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joe-2080
FLUTTER SPEED LIMITS OF SUBSONIC WINGS
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Flutter is a phenomenon resulting from the interaction between aerodynamic and structural dynamic forces and may lead to a destructive instability. The aerodynamic forces on an oscillating airfoil combination of two independent degrees of freedom have been determined. The problem resolves itself into the solution of certain definite integrals, which have been identified as Theodorsen functions. The theory, being based on potential flow and the Kutta condition, is fundamentally equivalent to the conventional wing-ection theory relating to the steady case. The mechanism of aerodynamic instability has been analyzed in detail. An exact solution, involving potential flow and the adoption of the Kutta condition, has been analyzed in detail. The solution is of a simple form and
is expressed by means of an auxiliary parameter K. The use of finite element modeling technique and unsteady aerodynamic modeling with the V-G method for flutter speed prediction was used on a fixed rectangular and tapered wing to determine the flutter speed boundaries. To build the wing the Ansys 5.4 program was used and the extract values were substituted in the Matlab program which is designed to determine the flutter speed and then predicted the various effects on flutter speed. The program gave us approximately identical results to the results of the referred researches. The following wing design parameters were investigated skin shell thickness, material properties, cross section area for beams, and changing altitude. Results of these calculations indicate that structural mode shape variation plays a significant role in the determination of wing flutter boundary.

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Publication Date
Wed Dec 22 2021
Journal Name
Polymers
Modifications of Polymers through the Addition of Ultraviolet Absorbers to Reduce the Aging Effect of Accelerated and Natural Irradiation
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The photooxidative degradation process of plastics caused by ultraviolet irradiation leads to bond breaking, crosslinking, the elimination of volatiles, formation of free radicals, and decreases in weight and molecular weight. Photodegradation deteriorates both the mechanical and physical properties of plastics and affects their predicted life use, in particular for applications in harsh environments. Plastics have many benefits, while on the other hand, they have numerous disadvantages, such as photodegradation and photooxidation in harsh environments and the release of toxic substances due to the leaching of some components, which have a negative effect on living organisms. Therefore, attention is paid to the design and use of saf

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Publication Date
Sun Jul 01 2012
Journal Name
Journal Of Engineering
Preparation of Design Charts for Estimation of the Length of an Upstream Impervious Blanket in a Homogenous Earth Dam
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Publication Date
Tue Nov 01 2022
Journal Name
Baghdad Science Journal
Effect of Secondary Metabolite Crude of Metarhizum anisopliea Fungus on the Second Larval Stage of the Housefly Musca domestica
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Publication Date
Thu Mar 01 2018
Journal Name
مجلة الباحث في العلوم الإنسانية و الإجتماعية
The Rate of Performance of Scientific Committees in the University of Baghdad in Accordance to the Department’s Heads’ Viewpoint
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The research aims at recognition of The rate of performing tasks done by the scientific committees in the scientific departments in the University of Baghdad, within the evaluative perspective of the departments’ Heads. To find any statistically significant differences in the responses of the research sample to the rates performance of the scientific committees in scientific departments in the University of Baghdad, within the evaluative perspective of the departments’ Heads, according to the two variables of the social gender; male and females, and field of specialization of Scientific and Humanities. The research sample consisted if (107) heads of the scientific department in the University of Baghdad. The researchers designed a

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Publication Date
Tue Aug 01 2017
Journal Name
Journal Of Economics And Administrative Sciences
Relationship of the key elements of Knowledge management with strategic performance / filed research sample of private banks in Baghdad
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objective  the research to diagnosis and interpretation of the nature of the correlation between the  basic elements of knowledge management (tecgnology , structure , culture , process , human resource ) and the strategic performance of the Iraqi private banks, the research community and the level dimensions, and  tested this research in the private banking sector represented by (7), especially in Baghdad city, Iraqi banks, and applied on sample consisting of 100 distributors in several administrative levels Director (Director, Director of the department, branch manager), and use questionnaire Head to collect data and information tool, and some private banks annual reports, has sought research to test a number of h

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Publication Date
Wed Feb 27 2019
Journal Name
Asian Journal Of Chemistry
Estimation of Excess Properties of Binary Liquids Systems of Tetrahydrofurfuryl Alcohol with Short-Chain Carboxylic Acids at 298.15 K
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At the temperature 298.15 K, some physical properties such as: refractive indices (nD), viscosities (η) and densities (ρ) were studied in four liquid-liquid mixtures: carboxylic acids (HCOOH, CH3COOH, CH3CH2COOH and CH3CH2CH2COOH) with tetrahydrofurfuryl alcohol (THFA) with the identified configuration set. These empirical data were utilized to estimate the excess molar volumes (Vm E), refractive index perversions (ΔR), viscosity deviations (ηE) and excess molar Gibbs free energy (ΔG*E). Values of Vm E, ηE , ΔG*E and ΔR were plotted versus mole fraction of tetrahydrofurfuryl alcohol. In all cases, the values of Vm E, ηE , ΔG*E and ΔR that obtained in this study were found to be negative at 298.15 K. The excess parameters

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Publication Date
Sun Jun 05 2011
Journal Name
Baghdad Science Journal
Some Probability Characteristics Functions of the Solution of a Stochastic Non-Linear Fredholm Integral Equation of the Second Kind
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In this research, some probability characteristics functions (probability density, characteristic, correlation and spectral density) are derived depending upon the smallest variance of the exact solution of supposing stochastic non-linear Fredholm integral equation of the second kind found by Adomian decomposition method (A.D.M)

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Publication Date
Tue Jul 30 2024
Journal Name
Iraqi Journal Of Science
The Influence of Sucrose on Biomass and Glycosides Content of Callus Cultured from the Leaves of Stevia rebaudiana Berton
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Stevia rebaudiana Bertoni contains diterpenoid steviol glycosides that have no adverse impact on blood sugar levels despite being 300 times sweeter than sugar. This study aimed to investigate the rate of callus induction from stevia leaves and the content of glycosides when changing the sucrose percentage in the culture medium.. Murashige and Skoog (MS) culture medium supported by 4.0 mg/l naphthalene acetic acid (NAA) and 1.0 mg/l benzyl adenine (BA) was used, and different concentrations of sucrose (2, 3, 4, 5 and 6%) were tested .The extraction of glycosides from leaf and callus tissues was performed by using methanol. Extracted glycosides were analyzed by high-performance liquid chromatography (HPLC). The results showed signific

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Publication Date
Mon May 27 2019
Journal Name
Al-khwarizmi Engineering Journal
Effect of Using Air Guide Net in Front of the Condenser on the Performance of Automobile Air Conditioning System
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The work of this paper is an investigation to improve the condenser performance of the automobile air conditioning system by enhancing the air-side heat transfer from the condenser through the use of an air guide net installed in front of the condenser face which is basically an aluminum plate having a circular entrance shape for the air passage.  The A/C system was examined under two types of test. The first test was conducted the air guide net, while the second was done with the air guide net. The performances of the A/C system under these tests were compared. For the second type of test, the experiment was carried out with three different size of air guide net, three different circular diameters (2, 3 and 3.5 cm) a

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Publication Date
Thu Dec 28 2023
Journal Name
Journal Of Physical Education
Evaluating the academic achievement of graduate students working in the field of physical education from their point of view
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The research aimed to prepare a measure to evaluate the academic achievement of graduates working in the field of physical education from their point of view, to identify the extent to which graduating students benefit from the curriculum of the College of Physical Education and Sports Sciences, University of Baghdad/Al-Jadriya, and to identify the impact of academic subjects in the practical and theoretical fields. The researchers used the descriptive approach in the research procedures as it is an appropriate approach in achieving the research objectives. The following questions are: What are the academic subjects that have the most impact on graduating students? What are the academic subjects that have the least impact on the are

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