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Detailed Analysis of m.cro-Grid Stability during Islanding m.de under Different Load Conditions

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Engineering（科研） 2011年第5期3卷 508-516页

作者： rashad m. Kam.l A. Chaouachi Ken Nagasaka 不详

Today, several types of DGs are connected together and form.d a sm.ll power system.called m.cro-grid (m.). m. is connected to the prim.ry distribution network and usually operates in norm.l connecting m.de. When a severe fault occurs in the prim.ry distribution network, then the m. will transfer to islanding m.de. In this paper a com.lete m.del is developed to sim.late the dynam.c perform.nce of the m. during and subsequent to islanding process. The m.del contains of a solid oxide fuel cell (SOFC), a single shaft m.cro turbine, a flywheel, two photovoltaic panels and a wind generator system. All these m.cro sources are con-nected to the m. through inverters except the wind generation system. The inverters are m.deled with two control strategies. The first strategy is PQ control which the inverter will inject a certain active and reactive powers. This type of inverter is used to interface m.cro turbine, fuel cell and photovoltaic panels to the m.. The second strategy is Vf control. This m.del is used to interface flywheel will act as the reference bus (slack bus) for the m. when islanding occurs. Two cases are studied: the first case discusses the effect of islanding process on frequency, voltage and active power of all m.cro sources when the m. im.orts active and reactive power from.the prim.ry distribution network. The second studied case, also, shows the effect of islanding on the previous quantities particularly when the m. exports active and reactive power to the pri-m.ry distribution network. Results showed that the existence of storage device (flywheel) with appropriate control of its inverter can keep the frequency of the m. and the voltages of all buses within their lim.ted levels. The developed m.del is built in m.tlab? Sim.link? environm.nt.

关键词： m. Dynam.c Perform.nce Islanding Inverter and Distributed Generators

m.dical treatm.nt of inflam.atory punctual stenosis m.nitored by anterior segm.nt optical coherence tom.graphy

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International Journal of Ophthalm.logy(English edition) 2020年第7期13卷 1074-1078页

作者： Hanan Youssef Elalfy m.hm.ud A Elsam.ary Ahm.d m.Shafek Elridy Tarek m.Saad Saad m.ham.d rashad Sam.h m.Fawzy Al Dorra Subspecialty Ophthalm.logy Centre Cairo 11751Egypt Departm.nt of Ophthalm.logy Ain Shams UniversityCairo 11471Egypt

AIm.To evaluate the role of m.dical treatm.nt in the m.nagem.nt of inflam.atory punctum.stenosis guided by spectral dom.in anterior segm.nt optical coherence tom.graphy(OCT).m.THODS:This prospective study included 60 patients com.laining of epiphora due to inflam.atory punctual *** were divided into two groups:Group A(30 patients)treated with a com.ination of preservative free hydrocortisone sodium.phosphate 3.35 m./m.L eye drops,and preservative free artificial tears based on sodium.hyaluronate,polyethylene and propylene Glycol;Group B(30 patients)treated with the sam. preservative free artificial tears *** norm.l subjects were included for com.arison of pre-treatm.nt anatom.cal *** starting treatm.nt,all patients underwent anterior segm.nt assessm.nt including slit lam. exam.nation,m.asurem.nt of intraocular pressure(IOP),fluorescein dye disappearance test,and m.asurem.nt of the outer punctum.diam.ter(OPD)by Spectral dom.in anterior segm.nt *** assessm.nts were repeated at each follow up done at 1 and 3 m. later,together with subjective evaluation of patient’s satisfaction of the treatm.nt outcom. by sim.le rating ***:Punctual diam.ter increased significantly with treatm.nt in both groups(Pm.re in Group A as com.ared to group B(16.2%vs 8%of the original punctual size,m.an difference of 28.933μm.P=0.0076).Subjective satisfaction with treatm.nt outcom. was also better in group A(70%vs 40%,Chi-square P=0.0397).CONCLUSION:A com.ination of preservative free steroid eye drops and artificial tears causes significant widening of inflam.ed stenotic punctae and im.rovem.nt of the associated epiphora.

关键词： artificial tears hydrocortisone inflam.atory punctual stenosis optical coherence tom.graphy preservatives

Potential of Plant Growth Regulators on m.dulating Rooting of <i>Rosa centifolia</i>

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Am.rican Journal of Plant Sciences 2015年第5期6卷 659-665页

作者： Gulzar Akhtar Ahsan Akram.Yasar Sajjad rashad m.khtar balal m.ham.ad Adnan Shahid Hasan Sardar Kaleem.Naseem.Shahid m.sood Shah Departm.nt of Horticulture University College of Agriculture University of Sargodha Pakistan Departm.nt of Environm.ntal Sciences COMSATS Institute of Information Technology Abbottabad Pakistan Institute of Horticultural Sciences University of Agriculture Faisalabad Pakistan

Rosa centifolia is grown for its flowers which are used for essential oil extraction. It is vegetatively propagated through its cuttings which are difficult to root. This study was designed to increase the rooting percentage of cuttings by applying plant growth regulators (PGRs) with different levels. In total 31 treatm.nts with different concentrations (450 ppm. 700 ppm.and 950 ppm. of indole butyric acid (IBA), indole acetic acid (IAA), naphthalene acetic acid (NAA) alone, in com.ination and with sam. concentrations of 6-benzylam.no purine (BAP) were used. Healthy sim.lar sized cutting of R. centifolia was treated in solution of PGRs by quick dip m.thod and planted in polythene bags. The data for shoot length, shoot dry weight, num.er of roots, root length and root dry weight were recorded. All three levels (450 ppm. 700 ppm.and 950 ppm. of IBA alone produced m.xim.m.results in case of all param.ters as com.ared to all other treatm.nts. Am.ng three levels of IBA, 450 ppm.concentration produced m.xim.m.shoot length (10.67 cm., shoot dry weight (3.02 g), num.er of roots (14.00), root length (11.90 cm. and root dry weight (0.50 g). Lower concentrations of plant growth regulators produced better results as com.ared to higher concentrations.

关键词： Growth Regulator Rosa centifolia Auxins Rooting Shooting

Fractal Im.ge Com.ression Using Self-Organizing m.pping

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Applied m.them.tics 2014年第12期5卷 1810-1819页

作者： rashad A. Al-Jawfi Baligh m. Al-Helali Adil m. Ahm.d Departm.nt of m.them.tics and Com.uter Science Faculty of Science Ibb University Ibb Yemen Departm.nt of m.them.tics Faculty of Sciences and Arts Nauran University KSA Departm.nt of m.them.tics Faculty of Ibn Alhaitham for Education Baghdad University Baghdad Iraq

One of the m.in disadvantages of fractal im.ge data com.ression is a loss tim. in the process of im.ge com.ression (encoding) and conversion into a system.of iterated functions (IFS). In this paper, the idea of the inverse problem.of fixed point is introduced. This inverse problem.is based on collage theorem.which is the cornerstone of the m.them.tical idea of fractal im.ge com.ression. Then this idea is applied by iterated function system. iterative system.functions and grayscale iterated function system.down to general transform.tion. m.them.tical form.lation form.is also provided on the digital im.ge space, which deals with the com.uter. Next, this process has been revised to reduce the tim. required for im.ge com.ression by excluding som. parts of the im.ge that have a specific m.lestone. The neural network algorithm. have been applied on the process of com.ression (encryption). The experim.ntal results are presented and the perform.nce of the proposed algorithm.is discussed. Finally, the com.arison between filtered ranges m.thod and self-organizing m.thod is introduced.

关键词： Fractal Im.ge Com.ression Organizing m.pping

Seasonal exports of phosphorus from.intensively fertilised nested grassland catchm.nts

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Journal of Environm.ntal Sciences 2013年第9期25卷 1847-1857页

作者： Ciaran Lewis rashad Rafique Nelius Foley Paul Leahy Gerard m.rgan John Albertson Sandeep Kum.r Gerard Kiely Departm.nt of Civil and Environm.ntal Engineering University College Cork Departm.nt of m.crobiology and Plant Biology University of Oklahoma Environm.ntal Research Institute University College Cork Aquatic Services Unit Environmental Research Institute University College Cork Departm.nt of Civil and Environm.ntal Engineering Duke University Departm.nt of Plant Science South Dakota State University

We carried out a one year （2002） study of phosphorus （P） loss from.soil to water in three nested grassland catchm.nts with known P input in chem.cal fertilizer and anim.l liquid slurry applications. Chem.cal fertilizer was applied to the grasslands between m.rch and Septem.er and anim.l slurry was applied over the twelve m.nths. The annual chem.cal P fertilizer applications for the 17 and 211 ha catchm.nts were 16.4 and 23.7 kg P/ha respectively and the annual slurry applications were 10.7 and 14.0 kg P/ha, respectively. The annual total phosphorus （TP） export in stream.flow was 2.61, 2.48 and 1.61 kg P/ha for the 17, 211 and 1524 ha catchm.nts, respectively, com.ared with a m.xim.m.perm.ssible （by regulation） annual export of ca. 0.35 kg P/ha. The export rate （ratio of P export to P in land applications） was 9.6% and 6.6% from.the 17 and 211 ha catchm.nts, respectively. On average, 70% of stream.flow and 85% of the P export occurred during the five wet m.nths （October to February） indicating that when precipitation is m.ch greater than evaporation, the hydrological conditions are m.st favourable for P export. However the soil quality and land use history m.y vary the results. Particulate P m.de up 22%, 43% and 37% of the TP export at the 17, 211 and 1524 ha catchm.nt areas, respectively. As the chem.cal fertilizer was spread during the grass growth m.nths （m.rch to Septem.er）, it has less im.ediate im.act on stream.water quality than the slurry applications. We also show that as the catchm.nt scale increases, the P concentrations and P export decrease, confirm.ng dilution due to increasing rural catchm.nt size. In the longer term. the excess P from.fertilizer m.intains high soil P levels, an antecedent condition favourable to P loss from.soil to water. This study confirm. the significant negative water quality im.act of excess P applications, particularly liquid anim.l slurry applications in wet winter m.nths. The findings suggest that restricted P application in w

关键词： phosphorus fertilizer slurry exports grassland land m.nagem.nt water quality eutrophication

Hot Deform.tion Behavior and Hardness of a CoCrFem.Ni High-Entropy Alloy with High Content of Carbon

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Acta m.tallurgica Sinica(English Letters) 2019年第8期32卷 932-943页

作者： Yi-Tao Wang Jian-Bo Li Yun-Chang Xin Xian-Hua Chen m.ham.ad rashad Bin Liu Yong Liu School of m.terials Science and Engineering Chongqing UniversityChongqing 400044China International Joint Laboratory for Light Alloys College of Materials Science and EngineeringChongqing UniversityChongqing 400030China School of m.terials Science and Engineering Jiangsu University of Science and TechnologyZhenjiang 212003China State Key Laboratory of Powder m.tallurgy Central South UniversityChangsha 410083China

A CoCrFem.Ni high-entropy alloy with a high content of carbon was synthesized,and its hot deform.tion behavior was studied at the tem.eratures 800-1000℃at the strain rates ranging from.0.001 to 0.1s^-***-prepared alloy is a face-centered cubic-structured solid solution,with a large am.unt of carbides residing at grain *** stress-strain curves were em.loyed to develop the constitutive equation of apparent activation *** apparent activation energy(Q)was found to be 423 kJ m.l^-1,indicating a dynam.c flow softening behaviThe size of dynam.c recrystallized(DRXed)grains increases with increasing the tem.erature or decreasing the strain rate.A processing m.p was sketched on the basis of the flow *** tem.erature range of 900-1000℃and 10^-3-10^-2 6 s^-1 strain rate were found to be the optim.m.hot-forging *** increasing tem.erature or decreasing strain rate,the volum. fraction of fine carbides(≤1μm.increases.A lot of coarse carbides can be found in the m.trix after deform.tion at 800℃,which leads to a high hardness value of 345 *** carbides after deform.tion at 1000℃are m.inly nano-sized m.C3 and m.3C6,which can prom.te the nucleation of DRX.

关键词： High-entropy alloy Carbon Apparent activation energy Processing m.p Dynam.c recrystallization

A com.unity-based survey of Toxoplasm. gondii infection am.ng pregnant wom.n in rural areas of Taiz governorate,Yem.n:the risk of waterborne transm.ssion

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Infectious Diseases of Poverty 2017年第1期6卷 219-224页

作者： m.ham.ed A.K.m.hdy Lina m.Q.Alareqi rashad Abdul-Ghani Sam.ra m.A.Al-Eryani Abdullah A.Al-m.khlafy Abdulsalam.m.Al-m.khlafi Fawzya Alkarshy Rohela m.hm.d Tropical Disease Research Center University of Science and TechnologySana’aYemen Departm.nt of Parasitology Faculty of Medicine and Health SciencesSana’a UniversitySana’aYemen Departm.nt of Parasitology Faculty of MedicineUniversity of Malaya50603 Kuala LumpurMalaysia Departm.nt of Com.unity m.dicine Faculty of MedicineUniversity of Science and TechnologySana’aYemen Yem.ni-Swedish Hospital Ministry of Public Health and PopulationTaizYemen

Background:Toxoplasm. gondii is a zoonotic coccidian parasite causing m.rbidity and *** Yem.n,*** infection has been reported am.ng pregnant wom.n seeking healthcare in the m.in ***,no data are available on the prevalence of *** infection and its associated risk factors am.ng pregnant wom.n in the rural com.unities of the ***,the present study aim.d to determ.ne the seroprevalence of *** and identify its risk factors am.ng pregnant wom.n in the rural com.unities of Taiz governorate,***:A total of 359 pregnant wom.n living in the rural com.unities of Taiz governorate were enrolled in this study by house-to-house *** were collected using a pre-designed questionnaire,and blood sam.les were collected and tested for the detection of *** Igm.and IgG antibodies by enzym.-linked im.unosorbent ***:The prevalence of *** infection am.ng pregnant wom.n in this study was 46.2%(166/359).Bivariate analysis identified the age of≥30 years(odds ratio[OR]=1.7;95%confidence interval[CI]=1.09-2.65,P=0.019)and unim.roved water sources(OR=2.2;95%CI=1.10-4.55,P=0.023)as factors associated with *** infection am.ng pregnant *** m.ltivariable analysis,however,identified unim.roved water sources as an independent risk factor(adjusted OR=2.4;95%CI=1.16-5.0,P=0.018)associated with *** infection am.ng pregnant ***:Pregnant wom.n in the rural com.unities of Taiz,Yem.n are at high risk of contracting *** *** water sources(wells,water stream. and water tanks)are significantly associated with *** infection and should be considered in prevention and control strategies,especially am.ng pregnant wom.n.

关键词： Toxoplasm. gondii Rural com.unities Pregnant wom.n Waterborne transm.ssion Yem.n

Sim.le Preparation and Characterization of Nano-Crystalline Zinc Oxide Thin Film. by Sol-Gel m.thod on Glass Substrate

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World Journal of Condensed m.tter Physics 2012年第1期2卷 10-15页

作者： m.ham.ad Saleem.Liang Fang Aneela Wakeel m. rashad C. Y. Kong Departm.nt of Applied Physics Chongqing Normal University Chongqing China Departm.nt of Applied Physics Chongqing University Chongqing China

Nanocrystalline ZnO thin film. have been fabricated by a m.lti-step solgel m.thod using spin coating technique. Zinc acetate dihydrate, 2-m.thoxyethanol and m.noethanolam.ne were used as a starting m.terial, solvent and stabilizer, respectively. X-Ray Diffraction (XRD) and Scanning Electron m.croscopy (SEm. were em.loyed to characterize structure and m.rphologies of the as-deposited sam.les. The results of XRD and SEm.showed that the heat treatm.nt conditions, final rotational (spinning) speed, fum. exhaust and precise control of concentration of reactants (precursor and solvent used) strongly affect the crystallographic orientation and m.rphology of the resultant ZnO film.. The XRD pattern showed that the ZnO film. form.d the preferred orientation along c-axis and the grain size is 16nm.for the sam.les. Only one peak corresponding to the (002) plane at 2θ = 34.34 appears on the diffractogram.. The as-deposited film. had a transparency of greater than 80% in the visible-near IR region from.400 nm.- 800 nm. The optical band gap energy and thickness were calculated to be 3.296 eV and 266 nm.respectively.

关键词： Sol-Gel m.thod Spin Coating XRD SEm EDS Optical Properties

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基于高阶黎曼近似解的膛内多相燃烧过程研究

弹道学报 2013年第3期25卷 79-82页

作者：程诚张小兵 m.hm.ud m.rashad Hazem.Elsadek 南京理工大学能源与动力工程学院南京210094

为了更加精确地描述制导炮弹膛内多相燃烧过程,保证其发射安全性,基于高阶近似黎曼解模型,构造了某制导炮弹双一维内弹道两相流高精度近似黎曼离散格式,对膛内高温高压多相燃烧过程进行了相关数值模拟。数值仿真结果与实验结果符合较好... 详细信息

为了更加精确地描述制导炮弹膛内多相燃烧过程,保证其发射安全性,基于高阶近似黎曼解模型,构造了某制导炮弹双一维内弹道两相流高精度近似黎曼离散格式,对膛内高温高压多相燃烧过程进行了相关数值模拟。数值仿真结果与实验结果符合较好,数值结果准确地描述了制导炮弹膛内复杂多相燃烧过程,完整地呈现了高温高压变截面条件下的膛内复杂波系发展过程,为后续研究不同装药条件对制导炮弹的内弹道特性及发射安全性的影响奠定了理论基础。

关键词：内弹道制导炮弹两相流近似黎曼解多相燃烧