following: the need to set up a unified educational plan for the priv

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Publication Date
Sun Jun 01 2008
Journal Name
Journal Of The College Of Languages (jcl)
Pain and pleasure in Ibn – Zaidoon poetry
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Pain and pleasure is when a human being feels pain because one of his sensesُ organs has extremely stressed itself. Where as pleasure is when someone indulges himself as much as he could and get away from anything that causes pain to himself and hurts it. The beauty of the poetic text appears when two contradictions occur together in the same poetic line, just like when two contradictions live together in life; they live and struggle in one poem. Contradictory duet is not something new poetry was based on this duet since it was found until this day. It forms the essential source from which meanings come, and the guide lines that drawn by the personal experience of the poet are formed from it.I preferred to study the duet of Ibn- Zaido
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Publication Date
Tue Mar 31 2020
Journal Name
College Of Islamic Sciences
Ruling on abortion in Sharia and law
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Research title: Ruling on abortion in Sharia and law.

The importance of research: Projection is of great importance because it touches the life of a living being who enjoys human qualities. However, this organism often wastes its rights and does not protect its human beings. These souls are lost in millions by the sake of casual desire or hidden desire.

The research plan: The research dealt with an introductory topic, four topics, and in each topic there are demands, branches, and a conclusion.

The most important findings of the study: The ruling on aborting the fetus in the Sharia is only permissible (and the necessity is valued at its va

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Publication Date
Wed Jul 16 2025
Journal Name
Al-academy
Hijab and Burqa in Islamic Fashion System
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Publication Date
Sun Sep 01 2013
Journal Name
Baghdad Science Journal
Synthesis and Characterization of New Thioxanthone Derivatives
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This work comprises the synthesis of new thioxanthone derivatives containing C-substituted thioxanthone. To obtain these derivatives, the o-mercapto benzoic acid was chosen as the starting material, which was reacted with dry benzene in sulfuric acid (98 %) to produce the thioxanthone (1). The 2,7-(disulfonyl phosphine imine) thioxanthone (4-8) were prepared from reaction of compound (1) with chlorosulfonic acid gave 2,7-(disulfonyl chloride) thioxanthone (2). Treatment of (2) with sodium azide to produce 2,7-(disulfonyl azide) thioxanthone (3). Condensation of (3) with phosphorus compounds afforded compounds (4-8). The 2,7-(disulfonamide) thioxanthone (9-21) was obtained when co

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Publication Date
Fri Feb 14 2020
Journal Name
Journal Of Mechanical Engineering Research And Developments
Noise effects in skill discretion and modeling
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Diesel generators is widely used in Iraq for the purpose of maintaining electric power demand. Large number of operators engaged in this work encounters high level of noise generated by back pack type diesel generators used for this purpose. High level of noise exposure gives different kinds of ill effect on human operators. Exact nature of deteriorated work performance is not known., in present research , quastionaire was adsministered 86 repondents in Baghdad city were exposured to wide range of noise level (80-110) dB(A) with different ages and they have different skill discretion levels. Noise levels A-weigthed decibles dB(A) were measured over 8 weeks two times aday during the 2019 summer using a sound level meter.For predicting the wo

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Publication Date
Fri Jul 01 2016
Journal Name
Al–bahith Al–a'alami
Narrative and Electronic news Story: (Semiotic approach)
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The e-news is one of the most important journalistic arts in new media (the Internet). The process of telling the story by the journalist is an important aspect of the communicative process between the users of the internet and the reporter. The electronic news is characterized by having text, fixed images, animations, videos and sound. All these give greater vitality to the communicative process and increase the semiotic dimensions. Also, it makes the narrative process more distinctive and embodied of the elements of the event. This research studies all these aspects and tries to show the distinction between the semiotics of narration and the electronic news.

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Publication Date
Mon Sep 16 2019
Journal Name
Ibn Al-haitham Journal For Pure And Applied Sciences
Filter Bases and j-ω-Perfect Mappings
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This paper consist some new generalizations of some definitions such: j-ω-closure converge to a point,  j-ω-closure directed toward a set, almost  j-ω-converges to a set, almost  j-ω-cluster point, a set  j-ω-H-closed relative, j-ω-closure continuous mappings, j-ω-weakly continuous mappings, j-ω-compact mappings, j-ω-rigid a set, almost j-ω-closed mappings and  j-ω-perfect mappings. Also, we prove several results concerning it, where j ÃŽ{q, δ,a, pre, b, b}.

 

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Publication Date
Sat Aug 01 2015
Journal Name
International Journal Of Science And Research
Bacteriological and Immunological Study of Rheumatoid Arthritis
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The current study included the collection of 175 samples of blood (Urea-blood) of patients with rheumatoid arthritis from Al–Al-Kindy Teaching Hospital, Baghdad Teaching Hospital and Al-Imamian Al-Kadhimyain Medical City in Baghdad from both sexes with different ages at the period between 1/10/2016-1/2/2017. Bacterial growth results showed that 80% of urea for bacterial transplantation were positive results, while the number of samples showing no bacterial growth was 20%. The bacterial isolation evaluate for morphological testes and biochemical microscopy, as well as identification by Api system. The highest frequency of inflectional bacteria was E. coli (41.97%), followed by E. cloacae (21.25%), P. aeruginosa (12.5%), Salmonella (10%), K

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Publication Date
Thu Oct 18 2018
Journal Name
Al–bahith Al–a'alami
Modalities and Methodological Techniques in Media Studies
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There have been many writings and discussions that dealt with the details and interpretation of the research methods and the identification of the methods and methodological methods used by researchers and writers as they deal with research topics and problems in all fields of natural and human sciences. But we noticed that the movement of science and its knowledge and development requires the identification of suitable tools and methodological methods appropriate for each type of science. In other words, attempts should be established to build appropriate methodological tools for human and cognitive activity that can be referred to as a specific science that sets out certain paths of the human sciences which is certainly the ori

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