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A Comparative Study for Estimate Fractional Parameter of ARFIMA Model

      Long memory analysis is one of the most active areas in econometrics and time series where various methods have been introduced to identify and estimate the long memory parameter in partially integrated time series. One of the most common models used to represent time series that have a long memory is the ARFIMA (Auto Regressive Fractional Integration Moving Average Model) which diffs are a fractional number called the fractional parameter. To analyze and determine the ARFIMA model, the fractal parameter must be estimated. There are many methods for fractional parameter estimation. In this research, the estimation methods were divided into indirect methods, where the Hurst parameter is estimated first, and then the fractional integration parameter is estimated from it by a relation between them. As for direct methods, the fractional integration parameter is estimated directly without relying on Hurst's parameter, and most of them are semi parametric methods. In this paper, some of the most common direct methods were used to estimate the fraction modulus namely (Geweke-Porter-Hudak, Smoothed Geweke-Porter-Hudak, Local Whittle, Wavelet and weighted wavelet), using simulation method with different value of (d) and different size of time series. The comparison between the methods was done using the mean squared error (MSE). It turns out that the best methods to estimate the fractional parameter is (Local Whittle).

      The ARFIMA model was generated by a function programmed by the MATLAB statistical program

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Publication Date
Sun Mar 01 2009
Journal Name
Baghdad Science Journal
Evaluation of the electron correlation for lithium atom (Li) in ground state

The aim of this work is to study the correlation between the electrons for Li atom in ground state through the calculation of the inter-particle distribution function f (r12) and inter-particle expectation values . By using the f(r12) function for KL shell in both singlet and triplet state .The Fermi hole have been evaluated .In this work the Hartree-Fock wave function (1993) have been used.

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Publication Date
Thu May 11 2017
Journal Name
Ibn Al-haitham Journal For Pure And Applied Sciences
Using Gamma Ray Transmission for Determination of Porosity in Doped Alumina Samples

     In this study, gamma ray transmission method have been used to determine the total porosity in four samples: pure Alumina  ( Al2O3   ),  Al2O3 + (0.2wt%)MgO ,  Al2O3 + (0.6wt% )Y2O3  and Al2O3+ (8wt% ) ZrO2 .

      The experimental setup for the gamma ray transmission consist of 137Cs gamma source ( 662 KeV  ), a  NaI (Tl) scintillation detector measured the attenuation of strongly collimated  gamma beam through alumina samples.

The porosity obtained by the gamma ray transmission method were compare

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Publication Date
Tue Jun 15 2021
Journal Name
Al-academy
Diversity of design methods for global competitive advertising: عمار صباح شاكر ناجي

As a result of the development and global openness and the possibility of companies providing their services outside their spatial boundaries that were determined by them, and the transformation of the world due to the development of the means of communication into a large global market that accommodates all products from different regions and of the same type and production field, competition resulted between companies, and the race to obtain the largest market share It ensures the largest amount of profits, and it is natural for the advertising promotion by companies for their product to shift from an advertisement for one product to a competitive advertisement that calls on the recipient to leave the competing product and switch to it

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Publication Date
Wed Jun 27 2018
Journal Name
Iraqi Journal Of Science
Coefficient Bounds for Certain Subclass of Analytic Functions Defined By Quasi-Subordination

In this paper, we define certain subclasses of analytic univalent function associated with quasi-subordination. Some results such as coefficient bounds and Fekete-Szego bounds for the functions belonging to these subclasses are derived.

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Publication Date
Thu Apr 27 2017
Journal Name
Ibn Al-haitham Journal For Pure And Applied Sciences
Numerical Solutions Of The Nonlocal Problems For The Diffusion Partial Differential Equations

    In this work, we use the explicit and the implicit finite-difference methods to solve the nonlocal problem that consists of the diffusion equations together with nonlocal conditions. The nonlocal conditions for these partial differential equations are approximated by using the composite trapezoidal rule, the composite Simpson's 1/3 and 3/8 rules. Also, some numerical examples are presented to show the efficiency of these methods.

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Publication Date
Wed Aug 30 2023
Journal Name
Iraqi Journal Of Science
Evaluation of Climate Change Indicators for Bagdad City Using Remote Sensing Technology

Climate change is a severe problem due to the continuous dynamic changes in urbanization in cities, and reaching it requires high-resolution spatial data represented by using remote sensing technology, as the data of the Space Science Network of NASA was relied on to measure the change in the climate of Baghdad city for a period of four decades 1981-2021, using the climate change equation referred to in the research and then tabulating the data in Excel. The results showed evident changes in the climatic rates, especially during the fourth time cycle; the high rates of temperature and low rates of relative humidity and precipitation indicate that the city’s climate is heading towards drought, and similarities appeared between the rates

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Publication Date
Tue Mar 30 2021
Journal Name
Iraqi Journal Of Science
Wang-Ball Polynomials for the Numerical Solution of Singular Ordinary Differential Equations

This paper presents a new numerical method for the solution of ordinary differential equations (ODE). The linear second-order equations considered herein are solved using operational matrices of Wang-Ball Polynomials. By the improvement of the operational matrix, the singularity of the ODE is removed, hence ensuring that a solution is obtained. In order to show the employability of the method, several problems were considered. The results indicate that the method is suitable to obtain accurate solutions.

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Publication Date
Sat Mar 31 2018
Journal Name
Journal Of Engineering
Estimation of Minimum Miscibility Pressure for 〖CO〗_2 Flood Based on EOS

CO2 Gas is considered one of the unfavorable gases and it causes great air pollution. It’s possible to decrease this pollution by injecting  gas in the oil reservoirs to provide a good miscibility and to increase the oil recovery factor. MMP was estimated by Peng Robinson equation of state (PR-EOS). South Rumila-63 (SULIAY) is involved for which the miscible displacement by  is achievable based on the standard criteria for success EOR processes. A PVT report was available for the reservoir under study. It contains deferential liberation (DL) and constant composition expansion (CCE) tests.  PVTi software is one of the (Eclipse V.2010) software’s packages, it has been used to achieve the goal.

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Publication Date
Thu Jun 01 2023
Journal Name
Journal Of Engineering
The Effect of Rubber Crumbs on Marshall Properties for Warm Mix Asphalt

A new pavement technology has been developed in Highway engineering: asphalt pavement production is less susceptible to oxidation and the consequent damages. The warm mix asphalt (WMA) is produced at a temperature of about (10-40) oC lower than the hot asphalt paving. This is done using one of the methods of producing a WMA. Although WMA's performance is rather good, according to previous studies, as it is less susceptible to oxidation, it is possible to modify some of its properties using different materials, including polymers. Waste tires of vehicles are one of the types of polymers because of their flexible properties. The production of HMA, WMA, and WMA modified with proportions of (1, 1.5, and 2%) of rub

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Publication Date
Wed Apr 01 2009
Journal Name
Journal Of The Faculty Of Medicine Baghdad
The Value of the chest X-Ray for diagnosing left ventricular Dysfunction

Background: The use of the chest x-ray measurements which includes the cardiothoracic ratio(C-T) and frontal area (FA) of the heart by the CXR are useful measures for primary assessment of the cardiac dysfunction.
Patients and Methods: A Prospective study was done from the 1st of January 2005 to the 1st of October in the same year on a 120 consecutive patients who have been admitted for coronary and L.V angiogram at IBN-AL-BITAR hospital. The C-T ratio and the frontal area were measured.
Results: The study comprised 120 subjects who were admitted for coronary and L.V angiogram for diagnostic reasons. 89subjects (74.2%) are male and 31subjects (25.8%) are female .17(14%) subjects have left ventricular d

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