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Connectivity and rendezvous in distributed DSA networks
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In this paper, we use concepts and results from percolation theory to investigate and characterize the effects of multi-channels on the connectivity of Dynamic Spectrum Access networks. 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-channels, 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 protocol, 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 define and characterize connectivity of the secondary network in terms of the available number of channels, deployment densities, number of transceivers per node, and communication range. When primary users are absent, we derive the critical number of channels which maintains super-criticality 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. Our results can be used to decide on the goodness of any channel rendezvous algorithm by computing the expected resultant connectivity.

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Publication Date
Sat Jul 20 2019
Journal Name
Al-nahrain Journal For Engineering Sciences
Inducing Frictional Force to Enhance the Transient Response in Beams
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This paper studies the effect of contact areas on the transient response of mechanical structures. Precisely, it investigates replacing the ordinary beam of a structure by two beams of half the thickness, which are joined by bolts. The response of these beams is controlled by adjusting the tightening of the connecting bolts and hence changing the magnitude of the induced frictional force between the two beams which affect the beams damping capacity. A cantilever of two beams joined together by bolts has been investigated numerically and experimentally. The numerical analysis was performed using ANSYS-Workbench version 17.2. A good agreement between the numerical and experimental results has been obtained. In general, results s

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Publication Date
Fri Feb 08 2019
Journal Name
Journal Of The College Of Education For Women
The role of kindergarten teachers in developing children's emotional intelligence
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The study aimed to get acquainted with kindergarten teachers in the development of
emotional intelligence in children, To achieve this a study too, which consisted of 40 items,
within four areas was condncted: (managing emotions, emotional knowledge, empathy, social
networking) The study tool was applied to the sample amounting (200) teachers of the
kindergarten teachers in the province of Jerash and after analyzing the results statistically
using arithmetic averages standard deviations and variance analysis quartet the following
results were reached :
- presence of statistically significant differences at the level of (α =0,05) is attributable to the
impact of the educational level in the areas of empathy and so

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Publication Date
Wed Mar 01 2023
Journal Name
Egyptian Journal Of Aquatic Biology And Fisheries
Environmental factors drive phytoplankton primary productivity in a shallow Lake
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Publication Date
Sat Sep 20 2025
Journal Name
Journal Of Baghdad College Of Dentistry
Orthodontic considerations of functional occlusion in Class І normal occlusion
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Background: The therapeutic goal of orthodontic treatment is to establish ideal occlusion which includes both static and functional aspects. The objective of this study was to clarify functional occlusal treatment goals by analyzing functional occlusion in subjects with established normal occlusion and identify the differences between canine protected occlusion and group function occlusion. Materials and Methods: The sample consisted of 62 subjects with normal occlusion and with an age range of (18-25 years).Functional occlusal contacts during lateral excursion were identified on a fully adjustable articulator, and then the samples were classified according to: 1) Type of functional occlusion: A) Canine protected occlusion group (canine pr

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Publication Date
Fri Jan 31 2020
Journal Name
Iraqi Geological Journal
GEOLOGICAL MODEL OF HARTHA FORMATION IN MAJNOON OILFIELD, SOUTHERN IRAQ
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Publication Date
Thu Mar 30 2017
Journal Name
Iraqi Journal Of Pharmaceutical Sciences ( P-issn 1683 - 3597 E-issn 2521 - 3512)
Single Dose Antibiotic Prophylaxis in Outpatient Oral Surgery Comparative Study
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         It is clear that correct application of antibiotic prophylaxis can reduce the incidence of infection  resulting from the bacterial  inoculation in a variety of clinical situations; it cannot   prevent  all  infections  any  more  than it  can   eliminate  all  established infections. Optimum  antibiotic   prophylaxis  depends on:  rational  selection  of the drug(s),  adequate  concentrations  of the  drug  in  the  tissues that  are at risk, and attention to  timing  of  administration.  Moreover,  the  risk  of

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Publication Date
Fri Jan 01 2021
Journal Name
Journal Of Economics And Administrative Sciences
Predicting Social Security Fund compensation in Iraq using ARMAX Model
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Time series have gained great importance and have been applied in a manner in the economic, financial, health and social fields and used in the analysis through studying the changes and forecasting the future of the phenomenon. One of the most important models of the black box is the "ARMAX" model, which is a mixed model consisting of self-regression with moving averages with external inputs. It consists of several stages, namely determining the rank of the model and the process of estimating the parameters of the model and then the prediction process to know the amount of compensation granted to workers in the future in order to fulfil the future obligations of the Fund. , And using the regular least squares method and the frequ

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Publication Date
Sat Mar 01 2014
Journal Name
Computers & Mathematics With Applications
Simultaneous determination of time-dependent coefficients in the heat equation
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Publication Date
Tue May 01 2018
Journal Name
Journal Of Physics: Conference Series
Application of Weyl Module In The Case Of Two Rows
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Publication Date
Fri Nov 29 2019
Journal Name
Iraqi Journal Of Physics
Enhancement In Ballistic Performance Of Composite Armor Through Nano Ceramic
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In this study, industrial fiber and polymer mixtures were used for high-speed impact (ballistic) applications where the effects of polymer (epoxy), polymeric
mixture (epoxy + unsaturated polyester), synthetic rubber (polyurethane), Kevlar fiber, polyethylene fiber (ultra High molecular weight) and carbon fiber.
Four successive systems of samples were prepared. the first system component made of (epoxy and 2% graphene and 20 layer of fiber), then ballistic test was
applied, the sample was successful in the test from a distance of 7 m. or more than, by using a pistol personally Glock, Caliber of 9 * 19 mm. The second
system was consisting of (epoxy, 2% graphene, 36 layers of fiber and one layer of hard rubber), it was succeeded

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