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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 May 20 2026
Journal Name
Journal Of Engineering
DESIGN, CONSTRUCTION AND TESTING OF LOW SPEED WIND TUNNEL WITH ITS MEASUREMENT AND INSPECTION DEVICES
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A low speed open circuit wind tunnel has been designed, manufactured and constructed at the Mechanical Engineering Department at Baghdad University - College of Engineering. The work is one of the pioneer projects adapted by the R & D Office at the Iraqi MOHESR. The present paper describes the first part of the work; that is the design calculations, simulation and construction. It will be followed by a second part that describes testing and calibration of the tunnel. The proposed wind tunnel has a test section with cross sectional area of (0.7 x 0.7 m2) and length of (1.5 m). The maximum speed is about (70 m/s) with empty test section. The contraction ratio is (8.16). Three screens are used to minimize flow disturbances in the test section.

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Publication Date
Sat Oct 28 2023
Journal Name
Baghdad Science Journal
Synthesis and investigation of structural and optical properties of CdO: Ag nanoparticles of various concentrations
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This study discussed the effects of doping with silver (Ag) on the optical and structural properties of
CdO nanoparticles at different concentrations 0, 1, 2, 3, 4, 5 wt% prepared by the precipitation method. The
materials were annealed at 550˚C for 1 h. The structural, topographical, and optical properties were
diagnosed by X-ray diffraction analysis, atomic force instrument, and visible and ultraviolet spectrometers.
The results show that the average diameter of the grains depends on the percentage of added silver to the
material, as the diameter decreased from 88.8 to 59.7 nm, and it was found that the roughness increased from
5.56 to 26.5. When studying the optical properties, it was noted that th

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Publication Date
Tue Jun 30 2015
Journal Name
Al-kindy College Medical Journal
Knowledge, attitude and practice regarding measles vaccine campaign among medical and engineering students: Baghdad, 2011
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Background: The strategy for eliminating measles from Iraq includes conducting mass immunization campaign against measles, within the framework of the national strategic plan for the elimination of this disease. Awareness about this campaign is fundamental for their success.Objective: The study aims at finding out the knowledge, attitudes and practices regarding vaccination against measles among two groups of students in two different colleges ( medical and engineering) .To report uptake of Measles vaccine and reasons for declining the vaccine among medical and non-medical students in the campaignMethod: Across sectional study has been conducted at Al-Kindy College of Medicine/ Baghdad University and University of Technology for the peri

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Publication Date
Sun Mar 02 2014
Journal Name
Baghdad Science Journal
Phenolic Content and Antioxidant, Antibacterial Activities of Ethanolic Extract From Lemon Balm and Oregano Plants
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The antioxidant and antibacterial activities of ethanolic extract and phenolic compounds extract of Lemon balm (Melissa officinalis) and Oregano (Oreganum vulgare) plants were studied; the phenolic content and the relationship between these compounds and the above activities were also investigated. The results showed that the Lemon balm had the highest phenolic content (56.5% mg g) and the phenolic content of Oregano was twice lower than Lemon balm. Lemon balm has the highest antioxidant activity which causes lipid peroxidation inhibition activity of linoleic acid (90.5%), this activity was more than ?-tocopherole antioxidant activity (79.3 %). It was found that the main source of antioxidant activity o

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Publication Date
Tue Mar 30 2021
Journal Name
College Of Islamic Sciences
Need and transgression in Surat (Abs) Semantic grammatical study: Need and transgression in Surat (Abs)
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      The research aims to highlight the significance and composition and the diversity of meanings and the Quranic context in the necessary and transgressive verbs in Surat (Abs).

      This research consists of : a preamble , and two studies . The researcher addressed in the preliminary the importance of the phenomenon of necessity and infringement, the signs of the necessary action , the structure and controls of the act , the methods of infringement , its sections and signs.

      As for the first topic : The researcher addressed the necessary verbs in Surat Abs , an applied study in terms of grammati

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Publication Date
Wed Jan 13 2021
Journal Name
Muthanna Journal Of Pure Science
"Applications of biological of Azo-Schiff base ligand and its metal complexes and: A review "
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"1998 onwards, a span reporting 1000s of studies depicts the ever-increasing Schiff bases and their complexes applicability; this study genetically tests the research of the last 20 years. The variety of these molecules structural has made them obtainable for a so broad ambit for implementations of biological. They are eminent and because of this unique feature they find their position in the quantitative and qualitative calculation of metals in the aqueous medium. It demonstrated to be prominent catalysts and showed an enjoyable effect of fluorescence. Definitively, Schiff base fissures gotten situation of a unique during bio-experiments and in vitro to develop drugs with a large number of biological structures containing parasites

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Publication Date
Mon Oct 01 2018
Journal Name
Journal Of Economics And Administrative Sciences
Integration of Dissolved Analysis and Total Quality Management to reduce costs and improve product quality
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there is a need to use the teardown Technique in a various fields and different motives and used often by economic units as a technique to help other techniques for example, used by some economic units for the analysis of other economic units of products in order to work on the development of products and look for opportunities to improve product quality and avoid product errors competitor or reduce its costs, in addition to the services provided by quality control is used ISO 17025 integration with unassembled analysis to adjust the quality of the product by comparing the pieces produced with designed models that are also the product as a whole compared with the original design

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Publication Date
Thu Jun 01 2023
Journal Name
Baghdad Science Journal
Design and construction of anair pollution detection system using a laser beam and absorption spectroscopy
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Air pollution is one of the important problems facing Iraq. Air pollution is the result of uncontrolled emissions from factories, car exhaust electric generators, and oil refineries and often reaches unacceptable limits by international standards. These pollutants can greatly affect human health and regular population activities. For this reason, there is an urgent need for effective devices to monitor the molecular concentration of air pollutants in cities and urban areas. In this research, an optical system has been built consisting of aHelium-Neonlaser,5mWand at 632.8 nm, a glass cell with a defined size, and a power meter(Gentec-E-model: uno) where a scattering of the laser beam occurs due to air pollution. Two pollutants were examin

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Publication Date
Thu Jan 30 2020
Journal Name
Journal Of Engineering
Comparison of Single and Group Bored Piles Settlement Based on Field Test and Theoretical Methods
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 Bored piles settlement behavior under vertical loaded is the main factor that affects the design requirements of single or group of piles in soft soils. The estimation of bored pile settlement is a complicated problem because it depends upon many factors which may include ground conditions, validation of bored pile design method through testing and validation of theoretical or numerical prediction of the settlement value. In this study, a prototype single and bored pile group model of arrangement (1*1, 1*2 and 2*2) for total length to diameter ratios (L/D) is 13.33 and clear spacing three times of diameter, subjected to vertical axial loads. The bored piles model used for the test was 2000

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Publication Date
Mon Jun 05 2023
Journal Name
Journal Of Engineering
Simulation and Modeling of Detailed Load flow Analysis for the 400kVA and 132kVA Iraqi Grid
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A load flow program is developed using MATLAB and based on the Newton–Raphson method,which shows very fast and efficient rate of convergence as well as computationally the proposed method is very efficient and it requires less computer memory through the use of sparsing method and other methods in programming to accelerate the run speed to be near the real time.
The designed program computes the voltage magnitudes and phase angles at each bus of the network under steady–state operating conditions. It also computes the power flow and power losses for all equipment, including transformers and transmission lines taking into consideration the effects of off–nominal, tap and phase shift transformers, generators, shunt capacitors, sh

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