Yousif Shoaib Mohammed - Academia.edu (original) (raw)

Papers by Yousif Shoaib Mohammed

American Journal of Physics and Applications, 2016

In this work, we are presenting the results of radium concentration, surface and mass radon exhal... more In this work, we are presenting the results of radium concentration, surface and mass radon exhalation rates for a number of 209 soil samples collected from different locations of Kassala town, Sudan, by using the can technique, containing CR-39. The values of radium concentrations from soil samples were found to be ranging from 3.9 to 34.2 Bq.kg-1 , with an average of 16.3 ± 1.6 Bq.kg-1. The surface and mass exhalation rates of radon were found to be from 0.84 to 7.35 Bq.m-2 .h-1 and 17 to 148 mBq.kg-1 .h-1 , with an averages of 3.50 ± 0.35 Bq.m-2 .h-1 and 70 ± 7 mBq.kg-1 .h-1 , respectively for the studied soil samples. From the results of this study we found that, there was a good correlation between radium concentration and radon exhalation rates in soil samples. The values of radium concentration determined in soil samples are less than the permissible value of 370 Bq.kg-1 recommended by Organization for Economic Cooperation and Developments, which is acceptable for safe use. Thus, results reveal that the area is safe as far the health hazard effects are concerned. Finally we compare our results with similar findings in different regions of Sudan and among other Countries.

Neurocomputing, 2017

ℓ p regularization has been a popular pruning method for neural networks. The parameter p was usu... more ℓ p regularization has been a popular pruning method for neural networks. The parameter p was usually set as p 0 < ≤ 2 in the literature, and practical training algorithms with ℓ 0 regularization are lacking due to the NPhard nature of the ℓ 0 regularization problem; however, the ℓ 0 regularization tends to produce the sparsest solution, corresponding to the most parsimonious network structure which is desirable in view of the generalization ability. To this end, this paper considers an online gradient training algorithm with smoothing ℓ 0 regularization (OGTSL0) for feedforward neural networks, where the ℓ 0 regularizer is approximated by a series of smoothing functions. The underlying principle for the sparsity of OGTSL0 is provided, and the convergence of the algorithm is also theoretically analyzed. Simulation examples support the theoretical analysis and illustrate the superiority of the proposed algorithm.

In this study we investigate the current status of physical education Curriculum in Sudanese High... more In this study we investigate the current status of physical education Curriculum in Sudanese High Secondary schools. The main tools for collecting data in this research are analyzing educational polices, Questionnaires and Interviews. Our questionnaire form contains 5 parts for our most important 18 items, and the sample size are 60 forms. The Cranach alpha coefficient for identification equals to 0.8570 which confirms the stability of resolution and suitability for use. The Statistical Software (SPSS) also used for analyzing our questionnaire data. We found that the main problem facing physical education and sport activities in Sudanese High Secondary schools is the absence of the special physical educations curriculum. In addition to that, the shortage in the textbook of physical education, and the scarcity of the physical education teachers at high schools.

Advances in Applied Science Research, 2015

First-principles calculations are performed to study the electronic structures and magnetic prope... more First-principles calculations are performed to study the electronic structures and magnetic properties of nonmagnetic B-doped ZnO. We investigate the following three cases: (i) single B atom substituted at Zn site, (ii) single B atom substituted at O site, and (iii) two B atoms substituted at O sites. Both generalized gradient approximation (GGA) and GGA+U calculations show that a substitutional B atom at Zn sites is non-magnetic. While a substitutional B atom at O site introduces magnetic moment of about 3.0 µB, respectively. The magnetic moment mainly comes from the partially occupied 2p orbitals of substitutional B, its nearest neighboring Zn and second neighboring O atoms, and the biggest atomic moment is of B. The U correction for the 3d Zn and for the 2p O and B states obviously changes the magnetic moment of the B atom. Total energy calculations show that the antiferromagnetic (AFM) state is predicted to be the ground state for all configuration systems.

Electronic structure and magnetic moments of (Boron) B-doped ZnO was investigated by ab initio el... more Electronic structure and magnetic moments of (Boron) B-doped ZnO was investigated by ab initio electronic structure calculations based on the density functional theory (DFT) with the generalized gradient approximation (GGA). We also performed GGA+U calculations to further refine our results. It is found that single B atom at O site in ZnO becomes spin polarized with its many neighboring atoms with a total magnetic moment of 0.94 and 1.27 μB for GGA and GGA+U respectively. The magnetic coupling between doped B atoms is substantial leading to either antiferromagnetism or ferromagnetism with GGA+U. For the B-B distance is 7.942 Å by replacing two oxygen atoms at the opposite vertices of a ZnO wutizte. A strong antiferromagnetic coupling occurs.

Physica Status Solidi B-basic Solid State Physics, Oct 1, 2002

ABSTRACT Spin polarization is investigated for Cr/Mn systems at T = 0 K using real-space tight-bi... more ABSTRACT Spin polarization is investigated for Cr/Mn systems at T = 0 K using real-space tight-binding approach. The magnetism is described in the Hartree-Fock approximation of Hubbard Hamiltonian and the local density of states is calculated within the recursion technique. The magnetic moments for bulk Cr, and Crn/Mn interfaces for n = 1–3 overlayers with and without relaxation for low index crystallographic orientations are calculated. The antiferromagnetic ground state is considered for Mn (Cr) structures. The magnetism is most favored in the (111) orientation, whereas it has the least value in (011) orientation in all systems due to the coordination.

Transactions on Machine Learning and Artificial Intelligence, Dec 31, 2018

The description of this study is to make possibility analysis solution of online gradient method ... more The description of this study is to make possibility analysis solution of online gradient method with smoothing 0 regularization for pi-sigma network training. Due to the effectiveness computational and theoretical analysis are a very important issues to improve the generalization performance of networks and the gradient descent algorithm with regularization is widely used method. However, 0 regularization is reefed to NP-hard nature problems, which has not differentiable objective functional-penalty term. In this paper to avoid this trick, we use a smoothing function to recover the origin 0 regularization into smoothing 0 regularization. Under this condition, the resulting obtained as a good decreases solution when compared with others. The monotonically of the error function, weak and strong convergence theorems are proved.

Physics Letters, 2010

The electronic structure and magnetic properties of nonmagnetic phosphorus doped ZnO are investig... more The electronic structure and magnetic properties of nonmagnetic phosphorus doped ZnO are investigated using first-principles calculation. Both generalized gradient approximation (GGA) and GGA+U calculations show that each substitutional P atom in ZnO induces a magnetic moment of about 1.0 μ B , which come mainly from the partially filled p orbitals of the substitutional P and its 12 second neighboring O atoms. The magnetic coupling between the moments induced by P doping is ferromagnetic. The calculated electronic structures indicate that the ferromagnetic coupling can be explained in terms of the two band coupling model.

Journal of Magnetism and Magnetic Materials, Mar 1, 2009

The effects of Co dopants and oxygen vacancies on the electronic structure and magnetic propertie... more The effects of Co dopants and oxygen vacancies on the electronic structure and magnetic properties of the Co-doped SnO 2 are studied by the first-principle calculations in full-potential linearized augmented plane wave formalism within generalized gradient approximations. The Co atoms favorably substitute on neighboring sites of the metal sublattice. Without oxygen vacancies, the Co atoms are at low spin state independent of concentration and distribution of Co atoms, and only the magnetic coupling between nearest-neighbor Co atoms is ferromagnetic through direct exchange and super-exchange interaction. Oxygen vacancies tend to locate near the Co atoms. Their presence strongly increases the local magnetic moments of Co atoms, which depend sensitively on the concentration and distribution of Co atoms. Moreover, oxygen vacancies can induce the long-range ferromagnetic coupling between wellseparated Co atoms through the spin-split impurity band exchange mechanism. Thus the room temperature ferromagnetism observed experimentally in the Co-doped SnO 2 may originate from the combination of short-range direct exchange and super-exchange interaction and the long-range spin-split impurity band exchange model.

The Medical Journal of Basrah University, 2021

International Journal of Science and Research (IJSR)

This paper considers a batch gradient method with 𝑳𝟏⁄𝟐 regularization for Pi –sigma neural networ... more This paper considers a batch gradient method with 𝑳𝟏⁄𝟐 regularization for Pi –sigma neural networks. In origin, by introducing an 𝑳𝟏⁄𝟐 regularization term involves absolute value and is not differentiable into the error function. A key point of this paper, specifically, the smoothing 𝑳𝟏⁄𝟐 regularization is a term proportional to the norm of the weights. The role of the smoothing 𝑳𝟏⁄𝟐 regularization term is to control the magnitude of the weights and to improve the generalization performance of the networks. The weights are proved to be bounded during the training process, thus the conditions that are required for convergence analysis of batch gradient method in literature are simplified.

Physica B: Condensed Matter, 2002

We have investigated the magnetic ordering of Cr/Mn systems at T ¼ 0 K using real-space tight-bin... more We have investigated the magnetic ordering of Cr/Mn systems at T ¼ 0 K using real-space tight-binding approach. The magnetic moments of Cr n /Mn interfaces are calculated for n ¼ 123 overlayers in the crystallographic orientations (0 0 1), (1 1 1), and (0 1 1). The onset of magnetism depends on the faces considered. The magnetism is most favored in the (1 1 1) orientation, whereas it has the least value in (0 1 1) orientation in all systems due to the coordination.

Abstract- In this study we investigate the current status of

International Journal of Innovation and Applied Studies, 2014

In this paper, we study the convergence of offline gradient method with smoothing L_(1/2) regular... more In this paper, we study the convergence of offline gradient method with smoothing L_(1/2) regularization penalty for training multi-output feed forward neural networks. The monotonicity of the error function and weight boundedness for the offline gradient with smoothing L_(1/2) regularization. the usual L_(1/2) regularization term involves absolute value and is not differentiable at the origin. The key point of this paper is modify the usual L_(1/2) regularization term by smoothing it at the origin are presented, the convergence results are proved, which will be very meaningful for theoretical research or applications on multi

Results are presented of a first-principle calculat ion of the Density Functional Theory (DFT) fe... more Results are presented of a first-principle calculat ion of the Density Functional Theory (DFT) ferromagnetic (FM) face-centered cubic (fcc) of Nic kel Ni n (100) and (111) surfaces for n = 3, 5 and 7 layers. The relaxed and non-relaxed electroni c structures of both surfaces are determined with generalized gradient approximation (GGA) and generalized gradient approximation + Hubbard (GGA+U). The observed trends can be explained as in earlier studies in terms of the hybridization between d states of Ni substrate, als o some interesting specific behavior of the magnetization in the fcc Ni (100) and (111) surface s with different layers has been observed.

Advances in Applied Science Research, 2015

First-principles calculations are performed to study the electronic structures and magnetic prope... more First-principles calculations are performed to study the electronic structures and magnetic properties of nonmagnetic B-doped ZnO. We investigate the following three cases: (i) single B atom substituted at Zn site, (ii) single B atom substituted at O site, and (iii) two B atoms substituted at O sites. Both generalized gradient approximation (GGA) and GGA+U calculations show that a substitutional B atom at Zn sites is non-magnetic. While a substitutional B atom at O site introduces magnetic moment of about 3.0 μB, respectively. The magnetic moment mainly comes from the partially occupied 2p orbitals of substitutional B, its nearest neighboring Zn and second neighboring O atoms, and the biggest atomic moment is of B. The U correction for the 3d Zn and for the 2p O and B states obviously changes the magnetic moment of the B atom. Total energy calculations

Electronic structure and magnetic moments of (Boron) B-doped ZnO was investigated by ab initio el... more Electronic structure and magnetic moments of (Boron) B-doped ZnO was investigated by ab initio electronic structure calculations based on the density functional theory (DFT) with the generalized gradient approximation (GGA). We also performed GGA+U calculations to further refine our results. It is found that single B atom at O site in ZnO becomes spin polarized with its many neighboring atoms with a total magnetic moment of 0.94 and 1.27 μB for GGA and GGA+U respectively. The magnetic coupling between doped B atoms is substantial leading to either antiferromagnetism or ferromagnetism with GGA+U. For the B-B distance is 7.942 A by replacing two oxygen atoms at the opposite vertices of a ZnO wutizte. A strong antiferromagnetic coupling occurs.

American Journal of Physics and Applications, 2016

Neurocomputing, 2017

Advances in Applied Science Research, 2015

Physica Status Solidi B-basic Solid State Physics, Oct 1, 2002

Transactions on Machine Learning and Artificial Intelligence, Dec 31, 2018

Physics Letters, 2010

Journal of Magnetism and Magnetic Materials, Mar 1, 2009

The Medical Journal of Basrah University, 2021

International Journal of Science and Research (IJSR)

Physica B: Condensed Matter, 2002

Abstract- In this study we investigate the current status of

International Journal of Innovation and Applied Studies, 2014

Advances in Applied Science Research, 2015

First-principles calculations are performed to study the electronic structures and magnetic prope... more First-principles calculations are performed to study the electronic structures and magnetic properties of nonmagnetic B-doped ZnO. We investigate the following three cases: (i) single B atom substituted at Zn site, (ii) single B atom substituted at O site, and (iii) two B atoms substituted at O sites. Both generalized gradient approximation (GGA) and GGA+U calculations show that a substitutional B atom at Zn sites is non-magnetic. While a substitutional B atom at O site introduces magnetic moment of about 3.0 μB, respectively. The magnetic moment mainly comes from the partially occupied 2p orbitals of substitutional B, its nearest neighboring Zn and second neighboring O atoms, and the biggest atomic moment is of B. The U correction for the 3d Zn and for the 2p O and B states obviously changes the magnetic moment of the B atom. Total energy calculations

Electronic structure and magnetic moments of (Boron) B-doped ZnO was investigated by ab initio el... more Electronic structure and magnetic moments of (Boron) B-doped ZnO was investigated by ab initio electronic structure calculations based on the density functional theory (DFT) with the generalized gradient approximation (GGA). We also performed GGA+U calculations to further refine our results. It is found that single B atom at O site in ZnO becomes spin polarized with its many neighboring atoms with a total magnetic moment of 0.94 and 1.27 μB for GGA and GGA+U respectively. The magnetic coupling between doped B atoms is substantial leading to either antiferromagnetism or ferromagnetism with GGA+U. For the B-B distance is 7.942 A by replacing two oxygen atoms at the opposite vertices of a ZnO wutizte. A strong antiferromagnetic coupling occurs.