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Aircraft Lateral-Directional Stability in Critical Cases via Lyapunov Exponent Criterion

Based on Lyapunov exponent criterion, the aircraft lateral-directional stability during critical flight cases is presented. A periodic motion or limit cycle oscillation isdisplayed. A candidate mechanism for the wing rock limit cycle is the inertia coupling between an unstable lateral-directional (Dutch roll) mode with stable longitudinal (short period) mode. The coupling mechanism is provided by the nonlinear interaction of motion related terms in the complete set equations of motion. To analyze the state variables of the system, the complete set of nonlinear equations of motion at different high angles of attack are solved. A novel analysis including the variation of roll angle as a function of angle of attack is proposed. Furthermore the variation of Lyapunov exponent parameter as function of time is introduced. The numerical result indicated that the system became lightly damped at high angle of attack with increasing the amplitude of aircraft state variables limit cycle. A good agreement between the numerical result and published work is obtained for the onset of limit cycle oscillation, almost at .

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Publication Date
Sun Oct 02 2016
Journal Name
Journal Of The Faculty Of Medicine Baghdad
Non discogenic lumbar radiculopathy ((A study of 104 cases))

Background: All though the most common etiology of lumbar radiculopathy is herniated disc or spinal stenosis, however there are several intraspinal or extra spinal pathogenic processes that may cause lumbar radiculopathy.
Objective: To assess how often, and review the pathologies that cause non discogenic lumbar radiculopathy.
Patients and Methods: A prospective study was conducted on 600 patients who had lumbar radiculopathy. During one year period we examined 600 patients in outpatient clinic with presumed diagnosis of lumbar disc herniation.Through history and comprehensive physical and neurological examination were performed for all patients. Diagnostic test were done including laboratory, electrophysiological and radiological

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Publication Date
Wed Apr 01 2009
Journal Name
Journal Of The Faculty Of Medicine Baghdad
A study of 62 cases of sciatic nerve injury

Objectives: a study of surgical procedures used in the management of sciatic n injury & acomparism between them including comparism with other universal studies.
Patients and methods: 62 patients collected from the neuro-surgical unit in the specialized surgical hospital from Jan-2004 till October 2007, all patients studied thoroughly regarding age, Gender, type of injury, time of injury & outcome.
Results: 85% of our patients were ♂, 45% were in the age of 21-30 years, most injured by bullet or shells, the delay in surgery was mostly 1-3m, the repair is by direct suture 45%, 29% release of adhesions 16%, excision of neuroma & suturing, 9.6% by nerve graft, the direct suturing carried the&nbsp

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Publication Date
Mon Aug 07 2017
Journal Name
Ibn Al-haitham Journal For Pure And Applied Sciences
The Dwelling OF Two Previous Cases OF Kala Azar

 This is a contribution to study the dwelling of two previous cases of kala azar in the endemic area.  In order to assess the possible ecological causes of the incidence and the prevalence of visceral leishmaniasis in central Iraq.  

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Publication Date
Thu Jun 15 2023
Journal Name
Romanian Neurosurgery
Similarities and differences between two coincidently gravitational bullet cases

Many cases of gravitational bullets are reported in developed and non-developed countries. However, few papers highlighted these cases in the literature. In our study, we present two cases of gravitational bullets that have an unusual coincidence in the injury characteristics through their ages, and gender, the site of the inlet.

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Publication Date
Sat Jan 01 2011
Journal Name
Iraqi Journal Of Physics
Effect of SiC particles and water absorption on thermal conductivity of epoxy reinforcement by (bi-directional) glass fiber

In this study the thermal conductivity of the epoxy composites were characterized as function of volume fraction, particle size of fillers and the time of immersion(30,60,90)days in water .Composites plates were prepared by incorporating (bi-directional) (0º-90º) glass fiber and silicon carbide (SiC) particles of (0.1,0.5,1)mm as particle size at (10%,20%,30%,40%) percent volume in epoxy matrix.
The composites shows slightly increase of the thermal conductivity with increasing volume fraction, particle size and increase with increasing the days of immersion in water. The maximum thermal conductivity (0.51W/m.K) was obtained before the immersion in water at 90 days for epoxy reinforcement by bi-directional glass fiber and SiC particl

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Publication Date
Tue Mar 01 2016
Journal Name
Journal Of Engineering
Critical Success Factors in Construction Projects (Governmental Projects as a Case Study)

The importance of the construction sector and its Great role in the provision of services and infrastructure, reduce poverty, improve living conditions and improve the economic situation in the country, impose attention to the way in which the projects implemented for its improvement and to get successful projects. The objective of this research was to determine the criteria for success as well as critical success and failure factors that have a significant impact on project success. A selected 75 engineer (department managers, project managers and engineers) are asked to fill  the questionnaire form, Sixty-seven valid questionnaire forms were analyzed statistically to get search results, which were as follows : Twe

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Publication Date
Sat Jun 06 2020
Journal Name
Journal Of The College Of Education For Women
A Critical Pragmatic Study of Racism as Conceptualized in the Glorious Quran

Racism changes its meaning, shape, purpose or function according to various factors such as time, place, motives, and backgrounds; among others. It seems, however, to have deep roots back in the history of mankind. Such a concept stems from a perceived difference with the other. It is fed by the feeling of being hierarchically superior in opposition to another party that is depicted as inferior. Since ancient times, racism is disguised in different forms and manifests itself on various levels. It is a truism that this ideology can be best presented via language.

Due to its negative implication, racism lends itself to a critical kind of research.  As such, this paper is a critical pragmatic investigation for this phenomenon a

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Publication Date
Thu Oct 31 2024
Journal Name
Mathematical Modelling Of Engineering Problems
Investigating the Effects of Canard Dihedral Angle on the Wing Span Loading in a Forward-Swept Wing Aircraft at Transonic Speeds at Steady State Conditions Using Computational Fluid Dynamics

Forward-swept wings were researched and introduced to improve maneuverability, control, and fuel efficiency while reducing drag and they are often used alongside canards, to further enhance their characteristics. In this research, the effects of canard dihedral angles on the wing loading of a forward-swept wing in transonic flow conditions were studied, as the wing loading provides a measure of wing’s efficiency (lift/drag). A generic aircraft model from literatures was selected, simulated, and compared to, using CFD software ANSYS/Fluent where the flow equations were solved to calculate the aerodynamic characteristics. The research was carried at two different Mach numbers, 0.6 and 0.9, for five different canard dihedral angles which tra

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Publication Date
Wed Mar 28 2018
Journal Name
Iraqi Journal Of Science
Determination of Lateral Hydraulic Connection of the Regional Aquifers in the Western Desert-Iraq using Hydrochemical and Hydrogeological data

     In this study, lateral groundwater inflow was examined, according to the phenomena of groundwater mixing, groundwater flow and groundwater chemistry. The study region is composed of different aquifer systems; including karst-fracture media (Rattga-Jeed carbonates aquifer), fissure–porous media (Mullusi, Mullusi-Ubaid, Hartha-Rutba, and Digma-Tayarat aquifers) and porous media (Permo-carboniferous clastics rocks of Ga’ra aquifer).The aquifers are vertically super-imposed or of lateral contacts make open hydraulic connection between aquifers system. There is a severe shortage of water resources in the region because of rare precipitation and strong evapotranspiration. These conditions have hampered eco-environm

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Publication Date
Wed Nov 20 2024
Journal Name
Philosophy Journal
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