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Experimental evidence of Phase Control method in chaotic Semiconductor Laser
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we study how to control the dynamics of excitable systems by using the phase control technique.We study how to control nonlinear semiconductor laser dynamics with optoelectronic feedback using the phase control method. The phase control method uses the phase difference between a small.added frequenc y and the main driving frequency to suppress chaos, which leads to various periodic orbits. The experimental studying for the evaluation of chaos modulation behavior are considered in two conditions, the first condition, when one frequency of the external perturbation is varied, secondly, when two of these perturbations are changed. The chaotic system becomes regular under one frequency or two frequencies, But in two frequencies, phase control showed an excellent ability to maintain regular behavior in chaotic window and reexcite chaotic behavior when destroyed. This dynamics of the laser output are analyzed by time series and bifurcation diagram.

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Publication Date
Fri Apr 30 2021
Journal Name
International Medical Journal
Knowledge, Attitude, and Practice of Infection Control by Dental Students at Pedodontic Clinic, College of Dentistry, University of Baghdad, Iraq
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Objectives: This study explored knowledge, attitude, and practice of infection control by dental students at College of Dentistry/ University of Baghdad, Iraq. Material and Methods: Three hundred dental students participated in this study. A self administrated questionnaire with 21 close ended questions related to use of personal protective equipments, infection control awareness, vaccination status, percutaneous exposures, and attitude towards treatment of patients with hepatitis B (HBV)/ or human immunodeficiency virus (HIV) was distributed to dental students. Data were analyzed using Statistical Package for Social Sciences (SPSS) version 21. Fisher exact and Chi-square test were used with significance level set to 0.05. Results: The

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Publication Date
Mon Feb 25 2019
Journal Name
Iraqi Journal Of Physics
Simulation of thermal lensing in an end-pumped Nd:YAG laser rod with Gaussian and super-Gaussian pump beam profile
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A numerical simulation is made on the thermal lensing effect in an laser diode end-pumped Nd:YAG laser rod. Based on finite element method (FEM), the laser rod temperature distribution is calculated and the focal length is deduced for a Gaussian and super-Gaussian pump beam profiles.

At the pump power of 20W, the highest temperature located at the center of end-pumped face was 345K, and the thermal lens focal length was 81.4mm along the x-z axis. 

The results indicate that the thermal lensing effect sensitively depend on the pump power, waist radius of the pump beam and the pump distribution in a laser rod geometry.

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Publication Date
Sat Jan 20 2024
Journal Name
Ibn Al-haitham Journal For Pure And Applied Sciences
Theoretical Study of the Lasing Output for a Quasi-Three-Level Operation in Nd 3+:YAG Thin- Disk Laser
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In this research, the effect of each of the concentrations ( Nd+3) was studied (N) the thickness of the thin disk (d) the number of times that the pumping beam passes through the effective medium of this laser (Mp) the reflectivity of the laser output mirror (R 2) The losses of the effective medium (L) and the pumping power used in achieving the reverse qualification (PP) on each of the pumping threshold capacities (Pp.th) and the output power of the laser (Pout) and the efficiency (ŋ) in Nd3+ thin-disk lasers (TDLs) pumping quasi-three-level With continuous operation (cw), at room temperature, and in the Gaussian mode (TEM00),

We found under these opera

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Publication Date
Mon Apr 01 2019
Journal Name
Biochem. Cell. Arch
Improvement the surface properties of metal valves used in agriculture engine by using CO<inf>2</inf> laser beam
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Publication Date
Sun Dec 06 2009
Journal Name
Baghdad Science Journal
The influence of He-Ne Laser (632.8 nm) on Candida albicans isolated from complete upper dentures: In vitro study
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The main objective of this study is to determine whether the use of He-Ne Laser (632.8 nm wavelength and power 0.5 mW) is an eligible and effective tool to kill or reduce the cell viability of Candida albicans isolated from complete upper dentures. Twenty one swabs were taken from the complete upper dentures. Only six swabs showed positive cultures for C. albicans. The isolate was divided into two groups, group I was not irradiated (control), and group II was irradiated by He-Ne Laser for different periods (10, 15, 20, and 30) min. After irradiation, the results showed a significant reduction in the viable cell count and colonies diameters especially at exposure periods 10 and 15 min. Although the low power He-Ne Laser was not eradicating t

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Publication Date
Mon Jul 20 2020
Journal Name
Ibn Al-haitham Journal For Pure And Applied Sciences
The Continuous Classical Boundary Optimal Control Vector Governing by Triple Linear Partial Differential Equations of Parabolic Type
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In this paper, the continuous classical boundary optimal control problem (CCBOCP) for triple linear partial differential equations of parabolic type (TLPDEPAR) with initial and boundary conditions (ICs & BCs) is studied. The Galerkin method (GM) is used to prove the existence and uniqueness theorem of the state vector solution (SVS) for given continuous classical boundary control vector (CCBCV). The proof of the existence theorem of a continuous classical boundary optimal control vector (CCBOCV) associated with the TLPDEPAR is proved. The derivation of the Fréchet derivative (FrD) for the cost function (CoF) is obtained. At the end, the theorem of the necessary conditions for optimality (NCsThOP) of this problem is stated and prov

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Publication Date
Wed Dec 18 2019
Journal Name
Baghdad Science Journal
The Continuous Classical Boundary Optimal Control of Couple Nonlinear Hyperbolic Boundary Value Problem with Equality and Inequality Constraints
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The paper is concerned with the state and proof of the existence theorem of a unique solution (state vector) of couple nonlinear hyperbolic equations (CNLHEQS) via the Galerkin method (GM) with the Aubin theorem. When the continuous classical boundary control vector (CCBCV) is known, the theorem of existence a CCBOCV with equality and inequality state vector constraints (EIESVC) is stated and proved, the existence theorem of a unique solution of the adjoint couple equations (ADCEQS) associated with the state equations is studied. The Frcéhet derivative derivation of the "Hamiltonian" is obtained. Finally the necessary theorem (necessary conditions "NCs") and the sufficient theorem (sufficient conditions" SCs") for optimality of the stat

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Publication Date
Sun Jan 01 2023
Journal Name
8th Engineering And 2nd International Conference For College Of Engineering – University Of Baghdad: Coec8-2021 Proceedings
Impact of project delivery method on geotechnical site conditions for implementing water treatment plants in Iraq
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Publication Date
Wed Jun 27 2018
Journal Name
Iraqi Journal Of Science
Proposed Method of Air Traffic Routing in Dynamic Environment Usiing Modifed rrt With Collision Avoid Nace
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     In the current Airlines Air Traffic Management (ATM), the Air Traffic Control Operators (ATCO), with the Air Traffic Control systems (ATC), operate air traffic paths with a small number of fixed routes. Problems of fixed routes appear such that even when they reduce the chance for conflict, they also produce flight paths plans that do not reduce flight time or fuel usage. In nowadays Airlines are heavily overloaded and anxious to minimize the aircrafts fuel usage costs, increase airplanes, and optimize the paths or the flight routes in order to find the most optimal suitable flight paths. This paper presents a new path planning method that deal with such problem effectively, the idea was to produce flights routes

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Publication Date
Fri Dec 01 2023
Journal Name
Baghdad Science Journal
Synthesis of Carbon Nanotubes Using Modified Hummers Method for Cathode Electrodes in Dye-Sensitized Solar Cell
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      In this research, carbon nanotubes (CNTs) is prepared  through the Hummers method with a slight change in some of the work steps, thus, a new method has been created for preparing carbon nanotubes which is similar to the original Hummers method that is used to prepare graphene oxide. Then, the suspension carbon nanotubes is transferred to a simple electrode position platform consisting of two electrodes and the cell body for the coating and reduction of the carbon nanotubes on ITO glass which represents the cathode electrode while platinum represents the anode electrode. The deposited layer of carbon nanotubes is examined through the scanning electron microscope technique (SEM), and the images throughout the research show the

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