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Earthquake Engineering and Engineering Vibration 2013年第3期12卷 385-397页

作者： Mohammad AlHamaydeh Khaled Galal Sherif yehia Department of Civil Engineering American University of SharjahSharjah UAE Department of Building Civil & Environmental Engineering Concordia UniversityMontréal Québec Canada

The local design and construction practices in the United Arab Emirates （UAE）, together with Dubai＇s unique rate of development, warrant special attention to the selection of Lateral Force-Resisting Systems （LFRS）. This research proposes four different feasible solutions for the selection of the LFRS for tall buildings and quantifies the impact of these selections on seismic performance and cost. The systems considered are： Steel Special Moment-Resisting Frame （SMRF）, Concrete SMRF, Steel Dual System （SMRF with Special Steel Plates Shear Wall, SPSW）, and Concrete Dual System （SMRF with Special Concrete Shear Wall, SCSW）. The LFRS selection is driven by seismic setup as well as the adopted design and construction practices in Dubai. It is found that the concrete design alternatives are consistently less expensive than their steel counterparts. The steel dual system is expected to have the least damage based on its relatively lesser interstory drifts. However, this preferred performance comes at a higher initial construction cost. Conversely, the steel SMRF system is expected to have the most damage and associated repair cost due to its excessive flexibility. The two concrete alternatives are expected to have relatively moderate damage and repair costs in addition to their lesser initial construction cost.

关键词： special moment-resisting frames (SMRF) special shear wall Dubai, UAE seismicity steel concrete dual system

Equilibria of a charged artificial satellite subject to gravitational and Lorentz torques

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Research in Astronomy and Astrophysics 2014年第7期14卷 891-902页

作者： yehia A.Abdel-Aziz Muhammad Shoaib National Research Institute of Astronomy and Geophysics (NRIAG) HelwanCairo 11721Egypt University of Hail Department of MathematicsPO Box 2440Kingdom of Saudi Arabia

The attitude dynamics of a rigid artificial satellite subject to a gravity gradient and Lorentz torques in a circular orbit are considered. Lorentz torque is developed on the basis of the electrodynamic effects of the Lorentz force acting on the charged satellite＇s surface. We assume that the satellite is moving in a Low Earth Orbit in the geomagnetic field, which is considered to be a dipole. Our model of torque due to the Lorentz force is developed for an artificial satellite with a general shape, and the nonlinear differential equations of Euler are used to describe its attitude orientation. All equilibrium positions are determined and conditions for their existence are *** numerical results show that the charge q and radius ρ0of the center of charge for the satellite provide a certain type of semi-passive control for the attitude of the satellite. The technique for this kind of control would be to increase or decrease the electrostatic screening on the satellite. The results obtained confirm that the change in charge can affect the magnitude of the Lorentz torque, which can also affect control of the satellite. Moreover, the relationship between magnitude of the Lorentz torque and inclination of the orbit is investigated.

关键词： space vehicles -- atmospheric effects -- celestial mechanics -- kine-matics and dynamics

Simulation-based environmental-impact assessment of glycerol-to-hydrogen conversion technologies

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Clean Energy 2021年第3期5卷 387-402页

作者： yehia F.Khalil Department of Chemical&Environmental Engineering Yale UniversityNew HavenCT 06520USA

This simulation-based comparative assessment aims to quantify the environmental and human-health impacts of greener hydrogen(H2)production via three glycerol-based technologies,including:supercritical water reforming(SCWR),aqueous-phase reforming(APR)and autothermal reforming(ATR).The GaBi(2018 edition)life-cycle assessment(LCA)platform is used to develop cradle-to-gate product system models for these technologies and the TRACI 2.1 methodology is used to quantify their midpoint impact *** HYSYS(v11)process-simulation software is used to generate the life-cycle inventory(LCI)primary data required to produce 1 kg of H2 via each of the indicated glycerol-reforming *** ISO 14040:2006 reporting requirements for the LCA results interpretation step,three base case(BC)scenarios and four sensitivity scenarios(SS)are developed and quantified to compare the effects of different process electricity sources(US grid mix versus wind power)and thermal energy sources(natural gas versus biogas)on the LCA *** high operating pressure(viz.240 bar)of SCWR enabled assessment of the impact of in situ electricity generation to offset some of electricity required for this *** major insights from this research are as follows:(i)per 1 kg of produced H2,APR reduces CO_(2) emissions by≈95%compared to ATR and by≈92%compared to SCWR,(ii)for BC scenarios,the primary energy consumption(in MJ/kg of produced H2)is in the following order from highest to lowest:ATR>SCWR>APR and(iii)H2 production via glycerol APR is more environmentally sustainable than SCWR and ATR,and thus offers a promising path for greener H2 *** environmental sustainability studies should focus on expanding the scope of this study to include H2 production via water electrolysis using renewable electricity sources and via solar and nuclear-driven thermochemical water splitting.

关键词： glycerol hydrogen impact categories reforming supercritical water valorization

Attitude dynamics and control of spacecraft using geomagnetic Lorentz force

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Research in Astronomy and Astrophysics 2015年第1期15卷 127-144页

作者： yehia A.Abdel-Aziz Muhammad Shoaib National Research Institute of Astronomy and Geophysics (NRIAG) Helwan Cairo 11721Egypt University of Hail Department of Mathematics PO BOX 2440 Kingdom of Saudi Arabia

Attitude stabilization of a charged rigid spacecraft in Low Earth Orbit using torques due to Lorentz force in pitch and roll directions is considered. A spacecraft that generates an electrostatic charge on its surface in the Earth’s magnetic field will be subject to perturbations from the Lorentz force. The Lorentz force acting on an electrostatically charged spacecraft may provide a useful thrust for controlling a spacecraft’s orientation. We assume that the spacecraft is moving in the Earth’s magnetic field in an elliptical orbit under the effects of gravitational, geomagnetic and Lorentz torques. The magnetic field of the Earth is modeled as a non-tilted dipole.A model incorporating all Lorentz torques as a function of orbital elements has been developed on the basis of electric and magnetic fields. The stability of the spacecraft orientation is investigated both analytically and numerically. The existence and stability of equilibrium positions is investigated for different values of the charge to mass ratio（α＊）. Stable orbits are identified for various values of α＊. The main parameters for stabilization of the spacecraft are α＊and the difference between the components of the moment of inertia for the spacecraft.

关键词： space vehicles atmospheric effects celestial mechanics kinematics and dynamics

PERIODIC MOTIONS OF SPINNING RIGID SPACECRAFT UNDER INFLUENCE OF GRAVITATIONAL AND MAGNETIC FIELDS

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Applied Mathematics and Mechanics(English Edition) 2006年第8期27卷 1061-1069页

作者： yehia A.Abdel-aziz M.H.yehia F.A.Abd El-Salam M.Radwan National Research Institute of Astronomy and Geophysics Helwan. Cairo Egypt Mathematics Department Faculty of Science Mansoura University MansouraEgypt Astronomy Department Faculty of ScienceCairo UniversityCairo12613Egypt

The motion of a magnetized axisymmetric spacecraft about its center of mass in a circular orbit is considered, taking the gravitational and magnetic effects of the central body into account. Equations of motion of the reduced system are transformed to equations of plane motion of a charged particle under the action of electric and magnetic fields. Stationary motions of the system are determined and periodic motions near to them are constructed using the Lyapounoff theorem of the holomorphic integral.

关键词： periodic motions routhian rigid spacecraft

Electromagnetic effects on the orbital motion of a charged spacecraft

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Research in Astronomy and Astrophysics 2014年第5期14卷 589-600页

作者： yehia Ahmed Abdel-Aziz Khalil Ibrahim Khalil National Research Institute of Astronomy and Geophysics (NRIAG) Helwan Cairo 11721Egypt Department of Mathematics Hail University Hail 2440 Kingdom of Saudi Arabia

This paper deals with the effects of electromagnetic forces on the orbital motion of a spacecraft. The electrostatic charge which a spacecraft generates on its surface in the Earth＇s magnetic field will be subject to a perturbative Lorentz force. A model incorporating all Lorentz forces as a function of orbital elements has been developed on the basis of magnetic and electric fields. This Lorentz force can be used to modify or perturb the spacecraft＇s orbits. Lagrange＇s planetary equations in the Gauss variational form are derived using the Lorentz force as a perturbation to a Keplerian orbit. Our approach incorporates orbital inclination and the true anomaly. The numer- ical results of Lagrange＇s planetary equations for some operational satellites show that the perturbation in the orbital elements of the spacecraft is a second order perturba- tion for a certain value of charge. The effect of the Lorentz force due to its magnetic component is three times that of the Lorentz force due to its electric component. In addition, the numerical results confirm that the strong effects are due to the Lorentz force in a polar orbit, which is consistent with realistic physical phenomena that occur in polar orbits. The results confirm that the magnitude of the Lorentz force depends on the amount of charge. This means that we can use artificial charging to create a force to control the attitude and orbital motion of a spacecraft.

关键词： space vehicles -- atmospheric effects -- celestial mechanics -- kine-matics and dynamics

Rational Design of T-Girders via Finite Element Method

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Journal of Marine Science and Application 2021年第2期20卷 302-316页

作者： Ahmed Hammad yehia Abdel-Nasser Mohamed Shama Department of Naval Architecture and Marine Engineering Faculty of EngineeringAlexandria UniversityAlex andria 21544Egypt

The main configuration of ship construction consists of standard and fabricated stiffening members,such as T-sections,which are commonly used in *** the welding process,the nonuniform heating and rapid cooling lead to welding imperfections such as out-of-plane distortion and residual *** to these imperfections,the fabricated structural members may not attain their design load,and removing these imperfections will require extra *** present work investigated controlling these imperfections at both the design and fabrication stages.A typical fabricated T-girder was selected to investigate the problem of these imperfections using double-sided welding.A numerical simulation based on finite element modeling(FEM) was used to investigate the effects of geometrical properties and welding sequence on the magnitude of the welding imperfections of the *** FEM results were validated with the experimental measurements of a double-sided fillet *** the design stage,the optimum geometry of the fabricated T-girder was determined based on the minimum steel weight and out-of-plane ***,regarding the fabrication stage,a parametric study with two variables(geometrical properties and welding sequence)was conducted to determine the optimum geometry and welding sequence based on the minimum welding out-of-plane *** the flange thickness and reducing the breadth while keeping the T-girder section modulus constant reduced the T-girder weight and out-of-plane *** welding produced a significant reduction in the out-of-plane distortion,while an insignificant increase in the compressive residual stress occurred.

关键词： Out-of-plane distortion Finite element modeling Welding residual stresses Fabricated T-girder Section modulus

MTP genetic variants associated with non-alcoholic fatty liver in metabolic syndrome patients

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Genes & Diseases 2017年第4期4卷 222-228页

作者： Weaam Gouda Esmat Ashour yehia Shaker Wafaa Ezzat Biochemistry Dept. National Research CenterDokkiGizaEgypt Internal Medicine Dept. National Research CenterDokkiGizaEgypt

This study was performed for investigation the relationship between variants of MTP gene polymorphism and the development of NAFLD in patients with and without *** study was included 174 NAFLD patients(106 with MS and 68 without MS),and 141 healthy control *** 493 G/T polymorphism of MTP gene was evaluated by PCR-RFLP *** frequency of MTP TT genotype and T allele were significantly higher in NAFLD patients when compared to healthy ***,a significant association in MTP gene polymorphism was observed in NAFLD patients with MS compared to NAFLD patients without MS and *** study suggested that MTP 493 G/T gene polymorphism may act as susceptibility biomarker for NAFLD and MS.

关键词： Genetic variants Metabolic syndrome(MS) Microsomal triglyceride transfer protein(MTP) Non-alcoholic fatty liver disease(NAFLD) PCR-RFLP

Priority Detector and Classifier Techniques Based on ML for the IoMT

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Computers, Materials & Continua 2023年第8期76卷 1853-1870页

作者： Rayan A.Alsemmeari Mohamed yehia Dahab Badraddin Alturki Abdulaziz A.Alsulami Department of Information Technology Faculty of Computing and Information TechnologyKing Abdulaziz UniversityJeddah21589Saudi Arabia Department of Computer Science Faculty of Computing and Information TechnologyKing Abdulaziz UniversityJeddah21589Saudi Arabia Department of Information Systems Faculty of Computing and Information TechnologyKing Abdulaziz UniversityJeddah21589Saudi Arabia

Emerging telemedicine trends,such as the Internet of Medical Things(IoMT),facilitate regular and efficient interactions between medical devices and computing *** importance of IoMT comes from the need to continuously monitor patients’health conditions in real-time during normal daily activities,which is realized with the help of various wearable devices and *** major health problem is workplace stress,which can lead to cardiovascular disease or psychiatric ***,real-time monitoring of employees’stress in the workplace is *** levels and the source of stress could be detected early in the fog layer so that the negative consequences can be mitigated ***,overwhelming the fog layer with extensive data will increase the load on fog nodes,leading to computational *** study aims to reduce fog computation by proposing machine learning(ML)models with two *** first phase of theMLmodel assesses the priority of the situation based on the stress *** the second phase,a classifier determines the cause of stress,which was either interruptions or time pressure while completing a *** approach reduced the computation cost for the fog node,as only high-priority records were transferred to the ***-priority records were forwarded to the *** MLapproaches were compared in terms of accuracy and prediction speed:Knearest neighbors(KNN),a support vector machine(SVM),a bagged tree(BT),and an artificial neural network(ANN).In our experiments,ANN performed best in both phases because it scored an F1 score of 99.97% and had the highest prediction speed compared with KNN,SVM,and BT.

关键词： Machine learning priority detector Internet of Medical Things IoMT fog computing cloud computing

Hepato-cardiac disorders

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World Journal of Hepatology 2014年第1期6卷 41-54页

作者： Yasser Mahrous Fouad Reem yehia Gastroenterology and Hepatology Unit Endemic Medicine Department Minia University

Understanding the mutual relationship between the liver and the heart is important for both hepatologists and cardiologists. Hepato-cardiac diseases can be classified into heart diseases affecting the liver, liver diseases affecting the heart, and conditions affecting the heart and the liver at the same time. Differential diagnoses of liver injury are extremely important in a cardiologist's clinical practice calling for collaboration between cardiologists and hepatologists due to the many other diseases that can affect the liver and mimic haemodynamic injury. Acute and chronic heart failure may lead to acute ischemic hepatitis or chronic congestive hepatopathy. Treatment in these cases should be directed to the primary heart disease. In patients with advanced liver disease, cirrhotic cardiomyopathy may develop including hemodynamic changes, diastolic and systolic dysfunctions, reduced cardiac performance and electrophysiological abnormalities. Cardiac evaluation is important for patients with liver diseases especially before and after liver transplantation. Liver transplantation may lead to the improvement of all cardiac changes and the reversal of cirrhotic cardiomyopathy. There are systemic diseases that may affect both the liver and the heart concomitantly including congenital, metabolic and inflammatory diseases as well as alcoholism. This review highlights these hepatocardiac

关键词： Cardiac cirrhosis Ischemic hepatitis Fatty liver Liver cirrhosis Heart failure