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Journal of Advanced Dielectrics 2021年第4期11卷 64-73页

作者： ahmed Thabet M.fouad Nanotechnology Research Center Electrical Engineering Dept.Faculty of Energy Engineering Aswan University AswanEgypt Electrical Engineering Dept.College of Engineering and Information Technology Buraydah Colleges KSA Hydro Power Plant Generation Company Nag Hammadi Hydro Power Plant QenaEgypt

Nanoparticles succeeded to enhance the dielectric properties of industrial insulation but the presence of voids inside the power cable insulation still leads to formation high electrical stress inside power cable insulation material and *** this paper,the dielectric strength of new design nanocomposites has been deduced as experimental work done to clarify the benefit of filling nanoparticles with different patterns inside ***,it has been studied the effect of electrical stress distribution in presence of air,water and copper impurities with different shapes(cylinder,sphere and ellipse)inside insulation of single *** simulation model,it has been used finite element method(FEM)for estimating the electrostatic field distribution in power cable *** has been applied new strategies of nanotechnology techniques for designing innovative polyvinyl chloride insula-tion materials by using nanocomposites and ***,this research succeeded to remedy different partial discharges(PD)patterns according to using certain types and concentrations of nanoparticles.

关键词： Partial discharges dielectric strength single core cables FEM nanocomposites nanoparticles

Using nanotechnology to prevent fines migration while production

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Petroleum 2021年第2期7卷 168-177页

作者： mohamed Mansour mohamed Eleraki ahmed Noah El-Abbas Moustafa Faculty of Science Zagazig UniversityEgypt Egyptian Petroleum Research Institute(EPRI) Egypt The British University Egypt

Formation damage due to fines migration is a major reason for well productivity decline for oil and gas *** fines are small enough to pass through pore throats causing pore plugging and permeability *** factors affect fines migration such as flow rate,salinity,pH value,reservoir temperature and oil polarity,as well as changes in chemical environment induced by Enhanced Oil Recovery(EOR)*** paper focuses on the effect of flow rates on fines detachment from the grain surfaces,which causing permeability *** the fluid inside the reservoir moves towards the wellbore,the fluid velocity increases,when the fluid reaches the critical flow rate these fines can be picked up into the *** fines captured by thinner pore throats causing pore plugging and permeability *** concentrations of nanoparticles were used to fix these fines on their sources and prevent their mobilization at high flow *** unique technique used in this study is changing the potential surfaces between fines and grain surfaces to prevent fines movement above the critical flow ***_(2)and MgO NPs used in this study can be adsorbed on the pore surfaces and reduce the repulsion forces between fines and pore ***_(2) and MgO nanoparticles at different concentrations(0.25,0.50 and 0.75 g/L)were used on treating the Abu-Rawash sandstone reservoir using Formation Damage System Cell *** experimental studies showed that using MgO NPs would prevent fines detachment from the pore surfaces and decrease the reduction of permeability at high flow rates more than SiO_(2) *** optimum concentration of MgO NPs was at 0.5 g/L as the permeability remediation at this concentration reaches to 64.83%.

关键词： Formation damage Fines migration Nanoparticles Zeta potential Permeability reduction Fluid flow rate

Contralateral eye study of refractive,topographic and aberrometric outcomes after femtosecond assisted Myo Ring implantation and DALK for management of keratoconus

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International Journal of Ophthalmology(English edition) 2018年第10期11卷 1621-1630页

作者： mohamed Omar Yousif Azza mohamed ahmed Said Department of Ophthalmology Faculty of Medicine Ain Shams University

AIM：To evaluate the efficacy of femtosecond laser assisted MyoRing intrastromal corneal implant and deep anterior lamellar keratoplasty （DALK） for management of moderate to advanced keratoconus regarding the degree of changes in visual acuity, refraction, corneal asphericity and ***：A prospective non comparative interventional case study was conducted in Ophthalmology Department,Ain Shams University Hospital in the period from January 2015 to February 2017. The study included 30 eyes of moderate to advanced keratoconus. MyoRing was implanted in one eye （Group Ⅰ） and DALK operation was performed in the contralateral eye of the same patient （Group Ⅱ）.Preoperative and 6mo post-operative uncorrected visual acuity（UCVA）, corrected distance visual acuity （CDVA）, spherical equivalent （SE）, corneal and refractive astigmatisms,keratometry and Q-value using topography images were acquired. Quality of vision was assessed in all eyes including total corneal, anterior corneal high order aberrations analysis at 5 mm pupil size and the Strehl ratio of point spread function （PSF） as an objective measure of ***：Mean postoperative UCVA, CDVA, SE, refractive astigmatism,keratometryreadingsandasphericity were statistically improved compared to preoperative parameters in both groups （P〈0.05）. Significant reduction of all corneal aberrations following both techniques（P〈0.05） was achieved except mean trefoil and mean PSF in Group Ⅰ （P〉0.05）. Postoperative corneal aberrations were significantly lower in Group Ⅱ compared to Group Ⅰ.A statistically significant negative correlation was found in Group Ⅰ between the mean change in CDVA （logMAR）and the mean preoperative and mean postoperative total corneal aberrations root mean square （RMS; r=-0.78,P=0.04）. Also a statistically significant negative correlation was found between mean preoperative coma RMS and mean post PSF （r=-0.86, P=0.01）. In Group Ⅱ, there was a statistically significant positive correlation between m

关键词： aberrations deep anterior lamellar keratoplasty femtosecond laser keratoconus MyoRing

Obstructive sleep apnea syndrome and fatty liver: Association or causal link?

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World Journal of Gastroenterology 2010年第34期16卷 4243-4252页

作者： mohamed H ahmed Christopher D Byrne Chemical Pathology Department Southampton University Hospital NHS Trust Southampton SO16 6YD United Kingdom Endocrinology and Metabolism DOHaD Division University of Southampton and Southampton University Hospitals Trust Southampton SO16 6YD United Kingdom

Obstructive sleep apnea (OSA) is a complex disorder that consists of upper airway obstruction, chronic intermittent hypoxia and sleep fragmentation. OSA is well known to be associated with hypoxia, insulin resistance and glucose intolerance, and these factors can occur in the presence or absence of obesity and metabolic syndrome. Although it is well established that insulin resistance, glucose intolerance and obesity occur frequently with non-alcoholic fatty liver disease (NAFLD), it is now becoming apparent that hypoxia might also be important in the development of NAFLD, and it is recognized that there is increased risk of NAFLD with OSA. This review discusses the association between OSA, NAFLD and cardiovascular disease, and describes the potential role of hypoxia in the development of NAFLD with OSA.

关键词： Sleep apnea syndrome Hyperlipidemia Non-alcoholic fatty liver disease Insulin resistance

Finding an optimization of the plate element of Egyptian research reactor using genetic algorithm

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Nuclear Science and Techniques 2008年第5期19卷 314-320页

作者： WAHED mohamed IBRAHIM Wesam EFFAT ahmed Mathematics Department Faculty of ScienceZagazic UniversityEgypt Atomic Energy Authority CairoEgypt

The second Egyptian research reactor ET-RR-2 went critical on the 27th of November *** National Center of Nuclear Safety and Radiation Control (NCNSRC) has the responsibility of the evaluation and assessment of the safety of this *** purpose of this paper is to present an approach to optimization of the fuel element plate. For an efficient search through the solution space we use a multi objective genetic algorithm which allows us to identify a set of Pareto optimal solutions providing the decision maker with the complete spectrum of optimal solutions with respect to the various *** aim of this paper is to propose a new approach for optimizing the fuel element plate in the *** fuel element plate is designed with a view to improve reliability and lifetime and it is one of the most important elements during the shut *** this present paper,we present a conceptual design approach for fuel element plate,in conjunction with a genetic algorithm to obtain a fuel plate that maximizes a fitness value to optimize the safety design of the fuel plate.

关键词：埃及核反应堆遗传算法燃料元件核技术

Investigating energy policies to boost grid-connected rooftop solar PV in Sudan

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Clean Energy 2023年第5期7卷 994-1005页

作者： Tarig Z.ahmed Ayah mohamed Mawahib Eltayeb ahmed ahmed Osman Elamin Abdalgader mohamed G.Hassan-Sayed Cambridge Institute for Sustainability Leadership(CISL) University of CambridgeCambridgeCB21QAUK Energy and Climate Change Division Faculty of Engineering and Physical ScienceThe University of SouthamptonSouthamptonSO171BJUK Institute of Engineering Research and Material Technology National Centre for ResearchKhartoumSudan/University of KhartoumSudan University of California Davis1 Shields AveDavisCA 95616USA School of Chemistry Faculty of Engineering and Physical SciencesThe University of SouthamptonSouthamptonSO171BJUK

Grid-connected rooftop solar photovoltaic(PV)systems can reduce the energy demand from the grid and significantly increase the power available to ***,rooftop solar PV has not yet been widely adopted in many sub-Saharan African countries,such as Sudan,although they are endowed with high solar radiation and in dire need of additional *** paper investigates risks and policies to increase grid-connected rooftop solar PV adoption in Sudan.A simplified United Nations Development Program Derisking Renewable Energy Investment framework is adopted to investigate this over three *** Stage 1,a list of risks and barriers was produced based on a literature review of solar PV studies in Sudan and interviews with nine *** was the risk most often mentioned(eight times from nine interviewees),followed by concerns about poor utility grid *** Stage 2,policy de-risking instruments and financial de-risking instruments were listed to overcome the *** include the intro-duction of net metering,the use of a third-party organization to monitor policy implementation,upgrade of the grid infrastructure,public awareness campaigns and energy-saving *** Stage 3,the levelized cost of electricity was estimated for a typical 2-kW rooftop PV system without policies(0.11$/kWh)and with a net-metering policy(0.07$/kWh).

关键词： energy policy rooftop solar PV Sudan energy poverty sustainable development photovoltaics

Improving low-voltage ride-through capability of a multimegawatt DFIG based wind turbine under grid faults

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Protection and Control of Modern Power Systems 2020年第1期5卷 390-402页

作者： mohamed Nadour ahmed Essadki Tamou Nasser Research Center of Engineering and Health Science and Technologies(STIS) High Normal School of Technical Education(ENSET)Mohammed V UniversityRabatMorocco Research Center of Engineering and Health Science and Technologies Higher National School of Computer Science and Systems Analysis(ENSIAS)Mohammed V UniversityRabatMorocco

Large integration of doubly-fed induction generator(DFIG)based wind turbines(WTs)into power networks can have significant consequences for power system operation and the quality of the energy supplied due to their excessive sensitivity towards grid *** voltage dips,the resulting overcurrent and overvoltage in the rotor circuit and the DC link of a DFIG,could lead to the activation of the protection system and WT *** potentially results in sudden loss of several tens/hundreds of MWs of energy,and consequently intensifying the severity of the *** paper aims to combine the use of a crowbar protection circuit and a robust backstepping control strategy that takes into consideration of the dynamics of the magnetic flux,to improve DFIG’s Low-Voltage Ride Through capability and fulfill the latest grid code *** the power electronic interfaces are protected,the WTs also provide large reactive power during the fault to assist system voltage *** results using Matlab/Simulink demonstrate the effectiveness of the proposed strategy in terms of dynamic response and robustness against parametric variations.

关键词： Wind turbine DFIG Grid faults Crowbar protection Backstepping control Low-voltage ride through

Composite Solid Rocket Propellant Based on GAP Polyurethane Matrix with Different Binder Contents

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火炸药学报 2020年第4期43卷 362-367页

作者： Islam KBoshra ahmed Elbeih GUO Lin mohamed GZaki School of Chemistry and Environment Beihang UniversityBeijing 100191China Military Technical College Kobry ElkobbahCairoEgypt

Different GAP-based CSRP samples with different binder contents were prepared and compared with that of conventional HTPB *** crosslinker mixture of trimethylol propane(TMP)and butane diol(BD)was used in the GAP matrix beside the addition of dibutyltin dilaurate(DBTDL)to ensure cross-linking and curing completion of the prepared *** viscosity and hardness of all prepared formulations were monitored continuously during the curing *** mechanical characteristics of cured samples were *** burning rate at operating pressure and specific impulse were measured,while the theoretical specific impulse(I sp)was calculated by ICT code and compared with the measured *** to the results,DOA was found to be a suitable plasticizer for GAP when using in *** mechanical properties of CSRP with 25%GAP can produce the optimum mechanical behavior,which is close to that of HTPB-based *** optimum GAP-based formulation is one candidate to replace the traditional HTPB-based CSRP with high burning rate for some applications.

关键词： physical chemistry glycidyl azide polymer(GAP) hydroxyl terminated polybutadiene(HTPB) cross-linker mechanical properties

The fate of prazosin and levonorgestrel after electrochemical degradation process: Monitoring by-products using LC-TOF/MS

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Journal of Environmental Sciences 2018年第12期30卷 134-146页

作者： fouad Fadhil Al-Qaim Zainab Haider Mussa Ali Yuzir Jalifah Latip mohamed Rozali Othman Malaysia-Japan International Institute of Technology Universiti Teknologi Malaysia Department of Chemistry Faculty of Science for Women University of Babylon School of Chemical Sciences and Food Technology Faculty of Science and Technology Universiti Kebangsaan Malaysia (UKM) Centre for Water Research and Analysis (ALIR) Faculty of Science and Technology Universiti Kebangsaan Malaysia (UKM)

Prazosin（PRZ） and levonorgestrel（LNG） are widely used as an anti-disease drugs due to their biological activity in the human body. The frequent detection of these compounds in water samples requires alternative technologies for the removal of both compounds. After electrochemical degradation of PRZ and LNG, the parent compounds could be completely removed after treatment, but the identification and characterization of by-products are necessary as well. In this study, the effects of NaCl concentration and applied voltage were investigated during the electrochemical degradation process. The results revealed that the increase of NaCl concentration and applied voltage could promote the generation of hypochlorite OCl-and then enhance the degradation of PRZ and LNG. After initial study, 6 V and 0.2 g NaCl were selected for further experiments（96% and 99% removal of PRZ and LNG after 40 min, respectively）. Energy consumption was also evaluated and calculated for PRZ and LNG at 3, 6 and 8 V. Solid phase extraction（SPE） method plays an important role in enhancing the detection limit of by-products. Furthermore, characterization and identification of chlorinated and non-chlorinated by-products were conducted using an accurate liquid chromatography-time of flight/mass spectrometry LC-TOF/MS instrument. The monitoring of products during the electrochemical degradation process was performed at6 V and 0.2 g NaCl in a 50 m L solution. The results indicated that two chlorinated products were formed during the electrochemical process. The toxicity of by-products toward E. coli bacteria was investigated at 37°C and 20 hr incubation time.

关键词： Prazosin Levonorgestrel Electrochemical degradation Solid phase extraction Chlorinated by-products Toxicity

Terlipressin and hepatorenal syndrome: What is important for nephrologists and hepatologists

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World Journal of Gastroenterology 2010年第41期16卷 5139-5147页

作者： ahmed A Magan Atif A Khalil mohamed H ahmed Department of Surgery Cambridge Uni-versity Hospital NHS foundation Trust Hills Road Cambridge CB2 0QQ United Kingdom Department of Nephrology Royal Liverpool and Broadgreen University Hospitals Liverpool L7 8XP United Kingdom Division of Acute Medicine James Cook University Hospital Marton Road Middlesbrough TS4 3BW United Kingdom

Hepatorenal syndrome (HRS) is a reversible form of functional renal failure that occurs with advanced hepatic cirrhosis and liver failure. Despite mounting research in HRS, its etiology and medical therapy has not been resolved. HRS encompasses 2 distinct types. Type 1 is characterized by the rapid development of renal failure that occurs within 2 wk and involves a doubling of initial serum creatinine. Type 2 has a more insidious onset and is often associated with ascites. Animal studies have shown that both forms, in particular type 1 HRS, are often precipitated by bacterial infections and cir-culatory changes. The prognosis for HRS remains very poor. Type 1 and 2 both have an expected survival time of 2 wk and 6 mo, respectively. Progression of liver cir-rhosis and the resultant portal hypertension leads to the pooling of blood in the splanchnic vascular bed. The ensuing hyperdynamic circulation causes an ineffective circulatory volume which subsequently activates neuro-hormonal systems. Primarily the sympathetic nervoussystem and the renin angiotensin system are activated, which, in the early stages of HRS, maintain adequate circulation. Both advanced cirrhosis and prolonged ac-tivation of neurohormonal mechanisms result in fatal complications. Locally produced nitric oxide may have the potential to induce a deleterious vasodilatory effect on the splanchnic circulation. Currently medical therapy is aimed at reducing splanchnic vasodilation to resolve the ineffective circulation and maintain good renal per-fusion pressure. Terlipressin, a vasopressin analogue, has shown potential benefit in the treatment of HRS. It prolongs both survival time and has the ability to re-verse HRS in the majority of patients. In this review we aim to focus on the pathogenesis of HRS and its treatment with terlipressin vs other drugs.

关键词： Heptorenal syndrome Terlipressin Kidney Liver