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Linear instability of the electrified free interface between two cylindrical shells of viscoelastic fluids through porous media

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Acta Mechanica Sinica 2012年第6期28卷 1572-1589页

作者： magdy A. Sirwah Department of Mathematics Faculty of Science Tanta University

In this paper, we have discussed the linear stabil- ity analysis of the electrified surface separating two coaxial Oldroyd-B fluid layers confined between two impermeable rigid cylinders in the presence of both interfacial insoluble surfactant and surface charge through porous media. The case of long waves interfacial stability has been studied. The dispersion relation is solved numerically and hence the ef- fects of various parameters are illustrated graphically. Our results reveal that the influence of the physicochemical pa- rameterβ is to shrink the instability region of the surface and reduce the growth rate of the unstable normal modes. Such important effects of the surfactant on the shape of in- terfacial structures are more sensitive to the variation of the βcorresponding to non-Newtonian fluids-model compared with the Newtonian fluids model. In the case of long wave limit, it is demonstrated that increasing r, has a dual role in- fluence （de-stabilizing effects） depending on the viscosity of the core fluid. It has a destabilizing effect at the large values of the core fluid viscosity coefficient, while this role is ex- changed to a regularly stabilizing influence at small values of such coefficient.

关键词： Modified Darcy's law Oldroyd-B model Cap-illary stability flow Insoluble surfactant Surface charges Porous media

Irritable bowel syndrome:Diagnosis and pathogenesis

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World Journal of Gastroenterology 2012年第37期18卷 5151-5163页

作者： magdy El-Salhy Section for Gastroenterology Department of MedicineStord Helse-Fonna Hospital Section for Gastroenterology Institute of MedicineUniversity of Bergen

Irritable bowel syndrome (IBS) is a common gastro-intestinal (GI) disorder that considerably reduces the quality of life. It further represents an economic burden on society due to the high consumption of healthcare resources and the non-productivity of IBS patients. The diagnosis of IBS is based on symptom assessment and the Rome Ⅲ criteria. A combination of the Rome Ⅲ criteria, a physical examination, blood tests, gastros-copy and colonoscopy with biopsies is believed to be necessary for diagnosis. Duodenal chromogranin A cell density is a promising biomarker for the diagnosis of IBS. The pathogenesis of IBS seems to be multifactorial, with the following factors playing a central role in the pathogenesis of IBS:heritability and genetics, dietary/intestinal microbiota, low-grade inflammation, and disturbances in the neuroendocrine system (NES) of the gut. One hypothesis proposes that the cause of IBS is an altered NES, which would cause abnormal GI motility, secretions and sensation. All of these abnormalities are characteristic of IBS. Alterations in the NES could be the result of one or more of the following:genetic factors, dietary intake, intestinal flora, or lowgrade inflammation. Post-infectious IBS (PI-IBS) and inflammatory bowel disease-associated IBS (IBD-IBS) represent a considerable subset of IBS cases. Patients with PI-and IBD-IBS exhibit low-grade mucosal inflammation, as well as abnormalities in the NES of the gut.

关键词： Cholecystokinin Chromogranin A Diagno-sis Diet Endocrine cells Intestinal flora hereditary Low-grade inflammation Peptide YY Serotonin

Effective Control of Smart hybrid Power Systems:Cooperation of Robust LFC and Virtual Inertia Control Systems

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CSEE Journal of Power and Energy Systems 2022年第6期8卷 1583-1593页

作者： Gaber magdy hossam Ali Dianguo Xu Electrical Engineering Department Faculty of Energy EngineeringAswan UniversityAswan 81528Egypt Institute of Technology HarbinHeilongjiang 150001Chinaand Electrical Engineering DepartmentFaculty of Energy EngineeringAswan UniversityAswan 81528Egypt harbin Institute of Technology HarbinHeilongjiang 150001China

A modern power system is expected to consist primarily of renewables,which either lack or have less rotating masses(i.e.,source of inertia)compared to the traditional generation ***,the growth of renewables generation,based on power electronics,can substantially decrease the inertia levels of renewable power grids,which can create several frequency stability issues,resulting in power system *** address this issue,this paper presents a recent virtual inertia scheme predicated on electric vehicles(EVs)to mimic the necessary inertia power in low-inertia smart hybrid power systems(ShPSs),thus regulating the system frequency and avoiding system ***,to guarantee robust performance and more stability for ShPSs against multiple perturbations,system uncertainties,and physical constraints,this paper also proposes a robust control strategy relying on a coefficient diagram method(CDM)for the load frequency control(LFC)of ShPSs considering high renewables penetration and *** efficacy of the proposed system(i.e.,robust LFC with the proposed VIC strategy)is validated by comparison with a conventional LFC with/without the proposed VIC *** addition,the simulation outcomes show that the proposed system can considerably support smart low-inertia hybrid power systems for many different contingencies.

关键词： Electric vehicles renewable energy sources robust frequency control smart hybrid power system virtual inertia control

Possible role of intestinal stem cells in the pathophysiology of irritable bowel syndrome

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World Journal of Gastroenterology 2020年第13期26卷 1427-1438页

作者： magdy El-Salhy Section for Gastroenterology Department of MedicineStord HospitalStord 5409Norway Department of Clinical Medicine University of BergenBergen 5021Norway

The pathophysiology of irritable bowel syndrome(IBS)is not completely ***,several factors are known to play a role in pathophysiology of IBS such as genetics,diet,gut microbiota,gut endocrine cells,stress and low-grade *** the pathophysiology of IBS may open the way for new treatment *** density of intestinal stem cells and low differentiation toward enteroendocrine cells has been reported recently in patients with *** abnormalities are believed to be the cause of the low density of enteroendocrine cells seen in patients with *** cells regulate gastrointestinal motility,secretion,absorption and visceral *** dysmotility,abnormal absorption/secretion and visceral hypersensitivity are all seen in patients with IBS and haven been attributed to the low density the intestinal enteroendocrine cells in these *** present review conducted a literature search in Medline(Pub Med)covering the last ten years until November 2019,where articles in English were *** about the intestinal stem cells and their possible role in the pathophysiology of IBS are discussed in the present *** present review discusses the assumption that intestinal stem cells play a central role in the pathophysiology of IBS and that the other factors known to contribute to the pathophysiology of IBS such as genetics,diet gut microbiota,stress,and lowgrade inflammation exert their effects through affecting the intestinal stem *** reports further the data that support this assumption on genetics,diet,gut microbiota,stress with depletion of glutamine,and inflammation.

关键词： Diet Gut enteroendocrine cells Gut microbiota Low grade inflammation Stress

Fractional thermoelasticity applications for porous asphaltic materials

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Petroleum Science 2016年第3期13卷 550-560页

作者： magdy Ezzat Shereen Ezzat Department of Mathematics Faculty of Science and Letters in Al Bukayriyyah Al-Qassim University Faculty of Education Alexandria University

A new mathematical model of poro-thermoelasticity has been constructed in the context of a new consideration of heat conduction with fractional ***-dimensional application for a poroelastic half-space saturated with fluid is *** surface of the halfspace is assumed to be traction-free,permeable,and subjected to *** Laplace transform technique is used to solve the *** inversion of the Laplace transform will be obtained numerically and the numerical values of the temperature,stresses,strains,and displacements will be illustrated graphically for the solid and the liquid.

关键词： Generalized thermo-poroelasticity Asphaltic material Thermal shock Fractional calculus Numerical results

Recent developments in the pathophysiology of irritable bowel syndrome

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World Journal of Gastroenterology 2015年第25期21卷 7621-7636页

作者： magdy El-Salhy Section for Gastroenterology Department of Medicine Stord Hospital Section of Neuroendocrine Gastroenterology Division of Gastroenterology Department of Clinical MedicineUniversity of Bergen National Centre for Functional Gastrointestinal Disorders Department of Medicine Haukeland University Hospital

Irritable bowel syndrome(IBS) is a common gastrointestinal disorder, the pathophysiology of which is not completely known, although it has been shown that genetic/social learning factors, diet, intestinal microbiota, intestinal low-grade inflammation, and abnormal gastrointestinal endocrine cells play a major role. Studies of familial aggregation and on twins have confirmed the heritability of IBS. however, the proposed IBS risk genes are thus far nonvalidated hits rather than true predisposing factors. There is no convincing evidence that IBS patients suffer from food allergy/intolerance, with the effect exerted by diet seemingly caused by intake of poorly absorbed carbohydrates and fiber. Obesity is a possible comorbidity of IBS. Differences in the microbiota between IBS patients and healthy controls have been reported, but the association between IBS symptoms and specific bacterial species is uncertain. Low-grade inflammation appears to play a role in the pathophysiology of a major subset of IBS, namely postinfectious IBS. The density of intestinal endocrine cells is reduced in patients with IBS, possibly as a result of genetic factors, diet, intestinal microbiota, and low-grade inflammation interfering with the regulatory signals controlling the intestinal stem-cell clonogenic and differentiation activities. Furthermore, there is speculation that this decreased number of endocrine cells is responsible for the visceral hypersensitivity, disturbed gastrointestinal motility, and abnormal gut secretion seen in IBS patients.

关键词： Diet Endocrine cells Genetic factors Low-grade inflammation Microbiota Stem cells

Magnetohydrodynamics instability of interfacial waves between two immiscible incompressible cylindrical fluids

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Acta Mechanica Sinica 2008年第5期24卷 497-514页

作者： Kadry Zakaria magdy A.Sirwah Ahmed Assaf Department of Mathematics Faculty of ScienceTanta UniversityTantaEgypt

The problem of nonlinear instability of interfacial waves between two immiscible conducting cylindrical fluids of a weak Oldroyd 3-constant kind is studied. The system is assumed to be influenced by an axial magnetic field, where the effect of surface tension is taken into account. The analysis, based on the method of multiple scale in both space and time, includes the linear as well as the nonlinear effects. This scheme leads to imposing of two levels of the solvability conditions, which are used to construct like-nonlinear Schr6dinger equations （1-NLS） with complex coefficients. These equations generally describe the competition between nonlinearity and dispersion. The stability criteria are theoret- ically discussed and thereby stability diagrams are obtained for different sets of physical parameters. Proceeding to the nonlinear step of the problem, the results show the appearance of dual role of some physical parameters. Moreover, these effects depend on the wave kind, short or long, except for the ordinary viscosity parameter. The effect of the field on the system stability depends on the existence of viscosity and differs in the linear case of the problem from the nonlinear one. There is an obvious difference between the effect of the three Oldroyd constants on the system stability. New instability regions in the parameter space, which appear due to nonlinear effects, are shown.

关键词： Magnetohydrodynarmics (MhD) Instability ,Interfacial waves Immiscible fluids

Predictive Control Based on Ranking Multi-objective Optimization Approaches for a quasi-Z Source Inverter

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CSEE Journal of Power and Energy Systems 2021年第6期7卷 1152-1160页

作者： Abualkasim Bakeer Gaber magdy Andrii Chub Dmitri Vinnikov the Department of Electrical Engineering Faculty of EngineeringAswan University81542 AswanEgypt the Power Electronics Group Department of Electrical Power Engineering and MechatronicsTallinn University of TechnologyTallinn 19086Estonia the Department of Electrical Engineering Faculty of Energy EngineeringAswan University81542 AswanEgypt

In power converter control,predictive control has several merits,such as simple concept and fast ***,the necessity to use the weighting factor inside the cost function makes the control design complex in the case of regulating multivariables where the value of the weighting factor is obtained by a nontrivial ***,it primarily depends on the system parameters and operating points of the control *** paper aims to enhance the model predictive algorithm of the singlestage topology of a quasi-Z Source Inverter(qZSI).The concept of a multi-objective optimization approach is used in addition to the sub-cost function definition to remove the weighting *** using the sub-cost function definition,the inductor current is pushed away from the main loop of the predictive ***,no weighting factor is needed to manage the priority of the inductor *** other two control targets,which are the capacitor voltage and load currents,will be controlled by the multi-objective optimization approach without using any weighting factors.A detailed theoretical analysis of the proposed technique will be given and validated based on simulation results.

关键词： Cost function definition model predictive control optimization methods quasi-Z Source Inverter(qZSI) weighting factors

Superconducting energy storage technology-based synthetic inertia system control to enhance frequency dynamic performance in microgrids with high renewable penetration

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Protection and Control of Modern Power Systems 2021年第1期6卷 460-472页

作者： Gaber magdy Abualkasim Bakeer Mohammed Alhasheem Electrical Engineering Department Faculty of Energy EngineeringAswan UniversityAswan81528Egypt Electrical Engineering Department Faculty of EngineeringAswan UniversityAswan81542Egypt Electrical Power Engineering and Mechatronics Department School of EngineeringTallinn University of Technology19086TallinnEstonia Department of Electrical and Control Arab Academy for ScienceTechnologyand Maritime TransportCairo2033Egypt

With high penetration of renewable energy sources(RESs)in modern power systems,system frequency becomes more prone to fluctuation as RESs do not naturally have inertial properties.A conventional energy storage system(ESS)based on a battery has been used to tackle the shortage in system inertia but has low and short-term power support during the *** address the issues,this paper proposes a new synthetic inertia control(SIC)design with a superconducting magnetic energy storage(SMES)system to mimic the necessary inertia power and damping properties in a short time and thereby regulate the microgrid(µG)frequency during *** addition,system frequency deviation is reduced by employing the proportional-integral(PI)controller with the proposed SIC *** efficacy of the proposed SIC system is validated by comparison with the conventional ESS and SMES systems without using the PI controller,under various load/renewable perturbations,nonlinearities,and *** simulation results highlight that the proposed system with SMES can efficiently manage several disturbances and high system uncertainty compared to the conventional ESS and SMES systems,without using the PI controller.

关键词： Synthetic inertia control(SIC) Load frequency control(LFC) Superconducting magnetic energy storage(SMES) Renewable energy sources(RESs) Microgrid(µG)