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.
If we go beyond the technical aspects of the Web 2.0, and we focus specifically on its interactive characteristics, we may say it represents not only a fundamental shift in the structure of the press institutions and its practices but also a shift in the relationships that existed, previously, between the press and the audience. Web 2.0 has enabled the newspapers to renovate their representations and practices of the profession and opens to the new horizons either in terms of readership or advertising revenues. Parallel to that it also has empowered the user to transcend the passivity he has always been confined in and has become a more active participant in the creation and generation of media contents even though this practice is somew
... Show MoreMefenamic acid was esterified with starchwith[1:1] Molar ratio, as drug substituted with natural polymer, to prolongthe period of hydrolysis of drug polymer with other advantages. The new prodrug starch was characterized by FT-IR and UV-Visible and 1H-NMR spectroscopies. The physical properties were studied and controlled drug release was studied in different pH values at 37oC. The stability of drug was carried out by measuring the absorbance of mefenamic starch which hydrolyzed in HCl solution of pH 1.1 (artificial gastric fluid) and phosphate buffer of pH 7.4 (simulating intestinal fluid SIF) at 37oC for several days. The thermal analysis such as DSC was studied.
The aesthetic dimension in popular subjects is one of the important topics in the history and culture of peoples, as it is the vessel from which their faith, traditions, original values, language, ideas, practices and way of life are derived, which expresses their culture and national identity, and it is the bridge of communication between generations throughout the ages.
It is one of the main pillars in the process of development and development, and popular subjects have special images related to real daily life, and they are the best source for man to narrate through him in his portrayal of daily life in general, and for the artist in particular, who is part of this daily life and its vocabulary, as he interacts with it so that
... Show MoreIn this study, the behavior of square helical piles models (5×5) mm2 embedded in expansive soil bed overlaying a layer of sandy soil was investigated. The sand layer 200mm thickness was compacted into four sub layers in a steel container with diameter 400mm in size. Sandy soil layer was compacted into two relative densities 40% and 80%. The bed of ثءحties 40% and 80%.The bed of o00mm in size.Sandy soil layer was compacted into two relative densities 40% and 80%.The bed of oexpansive soil 300mm thickness was compacted into six sub layers on sandy soil layer. Model tests are performed with helical pile length 350mm, 400mm and 450mm and with helix diameter 15mm and 20mm. Also, one helix and double helix were
... Show MoreThe study aims to identify the neurological perfectionism of talented girls with disabilities and do a case study for one of these girls. The sample of the study consisted of (11) female students at the university level, 5 females with disability and (6) normal female-students. The sample also included (19) secondary school female students in Tabuk region, including 10 students with visual disability and (9) normal students. The case study was limited to one case of mentally superior girls (talented) with kinetic disability. The researcher adopted the descriptive methodology (case study), he used neurological perfectionism scale, Salah Mekhemar interview, Stanford interfacial intelligence scale fifth picture, case study form. The re
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In the name of God, praise be to God, and prayers and peace be upon the best of God’s creation, Muhammad bin Abdullah, and upon his family and companions, and from his family:
And after:
He saw from verbs that transcend one effect if it is visual and to two effects if it is heart and this action has several strokes and it is an awareness of the sense and illusion and imagination and reason and in addition to that it has many meanings dealt with in the glossary books and as for what the verb included in the audio studies it is the explanation and deletion and slurring The heart of my place. As for what the grammatical studies included, it focuses on one or two effects according to its l
The current research is concerned with the study of (aesthetic discourse in the significance of commercial advertisement designs), according to a knowledge structure defined by function and creativity, and the main goal is to interpret the reality of forms, their various sources, their essence, meanings, formal relationships, and design ideas in order to achieve the visual goal as a typographic achievement. It arises through the designer’s internal mental intuition to produce shapes based on subjective feelings that refer his preconceptions about those shapes with his feelings to creative formations. Aesthetic discourse is produced from the mind depending on the various symbolic, psychological and social functions, production methods,
... Show MoreTheatrical art, from (Plato) to (Heidegger), passing through (Husserl) and (Husserl) has propagated the parallel relations between the overlapping formal patterns in the world of hypotheses crowded with diaspora and scattering, leading to the manifestations of implicit meaning in the intellectual and aesthetic discourse, through the deconstructive pattern that restructures The aesthetic image according to the aesthetic data to be employed, so the effectiveness of the deconstructive system had an important role in authorizing the Ghanaian logic and continuity on which the Western meta meaning was based, and the artistic scene was subjected to it in line with literature and art to be able to pay attention to the achievement and clarify it
... Show MoreBackground: Insulin resistance is present in 50% or more of patients with primary hypothyroidism. Metformin can decrease TSH levels in these patients by a complex matter, this can be of great help in clinical practice.
Objective: This study was designed to evaluate the effect of metformin in reducing TSH levels in patients with primary hypothyroidism.
Methods: Hundred patients with primary hypothyroidism, 82 females, 18 males were included in this study, everyone was followed up for two months after adding metformin 850 mg twice daily in addition to thyroxin.
Results: 36 patients (36%) have a normal baseline TSH and no change after 2 months, 64 pa
... Show MoreEfficient cuttings transport and hole cleaning are very important factors for obtaining an effective drilling operation. In an inclined and horizontal drilling, hole cleaning issue is a common and complex problem.
The scope of this research is to study the drilling parameters which affect hole cleaning in Iraqi directional wells through studying and analyzing some drilled wells ( vertical , directional (30 degree) , directional (60 degree) and horizontal ).An excel sheet is prepared to calculate carrying capacity index which represents an indicator for good hole cleaning in different sections. The study indicated through the field investigations, practical experiences and theoretical calculations tha
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