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A Comparative Study of Some Methods of Estimating Robust Variance Covariance Matrix of the Parameters Estimated by (OLS) in Cross-Sectional Data
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Abstract

The Classical Normal Linear Regression Model Based on Several hypotheses, one of them is Heteroscedasticity as it is known that the wing of least squares method (OLS), under the existence of these two problems make the estimators, lose their desirable properties, in addition the statistical inference becomes unaccepted table. According that we put tow alternative,  the first one is  (Generalized Least Square) Which is denoted by (GLS), and the second alternative is to (Robust covariance matrix estimation) the estimated parameters method(OLS), and that the way (GLS) method neat and certified, if the capabilities (Efficient) and the statistical inference Thread on the basis of an acceptable but this method requires knowledge and knowledge of the nature of the problem and the private model of the problem, whether the Heteroscedasticity otherwise, the method (GLS) become inappropriate. The second alternative is a matrix contrast common variation fortified it does not require prior knowledge of the nature of your problem model, it's also an easy way and by this method has met with popular and interest in more than two decades by researchers, that the estimated of Robust covariance matrix the estimated parameters method(OLS), shall be according to data that is handled type, and we have dealt with in this study, cross-sectional data where the problem of Heteroscedasticity in contrast may be contained therein(Heteroscedasticity- Consistent Covariance matrix Estimation) and symbolized by the (HCCME) and includes many ways, and we have dealt with in our study of these methods  

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Publication Date
Tue Mar 30 2021
Journal Name
Journal Of Economics And Administrative Sciences
Employing the indicators of stereotypes and the dimensions of organizational clarity and their role in achieving the planned organizational behavior Analytical study on a sample of workers in some departments of the Faculties of Engineering, University of
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The current research examines the employment of indicators of stereotypes and the dimensions of organizational clarification to achieve planned organizational behaviour on a sample of employees in a number of departments of the Faculties of Engineering, University of Kufa, for a sample of (122) teaching staff. This research proposes the use of positive indicators of stereotypes for both the organization and employees and their awareness of what they want to obtain and what should be done for both parties and the removal of organizational clarity represented by the functional dimension that explores to what degree the employee's understanding of the internal strategy of the organization and the strategic dimension that searches fo

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Publication Date
Tue Dec 01 2009
Journal Name
Iraqi Journal Of Physics
Study of Some Structural Properties of Porous Silicon Preparing by Photochemical Etching
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Abstract:Porous Silicon (PSi) has been produced in this work by using Photochemical (PC) etching process by using a hydrofluoric acid (HF) solution. The irradiation has been achieved using quartz- tungsten halogen lamp. The influence of various irradiation times on the properties of PSi اmaterial such as layer thickness, etching rate and porosity was investigated in this work too. The XRD has been studied to determine the crystal structure and the crystalline size of PSi material

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Publication Date
Wed Dec 30 2009
Journal Name
Iraqi Journal Of Physics
Study of Some Structural Properties of Porous Silicon Preparing by Photochemical Etching
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Porous Silicon (PSi) has been produced in this work by using Photochemical (PC) etching process by using a hydrofluoric acid (HF) solution. The irradiation has been achieved using quartz- tungsten halogen lamp. The influence of various irradiation times on the properties of PSi اmaterial such as layer thickness, etching rate and porosity was investigated in this work too.
The XRD has been studied to determine the crystal structure and the crystalline size of PSi material

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Publication Date
Sun Jan 01 2023
Journal Name
Inorganic Chemistry Communications
Detection of nitrotyrosine (Alzheimer's agent) by B24N24 nano cluster: A comparative DFT and QTAIM insight
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A nano-sensor for nitrotyrosine (NT) molecule was found by studying the interactions of NT molecule with new B24N24 nanocages. It was calculated using density functionals in this case. The predicted adsorption mechanisms included physical and chemical adsorption with the adsorption energy of −2.76 to −4.60 and −11.28 to −15.65 kcal mol−1, respectively. The findings show that an NT molecule greatly increases the electrical conductivity of a nanocage by creating electronic noise. Moreover, NT adsorption in the most stable complexes significantly affects the Fermi level and the work function. This means the B24N24 nanocage can detect NT as a Φ–type sensor. The recovery time was determined to be 0.3 s. The sensitivity of pure BN na

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Publication Date
Mon May 08 2017
Journal Name
Ibn Al-haitham Journal For Pure And Applied Sciences
Calculation the Cross Sections of 10B(n,p)10Be Reaction by Using the Reciprocity Theory for the First Excited State
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  In this study light elements 10B , 10Be for 10B(n,p)10Be reaction as well as proton energy from 0.987 MeV to 2.028 MeV with threshold energy (1.04MeV) are used according to the available data of reaction cross sections. The more recent cross sections data of 10Be(p,n)10B reaction is reproduced in fin steps in the specified energy range , as well as cross section (p,n) values were derived from the published data of (n,p) as a function of energy in the same fine energy steps by using the reciprocity theory of principle inverse reaction . This calculation involves only the first excited state of  10B , 10Be in the reactions 10Be(p,n)10B and  10B(n,p)10Be. 

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Publication Date
Fri Mar 01 2019
Journal Name
Al-khwarizmi Engineering Journal
Comparison Study of Electromyography Using Wavelet and Neural Network
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In this paper we present a method to analyze five types with fifteen wavelet families for eighteen different EMG signals. A comparison study is also given to show performance of various families after modifying the results with back propagation Neural Network. This is actually will help the researchers with the first step of EMG analysis. Huge sets of results (more than 100 sets) are proposed and then classified to be discussed and reach the final.

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Publication Date
Tue Jan 19 2021
Journal Name
Isprs International Journal Of Geo-information
The Potential of LiDAR and UAV-Photogrammetric Data Analysis to Interpret Archaeological Sites: A Case Study of Chun Castle in South-West England
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With the increasing demands to use remote sensing approaches, such as aerial photography, satellite imagery, and LiDAR in archaeological applications, there is still a limited number of studies assessing the differences between remote sensing methods in extracting new archaeological finds. Therefore, this work aims to critically compare two types of fine-scale remotely sensed data: LiDAR and an Unmanned Aerial Vehicle (UAV) derived Structure from Motion (SfM) photogrammetry. To achieve this, aerial imagery and airborne LiDAR datasets of Chun Castle were acquired, processed, analyzed, and interpreted. Chun Castle is one of the most remarkable ancient sites in Cornwall County (Southwest England) that had not been surveyed and explored

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Publication Date
Tue Oct 01 2013
Journal Name
Journal Of Economics And Administrative Sciences
Determinants of economic growth in Arab Countries: An Empirical Study compared with South-east Asia
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The study addresses the problem of stagnation and declining economic growth rates in Arab countries since the eighties till today after the progress made by these countries in the sixties of the last century. The study reviews the e

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Publication Date
Fri May 31 2019
Journal Name
Journal Of Engineering
A Comparative Study of Various Intelligent Algorithms based Path Planning for Mobile Robots
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In general, path-planning problem is one of most important task in the field of robotics. This paper describes the path-planning problem of mobile robot based on various metaheuristic algorithms. The suitable collision free path of a robot must satisfies certain optimization criteria such as feasibility, minimum path length, safety and smoothness and so on. In this research, various three approaches namely, PSO, Firefly and proposed hybrid FFCPSO are applied in static, known environment to solve the global path-planning problem in three cases. The first case used single mobile robot, the second case used three independent mobile robots and the third case applied three follow up mobile robot.  Simulation results, whi

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Publication Date
Tue Dec 31 2019
Journal Name
Revue Académique De La Recherche Juridique
Compliance in Reality Television Programming Contracts -A Legal Study in light of the American Experience
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The development of the television industry has led to the emergence of a new type of entertainment program in which producers have abandoned stereotypes in traditional programs, known as (Reality TV show). This type of program has spread rapidly in America, (where there are more than 40 series of these programs), as well as Europe and more than twenty countries around the world, including the Arab countries, where the number of these programs today to about 1000 programs and the number is increasing , Especially with the readiness of the production networks to produce more of these programs for the huge profits they derive from them (because of the high viewing rates and the large number of ads broadcast through them) in return for low prod

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