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Experimental and numerical investigation of the abrasive waterjet machining of aluminum-7075-T6 for aerospace applications

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Advances in Manufacturing 2021年第2期9卷 286-303页

作者： Joseck Nyaboro Mahmoud Ahmed Hassan el-Hofy mohamed el-Hofy Department of Industrial and Manufacturing Engineering Egypt-Japan University of Science and Technology(E-JUST)Alexandria 21934Egypt Department of Energy Resources Engineering Egypt-Japan University of Science and Technology(E-JUST)Alexandria 21934Egypt Advanced Manufacturing Research Centre(AMRC)with Boeing The University of SheffieldRotherham S605TZUK

The machining of hard-to-cut materials with a high degree of precision and high surface quality is one of the most critical considerations when fabricating various state-of-the-art engineered *** this investigation,a comprehensive three-dimensional model was developed and numerically simulated to predict kerf profiles and material removal rates while drilling the aluminum-7075-T6 aerospace *** profile and material removal prediction involved three stages:jet dynamic flow modeling,abrasive particle tracking,and erosion rate *** investigations were conducted to validate the developed *** results indicate that the jet dynamic characteristics and flow of abrasive particles alter the kerf profiles,where the top kerf diameter increases with increasing jet pressure and standoff *** kerf depth and hole aspect ratio increase with jet pressure,but decrease with standoff distance and machining *** profiles were characterized by progressive edge rounding and parabolic *** can be minimized by utilizing high jet pressure and small standoff *** material removal rate increases with increasing jet pressure,abrasive particle size,and exposure time,but decreases with increasing standoff distance.

关键词： Non-traditional machining Abrasive waterjet machining Computational fluid dynamics(CFD) Erosion modeling Kerf characteristics

Salt response of the freshwater microalga Scenedesmus obliquus(Turp.)Kutz is modulated by the algal growth phase

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Journal of Oceanology and Limnology 2020年第3期38卷 802-815页

作者： Taha mohamed el-KATONY Magda Faiz el-ADL Department of Botany and Microbiology Faculty of ScienceDamietta UniversityNew Damietta City 34517Egypt

Growth and biochemical responses of the coenobial green alga Scenedesmus obliquus to salinity stress were monitored across different phases of *** alga was cultured on BG11 growth medium and subjected to 0,30,100,and 200 mmol/L NaCl for a period of 20 d,during which algal cultures were harvested at 4-d *** salinity-induced inhibition of algal growth was accompanied with prolongation of timing of the different growth *** sharp and progressive salinity-induced inhibition of algal growth rate during the early phase of growth points to salt shock but moderation of inhibition at the subsequent stages of growth means algal acclimation to *** concentrations of chlorophylls a and b,soluble sugars,proteins as well as those of K+and Na+in the alga exhibited peaks at the initiation of the exponential phase of growth,with increasing magnitude in proportion to the increase in the level of ***,whereas soluble sugars of the alga peaked at initiation of the exponential phase,starch concentration progressively increased with culture age,reaching saturation towards the stationary *** the salinity-induced increase in soluble sugars was most evident at the early stages of growth the reverse was true for *** present results point to fast acclimation of *** to salt stress post a brief salt shock,utilizing soluble sugars,K+and Na+for osmotic *** salinity from 0 to 200 mmol/L NaCl led to progressive increase in soluble sugars,proteins,K+and Na+concentrations of the algal cells,particularly at the early stages of ***,the salinity-induced increase in chlorophyll concentration approached a limit at 100 mmol/L NaCl whereas that in starch concentration was more evident at the later stages of growth.

关键词： carbohydrates growth phase minerals protein salt stress Scenedesmus obliquus

Optimal searching for a Helix target motion

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Science China Mathematics 2015年第4期58卷 749-762页

作者： mohamed Abd Allah el-Hadidy Department of Mathematics Faculty of Science Tanta University

This paper discusses a search problem for a Helix target motion in which any information of the target position is not available to the searchers. There exist three searchers start searching for the target from the origin. The purpose of this paper is to formulate a search model and finds the conditions under which the expected value of the first meeting time between one of the searchers and the target is finite. Also, the existence of the optimal search plan that minimizes the expected value of the first meeting time is shown. Furthermore,this optimal search plan is found. The effectiveness of this method is illustrated by using an example with numerical results.

关键词： Helix motion optimal search plan first meeting time probability measure multiobjective nonlinear programming problem

Remote Monitoring of electric Vehicle Charging Stations in Smart Campus Parking Lot

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Journal of Modern Power Systems and Clean Energy 2020年第1期8卷 124-132页

作者： mohamed A.Ahmed mohamed R.el-Sharkawy Young-Chon Kim Department of electronic Engineering Universidad Técnica Federico Santa MaríaValparaíso 2390123Chile Department of Communications and electronics Higher Institute of Engineering&TechnologyKing MarriottAlexandria 23713Egypt Department of Automotive and Tractor Engineering Minia UniversityEl-Minia 61111Egypt Department of Computer Engineering Chonbuk National UniversityJeonju 561-756Korea

Smart parking lots are smart places capable of supporting both parking and charging services for electric vehicles(EVs).In order to manage EV charging,the parking lot local controller(PLLC)requires data exchange with EV charging stations(EVCSs)through communication ***,data losses and communication delays are unavoidable and may significantly degrade the system *** work aims to investigate the underlying communication networks for remote monitoring of EVCSs in a smart campus parking *** communication network consists of two subnetworks:parking area network(PAN)and campus area network(CAN).PAN covers communication among EVs,charging stations and PLLC,while CAN enables dedicated communication between PLLCs and a global controller of the *** one of the major obstacles in EV system is the lack of unified communication architecture to integrate EVCS in the power grid,we develop communication models for the in-vehicle system and EVCSs based on logical node concept of IEC 61850 ***,we implement network models for EVCSs using OPNET *** communication technologies and configurations are considered in modeling and simulations,and end-toend delay is evaluated and discussed.

关键词： Communication network electric vehicle(EV) electric vehicle charging station(EVCS) IEC 61850 OPNET smart parking lot

WelL-POSEDNESS AND STABILITY FOR THE GENERALIZED INCOMPRESSIBLE MAGNETO-HYDRODYNAMIC EQUATIONS IN CRITICAL FOURIER-BESOV-MORREY SPACES

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Acta Mathematica Scientia 2019年第6期39卷 1551-1567页

作者： Azzeddine el BARAKA mohamed TOUMLILIN FST FES Laboratory AAFA Department of Mathematics University Sidi Mohamed Ben Abdellah

This paper concerns the Cauchy problem of the 3D generalized incompressible magneto-hydrodynamic(GMHD) equations. By using the Fourier localization argument and the Littlewood-Paley theory, we get local well-posedness results of the GMHD equations with large initial data(u0, b0) belonging to the critical Fourier-Besov-Morrey spaces FN^1-2α+3/p'+λ/pp,λ,q(R^3) Moreover, stability of global solutions is also discussed.

关键词： magneto-hydrodynamic Fourier-Besov-Morrey space stability

Synthesis of Certain 3-Aminopyrazolo[5,4-b]pyridine and 3,4-Substituted Pyrido[2′,3′：3,4]pyrazolo[5,1-c][1,2,4]triazine Derivatives

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Chinese Journal of Chemistry 2007年第12期25卷 1887-1891页

作者： el-LOUH, Ali Khader Khalil ABUNADA, Nada mohamed el-SHOUBAKI, mohamed Chemistry Department Faculty of Science Al-Azhar University-Gaza Gaza 76888 Palestine Chemistry Department Faculty of Applied Sciences Al-Aqsa University Gaza Palestine 4051 Israel

2-Thioxo-1,2-dihydropyridine derivatives 2a, 2b were reacted with methyl iodide to give 2-methylthiopyridines 3a, 3b, which were reacted with hydrazine hydrate to produce 3-aminopyrazolo[5,4-b]pyridines 4a, 4b. Compounds 4a, 4b were diazotized to afford the corresponding diazonium salts 5a, 5b, which were reacted with some active methylene compounds 6a-6h to give the corresponding pyrido[2′,3′ ： 3,4]pyrazole[5,1-c][1,2,4]triazines 7-14.

关键词： pyrazolo[3,4-b]pyridine pyrido[2′,3′ : 3,4]pyrazole[5 1-c] [ 1,2,4]triazine 2-arylmethylidene-2-cyanothioacetamine 2-thioxopyridine

Neoproterozoic Tectonic Events of Egypt

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Acta Geologica Sinica(English Edition) 2021年第4期95卷 1366-1405页

作者： mohamed ABD el-WAHED Zakaria HAMIMI Geology Department Faculty of ScienceTanta UniversityTanta 31527Egypt Department of Geology Faulty of ScienceBen ha UniversityBenha 13518Egypt

The Egyptian Nubian Shield(ENS)represents the northwestern part of the Arabian-Nubian Shield and the northern extension of the East African *** ENS is regarded as being formed due to northward-directed escape *** is characterized by mild accretion and suture zones dominated by major strike-slip zones with a commonly sinistral sense of movement;some shear zones display a dextral sense of *** is dominated by gneisses and migmatites in the south,arc volcaniclastic metasediments and highly dismembered ophiolites in the central parts,whereas its northern part is dominated by late-to post-tectonic *** southern Sinai,the Neoproterozoic rocks are grouped into four complexes,namely Feiran–Solaf,Sa’al–Zaghra,Kid and *** ENS ophiolites were formed between 730–750 Ma,mainly in a supra-subduction zone *** ENS has undergone a Neoproterozoic deformation history involving three successive phases:(1)Early N–S shortening phase(D1),(2)Syn-accretionary phase(D2)and(3)Post-accretionary phase(D3).The initial island-arc stage(780–730 Ma)is a N–S shortening phase initiated by collision between the Eastern Desert tectonic terrane to the north with both the Gebeit and Gabgaba terranes to the south(830–720 Ma).During the arc-splitting and back-arc spreading stage(730–620),voluminous syn-tectonic granitoids intruded into the ENS(750–610 Ma).The E–W-directed compressional/transpressional phase(620–450 Ma)led to the overall uplift of the central part of the ENS and consequently the development and exhumation of the core complexes in oblique convergent *** E–W intense shortening deformation resulted also in the formation of NW-and NE-striking sinistral and dextral strike-slip shear zones,*** latest periods of the E–W-directed compressional/transpressional regime were characterized by deposition of the molasse-type Hammamat Sediments unconformably over the Dokhan Volcanics,or interbedded with *** combined thrusting,folding and sin

关键词： Neoproterozoic deformation N–S shortening syn-accretionary phase post-accretionary phase Egyptian Nubian Shield

Liver graft preservation:an overview

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Hepatobiliary & Pancreatic Diseases International 2007年第1期6卷 12-16页

作者： mohamed el-Wahsh University Department of Surgery Al Zhraa University Hospital Cairo Egypt

BACKGROUND: The quality of liver graft and outcome of liver transplantation is affected by the length of ischemia time during the donor operation. The retrieved graft may have a serious damage during the time of stoppage of the circulation in the donor until revascularization in the recipient. It is very important to develop a suitable preservation fluid to minimise the damage caused by the ischemic period and to make the surgical procedure semi- elective. DATA SOURCES: An English-language literature search was conducted using MEDLINE (1960-2006) on liver preservation solution, liver transplantation, kidney transplantation and other related subjects. RESULTS: Since 1960 until 2006 many preservation solutions have been introduced. Most of them are based on the effect of hypothermia to minimise the metabolic pathway in the liver graft. In the earlier studies electrolyte solutions were used to perfuse the liver through the portal vein. The first modification in preservation solution was done by Collins who was able to extend the kidney preservation time up to 30 hours. In recent years, the introduction of University of Wisconsin (UW) preservation solution has made a revolution in the field of organ preservation. The UW solution is based on lactobionate and raffinose as impermeants to suppress hypothermic-induced tissue swelling, replacing glucose and mannitol in Collin's solution and hypertonic citrate respectively. Recently a research group in Kyoto University works to produce a more reliable preservation solution. They investigated the importance of saccharides and electrolytes in lung preservation and developed their original ET-Kyoto solution. However, more studies are still needed to evaluate the new ET-Kyoto solution. CONCLUSIONS: The development of new preservation solutions represents a corner stone in the field of organtransplantation. In the future we might be able to extend the time of organ preservation from hours to days.

关键词： organ preservation liver transplantation preservation solution ischemic damage UW solution

Magnetoresistive properties of Ni-doped La_(0.7)Sr_(0.3)MnO_3 manganites

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Rare Metals 2016年第7期35卷 551-558页

作者： Ahmed mohamed Ahmed Abd el-Moez Ahmed mohamed Medhat Abdelrady Abdellateef Hassan Ahmed Abd el-Ghanny Physics Department Faculty of ScienceSohag University

Lao.7Sr0.3Mnl_xNixO3 （x = 0, 0.025, 0.050 and 0.075） ceramics were prepared by the conventional solid-state reaction method. The partial substitution of Mn by Ni2＋ leads to a decrease in cell volume as well as a structural transition from the rhombohedral to the orthorhombic structure. Ni2＋ doping increases the electrical resistivity, decreases the semiconductor-metal transition temperature （Tms） and relatively enhances the room temperature magnetoresistance （MR）, especially in x = 0.025 and around Tins. With respect to conduction mechanism, the small polaron hopping （SPH） and the variable range hopping （VRH） models were used to ex- amine conduction in the semiconducting region.

关键词： Manganites X-ray diffraction Structure electrical resistivity Magnetoresistance