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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

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

Model Predictive Current Control for Low-Cost Shunt Active Power Filter

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CSEE Journal of Power and Energy Systems 2024年第4期10卷 1589-1598页

作者： Ali a.abdel-aziz Mohamed A.Elgenedy Barry W.Williams the Electronic and Electrical Engineering Department Strathclyde UniversityGlasgowG11XQUK School of Computing Engineering and the Built Environment(SCEBE)Glasgow Caledonian UniversityGlasgowG40BAUK

Performance of a three-phase shunt active power filter(SAPF)relies on the capability of the controller to track the reference ***,designing an accurate current controller is crucial to guarantee satisfactory SAPF *** paper presents a model predictive current controller(MPCC)for a low-cost,four-switch,shunt active power filter for power quality improvement.A four-switch,B4,converter topology is adopted as an SAPF,hence offering a simple,robust,and low-cost *** addition,to further reduce overall cost,only two interfacing filter inductors,instead of three,are used to eliminate switching current *** proposed SAPF model MPCC is detailed for implementation,where simulation and experimental results validate effectiveness of the proposed control algorithm showing a 20%improvement in total harmonic distortion compared with a conventional hysteresis band current controller.

关键词： Four-switch converter harmonic distortion model predictive current control power quality shunt active power filter

Influence of anodization conditions on deposition of Hydroxyapatite on α/β Ti alloys for Osseointegration: Atomic Force Microscopy Analysis

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Transactions of Nonferrous Metals Society of China 2024年

作者： Rania E.Hammam Engie M.Safwat Soha a.abdel-Gawad Madiha Shoeib Shimaa El-Hadad Faculty of Engineering， Modern University for Technology and Information (MTI) Restorative and Dental Materials Department， National Research Centre Giza Chemistry Department， Faculty of Science， Cairo University Central Metallurgical Research and Development Institute P.O.87

Integrating titanium-based implants with the surrounding bone tissue remains challenging. This study aims to explore the impact of different anodization voltages （20-80V） on the surface topography of two-phase （α/β） Ti alloys and to produce TiO2films with enhanced bone formation abilities. Scanning electron microscopy coupled with energy dispersive spectroscopy （SEM-EDS） and atomic force microscopy （AFM） were applied to investigate the morphological， chemical， and surface topography of the prepared alloys and to confirm the growth of hydroxyapatite （HA） on their surfaces. Results disclosed that the surface roughness of TiO2films formed on Ti-6Al-7Nb alloys was superior to that of Ti–6Al–4V alloys. Ti-6Al-7Nb alloy anodized at 80 V had the highest yields of HA after immersion in SBF with enhanced HA surface coverage. The developed HA layer had a mean thickness of 128.38 ± 18.13 μm， suggesting its potential use as an orthopedic implantable material due to its promising bone integration and， hence， remarkable stability inside the human body.

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Electrochemical anodization of cast titanium alloys in oxalic acid for biomedical applications

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Frontiers of Chemical Science and Engineering 2024年第1期18卷 13-24页

作者： Engie M.Safwat Soha a.abdel-Gawad Madiha A.Shoeib Shimaa El-Hadad Restorative and Dental Materials Department National Research CentreGiza 12622Egypt Chemistry Department Faculty of ScienceCairo UniversityGiza 12613Egypt Central Metallurgical Research and Development Institute Helwan 11421Egypt

Titanium and its alloys have numerous biomedical applications thanks to the composition and morphology of their oxide *** this study,the colorful oxide films were formed by anodizing cast Ti-6Al-4V and Ti-6Al-7Nb alloys in a 10%oxalic acid solution for 30 s at different voltages(20–80 V)of a direct current power *** force microscopy was used as an accurate tool to measure the surface roughness of thin films on the nanometer *** electron microscopy and X-ray diffraction were performed to analyze surface morphology and phase *** to the results,the produced titanium oxide layer showed high surface roughness,which increased with increasing anodizing *** impact of anodizing voltages on the color and roughness of anodized layers was *** corrosion resistance of the anodized samples was studied in simulated body fluid at pH 7.4 and a temperature of 37℃ utilizing electrochemical impedance spectroscopy and the potentiodynamic polarization *** anodized samples for both alloys at 40 V were at the optimal voltage,leading to a TiO_(2) layer formation with the best compromise between oxide thickness and corrosion ***,findings showed that TiO_(2) films produced on Ti-6Al-7Nb alloys had superior surface roughness properties compared to those of Ti-6Al-4V alloys,making them more appropriate for orthopedic *** the obtained data and the fruitful discussion,it was found that the utilized procedure is simple,low-cost,and ***,anodization in 10%oxalic acid proved a viable alternative for the surface finishing of titanium alloys for biomedical applications.

关键词： DC anodization Ti-6Al-4V alloy Ti-6Al-7Nballoy oxidefilm corrosion

My Dream of Translation and Predestination With China

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China News Release 2024年第4期 24-27页

作者： abdel aziz Hamdi the Chinese language department of Al-Azhar University in Egypt

Many years later,when looking back on my decision,I can’t help but think that a few things in life seem to be coincidences,but in fact they are imperceptibly predestined,just like my dream of translation and my experience with the Chinese *** 1977,when I was 18 years old,Ain Shams University in Egypt established the Chinese *** was the only Chinese department among Egyptian universities for the following two decades.

关键词： looking dream translation

Calculation of ship motions in steep waves with restoring and Froude-Krylov forces on an adaptive panel mesh with Gauss and analytic integration methods

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Journal of Hydrodynamics 2024年第2期36卷 275-289页

作者： Malwin Wermbter Moustafa.abdel-Maksoud Institute for Fluid Dynamics and Ship Theory Hamburg University of TechnologyHamburgGermany

The impulse response method is a frequently used method to calculate ship seakeeping *** this paper,the restoring and Froude-Krylov calculation is conducted with constant evaluation of panel pressures as well as Gauss quadrature and an analytical *** applied panel grid is coarsened by an adaptive algorithm which is based on a normal vector *** comparison of methods is based on grid convergence studies which are followed by a verification of forces with computational fluid dynamics(CFD)results on the fixed duisburg test case in *** with experimental results in head,oblique and following waves show that all integration methods are *** exact integration is numerically sensitive in some *** quadrature is highly accurate;however,the additional effort is not beneficial since the geometrical accuracy has-stronger influence on the force amplitudes than the integration *** grid coarsening reduces the simulation time and is accurate up to a level,where the panel length comes close the *** added resistance at the investigated Froude number of 0.05 shows higher uncertainty levels,this applies to the results of both the numerical methods and model tests.

关键词： Ship hydrodynamics seakeeping impulse response method added resistance wave loads

Mitigating diabetes-related complications:Empowering metformin with cholecalciferol and taurine supplementation in type 2 diabetic rats

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World Journal of Diabetes 2024年第8期15卷 1778-1792页

作者： Mai S Attia Fadwa Ayman Mohamed S Attia Galal Yahya Mansour H Zahra Magdi Mohamed Ibrahim Khalil abdel aziz A Diab Department of Zoology Faculty of ScienceZagazig 44519Egypt Department of Pharmaceutics Faculty of PharmacyZagazig 44519Egypt Department of Microbiology and Immunology Faculty of PharmacyZagazig UniversityZagazig 44519Egypt Department of Biochemistry Faculty of MedicineZagazig 44519Egypt

BACKGROUND Type 2 diabetes is one of the most prevalent chronic diseases worldwide,significantly impacting patients'quality of *** treatment options like metformin(MET)effectively counteract hyperglycemia but fail to alleviate diabetes-associated complications such as retinopathy,neuropathy,nephropathy,hepatopathy,and cardiovascular *** To propose the supplementation of cholecalciferol(CHO)and taurine(TAU)to enhance MET efficacy in controlling diabetes while minimizing the risk of associated *** The study involved sixty rats,including ten non-diabetic control rats and fifty experimental rats with type 2 diabetes induced by *** experimental rats were further subdivided into positive control and treatment *** four treatment groups were randomly allocated to a single MET treatment or MET combined with supplements either CHO,TAU,or *** Diabetic rats exhibited elevated levels of glucose,insulin,Homeostasis Model Assessment of Insulin Resistance(HOMA-IR),glycated hemoglobin percentage,lipid markers,aspartate aminotransferase,and malondialdehyde,along with reduced levels of antioxidant enzymes(catalase and superoxide dismutase).The administration of CHO and TAU supplements alongside MET in diabetic rats led to a noticeable recovery of islet *** antioxidative,anti-inflammatory,and anti-apoptotic properties of the proposed combination therapy significantly ameliorated the aforementioned *** The supplementation of CHO and TAU with MET showed the potential to significantly improve metabolic parameters and protect against diabetic complications through its antioxidative,anti-inflammatory,and antiapoptotic effects.

关键词： Diabetes complications Metformin Cholecalciferol Taurine Glycated hemoglobin% Antioxidant

Modulation of oxidative damage and genotoxicity of biosynthesized zinc oxide nanoparticles via supplementation with modified cinnamaldehyde-loaded chitosan nanoparticles in mice

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Food Science and Human Wellness 2024年

作者： Mosaad a.abdel-Wahhab aziza A.El-Nekeety Asmaa S.Salman Zeinab K.Hamza Engy M.Akl Soher E.Aly Wenyi Kang Department of Food Toxicology & Contaminants， National Research Centre Dokki， Cairo， Egypt Genetic and Cytology Department， National Research Centre Dokki， Cairo， Egypt Department of Fats and Oils， National Research Centre Dokki， Cairo， Egypt National R & D Center for Edible Fungus Processing Technology， Henan University Joint International Research Laboratory of Food & Medicine Resource Function Functional Food Engineering Technology Research Center Henan

Synthesis of zinc oxide nanoparticles (Zn-NPs) via green method is an outstanding alternative to conventional/regular methods; however， the safety or toxicity of the biosynthesized ZnO-NPs in vivo is not fully explored. This study was conducted to evaluate the protective efficiency of cinnamaldehyde-loaded chitosan nanoparticles (Cin@CSNPs) against oxidative damage and genotoxicity of zinc oxide nanoparticles (ZnO-NPs) in mice. ZnO-NPs were biosynthesized using the extract of fresh leaves of Mentha pulegium L. Cin was extracted from cinnamon essential oil， and was loaded into chitosan nanoparticle (Cin@CSNPs). Both ZnO-NPs， Cin@CSNPs and CSNPs were characterized. The in vitro release of Cin@CSNPs was determined. In the biological study， 6 groups of male Balb/c mice were treated by gavage for 3 weeks as follows， control group， the group received ZnO-NPs (25 mg/kg b.w)， the groups received Cin@CSNPs at low dose (50 mg/kg b.w) or high dose (100 mg/kg b.w)， and the groups received ZnO-NPs plus Cin@CSNPs at the two tested doses. Blood and tissue samples were collected for different biochemical， genetical and histological studies. The particle size of ZnO-NPs， CSNPs， and Cin@CSNPs were (20.78 ± 2.6)， (170.0 ± 3.7)， and (218.23 ± 2.9) nm， and ξ-potential were (32.7 ± 4.6)， (8.32 ± 0.27) and (4.8 ± 0.21)， respectively. ZnO-NPs disturbed the biochemical and oxidative stress indices， AFP， CEA， TNF-α， chromosomal aberrations in somatic and germ cells， and sperm abnormality along with severe pathological changes in the hepatic， renal， and testicular tissues. Cin@CSNPs improved significantly all the parameters tested and the histological picture in a dose-dependent. Therefore， the biosynthesized ZnO-NPs exhibit oxidative damage and genotoxicity， and Cin@CSNPs have potential protective effects against the risks of ZnO-NPs and may be a promising tool to overcome the challenges of using Cin in food and pharmaceuticals applications.

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