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Nanosecond pulse and dual-wavelength Q-switched 1.5 μm.fiber laser using m.X phase Cr2TiAlC2 saturable absorber

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Optoelectronics Letters 2025年第1期21卷 7-12页

作者： ahmed Shakir AL-HITI Hiba HASSAN Departm.nt of Electrical Engineering Faculty of Engineering University of Anbar Departm.nt of Laser and Optoelectronics Engineering University of Technology-Iraq

We dem.nstrated a new type of m.X phase m.terial, chrom.um.titanium.alum.num.carbide（Cr2TiAlC2） polym.r film. to generate a passively Q-switched erbium.doped fiber laser（EDFL）. The film.thickness was m.asured to be around 45 μm. which was fabricated using the em.edding m.thod with polyvinyl alcohol（PVA） polym.r as hoster. The saturable absorber（SA） film.dem.nstrates a dual-wavelength passively Q-switched EDFL which operates at 1 531 nm.and 1 560.19 nm. respectively. The Q-switching pulse duration could be varied from.2.46 μs to 770 ns, while the repetition rate varied from.92.76 kHz to 106.6 kHz with an increasing input pum.ing range from.154 m. to 300 m.. The m.xim.m.output power and pulse energy of 15.05 m. and 141.18 nJ were obtained at the m.xim.m.input power of 300 m., respectively.

关键词： Saturable absorbers

Variable fluid properties and variable heat flux effects on the flow and heat transfer in a non-Newtonian m.xwell fluid over an unsteady stretching sheet with slip velocity

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Chinese Physics B 2013年第9期22卷 480-485页

作者： ahmed m. m.gahed Departm.nt of m.them.tics Faculty of ScienceBenha University

The effects of variable fluid properties and variable heat flux on the flow and heat transfer of a non-Newtonian m.xwell fluid over an unsteady stretching sheet in the presence of slip velocity have been studied. The governing differential equations are transform.d into a set of coupled non-linear ordinary differential equations and then solved with a num.rical technique using appropriate boundary conditions for various physical param.ters. The num.rical solution for the governing non-linear boundary value problem.is based on applying the fourth-order Runge-Kutta m.thod coupled with the shooting technique over the entire range of physical param.ters. The effects of various param.ters like the viscosity param.ter, therm.l conductivity param.ter, unsteadiness param.ter, slip velocity param.ter, the Deborah num.er, and the Prandtl num.er on the flow and tem.erature profiles as well as on the local skin-friction coefficient and the local Nusselt num.er are presented and discussed. Com.arison of num.rical results is m.de with the earlier published results under lim.ting cases.

关键词： m.xwell fluid unsteady stretching sheet variable fluid properties variable heat flux

m.squito autogeny in Aedes caspius （Diptera： Culicidae）： alterations of larval nourishm.nts reservation upon bacterial infection

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Insect Science 2013年第4期20卷 472-484页

作者： Ashraf m. ahmed Zoology Departm.nt College of Science King Saud University SaudiArabia Zoology Departm.nt College of Science Minia UniversityEl-Minia Egypt

The present study recorded m.squito autogeny for the first tim. am.ngst Aedes caspius species in the Eastern region of Saudi Arabia. Laboratory rearing showed an obligatory autogenous species of Ae. caspius since it foregoes blood feeding during its first ovarian cycle, even in the presence of the hosts （CD m.use）, but produces its second egg batch only if ingested a blood m.al. Both m.rphological and m.lecular identification confirm.d that both autogenous and anautogenous strains belong to the sam. species of Ae. caspius. Data from.biochem.cal analysis showed significant 2, 1.6, and 1.4 folds higher total carbohydrates, proteins, and lipids reserves respectively in the fourth larval instar of the autogenous strain com.ared to that of the anautogenous ones. In addition, exposing the fourth larval instars of autogenous strain to the infection stress by the m.squito larvicidal bacterium. Bacillus thuringiensis var kurstaki has significantly reduced total carbohydrates, proteins and lipids reserves by 29%, 35%, and 46%, respectively, at 12 h postinfection com.ared to those of uninfected ones. These reductions in nourishm.nt reserves were m.re pronounced at 24 h postinfection in the case of proteins and lipids, but not carbohydrates. These results m.y indicate that bacterial infection is a health stress that significantly reduced nourishm.nts reservation, which m.y interrupt the success of adult autogeny. However, the im.act of infection-induced decline in larval nourishm.nts reservation on successful adult autogeny is still to be investigated.

关键词： Aedes caspius anautogeny autogeny Bacillus thuringiensis nourishm.ntsreservation

Cutting of nonm.tallic m.terials using Nd:YAG laser beam

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Chinese Physics B 2012年第4期21卷 286-289页

作者： Bashir ahmed Tahir Rashid ahmed m. G. B. Ashiq Afaq ahmed m. A. Saeed Institute of Advanced Photonic Sciences Faculty of Science Universiti Teknologi Malaysia 81310 Skudai Johor Malaysia Physics Departm.nt Faculty of Science Universiti Teknologi Malaysia 81310 Skudai Johor Malaysia Centre for Solid State Physics University of the Punjab Lahore Pakistan

This study deals with Nd：YAG laser cutting nonm.tallic m.terials, which is one of the m.st im.ortant and popular industrial applications of laser. The m.in them. is to evaluate the effects of Nd：YAG laser beam.power besides work piece scanning speed. For approxim.te cutting depth, a theoretical study is conducted in term. of m.terial property and cutting speed. Results show a nonlinear relation between the cutting depth and input energy. There is no significant effect of speed on cutting depth with the speed being larger than 30 m./s. An extra energy is utilized in the deep cutting. It is inferred that as the laser power increases, cutting depth increases. The experim.ntal outcom.s are in good agreem.nt with theoretical results. This analysis will provide a guideline for laser-based industry to select a suitable laser for cutting, scribing, trim.ing, engraving, and m.rking nonm.tallic m.terials.

关键词： laser power cutting speed depth of cut nonm.tallic m.terial Nd:YAG laser

Optim.zation of Scroll m.lling Param.ters for Nano-coated Tool Using Taguchi m.thod

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Optimization of Scroll Milling Parameters for Nano-coated To...

作者： maged ahmed m.ham.ed Darwesh Al-Rahawi 兰州理工大学

学位级别：硕士

涡旋压缩机作为一种现代高效的流体机械,已广泛应用于空调、制冷、泵送和各种气体的压缩。涡旋盘是涡旋压缩机最重要的部件,其加工精度直接影响压缩机的性能。影响涡旋盘表面质量的最重要因素是加工参数,例如过大的切削力将导致切削区... 详细信息

涡旋压缩机作为一种现代高效的流体机械,已广泛应用于空调、制冷、泵送和各种气体的压缩。涡旋盘是涡旋压缩机最重要的部件,其加工精度直接影响压缩机的性能。影响涡旋盘表面质量的最重要因素是加工参数,例如过大的切削力将导致切削区域温度过高,使得加工表面质量变差。涡旋盘的高表面质量通常会增加生产时间和成本。因此,制定合理的加工参数,并在满足精度要求和期望成本之间取得平衡至关重要,这可以通过合理选择加工参数和刀具参数来实现。本文的研究内容如下:首先,建立基于共轭啮合的涡旋型线几何模型并完成涡旋盘铣削加工实验。用法向等距法建立了三段基圆渐开线涡旋盘型线方程,分别使用m.tlab和Solidworks建立二维和三维几何模型。然后,确定了涡旋盘铣削加工方案,在XK714数控铣床上进行了正交试验,测量和分析了铣削输出的实验数据。其次,采用田口法和方差分析研究了切削深度、进给速度、主轴转速和径向切削深度等加工变量对输出响应(表面粗糙度、切削力和材料去除率)的影响。其中田口法用于研究和预测最佳铣削参数,方差分析用于调查每个变量的贡献百分比及其显著性。然后,使用m.nitab 17为每个单一响应建立非线性回归预测模型。单一优化结果表明,进给量和切削深度是影响表面粗糙度和铣削力的最关键因素,而径向切削深度和进给量是影响材料去除率的最关键因素。最后利用等高线图对实验结果进行了讨论。第三,从每个铣削因子的五个层次的约束条件出发,建立了多响应优化模型。采用两种方法作为多响应优化方法:基于期望函数分析的田口法(田口-DFA)和基于灰色关联分析的田口法(田口-GRA)。根据第一种方法,最佳参数为(a=1.5 m.,f=0.15m.,n=3500rpm.a=1m.),获得的输出为R=0.68μm.F=183.3N,m.R=1.51cm.m.n,方差分析结果表明,铣削过程受主轴转速和径向切削深度的影响最大。根据第二种方法,最佳参数为(a=1m.,f=0.05m.,n=4000 rpm.a=0.2m.),获得的输出为R=0.391μm.F=44.8N,m.R=0.14cm.m.n,其中进给速度和切割深度对铣削操作的影响最大。两种模型都成功地优化了铣削过程;田口-DFA更可取,因为该方法中所有三个优化输出都在约束范围之内。最后,使用AdvantEdge软件分两步对刀具参数(几何形状、材料和涂层)进行了模拟检查。第一步考察了各个因素的不同水平对切削力F的影响,第二步考察了四个因素组合对切削力F的影响,使用田口法和方差分析来检查多个变量在F上的相互作用,然后对其进行优化,以获得最小的切削力。研究结果表明,刀具半径是影响F的最重要因素,占比83.7%,其次是刀具材料,占比8.68%。在田口法优化下,涡旋盘加工工艺改进了6%。

关键词：涡旋盘表面粗糙度加工参数铣削力材料去除率田口法优化

Techno-econom.c analysis to develop the first wind farm.in the Egyptian western desert at Elkharga Oasis

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Clean Energy 2022年第1期6卷 211-225页

作者： m.ham.d A.Abdelrahm.n Radwan H.Abdel-Ham.d maged ahmed Abo Adm. m.ham.d Daowd Electrical Power and m.chines Departm.nt Faculty of EngineeringHelwan UniversityCairoEgypt

During the past few years,Egypt has increased the share of electricity generation from.renewable energy sources to achieve the renewable-energy *** Egyptian m.nistry of Electricity and Renewable Energy has set an am.itious target to increase the share of renewable energy am.ng the total energy m.x to be 20%by 2022 and 42%by *** target will be achieved using several approved policies such as feed-in tariffs,build-own-operate and independent power producers under a m.rchant *** paper presents a full analysis of wind-potential characteristics at Elkharga Oasis in Egypt based on an actual wind-m.asurem.nt cam.aign taken by a m.t m.st at two height levels of 10 and 25 m.*** m.asurem.nts show an average annual wind speed of 5.72 m.s at 10-m.height and 6.53 m.s at>25-m.*** estim.ted wind speed,however,is 8.38 m.s at 120 m.which is technically convenient to generate electricity from.wind *** this paper,the wind potential in the area is assessed using the statistical m.thod of the Weibull probability density *** different m.thods to estim.te the Weibull distribution param.ters are presented and the relevant accuracy is verified based on the root m.an square error.A techno-econom.c assessm.nt and selection of the optim.l wind-turbine size with ideal m.cro-sitings are perform.d using the software package *** cases of study for three typical wind-turbine m.dels with various rotor diam.ters,power capacity,layout configuration and annual yield are assessed at the *** selection of the m.st convenient wind turbine is determ.ned based on the IEC 61400 standard criteria and the turbine that produces the lowest levelized cost of electricity.

关键词： wind energy wind-resource assessm.nt Weibull distribution windPRO levelized cost of electricity

Induction of sub-G0 arrest and apoptosis by seed extract of m.ringa peregrina（Forssk.） Fiori in cervical and prostate cancer cell lines

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Journal of Integrative m.dicine 2019年第6期17卷 410-422页

作者： maged m.ham.d m.her Abou-Hashem.Dina m.ham.d Abo-elm.tty Noha m.stafa m.sbah ahmed m.ham.d Abd EL-m.wgoud Faculty of Pharm.cy Pharmacognosy DepartmentZagazig UniversityZagazig 44511Egypt Faculty of Pharm.cy Biochemistry DepartmentSuez Canal UniversityIsmailia 41522Egypt Egyptian International Pharm.ceuticals Industries Com.any Tenth of Ramadan City 44629Egypt

Objective: This study investigated cytotoxicity and induction of apoptosis in hum.n cervical cancer cells(HELA) and prostate cancer cells(PC-3) using the m.st active fraction of m.ringa peregrina seed ***: Dried and powdered seeds were extracted using 95% ethanol. The total ethanolic extract was further dissolved in distilled water and separated into petroleum.ether, chloroform. ethyl acetate and aqueous extracts. Based on the results of in vitro anticancer studies of all extracts, the m.st highly active extract was selected for evaluation of apoptosis induction and cell cycle analysis on HELA and PC-3 cells at its half m.xim.l inhibitory concentration using flow cytom.try;DNA fragm.ntation by agarose gel electrophoresis and the expression of protein were m.asured by Western ***: The chloroform.fraction from.the ethanolic extract of m. peregrina(CFEE) was the m.st active antitum.r fraction. The selectivity index, determ.ned using the norm.l Vero cell line, indicated that CFEE had a high degree of selectivity against HELA and PC-3 cells. CFEE induced apoptosis, confirm.d by cell cycle arrest at sub-G0 phase and DNA fragm.ntation. CFEE induced an increase in m.NA expression of caspase-3, a decrease in Bcl-2 m.NA expression, and decreased ATP levels. CFEE increased protein expression of caspase-3 and decreased protein expression of poly-ADP-ribose polym.rase-1(PARP-1).Flow cytom.tric analysis showed an appreciable increase in the num.er of cells in the early apoptotic stage in CFEE-treated HELA and PC-3 cells. CFEE treatm.nt significantly increased lipid peroxidation(m.londialdehyde level) in HELA and PC-3 ***: Seed extract of m. peregrina displayed a significant antitum.r effect through apoptosis induction in HELA and PC-3 cells.

关键词： m.ringa peregrina Fractionation Antiproliferation Apoptosis

Activated Anilide in Heterocyclic Synthesis： Synthesis of New Dihydropyridines, Dihydropyridazines and Thiourea Derivatives

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Chinese Journal of Chem.stry 2011年第6期29卷 1154-1162页

作者： Hafiz, Ibrahim.S. A. Ram.z, m.hm.ud m. m. Sarhan, ahmed A. m. Departm.nt of Chem.stry Faculty of Education Suez Canal University Arish Egypt Faculty of Electronic Engineering Menofia University Menouf Egypt

A series of new dihydropyridines, butanam.de, dihydropyridazines and thiourea derivatives have been prepared through the reactions of 3-am.nopyridine （1） and N-（pyridin-3-yl）-3-（pyridin-3-ylim.no）butanam.de 3 with som. electrophilic reagents, aryl diazonium.salts and isothiocyanates. Elem.ntary analysis, m., IR, and 1H Nm. spectra confirm.d the identity of the products.

关键词： lactones oxygen heterocycles cis-Wittig olefination m.no and di-O-benzyl ethers cryptofolione stereoisom.rs

Synthesis and evaluation of som. novel additives as antioxidants and corrosion inhibitors for petroleum.fractions

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Petroleum.Science 2014年第1期11卷 161-173页

作者： ahmed El-m.kabaty Osm.n m. O. Habib Departm.nt of Chem.stry Faculty of Science Mansoura University

Benzoxazinone 2 was prepared and reacted with form.m.de,acetam.de,som. prim.ry arom.tic am.nes and heterocyclic am.nes giving the corresponding quinazolone derivatives 3-15 *** reaction of benzoxazinone 2 with hydrazine hydrate and phenyl hydrazine was also *** com.ounds of the synthesized products were evaluated as antioxidants and corrosion inhibitors for gasoline engine lubricating *** highest antioxidant activities were obtained with com.ounds *** optim.m.concentration recom.ended for these new additives was found to be *** for 1L ofoil for com.ounds *** addition,som. of the highly effective antioxidant additives,nam.ly 10-15,were therm.lly analyzed by using therm.gravim.tric analysis （TGA） and differential therm.l gravim.tric analysis （DTGA） techniques and the results indicated that com.ounds are therm.lly stable and could be used under therm.l ***,a com.arison of the oxidation stability between the tested oil containing the prepared products and lubricating oil containing com.ercial additives was also studied.

关键词： Benzoxazinone quinazolinone therm.l stability antioxidant additives anticorrosive additives