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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
Fri Jun 26 2020
Journal Name
Iraqi Journal Of Agricultural Sciences
IMPACT OF Conocarpus erectus L. FERTILIZER, AND SOME MICRONUTRIENTS ON GROWTH AND PRODUCTION OF POTATO
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This study was aimed to determine the impact of Conocarpus erectus L. compost fertilizer, and some micronutrients on growth and production of potato. This research was conducted at one of the fields of the College of Agricultural Engineering Sciences - University of Baghdad. The experiment was implemented using factorial arrangement (4X3X3) within randomized complete block design with three replicates. Conocarpus fertilizer was represented the first factor with three levels (7.5, 15, 30 ton.ha-1), which symbolized (C2, C3, C4). Chemical fertilizer as recommended dose as a control, which symbolized (C1). The second factor was foliar spraying with three levels of iron (0, 100, 200 mg.L-1), which symbolized (F0, F1, F2). The third fact

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Publication Date
Thu Apr 11 2024
Journal Name
J. Agric. And Veterinary Sci
Effect of adding humic acid and phosphate fertilizer levels on growth and yield of lettuce
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Publication Date
Thu Jan 01 2009
Journal Name
Ibn Al- Haitha M J. Fo R Pur E & Appl. Sc I
Synthesis and Structural Study of Some Mo(II) Carbonyl Complexes with Triazole and Oxadiazole Derivatives
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A new carbonyl complexes of triazole and oxadiazole were synthesized. These complexes were identified and their structural geometric were suggested by using FT-IR and UV-Vis spectra, conductivity measurements and other chemical and physical properties. The spectra data (FT-IR, UV, Vis.) with the substantial aid of group theoretical calculations gave so many evidences for the proposed geometries and the type of bonding of these compounds

Publication Date
Tue Jan 31 2017
Journal Name
Journal Of Engineering
Experimental and Numerical Simulation of an Airlift Pump with Conventional and Modified Air Injection Device
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The effect of air injection device on the performance of airlift pump used for water pumping has been studied numerically and experimentally. An airlift pump of dimensions 42mm diameter and 2200 mm length with conventional and modified air injection device was considered. A modification on conventional injection device (normal air-jacket type) was carried out by changing injection angle from 90  (for conventional) to 22.5  (for modified). Continuity and Navier-Stokes equations in turbulent regime with an appropriate two-phase flow model (VOF) and turbulent model (   ) in two dimensions axisymmetry flow were formulated and solved by using the known package FLUENT version (14.5). The numerical and experimental investiga

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Publication Date
Sun Dec 14 2014
Journal Name
Molecular Crystals And Liquid Crysta
Synthesis and Mesomorphic Behavior of Two New Homologous Series Containing Azobenzene and 1,3,4-Oxadiazole Units
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Two new nonsymmetrical mesogenic homologous series of terminal substituent ether (series [Vn]) and carboxy (series [VIn]) incorporating azobenzene and 1,3,4-oxadiazole group were synthesized. Both series have been All compounds thus isolated were purified and characterized by elemental analysis, Fourier Transform Infrared Spectroscopy, 1H NMR, along with thermal analysis and texture observation using Differential Scanning Calorimetry (DSC) and Polarizing Optical Microscopy (POM), respectively. All compounds of the first series exhibited liquid crystalline properties. The homologues [V1]-[V3] display a nematic mesophase, the compounds [V4]-[V7] exhibit a dimorphism behavior, nematic (N) and smectic A (SmA) mesophases, the compounds [V8] and

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Publication Date
Wed Mar 15 2023
Journal Name
Al-academy
The Developed Materials and Techniques and Its Role in Exposing the Aesthetic Of Art Work
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This study is targeting the new developed materials and techniques and how they were affected by the scientific and technological developments that contributed to revelated new and varied developed materials and techniques. And from the artist’s formulation by using the materials and techniques and through its embodiment and sensor the values, artistic and aesthetic standards by breaking from the familiar in aesthetic contemporary way.
The studies on questioning what’s the role of The New Developed Materials and Techniques in exposing the aesthetic of the art work?

This study is to show the aesthetic of the art work through the new developed materials and techniques. Which was based on descriptive analyzing method and hig

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Publication Date
Fri Aug 16 2024
Journal Name
Jurnal Arjuna: Publikasi Iimu Pendidkan,bahasa Dan Matematika
Some Physical and Motor Abilities and Their Contribution to The Scoring Skill of Futsal Players
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The game of futsal requires physical and motor abilities in order to perform it, as these abilities play a fundamental role in making the player have a wonderful physical level and be able to implement the skill aspect of futsal football, especially the scoring skill, which is the subject of the study. The importance of the research lies in arriving at knowledge of the percentage The contribution of some physical and motor abilities to the performance of the scoring skill in indoor soccer, in order to reach final scientific results that serve researchers, coaches, and players alike. The research aims to identify the most important physical and motor abilities of young players in futsal football, and to identify the percentage of contributio

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Publication Date
Fri Dec 01 2023
Journal Name
Case Studies In Construction Materials
Enhancing asphalt binder performance through nano-SiO2 and nano-CaCO3 additives: Rheological and physical insights
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During the last two decades, nanomaterial application has gained a significant attraction into asphalt technology due to their effect in enhancing asphalt binder improving the asphaltic mixture. This study will modify the asphalt binder with two different nano types, nano SiO2 and CaCO3, at levels ranging from 1% to 7%. The resulting optimum nano-modified Asphalt will be subject to a series of rheological tests, including dynamic shear rheometer (DSR), Viscosity, and bending beam rheometer (BBR) to determine asphalt binder sensitivity towards low-medium-high temperature range. Results indicate that both nano types improved the physical characteristics of Asphalt, and 5% by weight of Asphalt was suggested as a reasonable dosage of nano-SiO2

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Publication Date
Sun Oct 01 2023
Journal Name
Baghdad Science Journal
Synthesis and Characterization of Grafted Chitosan Blending with Polyvinyl alcohol / Nanocomposite and Study Biological Activity
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The study of biopolymers and their derivative materials had received a considerable degree of attention from researchers in the preparation of novel material. Biopolymers and their derivatives have a wide range of applications as a result of their bio-compatibility, bio-degradability and non-toxicity. In this paper, chitosan reacted with different aldehydes(2,4 –dichloro- benzaldehyde or 2-methyl benzaldehyde), different ketones (4-bromoacetophenone or 3-aminoacetophenone) to produce chitosan schiff base (1-4) . Chitosan schiff base (1-4) reacted with glutaric acid or adipic acid in acidic media in distilled water according to the steps of Fischer and Speier to produce compounds (5-12)

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Publication Date
Mon Sep 19 2022
Journal Name
International Journal Of Biomaterials
Green Biosynthesis of Silver Nanoparticles from Moringa oleifera Leaves and Its Antimicrobial and Cytotoxicity Activities
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The plant occupied the largest area in the biosynthesis of silver nanoparticles, especially the medicinal plants, and it has shown great potential in biotechnology applications. In this study, green synthesis of silver nanoparticles from Moringa oleifera leaves extract and its antifungal and antitumor activities were investigated. The formation of silver nanoparticles was observed after 1 hour of preparation color changing. The ultraviolet and visible spectrum, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy techniques were used to characterize synthesis particles. Ultraviolet and visible spectroscopy showed a silver surface plasmon resonance band at 434

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