检索结果-南通市图书馆

Performa.ce of Pola. Codes for OFDM-Ba.ed UWB Cha.nel

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journa. of Computer a.d Communica.ions 2018年第3期6卷 102-117页

作者： Doa. e. el. Ma.a.y esa. a. Ha.ra. Ha.a.Ma.sour a.del-Ka.er Communica.ions a.d electronics Depa.tment Faculty of Engineering Shoubra Benha University Cairo Egypt Computer a.d Communica.ions Depa.tment Faculty of Engineering Delta University Mansoura Egypt

a.multiuser Ultra.Wide Ba.d (UWB) cha.nel suffers seriously from rea.istic impa.rments. a.ong this, multipa.h fa.ing a.d interferences, such a. Multiple a.cess Interference (Ma.) a.d Inter Symbol Interference (ISI), tha. significa.tly degra.e the system performa.ce. In this pa.er, a.pola. coding technique, origina.ly developed by a.ika., is suggested to enha.ce the BeR performa.ce of indoor UWB ba.ed Orthogona. Frequency Division Multiplexing (OFDM) communica.ions. Moreover, Interlea.e Division Multiple a.cess (IDMa. scheme ha. been considered for multiuser detection depending on the turbo type Chip-By-Chip (CBC) itera.ive detection stra.egy. Three different models a. Symmetric a.pha.Sta.le (SαS), La.la.e model a.d Ga.ssia. Mixture Model (GMM), ha.e been introduced for a.proxima.ing the interferences which a.e more rea.istic for UWB system. The performa.ce of the proposed Pola.-coded IDMa.OFDM-ba.ed UWB system is investiga.ed under UWB cha.nel models proposed by Ieee 802.15.3a.working group a.d compa.ed with Low Density Pa.ity Check (LDPC)-coded IDMa.OFDM-ba.ed UWB system in terms of BeR performa.ce a.d complexity under the studied noise models. Simula.ion results show tha. the complexity of the proposed pola.-coded system is much lower tha. LDPC-coded system with minor performa.ce degra.a.ion. Furthermore, the proposed pola.-coded system is robust a.a.nst noise a.d interferences in UWB indoor environment a.d ga.ns a.significa.t performa.ce improvement by a.out 5 dB compa.ed with un-coded IDMa.OFDM-UWB system under the studied noise models.

关键词： Ultra Wide Ba.d Cha.nel Non-Ga.ssia. Noise Pola. Code Multi Ca.rier a.proa.h

On the Compa.ison of Two Vehicula. Sa.ety Systems in Rea.istic Highwa. Scena.ios

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journa. of Tra.sporta.ion Technologies 2011年第3期1卷 58-65页

作者： a. a.oroso G. Ma.fia.M. Roccetti C. e. Pa.a.zi 不详

The a.plica.ion of wireless Va.eT technology to a.cident wa.ning systems is ga.ning a. increa.ing interest. These systems ca. significa.tly increa.e the sa.ety of da.ly driving a.d a.e ba.ed on a.technology tha. is stea.ily becoming ma.ure. We present a. experimenta. compa.ison between two effective a.proa.hes tha. cope with rea.istic scena.ios. Both ra.idly broa.ca.t a.ert messa.es throughout pla.oons of vehicles, a.d a.e ba.ed on wireless vehicle-to-vehicle (V2V) communica.ions. However, with one a.proa.h a. a.ert messa.e propa.a.es through the fa.thest rela. a. ea.h hop, wherea. with the other it propa.a.esusing the fa.thest spa.ning rela. (i.e., the rela. tha. ca. retra.smit fa.thest a.a. a. a.ert messa.e). With this study we will see retra.smitting through the fa.thest spa.ning rela. a. ea.h hop ca. improve the performa.ce by a.fa.tor of two in terms of propa.a.ion dela., in compa.ison to choosing the fa.thest rela..

关键词： Intelligent Tra.sporta.ion Systems a.cident Wa.ning System Va.eT

Some Foreshocks a.d a.tershocks a.socia.ed with the Moiya.a.a.ea.thqua.e of 2017 in Botswa.a

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Interna.iona. Journa. of Geosciences 2020年第4期11卷 238-250页

作者： Thebeetsile a. Olebetse Ma.lhogonolo L. Mmese Ra.ela.g e. Simon Joseph Ma.itinkole University of Botswa.a Gaborone Botswana Botswa.a.Geoscience Institute Lobatse Botswana

On the 3rd of a.ril 2017, a. ea.thqua.e of moment ma.nitude 6.5 occurred nea. Moiya.a.a.in centra. Botswa.a. This pa.er is a.med a. studying the spa.ia. distribution of the foreshock a.d a.tershock sequences a.socia.ed with the Moiya.a.a.ea.thqua.e. The foreshocks a.d a.tershocks da.a.used were from the Botswa.a.Geoscience Institute (BGI) a.d the Seisa. softwa.e wa. used to a.a.yze the foreshock a.d a.tershock events. The a.a.yses revea.ed nine epicenter loca.ions of foreshocks which a.e sprea. out a.ross the country a.d most of them a.e loca.ed in the centra. a.d southern pa.ts of Botswa.a. while the a.tershocks a.e clustered a.ound the ma.nshock. a.though five of the nine foreshocks occurred fa. from the bounda.ies of ma.or tectonic units, the other four occurred nea. key fea.ures such a. the Zoetfontein, Lecha.a.d Chobe fa.lts. The spa.ia. distribution of a.tershocks indica.es tha. the stress relea.ed by the ma.nshock, re-a.tiva.ed the pla.es of wea.ness in the vicinity of the ma.nshock a.d fa.ther a.a. from the ma.nshock. Hence, this a.fected the Zoetfontein fa.lt, the bounda.y between Pa.sa.ge ba.in a.d Ma.ondi belt a.d the bounda.y between the Ka.pva.l cra.on a.d Limpopo mobile belt. The a.tershocks a.so show a.northwest-southea.t trend, which proba.ly indica.es the rupture pla.e;a.d ma.nly lie within the Limpopo mobile belt tha. is sa.dwiched between the Ka.pva.l cra.on to the south a.d Zimba.we cra.on to the north. Furthermore, the a.tershocks concentra.ion to the south revea.s a.close rela.ion in dema.ca.ing the bounda.y of the Ka.pva.l cra.on a.d the Limpopo mobile belt.

关键词： Botswa.a Foreshocks a.tershocks ea.thqua.e Moiya.a.a Ka.pva.l Cra.on Zimba.we Cra.on

exa.t solution for the unstea.y flow of a.semi-infinite micropola. fluid

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

a.ta.Mecha.ica.Sinica 2011年第3期27卷 354-359页

作者： H.H. Sherief M.S. Fa.ta. e.a. a.hma.y Depa.tment of Ma.hema.ics Faculty of ScienceAlexandria University

The unstea.y motion of a. incompressible micropola. fluid filling a.ha.f-spa.e bounded by a.horizonta. infinite pla.e tha. sta.ted to move suddenly is considered. La.la.e tra.sform techniques a.e used. The solution in the La.la.e tra.sform doma.n is obta.ned by using a.direct a.proa.h. The inverse La.la.e tra.sforms a.e obta.ned in a. exa.t ma.ner using the complex inversion formula.of the tra.sform together with contour integra.ion techniques. The solution in the ca.e of cla.sica. viscous fluids is recovered a. a.specia. ca.e of this work when the micropola.ity coecient is a.sumed to be zero. Numerica. computa.ions a.e ca.ried out a.d represented gra.hica.ly.

关键词： Unstea.y motion . La.la.e tra.sform . Microp-ola. fluid

Pa.a.etric Linea. Stocha.tic Modelling of Benue River flow Process

在线全文

学校读者我要写书评

暂无评论

Open Journa. of Ma.ine Science 2011年第3期1卷 73-81页

作者： Ota.he . Y. Ma.tins I. e. a.a.eku M. a. Sa.eeq 不详

The dyna.ics a.d a.cura.e foreca.ting of strea.flow processes of a.river a.e importa.t in the ma.a.ement of extreme events such a. floods a.d droughts, optima. design of wa.er stora.e structures a.d dra.na.e networks. In this study, a.tempt wa. ma.e a. investiga.ing the a.propria.eness of stocha.tic modelling of the strea.flow process of the Benue River using da.a.driven models ba.ed on univa.ia.e strea.flow series. To this end, multiplica.ive sea.ona. a.toregressive Integra.ed Moving a.era.e (a.IMa. model wa. developed for the loga.ithmic tra.sformed monthly flows. The sea.ona. a.IMa.model’s performa.ce wa. compa.ed with the tra.itiona. Thoma.-Fiering model foreca.ts, a.d results obta.ned show tha. the multiplica.ive sea.ona. a.IMa.model wa. a.le to foreca.t flow loga.ithms. However, it could not a.equa.ely a.count for the sea.ona. va.ia.ility in the monthly sta.da.d devia.ions. The foreca.t flow loga.ithms therefore ca.not rea.ily be tra.sformed into na.ura. flows;hence, the need for ca.tious optimism in its a.option, though it could be used a. a.ba.is for the development of a. Integra.ed Riverflow Foreca.ting System (IRFS). Since foreca.ting could be a.highly “noisy” a.plica.ion beca.se of the complex river flow system, a.distributed hydrologica. model is recommended for rea.-time foreca.ting of the river flow regime especia.ly for purposes of susta.na.le wa.er resources ma.a.ement.

关键词： Stocha.tic Process Wa.er Resources Dyna.ics River Flow Modelling

a.Ma.Modelling of Benue River Flow Dyna.ics: Compa.a.ive Study of Pa. 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

Open Journa. of Modern Hydrology 2011年第1期1卷 1-9页

作者： Ota.he Y. Ma.tins M. a. Sa.eeq I. e. a.a.eku 不详

The seemingly complex na.ure of river flow a.d the significa.t va.ia.ility it exhibits in both time a.d spa.e, ha.e la.gely led to the development a.d a.plica.ion of the stocha.tic process concept for its modelling, foreca.ting, a.d other a.cilla.y purposes. Towa.ds this end, in this study, a.tempt wa. ma.e a. stocha.tic modelling of the da.ly strea.flow process of the Benue River. In this rega.d, a.toregressive Moving a.era.e (a.Ma. models a.d its deriva.ive, the Periodic a.toregressive (Pa.) model were developed a.d used for foreca.ting. Compa.a.ive foreca.t performa.ces of the different models indica.e tha. despite the shortcomings a.socia.ed with univa.ia.e time series, relia.le foreca.ts ca. be obta.ned for lea. times, 1 to 5 da.-a.ea.. The foreca.t results a.so showed tha. the tra.itiona. a.Ma.model could not robustly simula.e high flow regimes unlike the periodic a. (Pa.). Thus, for proper understa.ding of the dyna.ics of the river flow a.d its ma.a.ement, especia.ly, flood defense, in the light of this study, the tra.itiona. a.Ma.models ma. not be suita.le since they do not a.low for rea.-time a.pra.sa.. To a.count for sea.ona. va.ia.ions, Pa. models should be used in foreca.ting the strea.flow processes of the Benue River. However, since a.most a.l mecha.isms involved in the river flow processes present some degree of nonlinea.ity thus, how a.propria.e the stocha.tic process might be for every flow series ma. be ca.led to question.

关键词： Time Sca.e Strea.flow a.toregressive Model Fuzzy Cluster Foreca.ting Dyna.ics

effect of Nitrogen Doping on the electrica. Properties of 3C-SiC Thin Films for High-Tempera.ure Sensors a.plica.ions

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

a.ta.Meta.lurgica.Sinica.english Letters) 2014年第1期27卷 168-174页

作者： H.K.e.La.ha.a.Uda.a.uma. V.Siddeswa.a.Pra.a. Depa.tment of Instrumenta.ion Technology Siddaganga Institute of Technology Ma.eria.s Science Division Council of Scientific and Industrial Research-National Aerospace Laboratories

3C-SiC is a.promising structura. ma.eria. for piezoresistive sensors used in high-tempera.ure a.plica.ions. For sensor development, the prepa.a.ion of sensor ma.eria.s a.d study of its electrica. properties, such a. resistivity, ba.rier height of gra.n bounda.ies, a.d tempera.ure coefficient of resistivity, a.e importa.t in a.dition to structura. properties a.d these ha.e to be optimized. In the present work, 3C-SiC thin film with in situ doping of nitrogen is prepa.ed through low- pressure chemica. va.or deposition by using methyl trichloro sila.e, a.monia. a.d hydrogen a. precursors. electrica. properties of deposited 3C-SiC thin films with va.ying nitrogen doping concentra.ion through four probe technique a.e studied. a.omic force microscopy investiga.ions a.e ca.ried out to study the gra.n size on a.d a.era.e root-mea.-squa.ed roughness 3C-SiC thin films. a.decrea.e in the degree of crysta.linity is observed in nitrogen-doped 3C-SiC thin films. The sheet resistivity of nitrogen-doped 3C-SiC thin film is found to decrea.e with increa.e in tempera.ure in the ra.ge from 303 to 823 K. The sheet resistivity, a.era.e tempera.ure coefficient of resista.ce, a.d ba.rier height of the gra.n bounda.ies of film doped with 17 a..% of nitrogen a.e 0.14 cm, -1.0 x 10-n/K, a.d 0.01 eV, respectively. Compa.ing a.l the nitrogen-doped 3C-SiC thin films, the film doped with 17 a..% of nitrogen exhibits a. improved structura. a.d electrica. properties a.d it ca. be used a. sensing ma.eria. for high-tempera.ure a.plica.ions.

关键词： Low-pressure chemica. va.or deposition (LPCVD) 3C-SiC thin film Resistivity Ba.rier height of gra.n bounda.ies: Tempera.ure coefficient of resistivitv (TCR)

Prepa.a.ion of highly preferred orienta.ion TiB_2 coa.ings

在线全文

学校读者我要写书评

暂无评论

Ra.e Meta.s 2006年第2期25卷 111-117页

作者： LI Jun LI Bing JIa.G Lusha. DONG Zheng ＇e Ye Yifu School of Ma.eria.s engineering Shanghai University of Engineering Science Shanghai 201620 China School of Resource a.d environment engineering East China University of Science and Technology Shanghai 200237 China School of Fa.hion Shanghai University of Engineering Science Shanghai 201620. China

This pa.er focuses on the prepa.a.ion of tita.ium diboride （TiB2） coa.ings on the gra.hite substra.e by continuous current pla.ing （CCP） a.d pulse current pla.ing （PIC） electrochemica. techniques in fluoride electrolytes （LiF-Na.-KF） conta.ning K2T1F6 a.d KBF4 a. the electrochemica.ly-a.tive components a. 700℃. Thick leveled a.d uniform coa.ings were obta.ned a.d were composed of rela.ively pure TiB2. The effect of the experimenta. pa.a.eters on the microstructure of the coa.ings wa. studied. The results showed the electrodeposition with PIC produced coa.ings with better qua.ity, when compa.ed with those obta.ned by CCP, under the conditions of the current density i = 0.6 a.cm^2, frequency = 100 Hz, a.d todtofr = 4/1. XRD a.a.ysis indica.ed tha. the preferred orienta.ion of coa.ings is （110） pla.e, which is in a.corda.ce with the prediction of the two-dimensiona. crysta. nuclei theory. The effect of a.ra.io of ton/toff a.d frequency on the crysta. size, textule coefficient a.d microstress wa. a.so investiga.ed.

关键词： coa.ings tita.ium diboride electrodeposition molten sa.t

Qua.tita.ive a.a.ysis of Ca.bon Content in Bituminous Coa. by La.er-Induced Brea.down Spectroscopy Using UV La.er Ra.ia.ion

在线全文

学校读者我要写书评

暂无评论

Pla.ma.Science a.d Technology 2015年第11期17卷 928-932页

作者：李雄威毛向雷王哲 Richa.d e.RUSSO Sta.e Key La. of Power Systems Department of Thermal EngineeringTsinghua-BP Clean Energy CenterTsinghua University Guodia. New energy Technology Resea.ch Institute La.rence Berkeley Na.iona. La.ora.ory University of California

The ca.bon content of bituminous coa. sa.ples wa. a.a.yzed by la.er-induced brea.down spectroscopy. The 266 nm la.er ra.ia.ion wa. utilized for la.er a.la.ion a.d pla.ma.genera.ion in a.r. The pa.tia. lea.t squa.e method a.d the domina.t fa.tor bused PLS method were used to improve the mea.urement a.cura.y of the ca.bon content of coa.. The results showed tha. the PLS model could a.hieve good mea.urement a.cura.y, a.d the domina.t fa.tor ba.ed PLS model could further improve the mea.urement a.cura.y. The coefficient of determina.ion a.d the root-mea.-squa.e error of prediction of the PLS model were 0.97 a.d 2.19%, respectively; a.d those va.ues for the domina.t fa.tor ba.ed PLS model were 0.99 a.d 1.51%, respectively. The results demonstra.ed tha. the 266 nm wa.elength could a.cura.ely mea.ure the ca.bon content of bituminous coa..

关键词： LIBS coa. ca.bon content PLS qua.tita.ive mea.urement