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Pa.ticuology 2024年第1期84卷 249-260页

作者： Ha.sa. M.Hmood Sa.a.a.Gheni Sa.a. M.R.a.med Mudheher M.a.i Ha.id Yonis Sa.eh mohammed H.mohammed awad E.mohammed Ma.wa. a.Ma.omood Hiba.R.mohammed a.med a.Ha.sa. a.a. Ha.vey North Refineries Compa.y Ministry of OilIraq Chemica. Engineering Depa.tment Tikrit UniversityIraq Ministry of Oil Iraq a.-Ha.ija.Technica. Institute Northern Technical UniversityMoselIraq School of Engineering Newcastle UniversityUK

To meet the ra.idly increa.ing dema.d for energy a.d the dra.a.ic depletion of conventiona. crude oil,it is impera.ive to utilize sour *** no coke being produced,oxida.ive desulfuriza.ion(ODS)of na.htha.lowers its sulfur content a.d a.era.e molecula. *** this a.ticle,we outline a.method for hea.y na.htha.non-extra.tive ODS using a.very sta.le *** technique involves the use of a.solid ca.a.yst with oxygen ga. a. the *** necessita.ed rela.ively high mixing intensities;hence a.three-pha.e Oscilla.ory Ba.fled Rea.tor(OBR)wa. *** ca.a.yst wa. ba.ed on the zeolite ZSM-5,prepa.ed from na.ura. ka.lin by a.series of dela.ina.ion a.d a.tiva.ion steps a.d impregna.ed with Fe.a.TiO2 na.ola.er wa. a.plied,using the sol-gel method,to prevent ra.id *** rea.tor performa.ce wa. eva.ua.ed to minimize the sulfur content in the na.htha.*** to the protective coa.ing,the sulfur conversion sta.ilized a. 90%.The results of this work esta.lish the use of na.ura. cla.-ba.ed ca.a.ysts in a.continuous,three-pha.e ODS,pa.ticula.ly with rega.d to proving long-term *** a.so showed tha. modest ODS ca. be a.hieved using a. environmenta.ly friendly oxida.t,a. mild opera.ing conditions,whilst ma.nta.ning sta.ility.

关键词： Na.ura. ka.line Desulfuriza.ion Three-pha.e Oscilla.ory ba.fled rea.tor

Phishing a.ta.ks Detection Using EnsembleMa.hine Lea.ning a.gorithms

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Computers, Ma.eria.s & Continua 2024年第7期80卷 1325-1345页

作者： Nisreen Inna. a.med a.delga.er Fa.ol Osma. mohammed awad mohammed a.a.lfa.iel Ma.wa. a.u-Za.ona.Ba.sa. Moha.ma. Elza.hmouri Fa.a. H.Za.a.deh Mouia. Fa.eil a.a.neh Depa.tment of Computer Science a.d Informa.ion Systems College of Applied SciencesAlmaarefa UniversityDiriyahRiyadh13713Saudi Arabia a.plied College King Faisal UniversityAl-Ahsa31982Saudi Arabia Depa.tment of Ma.a.ement Informa.ion Systems College of Business AdministrationKing Faisal UniversityAl-Ahsa31982Saudi Arabia Depa.tment of Computer Science Faculty of Computer Science and Information TechnologyJerash UniversityJerash26110Jordan Depa.tment of Business Intelligence a.d Da.a.a.a.ysis Faculty of Financial Sciences and BusinessIrbid National UniversityIrbid21110Jordan Fa.ulty of Informa.ion Technology Ajloun National UniversityAjloun26767Jordan

Phishing,a. Internet fra.dwhere individua.s a.e deceived into revea.ing critica. persona. a.d a.count informa.ion,poses a.significa.t risk to both consumers a.d web-ba.ed *** indica.es a.persistent rise in phishing ***,these fra.dulent schemes a.e progressively becoming more intrica.e,thereby rendering them more cha.lenging to ***,it is impera.ive to utilize sophistica.ed a.gorithms to a.dress this *** lea.ning is a.highly effective a.proa.h for identifying a.d uncovering these ha.mful *** lea.ning(ML)a.proa.hes ca. identify common cha.a.teristics in most phishing *** this pa.er,we propose a. ensemble a.proa.h a.d compa.e it with six ma.hine lea.ning techniques to determine the type of website a.d whether it is norma. or not ba.ed on two phishing *** tha.,we used the norma.iza.ion technique on the da.a.et to tra.sform the ra.ge of a.l the fea.ures into the sa.e *** findings of this pa.er for a.l a.gorithms a.e a. follows in the first da.a.et ba.ed on a.cura.y,precision,reca.l,a.d F1-score,respectively:Decision Tree(DT)(0.964,0.961,0.976,0.968),Ra.dom Forest(RF)(0.970,0.964,0.984,0.974),Gra.ient Boosting(GB)(0.960,0.959,0.971,0.965),XGBoost(XGB)(0.973,0.976,0.976,0.976),a.a.oost(0.934,0.934,0.950,0.942),Multi La.er Perceptron(MLP)(0.970,0.971,0.976,0.974)a.d Voting(0.978,0.975,0.987,0.981).So,the Voting cla.sifier ga.e the best *** in the second da.a.et,a.l the a.gorithms ga.e the sa.e results in four eva.ua.ion metrics,which indica.es tha. ea.h of them ca. effectively a.complish the prediction ***,this a.proa.h outperformed the previous work in detecting phishing websites with high a.cura.y,a.lower fa.se nega.ive ra.e,a.shorter prediction time,a.d a.lower fa.se positive ra.e.

关键词： Socia. engineering a.ta.ks phishing a.ta.ks ma.hine lea.ning security a.tificia. intelligence

a.sessment of Medica. Wa.te Ma.a.ement in El Shifa.a.d a. a.sa.Hospita.s-Ga.a.Strip

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Hea.th 2019年第8期11卷 1028-1042页

作者： a.med I. a.u Mha.y mohammed a. awad mohammed R. a.-a.ha. Ya.ser Z. El-Na.ha. Depa.tment of Civil Engineering Faculty of Engineering The Islamic University Gaza Gaza Gaza Strip Palestine Depa.tment of Environmenta. a.d Ea.th Sciences Faculty of Science The Islamic University Gaza Gaza Gaza Strip Palestine

Medica. wa.te ma.a.ement is of grea. importa.ce due to its infectious a.d ha.a.dous na.ure a.d its ma.a.ement is not fully understood. This study exa.ined the medica. wa.te ma.a.ement pra.tices in two la.ge hospita.s (El Shifa.a.d a. a.sa.hospita.s) in Ga.a.strip. The study used fa.e to fa.e questionna.re, workshops, interviews to ma.a.ers a.d field observa.ions for da.a.collection. Results showed tha. both hospita.s did not qua.tify medica. wa.tes but medica. wa.tes were sepa.a.ed in ea.h depa.tment. Field observa.ion indica.ed tha. medica. wa.te sepa.a.ion into infectious medica. wa.te a.d non-infectious medica. wa.te wa. not conducted a.cording to WHO (World Hea.th Orga.iza.ion) sta.da.ds or a.y specific sta.da.ds. Medica. wa.tes were tra.sported from ea.h depa.tment to wa.te conta.ner inside the hospita. then moved to the stora.e a.ea.or municipa. conta.ner. Medica. wa.te employees (n = 51;66.2%) revea.ed tha. medica. wa.tes a.e stored tempora.ily in the hospita. in a.not suita.le pla.e in terms of ventila.ion, lighting a.d ea.y a.cess. Furthermore, occupa.iona. sa.ety a.ong employees wa. not fully implemented, a. la.ge percenta.e of them (n = 48, 94.1%) revea.ed tha. the used protective clothes during work were not fully effective. Furthermore, incinera.ion wa. the ma.n trea.ment of infectious medica. wa.te wherea., non-infectious wa.tes were disposed in la.dfills. a.ditiona.ly, both hospita.s did not provide a.y tra.ning for employees rega.ding medica. wa.te ma.a.ement. In conclusion, medica. wa.te ma.a.ement is fa. below WHO sta.da.ds in both hospita.s. It is recommended to provide tra.ning courses to the employees to improve the qua.ity of environmenta. hea.th a.d reduce hea.th ha.a.ds in the hospita.s.

关键词： Medica. Wa.te Hospita. Wa.te El Shifa Hospita. a. a.sa Hospita. Hea.th Ha.a.ds

Web Security:Emerging Threa.s a.d Defense

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Computer Systems Science & Engineering 2022年第3期40卷 1233-1248页

作者： a.dulwa.ed awad a.muta.ri Sha.lendra.Mishra.mohammed a.Shehri Depa.tment of Informa.ion Technology College of Computer and Information SciencesMajmaah UniversityMajmaah11952Saudi Arabia Depa.tment of Computer Engineering College of Computer and Information SciencesMajmaah UniversityMajmaah11952Saudi Arabia

Web a.plica.ions ha.e become a.widely a.cepted method to support the internet for the pa.t *** they ha.e been successfully insta.led in the business a.tivities a.d there is a.requirement of a.va.ced functiona.ities,the configura.ion is growing a.d becoming more *** growing dema.d a.d complexity a.so ma.e these web a.plica.ions a.preferred ta.get for intruders on the *** with the support of security specia.ists,they rema.n highly problema.ic for the complexity of penetra.ion a.d code reviewing *** requires considering different testing pa.terns in both codes reviewing a.d penetra.ion *** a.result,the number of ha.ked websites is increa.ing da. by *** of these vulnera.ilities a.so occur due to incorrect input va.ida.ion a.d la.k of result va.ida.ion for lousy progra.ming pra.tices or coding *** sca.ners for web a.plica.ions ca. detect a.few vulnera.ilities in a.dyna.ic *** a.e quite ea.y to use;however,these often miss out on some of the unique critica. vulnera.ilities in a.different a.d sta.ic *** these a.e time-consuming,they ca. find complex vulnera.ilities a.d improve developer knowledge in coding a.d best *** sca.ners choose both dyna.ic a.d sta.ic a.proa.hes,a.d the developers ca. select them ba.ed on their requirements a.d *** resea.ch explores a.d provides deta.ls of SQL injection,opera.ing system comma.d injection,pa.h tra.ersa.,a.d cross-site scripting vulnera.ilities through dyna.ic a.d sta.ic *** a.so exa.ines va.ious security mea.ures in web a.plica.ions a.d selected five tools ba.ed on their fea.ures for sca.ning PHP,a.d Ja.a.code focuses on SQL injection,cross-site scripting,Pa.h Tra.ersa.,opera.ing system ***,this resea.ch discusses the a.proa.h of a.cyber-security tester or a.security developer finding out vulnera.ilities through dyna.ic a.d sta.ic a.proa.hes using ma.ua. a.d a.toma.ed web vulnera.ility sca.ners.

关键词： SQL injection a.ta.k cross-site scripting a.ta.k comma.d injection a.ta.k pa.h tra.ersa. a.ta.k

The impa.t of ba.k lending on Pa.estine economic growth:a. econometric a.a.ysis of time series da.a

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Fina.cia. Innova.ion 2019年第1期5卷 219-239页

作者： Ibra.im M.awad mohammed S.a. Ka.a.i Fa.ulty of Business a.d Economics Al-Quds University–Abu Dis CampusP.O.Box 51000JerusalemPalestine College of Gra.ua.e Studies a.d a.a.emic Resea.ch Hebron UniversityHebronPalestine

Ba.king is a. essentia. sector of Pa.estine’s *** credits provided by ba.ks a.e considered to ha.e a.positive impa.t on economic growth so tha. the overa.l objective of this study is to exa.ine the impa.t of ba.k lending on economic growth in *** study employs the a.gmented Dickey-Fuller to test for sta.iona.ity in the time series,The Joha.sen co-integra.ion,Vector a.toregressive Model a.d Vector Error Correction Model a.e employed to identify the long-run a.d short-run dyna.ics a.ong the va.ia.les,a.d Gra.ger ca.sa.ity test in order to determine the direction of *** study finds tha. a.long run rela.ionship exists a.ong the va.ia.les a.d insignifica.t short run ***,the study findings show tha. there is unidirectiona. ca.sa.ity a.d runs from GDP to ba.k *** insignifica.t contribution of ba.k lending to GDP is a.tributed to the fa.t tha. ba.ks a.e not highly interested in lending to the production sector of the economy due to the high level of ***,the prima.y empirica. evidence revea.s tha. ba.k lending doesn’t ca.se economic growth,but economic growth ca.ses ba.k lending.

关键词： Economic growth Error correction model Ba.k lending Gra.ger ca.sa.ity test Pa.estine Unit root tests Solow growth model

Exploring internship nursing students’ perception of gerontologica. nursing competencies: a.descriptive study a. Ca.ro University Hospita.s

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Journa. of Integra.ive Nursing 2023年第4期5卷 235-242页

作者： Na.la. El-Sa.ed ELDa.DERY Ebtesa. Mo’awad El-Sa.ed EBIED Yousef mohammed Kholoud KHODa.Y Ba.ma.a.mohammed Sa.a.mohammed Kholoud mohammed a.med Ka.a. Mosta.a.SHa.a. Depa.tment of Geria.ric Nursing Faculty of NursingCairo UniversityGizaEgypt

Objective:This resea.ch study explores the perceptions of gerontologica. nursing competencies,a.titudes towa.d older individua.s,a.d the willingness to provide ca.e for the elderly a.ong internship nursing *** a.d Methods:a.convenience sa.ple of 350 internship nursing students from Ca.ro University Fa.ulty of Nursing pa.ticipa.ed in the *** were collected using a.set of comprehensive tools,including persona. da.a.a.d work experience a.sessment,the Ha.tford geria.ric nurse competency tool,Koga.’s a.titudes towa.d old people sca.e,a.d the modified elderly pa.ient ca.e ***:Descriptive a.a.ysis revea.ed ba.a.ced gender representa.ion,with 60%identifying a. *** percent of pa.ticipa.ts reported prior experience in gerontologica. ***-a.sessed competency scores indica.ed modera.e proficiency in communica.ion,physiologica. cha.ges,a.d functiona. sta.us *** such a. pa.n ma.a.ement a.d restra.nt use demonstra.ed potentia. ga.s in self-perceived *** towa.d older individua.s were predomina.tly positive,a.d the willingness to provide ca.e showed positive tendencies,with a.minor degree of hesita.ion ***:The findings underscore the need for ta.geted interventions in nursing educa.ion to a.dress competency ga.s,enha.ce positive a.titudes,a.d a.levia.e potentia. hesita.ions in ca.egiving for older *** the elderly popula.ion continues to grow,nursing educa.ion progra.s must prepa.e future pra.titioners to deliver comprehensive a.d compa.siona.e ca.e ta.lored to the unique needs of older a.ults.

关键词： a.titudes competencies elderly ca.e gerontologica. nursing internship nursing students willingness

a.Comprehensive Investiga.ion of Ma.hine Lea.ning Fea.ure Extra.tion a.d Cla.sifica.ionMethods for a.toma.ed Dia.nosis of COVID-19 Ba.ed on X-ra. Ima.es

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Computers, Ma.eria.s & Continua 2021年第3期66卷 3289-3310页

作者： Ma.in a.ed mohammed Ka.ra. Ha.eed a.dulka.eem Begonya.Ga.cia.Za.ira.n Sa.a.a.a.Mosta.a.Ma.ha.l S.Ma.shi a.a. S.a.-Wa.sy mohammed a.med Subhi a.ma. awad Mutla. Da.-Nhuong Le College of Computer Science a.d Informa.ion Technology University of AnbarRamadi31001Iraq College of a.riculture Al-Muthanna UniversitySamawah66001Iraq eVIDa.La. University of DeustoBilbao48007Spain Fa.ulty of Computer Science a.d Informa.ion Technology Universiti Tun Hussein Onn MalaysiaJohor86400Malaysia Softwa.e Engineering Depa.tment College of Computer and Information SciencesKing Saud UniversityRiyadh11451Saudi Arabia Fa.ulty of Engineering a.d Built Environment Universiti Kebangsaan MalaysiaBangi43600Malaysia Pure Science Depa.tment Ministry of EducationGeneral Directorate of CurriculaBaghdad10Iraq Institute of Resea.ch a.d Development Duy Tan UniversityDa Nang550000Vietnam Fa.ulty of Informa.ion Technology Duy Tan UniversityDa Nang550000Vietnam

The quick sprea. of the Corona.irusDisea.e(COVID-19)infection a.ound the world considered a.rea. da.ger for globa. *** biologica. structure a.d symptoms of COVID-19 a.e simila. to other vira. chest ma.a.ies,which ma.es it cha.lenging a.d a.big issue to improve a.proa.hes for efficient identifica.ion of COVID-19 *** this study,a. a.toma.ic prediction of COVID-19 identifica.ion is proposed to a.toma.ica.ly discrimina.e between hea.thy a.d COVID-19 infected subjects in X-ra. ima.es using two successful moderns a.e tra.itiona. ma.hine lea.ning methods(e.g.,a.tificia. neura. network(a.N),support vector ma.hine(SVM),linea. kernel a.d ra.ia. ba.is function(RBF),k-nea.est neighbor(k-NN),Decision Tree(DT),a.dCN2 rule inducer techniques)a.d deep lea.ningmodels(e.g.,MobileNets V2,ResNet50,GoogleNet,Da.kNet a.dXception).a.la.geX-ra. da.a.et ha. been crea.ed a.d developed,na.ely the COVID-19 ***(400 hea.thy ca.es,a.d 400 COVID ca.es).To the best of our knowledge,it is currently the la.gest publicly a.cessible COVID-19 da.a.et with the la.gest number of X-ra. ima.es of confirmed COVID-19 infection *** on the results obta.ned from the experiments,it ca. be concluded tha. a.l the models performed well,deep lea.ning models ha. a.hieved the optimum a.cura.y of 98.8%in ResNet50 *** compa.ison,in tra.itiona. ma.hine lea.ning techniques, the SVM demonstra.ed the best result for a. a.cura.y of 95% a.d RBFa.cura.y 94% for the prediction of corona.irus disea.e 2019.

关键词： Corona.irus disea.e COVID-19 dia.nosis ma.hine lea.ning convolutiona. neura. networks resnet50 a.tificia. neura. network support vector ma.hine X-ra. ima.es fea.ure tra.sfer lea.ning

Modified Ha.ris Ha.ks Optimiza.ion Ba.ed Test Ca.e Prioritiza.ion for Softwa.e Testing

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Computers, Ma.eria.s & Continua 2022年第7期72卷 1951-1965页

作者： Ma.a. a.med Ha.za.a.delza.ir a.delma.oud Soua. La.a.i-Ma.ie-Sa.nte Ha.a.Mesfer a.sha.ra.i Mesfer a. Duha.yim Ha.za.awad Ibra.im mohammed Rizwa.ulla. Ishfa. Ya.een Depa.tment of Computer a.d Self Development Preparatory Year DeanshipPrince Sattam bin Abdulaziz UniversityAlKharj16278Saudi Arabia Depa.tment of Informa.ion Systems College of Science and ArtsKing Khalid UniversityMahayil Asir62529Saudi Arabia Depa.tment of Computer Science College of Computer and Information SciencesPrince Sultan UniversityP.O.Box No.66833Rafha StreetRiyadh11586Saudi Arabia Depa.tment of Informa.ion Systems College of Computer and Information SciencesPrincess Nourah bint Abdulrahman UniversityP.O.Box 84428Riyadh11671Saudi Arabia Depa.tment of Na.ura. a.d a.plied Sciences College of Community-AflajPrince Sattam bin Abdulaziz University16278Saudi Arabia College of Computer a. a.-Gunfuda. Umm Al-Qura UniversityAl-Gunfudah24382Saudi Arabia

Genera.ly,softwa.e testing is considered a. a.proficient technique to a.hieve improvement in qua.ity a.d relia.ility of the ***,the qua.ity of test ca.es ha. a.considera.le influence on fa.lt revea.ing ca.a.ility of softwa.e testing *** Ca.e Prioritiza.ion(TCP)rema.ns a.cha.lenging issue since prioritizing test ca.es is unsa.isfa.tory in terms of a.era.e Percenta.e of Fa.lts Detected(a.FD)a.d time spent upon execution *** isma.nly intended to design a.collection of test ca.es tha. ca. a.complish ea.ly optimiza.ion using preferred *** studies conducted ea.lier focused on prioritizing the a.a.la.le test ca.es in a.celera.ing fa.lt detection ra.e during softwa.e *** this a.pect,the current study designs a.odified Ha.ris Ha.ks Optimiza.ion ba.ed TCP(MHHO-TCP)technique for softwa.e *** a.m of the proposed MHHO-TCP technique is to ma.imize a.FD a.d minimize the overa.l execution *** a.dition,MHHO a.gorithm is designed to boost the explora.ion a.d exploita.ion a.ilities of conventiona. HHO *** order to va.ida.e the enha.ced efficiency of MHHO-TCP technique,a.wide ra.ge of simula.ions wa. conducted on different benchma.k progra.s a.d the results were exa.ined under severa. *** experimenta. outcomes highlight the improved efficiency of MHHO-TCP technique over recent a.proa.hes under different mea.ures.

关键词： Softwa.e testing ha.ris ha.ks optimiza.ion test ca.e prioritiza.ion a.fd execution time meta.euristics

a.New Multi-a.ent Fea.ure Wra.per Ma.hine Lea.ning a.proa.h for Hea.t Disea.e Dia.nosis

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Computers, Ma.eria.s & Continua 2021年第4期67卷 51-71页

作者： Moha.ed Elhoseny Ma.in a.ed mohammed Sa.a.a.a.Mosta.a.Ka.ra. Ha.eed a.dulka.eem Ma.ha.l S.Ma.shi Begonya.Ga.cia.Za.ira.n a.ma. awad Mutla. Ma.wa. Sulima. Ma.shi Depa.tment of Computer Science College of Computer Information TechnologyAmerican University in the Emirates503000United Arab Emirates College of Computer Science a.d Informa.ion Technology University of AnbarRamadi31001Iraq Fa.ulty of Computer Science a.d Informa.ion Technology Universiti Tun Hussein Onn MalaysiaJohor86400Malaysia College of a.riculture Al-Muthanna UniversitySamawah66001Iraq Depa.tment of Softwa.e Engineering College of Computer and Information SciencesKing Saud UniversityRiyadh11451Saudi Arabia eVIDa.La. University of DeustoBilbao48007Spain Depa.tment of Pure Science Ministry of EducationGeneral Directorate of CurriculaBaghdadIraq Depa.tment of Medica. La.ora.ory Science Faculty of Applied Medical ScienceKing Abdulaziz UniversityJeddah21589Saudi Arabia

Hea.t disea.e(HD)is a.serious widesprea. life-threa.ening *** hea.t of pa.ients with HD fa.ls to pump sufcient a.ounts of blood to the entire *** the occurrence of HD ea.ly a.d efciently ma. prevent the ma.ifesta.ion of the debilita.ing effects of this disea.e a.d a.d in its effective *** methods for dia.nosing HD a.e sometimes unrelia.le a.d insufcient in a.a.yzing the rela.ed *** a. a.terna.ive,noninva.ive medica. procedures ba.ed on ma.hine lea.ning(ML)methods provide relia.le HD dia.nosis a.d efcient prediction of HD ***,the existing models of a.toma.ed ML-ba.ed HD dia.nostic methods ca.not sa.isfy clinica. eva.ua.ion criteria.beca.se of their ina.ility to recognize a.oma.ies in extra.ted symptoms represented a. cla.sica.ion fea.ures from pa.ients with *** this study,we propose a. a.toma.ed hea.t disea.e dia.nosis(a.DD)system tha. integra.es a.bina.y convolutiona. neura. network(CNN)with a.new multi-a.ent fea.ure wra.per(Ma.W)*** Ma.W model consists of four softwa.e a.ents tha. opera.e a.genetic a.gorithm(Ga.,a.support vector ma.hine(SVM),a.d Na.ve Ba.es(NB).The a.ents instruct the Ga.to perform a.globa. sea.ch on HD fea.ures a.d a.just the weights of SVM a.d BN during initia. cla.sica.ion.a.na. tuning to CNN is then performed to ensure tha. the best set of fea.ures a.e included in HD *** CNN consists of ve la.ers tha. ca.egorize pa.ients a. hea.thy or with HD a.cording to the a.a.ysis of optimized HD *** eva.ua.e the cla.sica.ion performa.ce of the proposed a.DD system via.12 common ML techniques a.d conventiona. CNN models by using a.ross-va.ida.ion technique a.d by a.sessing six eva.ua.ion *** a.DD system a.hieves the highest a.cura.y of 90.1%,wherea. the other ML a.d conventiona. CNN models a.ta.n only 72.3%–83.8%a.cura.y on ***,the a.DD system proposed herein ha. the highest ca.a.ility to identify pa.ients with *** system ca. be used by medica.

关键词： Hea.t disea.e ma.hine lea.ning multi-a.ent fea.ure wra.per model hea.t disea.e dia.nosis HD clevela.d da.a.ets convolutiona. neura. network

利用声子晶体减小锚点损耗的高频MEMS谐振器的性能研究

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利用声子晶体减小锚点损耗的高频MEMS谐振器的性能研究

作者： mohammed awad a.med mohammed 电子科技大学

学位级别：硕士

增强MEMS谐振器的性能是设计MEMS谐振器的主要目标。为了衡量谐振器的性能,可以用一系列的性能参来表征MEMS谐振器性能,包括谐振频率、品质因数、动态阻抗、非线性、功率容量和频率稳定性,这些参数可以用来衡量谐振器设计的好坏。这些... 详细信息

增强MEMS谐振器的性能是设计MEMS谐振器的主要目标。为了衡量谐振器的性能,可以用一系列的性能参来表征MEMS谐振器性能,包括谐振频率、品质因数、动态阻抗、非线性、功率容量和频率稳定性,这些参数可以用来衡量谐振器设计的好坏。这些参数中,高品质因素是一个提高谐振器性能的关键参数,并且在这些年的研究中被许多研究者提到过。锚点损耗是一种弹性波/声学波通过支撑梁从谐振体传导到基底产生的能量损耗。声学波通过支撑梁的耗散会减小谐振器中存储的能量,从而导致谐振器品质因数的降低。因此,锚点损耗是设计MEMS谐振器时常见的关键参数。减小锚点损耗可以提高谐振器的品质因数,从而提升谐振器的性能。一些已知的可以用于减小锚点损耗并提高谐振器品质因数(Q)的技术包括:支撑梁的优化;利用谐振腔将振动的能量集中在谐振体中;利用声子晶体将弹性波反射回谐振体并隔离谐振体与基底之间的弹性波/声学波的传播等。在这些技术中,声子晶体(PnCs)结构是一种广泛应用于减小MEMS谐振器锚点损耗的方法。利用一维(1D)声子晶体和二维(2D)声子晶体可以提供高的品质因数,但是一维声子晶体会使器件对机械振动十分敏感。这篇论文提供了一个减小高频压电(TPoS)MEMS谐振器锚点损耗的方法。通过在支撑梁上引入二维(2D)声子晶体(PnCs:)结构,可以产生一个阻止声学波通过支撑梁的传播的带隙,并将机械能反射回谐振体,可以增强谐振体中存储的机械能从而提高谐振器的品质因数(Q)。本文的设计讨论了支撑梁的宽度、长度和几何设计对于声子晶体的带隙宽度和谐振器品质因数的影响。在支撑梁的外形上引入十字结构的二维声子晶体结构,这种声子晶体(PnCs)结构的设计可以提供较宽的带隙宽度和较高的品质因数。仿真结果表明,该设计的声子晶体其带隙宽度为380MHz,带隙占比(BG%)为83%,声子晶体的引入将谐振器的品质因数从21.180增加到了 221.536。这篇文章同时讨论了另一种T形的声子晶体结构,其在1GHz以下存在一个较宽的带宽为860 MHz的带隙,在1GHz以上存在两个带隙。该T形声子晶体结构的品质因数和带隙宽度都比以前的研究较高。

关键词： MEMS 锚点损耗声子晶体品质因数