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Aircraft Lateral-Directional Stability in Critical Cases via Lyapunov Exponent Criterion
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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
Wed Jan 08 2020
Journal Name
International Journal Of Advanced Science And Technology
The local stability of an eco-epidemiological model involving a harvesting on predator population
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In this paper a prey - predator model with harvesting on predator species with infectious disease in prey population only has been proposed and analyzed. Further, in this model, Holling type-IV functional response for the predation of susceptible prey and Lotka-Volterra functional response for the predation of infected prey as well as linear incidence rate for describing the transition of disease are used. Our aim is to study the effect of harvesting and disease on the dynamics of this model.

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Publication Date
Wed Jan 01 2020
Journal Name
Journal Of Clinical And Experimental Dentistry
The effect of osseodensification on implant stability and bone density: A prospective observational study
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Background: The aims of this study were to evaluate the effect of implant site preparation in low-density bone using osseodensification method in terms of implant stability changes during the osseous healing period and peri-implant bone density using CBCT. Material and methods: This prospective observational clinical study included 24 patients who received 46 dental implants that were installed in low-density bone using the osseodensification method. CBCT was used to measure the bone density pre- and postoperatively and implant stability was measured using Periotest® immediately after implant insertion and then after 6 weeks and 12 weeks postoperatively. The data were analyzed using paired t-test and the probability value <0.05 was conside

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Publication Date
Sun Jul 01 2018
Journal Name
Vacuum
Stability, electronic and vibrational properties of GaAlN wurtzoid molecules and nanocrystals: A DFT study
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Publication Date
Sat Dec 01 2018
Journal Name
Al-khwarizmi Engineering Journal
Vibration Analysis of Cross-Ply Plates Under Initial Stress Using Refined Theory
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Natural frequency under initial stresses for simply supported cross-ply composite laminated plates (E glass- fiber) are obtained using Refind theory (RPT). This theory accounts for parabolic distribution of the transverse shear strain through the plate thickness and satisfies the zero traction boundary conditions on the surfaces of the plate without using shear correction factors. The governing equations for Eigen value problem under initial stress are derived using Hamilton’s principle and solved using Navier solution for simply supported cross-ply symmetric and antisymmetric laminated plates. The effect of many design factors such as modulus ratio, thickness ratio and number of laminates on the Natural frequency and buckling stresses

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Publication Date
Wed Dec 27 2017
Journal Name
Al-khwarizmi Engineering Journal
The Determination of Critical-Sampling Scheme of Preprocessing for Multiwavelets Decomposition as 1st and 2nd Orders of Approximations.
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One of the important differences between multiwavelets and scalar wavelets is that each channel in the filter bank has a vector-valued input and a vector-valued output. A scalar-valued input signal must somehow be converted into a suitable vector-valued signal. This conversion is called preprocessing. Preprocessing is a mapping process which is done by a prefilter. A postfilter just does the opposite.

The most obvious way to get two input rows from a given signal is to repeat the signal. Two rows go into the multifilter bank. This procedure is called “Repeated Row” which introduces oversampling of the data by a factor of 2.

 For data compression, where one is trying to find compact transform representations for a

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Publication Date
Tue May 30 2023
Journal Name
Rawal Medical Journal
Elevated lactate dehydrogenase (LDH) and C- reactive protein (CRP) level as a risk factor for critical COVID-19
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Abstract Objective: To identify correlation of elevated LDH & CRP levels with the outcomes of COVID-19. Methodology: The cross-sectional retrospective study consisted of 200 COVID-19 patients who presented at a private clinical in Baghdad, Iraq. It was carried out from February 2021 to February 2022. Data included age, gender and clinical presentation. Blood samples were taken for high sensitivity CRP and LDH in the serum. Results: Out of 200 patients, 50 were critical and 150 severe according to clinical features. LDH and CRP showed a significant increase (p=0.000) in critical patients. This group involved admission to the respiratory intensive care unit requiring mechanical ventilation than in patients with severe COVID-19 (760.5±6.3 vs.

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Publication Date
Tue Sep 05 2023
Journal Name
Al-rafidain Journal Of Medical Sciences ( Issn 2789-3219 )
Protective Health Behaviors among Critical Care Nurses Concerning Pressure Ulcer Prevention for Hospitalized Patients at Baghdad Teaching Hospitals
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Background: Pressure ulcers remain a serious complication for immobile patients and a burden for healthcare professionals. Objectives: To assess health behavior prevention among critical care nurses regarding pressure ulcer prevention for hospitalized patients and to find out the relationship between critical care nurses health behavior prevention and sociodemographic variables. Methods: A cross-sectional design study was carried out in critical care units at three teaching hospitals. The study period extended from November 1, 2022, to January 28, 2023. Non-probability purposive sampling, whose target population was 100 nurses who work in critical care units in Baghdad, Iraq. The data were collected using a self-administered questio

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Publication Date
Sun Mar 28 2021
Journal Name
Journal Of The College Of Education For Women
A Critical Discourse Analysis of Martin Crimp’s Piece “Advice to Iraqi Women”: عفراء عبد الحسين ناصر , سراب خليل
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Language is a vehicle for social values and ideologies that a man intends or attempts to express. Dramatic texts are one of the discursive practices that embody values and ideologies. What is expressed in dramatic text is deliberate because it is meant to affect other’s values, trends and ideologies in one way or another. Such ideologies and values are not explicit. To bring them out requires putting language under scrutiny to unveil what is implied. The present study attempts to analyze a dramatic script entitled Advice to Iraqi Women by the British playwright Martin Crimp in an attempt to unveil the intended political ideologies underlying the text. The title reflects a political aspect embedded in the word “Iraqi” that

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Publication Date
Mon Apr 01 2024
Journal Name
Journal Of Environmental Chemical Engineering
A critical review describes wastewater photocatalytic detoxification over Bi5O7I-based heterojunction photocatalysts: Characterizations, mechanism insight, and DFT calculations
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Publication Date
Sun Oct 01 2023
Journal Name
Baghdad Science Journal
The Influence of Ablation Speed on the Synthesis of Carbon Nanostructures Via Pulsed Laser Ablation of Asphalt in Ethanol
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Pulsed liquid laser ablation is considered a green method for the synthesis of nanostructures because there are no byproducts formed after the ablation. In this paper, a fiber laser of wavelength 1.064 µm, peak power of 1 mJ, pulse duration of 120 ns, and repetition rate of 20 kHz, was used to produce carbon nanostructures including carbon nanospheres and carbon nanorods from the ablation of asphalt in ethanol at ablation speeds of (100, 75, 50, 10 mm/s).  The morphology, composition and optical properties of the synthesized samples were studied experimentally using FESEM, HRTEM, EDS, and UV-vis spectrophotometer. Results showed that the band gap energy decreased with decreasing the ablation speed (increasing the ablation time), the mi

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