A Generic Multi-Level Algorithm for Prioritized Multi-Criteria Decision Making

G., AlShorbagy,Eslam, Hamouda,A.S., Abohamama International Journal of Computer ScienceNetwork S 2023 International journal of computer science and netw Vol.23 No.1

Decision-making refers to identifying the best alternative among a set of alternatives. When a set of criteria are involved, the decision-making is called multi-criteria decision-making (MCDM). In some cases, the involved criteria may be prioritized by the human decision-maker, which determines the importance degree for each criterion; hence, the decision-making becomes prioritized multi-criteria decision-making. The essence of prioritized MCDM is raking the different alternatives concerning the criteria and selecting best one(s) from the ranked list. This paper introduces a generic multi-level algorithm for ranking multiple alternatives in prioritized MCDM problems. The proposed algorithm is implemented by a decision support system for selecting the most critical short-road requests presented to the transportation ministry in the Kingdom of Saudi Arabia. The ranking results show that the proposed ranking algorithm achieves a good balance between the importance degrees determined by the human decision maker and the score value of the alternatives concerning the different criteria.

Static analysis of nanobeams using nonlocal FEM

Amal E. Alshorbagy,M. A. Eltaher,F. F. Mahmoud 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.7

A very efficiently finite element model is developed for static analysis of nanobeams. Nonlocal differential equation of Eringen is exploited to reveal a scale effect of nanobeams through nonlocal Euler-Bernoulli beam theory. The equilibrium equation of nonlocal beam is derived based on the variational statement. The element stiffness matrix and force vector are presented. The novelty and accuracy of this model is presented and verified. It is found that, this model is more accurate than others and can consider as a benchmark. The effects of nonlocality, boundary conditions, and slenderness ratio are figured out. The deflection of multi-span nanobeam is also illustrated. The present model can be used for static analysis of single-walled carbon nanotubes. Complex geometry and nonlinear boundary conditions can also be included.

Open Transthoracic Plication of the Diaphragm for Unilateral Diaphragmatic Eventration in Infants and Children

Yasser Mubarak,Ashraf Alshorbagy 대한흉부외과학회 2015 Journal of Chest Surgery (J Chest Surg) Vol.48 No.5

Background: To evaluate our experience of early surgical plication for diaphragmatic eventration (DE) in infancy and childhood. Methods: This study evaluated infants and children with symptomatic DE who underwent plication through an open transthoracic approach in our childhood development department between January 2005 and December 2012. Surgical plication was performed in several rows using polypropylene U-stitches with Teflon pledgets. Results: The study included 12 infants and children (7 boys and 5 girls) with symptomatic DE (9 congenital and 3 acquired). Reported symptoms included respiratory distress (91.7%), wheezing (75%), cough (66.7%), and recurrent pneumonia (50%). Preoperative mechanical ventilatory support was required in 41.7% of the patients. The mean length of hospital stay was 6.3±2.5 days. The mean follow-up period was 24.3±14.5 months. Preoperative symptoms were immediately relieved after surgery in 83.3% of patients and persisted in 16.7% of patients one year after surgery. All patients survived to the end of the two-year follow-up and none had recurrence of DE. Conclusion: Early diagnosis and surgical plication of the diaphragm for symptomatic congenital or acquired diaphragmatic eventration offers a good clinical outcome with no recurrence.

Size-dependent analysis of functionally graded ultra-thin films

Shaat, M.,Mahmoud, F.F.,Alshorbagy, A.E.,Alieldin, S.S.,Meletis, E.I. Techno-Press 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.44 No.4

In this paper, the first-order shear deformation theory (FSDT) (Mindlin) for continuum incorporating surface energy is exploited to study the static behavior of ultra-thin functionally graded (FG) plates. The size-dependent mechanical response is very important while the plate thickness reduces to micro/nano scales. Bulk stresses on the surfaces are required to satisfy the surface balance conditions involving surface stresses. Unlike the classical continuum plate models, the bulk transverse normal stress is preserved here. By incorporating the surface energies into the principle of minimum potential energy, a series of continuum governing differential equations which include intrinsic length scales are derived. The modifications over the classical continuum stiffness are also obtained. To illustrate the application of the theory, simply supported micro/nano scaled rectangular films subjected to a transverse mechanical load are investigated. Numerical examples are presented to present the effects of surface energies on the behavior of functionally graded (FG) film, whose effective elastic moduli of its bulk material are represented by the simple power law. The proposed model is then used for a comparison between the continuum analysis of FG ultra-thin plates with and without incorporating surface effects. Also, the transverse shear strain effect is studied by a comparison between the FG plate behavior based on Kirchhoff and Mindlin assumptions. In our analysis the residual surface tension under unstrained conditions and the surface Lame constants are expected to be the same for the upper and lower surfaces of the FG plate. The proposed model is verified by previous work.

Size-dependent analysis of functionally graded ultra-thin films

M. Shaat,F.F. Mahmoud,A.E. Alshorbagy,S.S. Alieldin,E.I. Meletis 국제구조공학회 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.44 No.4

In this paper, the first-order shear deformation theory (FSDT) (Mindlin) for continuum incorporating surface energy is exploited to study the static behavior of ultra-thin functionally graded (FG) plates. The size-dependent mechanical response is very important while the plate thickness reduces to micro/nano scales. Bulk stresses on the surfaces are required to satisfy the surface balance conditions involving surface stresses. Unlike the classical continuum plate models, the bulk transverse normal stress is preserved here. By incorporating the surface energies into the principle of minimum potential energy, a series of continuum governing differential equations which include intrinsic length scales are derived. The modifications over the classical continuum stiffness are also obtained. To illustrate the application of the theory, simply supported micro/nano scaled rectangular films subjected to a transverse mechanical load are investigated. Numerical examples are presented to present the effects of surface energies on the behavior of functionally graded (FG) film, whose effective elastic moduli of its bulk material are represented by the simple power law. The proposed model is then used for a comparison between the continuum analysis of FG ultra-thin plates with and without incorporating surface effects. Also, the transverse shear strain effect is studied by a comparison between the FG plate behavior based on Kirchhoff and Mindlin assumptions. In our analysis the residual surface tension under unstrained conditions and the surface Lame constants are expected to be the same for the upper and lower surfaces of the FG plate. The proposed model is verified by previous work.

Nonlinear transient analysis of FG pipe subjected to internal pressure and unsteady temperature in a natural gas facility

Soliman, Ahmed E.,Eltaher, Mohamed A.,Attia, Mohamed A.,Alshorbagy, Amal E. Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.66 No.1

This study investigates the response of functionally graded (FG) gas pipe under unsteady internal pressure and temperature. The pipe is proposed to be manufactured from FGMs rather than custom carbon steel, to reduce the erosion, corrosion, pressure surge and temperature variation effects caused by conveying of gases. The distribution of material graduations are obeying power and sigmoidal functions varying with the pipe thickness. The sigmoidal distribution is proposed for the 1st time in analysis of FG pipe structure. A Two-dimensional (2D) plane strain problem is proposed to model the pipe cross-section. The Fourier law is applied to describe the heat flux and temperature variation through the pipe thickness. The time variation of internal pressure is described by using exponential-harmonic function. The proposed problem is solved numerically by a two-dimensional (2D) plane strain finite element ABAQUS software. Nine-node isoparametric element is selected. The proposed model is verified with published results. The effects of material graduation, material function, temperature and internal pressures on the response of FG gas pipe are investigated. The coupled temperature and displacement FEM solution is used to find a solution for the stress displacement and temperature fields simultaneously because the thermal and mechanical solutions affected greatly by each other. The obtained results present the applicability of alternative FGM materials rather than classical A106Gr.B steel. According to proposed model and numerical results, the FGM pipe is more effective in natural gas application, especially in eliminating the corrosion, erosion and reduction of stresses.

Factors Associated with Early Adverse Events after Coronary Artery Bypass Grafting Subsequent to Percutaneous Coronary Intervention

Yasser Ali Kamal, M.Sc.,Yasser Shaban Mubarak, M.D.,Ashraf Ali Alshorbagy, M.D. 대한흉부외과학회 2016 Journal of Chest Surgery (J Chest Surg) Vol.49 No.3

Background: A previous percutaneous coronary intervention (PCI) may affect the outcomes of patients who undergo coronary artery bypass grafting (CABG). The objective of this study was to compare the early in-hospital postoperative outcomes between patients who underwent CABG with or without previous PCI. Methods: The present study included 160 patients who underwent isolated elective on-pump CABG at the department of cardiothoracic surgery, Minia University Hospital from January 2010 to December 2014. Patients who previously underwent PCI (n=38) were compared to patients who did not (n=122). Preoperative, operative, and early in-hospital postoperative data were analyzed. The end points of the study were in-hospital mortality and postoperative major adverse events. Results: Non-significant differences were found between the study groups regarding preoperative demographic data, risk factors, left ventricular ejection fraction, New York Heart Association class, EuroSCORE, the presence of left main disease, reoperation for bleeding, postoperative acute myocardial infarction, a neurological deficit, need for renal dialysis, hospital stay, and in-hospital mortality. The average time from PCI to CABG was 13.9±5.4 years. The previous PCI group exhibited a significantly larger proportion of patients who experienced in-hospital major adverse events (15.8% vs. 2.5%, p=0.002). On multivariate analysis, only previous PCI was found to be a significant predictor of major adverse events (odds ratio, 0.16; 95% confidence interval, 0.03 to 0.71; p=0.01). Conclusion: Previous PCI was found to have a significant effect on the incidence of early major adverse events after CABG. Further large-scale and long-term studies are recommended.

Analysis of crack occurs under unsteady pressure and temperature in a natural gas facility by applying FGM

Eltaher, Mohamed A.,Attia, Mohamed A.,Soliman, Ahmed E.,Alshorbagy, Amal E. Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.66 No.1

Cracking can lead to unexpected sudden failure of normally ductile metals subjected to a tensile stress, especially at elevated temperature. This article is raised to study the application of a composite material instead of the traditional carbon steel material used in the natural gas transmission pipeline because the cracks occurs in the pipeline initiate at its internal surface which is subjected to internal high fluctuated pressure and unsteady temperature according to actual operation conditions. Functionally graded material (FGM) is proposed to benefit from the ceramics durability and its surface hardness against erosion. FGM properties are graded at the radial direction. Finite element method (FEM) is applied and solved by ABAQUS software including FORTRAN subroutines adapted for this case of study. The stress intensity factor (SIF), temperatures and stresses are discussed to obtain the optimum FGM configuration under the actual conditions of pressure and temperature. Thermoelastic analysis of a plane strain model is adopted to study SIF and material response at various crack depths.

Analysis of crack occurs under unsteady pressure and temperature in a natural gas facility by applying FGM

Mohamed A. Eltaher,Mohamed A. Attia,Ahmed E. Soliman,Amal E. Alshorbagy 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.66 No.1

Cracking can lead to unexpected sudden failure of normally ductile metals subjected to a tensile stress, especially at elevated temperature. This article is raised to study the application of a composite material instead of the traditional carbon steel material used in the natural gas transmission pipeline because the cracks occurs in the pipeline initiate at its internal surface which is subjected to internal high fluctuated pressure and unsteady temperature according to actual operation conditions. Functionally graded material (FGM) is proposed to benefit from the ceramics durability and its surface hardness against erosion. FGM properties are graded at the radial direction. Finite element method (FEM) is applied and solved by ABAQUS software including FORTRAN subroutines adapted for this case of study. The stress intensity factor (SIF), temperatures and stresses are discussed to obtain the optimum FGM configuration under the actual conditions of pressure and temperature. Thermoelastic analysis of a plane strain model is adopted to study SIF and material response at various crack depths.

Static analysis of nanobeams including surface effects by nonlocal finite element

F. F. Mahmoud,M. A. Eltaher,A.E. Alshorbagy,E.I. Meletis 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.11

In reality, there are two phenomena should be considered to describe behaviors of nanostructures adequately and accurately. The first one is the surface properties, especially for a relatively high ratio of the surface area to the volume of structural. The second phenomenon is the information about bulk material, which contains the forces between atoms and the internal length scale. Therefore, the objective of the current work is to study the coupled effects of surface properties and nonlocal elasticity on the static deflection of nanobeams. Surface elasticity is employed to describe the behavior of the surface layer and the Euler-Bernoulli beam hypothesis is used to state the bulk deformation kinematics. Both, the surface layer and bulk volume of the beam are assumed elastically isotropic. Information about the forces between atoms, and the internal length scale are proposed by the nonlocal Eringen model. Galerkin finite element technique is employed for the discretization of the nonlocal mathematical model with surface properties. The present results are compared favorably with those published results. The effects of nonlocal parameter and surface elastic constants are figured out and presented.