检索结果-南通市图书馆

Low band gap frequencies and multiplexing properties in 1D and 2D mass spring structures

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2016年第11期25卷 333-339页

作者： arafa h aly Ahmed Mehaney Physics Department Faculty of Sciences Beni-Suef University

This study reports on the propagation of elastic waves in 1D and 2D mass spring *** analytical and computation model is presented for the 1D and 2D mass spring systems with different *** enhancement in the band gap values was obtained by modeling the structures to obtain low frequency band gaps at small ***,the evolution of the band gap as a function of mass value is *** attention is devoted to the local resonance property in frequency ranges within the gaps in the band structure for the corresponding infinite periodic lattice in the 1D and 2D mass spring system.A linear defect formed of a row of specific masses produces an elastic waveguide that transmits at the narrow pass band *** frequency of the waveguides can be selected by adjusting the mass and stiffness coefficients of the materials constituting the ***,we pay more attention to analyze the wave multiplexer and DE-multiplexer in the 2D mass spring *** show that two of these tunable waveguides with alternating materials can be employed to filter and separate specific frequencies from a broad band input *** presented simulation data is validated through comparison with the published research,and can be extended in the development of resonators and MEMS verification.

关键词： multiplexing waveguide tunable separate dimensions devoted verification stiffness validated infinite

Influence of temperature on the properties of one-dimensional piezoelectric phononic crystals

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2018年第9期27卷 342-345页

作者： Ahmed Nagaty Ahmed Mehaney arafa h aly Physics Department Faculty of Sciences Beni-Suef University

The current study investigates the influence of temperature on a one-dimensional piezoelectric phononic crystal using tunable resonant frequencies. Analytical and numerical examples are introduced to emphasize the influence of temperature on the piezoelectric phononic crystals. It was observed that the transmission spectrum of a one-dimensional phononic crystal containing a piezoelectric material（0.7 PMN-0.3 PT） can be changed drastically by an increase in *** resonant peak can be shifted toward high or low frequencies by an increase or decrease in temperature, ***, we deduced that temperature can exhibit a large tuning in the phononic band gaps and in the local resonant frequencies depending on the presence of a piezoelectric material. Such result can enhance the harvesting energy from piezoelectric materials, especially those that are confined in a phononic crystal.

关键词： phononic crystals resonant modes piezoelectric material thermal properties and temperature

Comparative Study of the One Dimensional Dielectric and Metallic Photonic Crystals

在线全文

学校读者我要写书评

暂无评论

Optics and Photonics Journal 2012年第2期2卷 105-112页

作者： arafa h. aly Mohamed Ismaeel Ehab Abdel-Rahman Department of Physics Faculty of Sciences Beni-Suef University Beni-Suef Egypt Department of Physics The American University in Cairo New Cairo Egypt YJ-STRC The American University in Cairo New Cairo Egypt

The optical transmission properties of two types of photonic crystals have been analyzed by using the transfer matrix method. The first one is the dielectric photonic crystal (DPC), and the second is the metallic photonic crystal (MPC). We found the dielectric and metallic photonic crystals have different transmission spectra. The effect of the most prameters on the transmission spectra of the dielectric and metallic photonic crystals has been studied.

关键词： Transmission Metallic Photonic Crystals Dielectric Photonic Crystals Photonic Band Gap

Improve the Efficiency of Scintillation Detectors Using Reflectors Based on Photonic Crystals Arrays

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Electromagnetic Analysis and Applications 2014年第2期6卷 25-29页

作者： M. F. Eissa arafa h. aly Physics Department Faculty of Science Beni-Suef University Beni-Suef Egypt.

In the present work, we designed the new type of photonic crystals (PCs) as reflectors. Reflections from single layer of Al2O3/MgO PC help us in recapturing the light that does escape from the scintillation surface. Photonic crystals in one dimension array of Al2O3 and MgO with silver at periodicities N = 1, 2 and 3 were used as a reflector around the surface of the scintillation volume. Scintillation detectors are widely used in nuclear medicine. The efficiency is an important parameter for characterizing the capability of the detectors. The counting efficiency of the detectors depends on the light emission induced by radiation. The light then was converted by the photomultiplier tube into electrical pulses. The efficiency may increase by an amount of 1.64% if MgO-Ag photonic crystals are used at periodicity N = 1 as a reflector.

关键词： TMM Photonic Crystals Scintillation Detectors Radiation Photonic Band Gap

Numerical Studies on Electromagnetic Waves Properties in Metallic-Dielectric Photonic Crystal

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Electromagnetic Analysis and Applications 2011年第11期3卷 465-470页

作者： arafa h. aly Ehab Abdel-Rahman hassan S. hanafey 不详

We have performed numerical analyses to investigate the propagation characteristics of a simple-one dimensional metallic-dielectric structure. Several different metals have been studied (aluminum, gold, copper, and silver). Copper gives the smallest absorption and aluminum is more absorptive. We have compared between the transmittance of these structures with different metals and the same dielectric material. Also we used these different metals with the same layer thickness, incidence angels, number of layers and the same electromagnetic waves range.

关键词： Transmittance PC Pasmonic

Effect of nutrition-related infodemics and social media on maternal experience: A nationwide survey in a low/middle income country

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Clinical Pediatrics 2024年第1期13卷 93-106页

作者： Marwa M Zein Noha arafa Mortada h F El-Shabrawi Nehal Mohammed El-Koofy Department of Public health and Community Medicine Cairo UniversityCairo 515211Egypt Department of Pediatric Endocrinology and Diabetes Children's HospitalKasralainy Medical SchoolCairo UniversityCairo 515211Egypt Department of Pediatrics Cairo UniversityCairo 12411Egypt Department of Pediatrics The Children's HospitalCairo UniversityCairo 12411Egypt

BACKGROUND Undernutrition is a crucial cause of morbidity and mortality among children in low-or middle-income countries(LMICs).A better understanding of maternal general healthy nutrition knowledge,as well as misbeliefs,is highly essential,especially in such *** the current era of infodemics,it is very strenuous for mothers to select not only the right source for maternal nutrition information but the correct information as *** To assess maternal healthy nutritional knowledge and nutrition-related misbeliefs and misinformation in an LMIC,and to determine the sources of such information and their assessment *** This cross-sectional analytical observational study enrolled 5148 randomly selected Egyptian mothers who had one or more children less than 15 years *** data were collected through online questionnaire forms:One was for the general nutrition knowledge assessment,and the other was for the nutritional myth *** of information and ways of evaluating internet sources using the Currency,Relevance,Authority,Accuracy,and Purpose test were additionally *** The mean general nutrition knowledge score was 29±9,with a percent score of 70.8%±12.1%(total score:41).The median myth score was 9(interquartile range:6,12;total score:18).The primary sources of nutrition knowledge for the enrolled mothers were social media platforms(55%).half of the mothers managed information for currency and authority,except for considering the author's contact *** than 60%regularly checked information for accuracy and *** mothers with significant nutrition knowledge checked periodically for the author's contact information(P=0.012).The nutrition myth score was significantly lower among mothers who periodically checked the evidence of the information(P=0.016).Mothers dependent on their healthcare providers as the primary source of their general nutritional knowledge were less likely to hold myths by 13%(P=0.044).however,usi

关键词： Nutrition Infodemics Maternal knowledge Myth Low/middle income country

homotopy Analysis Method for Solving Biological Population Model

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2011年第11期56卷 797-800页

作者： A.A.M.arafa S.Z.Rida h.Mohamed Department of Mathematics Faculty of ScienceSouth Valley University

In this paper,the homotopy analysis method (hAM) is applied to solve generalized biological *** fractional derivatives are described by Caputo's *** method introduces a significant improvementin this field over existing *** obtained using the scheme presented here agree well with the analyticalsolutions and the numerical results presented in Ref.[6].however,the fundamental solutions of these equations stillexhibit useful scaling properties that make them attractive for applications.

关键词： biological populations model fractional calculus homotopy analysis method Mittag-Leffier function

Solving Nonlinear Fractional Differential Equation by Generalized Mittag-Leffler Function Method

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2013年第6期59卷 661-663页

作者： A.A.M.arafa Z.Rida A.A.Mohammadein h.M.Ali Department of Mathematics and Computer Science Faculty of Science Port Said University Department of Mathematics Faculty of Science South Valley University Department of Mathematics Faculty of Science Aswan University

In this paper, we use Mittag-Leffler function method for solving some nonlinear fractional differential equations. A new solution is constructed in power series. The fractional derivatives are described by Caputo's se... 详细信息

关键词： nonlinear fractional differential equations Mittag-Leffler function Caputo fractional derivative

Design, Sonosynthesis, Quantum-Chemical Calculations, and Evaluation of New Mono-and Bis-pyridine Dicarbonitriles as Antiproliferative Agents

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2020年第5期38卷 501-508页

作者： Wael Abdelgayd Ahmed arafa Modather F.hussein Chemistry Department College of ScienceJouf UniversityP.O.Box 2014SakakaAljoufKingdom of Saudi Arabia Chemistry Department Faculty of ScienceFayoum UniversityP.O.Box 63514Fayoum CityEgypt Chemistry Department Faculty of ScienceAl-Azhar UniversityAsyut branchEgypt

A highly efficient,simple,and clean single-step sonosynthetic procedure has been sophisticated for assembling new series of mono-and bis-pyridine dicarbonitriles from ketones,hCl,and *** presented protocol is applicable for the preparation of a broad range of uniquely substituted pyridine dicarbonitriles and seems to be superior in comparison with other previously reported *** antiproliferative impact of the newly synthesized derivatives was screened towards three representative cancer cell lines(MCF-7,A549,and hCT116).Most of the evaluated derivatives showed a moderate to excellent anti-proliferative activity towards the selected cell *** these,compounds 4h,4k,10,12a,and 12b showed both potent anticancer activity(ICs058μM)on non-tumorigenic cells(MCF-10A and NCM460),suggesting their promising potential to be lead molecules for future antitumor drug *** structure-activity relationships have been also ***,quantum chemical studies based on Density Functional Theory(DFT)of the synthesized compounds were investigated and found to be consistent with the in vitro inhibitory activities.

关键词： pyridine nitrile synthesis