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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
Thu Nov 30 2023
Journal Name
Iraqi Journal Of Science
Mean Square Exponential Stability of Semi-Linear Stochastic Perturbed Differential Equation Via Lyapunov Function Approach

    In this work, a class of stochastically perturbed differential systems with standard Brownian motion of ordinary unperturbed differential system is considered and studied. The necessary conditions for the existence of a unique solution of the stochastic perturbed semi-linear system of differential equations are suggested and supported by concluding remarks. Some theoretical results concerning the mean square exponential stability of the nominal unperturbed deterministic differential system and its equivalent stochastically perturbed system with the deterministic and stochastic process as a random noise have been stated and proved. The proofs of the obtained results are based on using the stochastic quadratic Lyapunov function meth

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Publication Date
Sun Oct 01 2023
Journal Name
Baghdad Science Journal
Nonlinear Ritz Approximation for the Camassa-Holm Equation by Using the Modify Lyapunov-Schmidt method

 

          In this work, the modified Lyapunov-Schmidt reduction is used to find a nonlinear Ritz approximation of Fredholm functional defined by the nonhomogeneous Camassa-Holm equation and Benjamin-Bona-Mahony. We introduced the modified Lyapunov-Schmidt reduction for nonhomogeneous problems when the dimension of the null space is equal to two.  The nonlinear Ritz approximation for the nonhomogeneous Camassa-Holm equation has been found as a function of codimension twenty-four.

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Publication Date
Sat Dec 01 2012
Journal Name
Journal Of Economics And Administrative Sciences
Scheduling Critical Activities of Stochastic Projects Management

In this paper, we consider the problem of stochastic project network when some or all activities are interrupted. An approach has been built to schedule the critical activities, by constructing some expressions based on the project lateness costs due to the interruption activities. Two simple example are presented to validate our approach.

Key words: Project Management, Project scheduling, Stochastic activity duration, Stochastic PERT.    

Introduction

   Recently, Projects planning and optimal timing, under uncertainty are extremely critical for many organizations, see [19]. Having an effective mathematical model wi

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Publication Date
Thu Dec 31 2015
Journal Name
Al-khwarizmi Engineering Journal
Hexapod Robot Static Stability Enhancement using Genetic Algorithm

Abstract

Hexapod robot is a flexible mechanical robot with six legs. It has the ability to walk over terrain. The hexapod robot look likes the insect so it has the same gaits. These gaits are tripod, wave and ripple gaits. Hexapod robot needs to stay statically stable at all the times during each gait in order not to fall with three or more legs continuously contacts with the ground. The safety static stability walking is called (the stability margin). In this paper, the forward and inverse kinematics are derived for each hexapod’s leg in order to simulate the hexapod robot model walking using MATLAB R2010a for all gaits and the geometry in order to derive the equations of the sub-constraint workspaces for each

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Publication Date
Thu Jan 02 2014
Journal Name
Journal Of The Faculty Of Medicine Baghdad
Lupus Nephritis, the therapy and the role of Rituximab in resistant cases

Background Systemic lupus erythematosus (SLE) is a common autoimmune disease that affects mainly young females and nephritis is an important complication of the disease that may end with end stage renal disease (ESRD). Early diagnosis and proper treatment is important in decreasing the morbidity. Multiple immunesupressor agents used and according to the histopathology stage of the disease, still the proper drug used and the duration and dose required not settled. Rituximab which is monoclonal antibody that reacts against CD20 antigen on lymphocytes that cause B cells depletion is recently introduced in treatment of lupus nephritis .

Objectives: to see the effect of different immunosuppressive age

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Publication Date
Mon Mar 11 2019
Journal Name
Baghdad Science Journal
Results on a Pre-T_2 Space and Pre-Stability

This paper contains an equivalent statements of a pre-  space, where  are considered subsets of with the product topology. An equivalence relation between the preclosed set  and a pre-  space, and a relation between a pre-  space and the preclosed set  with some conditions on a function  are found. In addition, we have proved that the graph  of  is preclosed in if  is a pre-  space, where the equivalence relation  on  is open.

     On the other hand, we introduce the definition of a pre-stable ( pre-stable) set by depending on the concept of a pre-neighborhood, where we get that every stable set is pre-stable. Moreover, we obtain that

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Publication Date
Sun Feb 21 2021
Journal Name
Journal Of The Faculty Of Medicine Baghdad
Artifacts in electrocardiogram interpreted as cardiac arrhythmias: Reports of clinical cases

Background: Artifact waves in the ECG and Holter recording are not rare in clinical practice and can be mistaken for tachyarrhythmia.

Objective: To orient the practicing physicians to differentiate these artifacts from cardiac arrhythmias.

Patients and Methods: Thirteen patients with incorrectly diagnosed cardiac arrhythmias by ECG or Holter recording then distinguished to be ECG artifacts were included in this study. The patients were collected from the author’s private practice in the northern Iraqi governorate of Sulaimanya during the period from June 2015 to August 2020. The differentiation of the artifact waves from the arrhythmias were made by careful inspection o

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Publication Date
Tue Jun 30 2015
Journal Name
Iraqi Journal Of Market Research And Consumer Protection
Possibilty Of Implementing Hazard Analysis Critical Control Points (HACCP) In One Of Local Dairy Plants.: Possibilty Of Implementing Hazard Analysis Critical Control Points (HACCP) In One Of Local Dairy Plants.

To limit or reduce common microbial contamination occurrence in dairy products in general and in soft cheese in particular, produced in locally plants, this study was performed to demonstrate the possibility of implementing HACCP in one of dairy plants in Baghdad city

            HACCP plan was proposed in soft cheese production line. A pre-evaluation was performed in soft cheese line production, HACCP Pre-requisites programs was evaluated from its presence and effectiveness. The evaluation was demonstrated risk in each of: Good Manufacturing Practice (GMP) program, evaluated as microbial and physical risk and considered as critical r

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Publication Date
Thu Oct 31 2013
Journal Name
Al-khwarizmi Engineering Journal
Enhancement of a Power System Transient Stability Using Static Synchronous Series Compensator SSSC

Static Synchronous Series Compensator (SSSC) is a well known device for effectively regulating the active power flow in a power system. In this paper, the SSSC linearized power flow equations are incorporated into Newton-Raphson algorithm in a MATLAB written program to investigate the control of active poweer flow and the transient stability of a five bus and a thirty bus IEEE test systems, during abnormal conduction (three phase fault near buses). A comparison of the results obtained for the base case without SSSC and with it to investigate the effectiveness of the device on both of the active power flow and the transient stability.

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Publication Date
Wed Dec 13 2023
Journal Name
Iraqi National Journal Of Nursing Specialties
Nurses Knowledge and Performance Toward Physical Restraint at Critical Care Units

      Abstract:

Objective: The study was done to evaluate nurses’ knowledge and practices toward physical restraint at critical care unit

Methodology: Fifty nurses, who were selected by a non-probability (convenient) sampling method, participated in this descriptive study. The instrument of the study was knowledge parts of the questionnaire were initially developed in the U.S.A for nursing homes; in 2006 they were adopted for all hospital units by the original developers. The knowledge section of the questionnaire consisted of 20 items, which were used to measure knowledge of nurses towards the definition, indications and contra

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