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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 Oct 01 2015
Journal Name
Al-academy
Problems between acter and director in film and t.v: صالح الصحن
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Constitute the relationship between the director and actor mainstay chock done to show art in film and television , both of which occupy what a big role in the mission accomplishment . The leadership of the director of the artwork in various joints require two features two important ( creativity and administration ) , The capabilities director of creative serves as an added intellectual and aesthetic saturated sensation that leaves its impact on all the technical elements involved in done. Either trait administration and leadership it is what requires multiple skills in dealing on according to technical standards and moral and humanitarian allow the transfer of ideas , concepts and visions to those elements to embody and implement the ki

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Publication Date
Mon Jan 01 2024
Journal Name
Journal Of Engineering
An Electronic and Web-Based Authentication, Identification, and Logging Management System
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The need for participants’ performance assessments in academia and industry has been a growing concern. It has attendance, among other metrics, is a key factor in engendering a holistic approach to decision-making. For institutions or organizations where managing people is an important yet challenging task, attendance tracking and management could be employed to improve this seemingly time-consuming process while keeping an accurate attendance record. The manual/quasi-analog approach of taking attendance in some institutions could be unreliable and inefficient, leading to inaccurate computation of attendance rates and data loss. This work, therefore, proposes a system that employs embedded technology and a biometric/ w

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Publication Date
Thu Mar 01 2012
Journal Name
Journal Of Economics And Administrative Sciences
Turkish water projects in the Tigris and Euphrates .. Goals and intentions
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Turkey Consider Tigris and Euphrates rivers as a national rivers, and not an a International rivers, so that . It insists on its absolute sovereignty on that resources. The block ( levee ) which Turkey established should not create International problems.

The All International agreements and laws in this sect warrant the rights of all the states that located in river stream to use it without any consider to the regional absolute right.

During the 1980s, Turkey construct water projects, started with GAP, project which is one of the greatest project in the world, in spite of the plane of construct of the keep an levee on the Euphrates was pre of that project. The

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Publication Date
Thu Dec 15 2022
Journal Name
Al-academy
Decorative supplements and their role in fabric designs and women's fashion
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The decorative supplements added are important factors in determining many decorative effects and how to implement them, whether in fabrics or fashion, and also work to determine the nature of perception for both the designer and the recipient and have a key role in shaping the human personality and determining his motives and emotional tendencies in the acquisition of fabrics and fashion and the vocabulary they carry A design that has certain connotations and symbols that gain its value from the effects it leaves on the physical formations of women. The problem of the research came with the following question (What are the decorative supplements and their role in the designs of fabrics and women’s fashion?) The research also dealt wit

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Publication Date
Wed Mar 29 2017
Journal Name
Iraqi Journal Of Pharmaceutical Sciences ( P-issn 1683 - 3597 E-issn 2521 - 3512)
Preparation and Evaluation of Physical and, Rheological Properties of Clotrimazole Emulgel
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         Recently, emulgel has emerged as one of the most interesting topical preparations in the field of pharmaceutics. In this research clotrimazole was formulated as topically applied emulgel ; different formulas were prepared. The prepared emulgels were evaluated for their physical appearance , rheological behaviour , and in vitro drug release . The influence of the type of gelling agent (carbopol 934 and methyl cellulose), the concentration of both the emulsifying agent (2% and 4% w/w of mixture of span 20 and tween 20) and the oil phase (5% and 7.5% w/w of liquid paraffin) and the type of oil phase (liquid paraffin and cetyl alcohol), on the drug release from the prepared emulgels was invest

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Publication Date
Tue Sep 01 2020
Journal Name
Baghdad Science Journal
Identification of Acinetobacter baumannii and Determination of MDR and XDR Strains
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The current study focuses on the bacterium Acinetobacter baumannii due to its importance as a nosocomial infections source in addition to its increased resistance against antibiotics. Different clinical and hospital environment samples were collected, and cultured on A. baumannii selective media: Leed Acinetobacter agar and Herellea agar. A. baumannii have been identified by traditional methods, followed by confirmation using molecular identification to detect blaoxa-51 like gene which is considered a diagnostic gene since it is present in genome of all A. baumannii strains. The result was, nineteen bacterial isolates of A.baumannii were obtained, from twenty-seven suspected isolate

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Publication Date
Sun Jan 01 2023
Journal Name
3rd International Conference On Smart Cities And Sustainable Planning
Power between potentiality and actuality in urban sustainability and urban resilience
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Publication Date
Wed Jun 29 2022
Journal Name
Journal Of The College Of Education For Women
Gender and Urban Studies as an Interactive Approach and Integrated Curriculum
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The integration of gender in urban studies is considered a goal and objective to build a society characterized by justice and equality. It further allows all its residents to enjoy the opportunities to live in a safe urban life. Based on the that, the limitations of the research and its field of interest related to the relationship between gender and urban studies have become clear. The insufficient knowledge in this regard considers gender as a concept that does not exist in itself, but rather overlaps and intersects with several concepts and studies, including urban studies. Thus, it has become necessary to adopt a descriptive methodology that helps reach a theoretical framework to explain the beginnings of such an interaction and inte

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Publication Date
Fri Jan 10 2025
Journal Name
Journal Of Baghdad College Of Dentistry
The Clinical Approach and Treatment of Benign and Malignant Parotid Masses
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Background: Parotid gland tumors account for 80% of all salivary gland neoplasms, 20% of these are malignant, but in daily clinical practice most parotid masses are operated on before obtaining the final histological diagnosis. This clinical setting further complicates the critical point of parotid surgery, which is the management of the facial nerve. Materials and methods: 45 patients underwent parotidectomy for benign and malignant neoplasms. A complete history is collected from the patients with the duration and the site of the tumor, the facial nerve examined and its associations, a medical consultation done for opinion and management. Clinical examination with facial nerve was mandatory to avoid any mistakes that may occur. The most si

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Publication Date
Tue Jan 02 2018
Journal Name
Journal Of Educational And Psychological Researches
Family violence, its causes and effects on society (women and children)
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Summary of the research Family violence, its causes and effects on society (women and children). Search Goal: The current research aims to identify: 1. Causes of family and social violence (for children and women). 2. How to process. research importance : Domestic violence is a major and devastating problem that has a negative and direct impact on children in particular and women or mothers in general. The problem of domestic violence is linked to many factors and individual, social, economic, psychological and environmental variables, which makes one theory that claims to be inaccurate. It is difficult to understand the nature of family violence without linking it to some of the concepts related to it. The negative effects that may lead

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