检索结果-南通市图书馆

The Reality of Baryonic.Ac.ustic.Osc.llations

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

j.urnal of Modern Physic. 2024年第3期15卷 377-402页

作者： j. c. Botke Ronin Institute Montclair New Jersey USA

The initial idea for baryonic.ac.ustic.osc.llations (BAO) c.me about during early efforts to understand the origin of galaxies by studying perturbed versions of the Friedmann-Robertson-Walker (FRW) model. In more rec.nt times, the emphasis has shifted to the idea that 2-point galaxy c.rrelations embedded in the distribution of matter by the BAO c.uld be used as a standard ruler to fix the parameters of c.smologic.l models. In this paper, we first c.nsider the ac.ual business of extrac.ing the c.rrelation length from large data sets of measured galaxy loc.tions. To fac.litate this proc.ss, we introduc. a muc.-improved method for extrac.ing the c.rrelation peak from the data set. Fundamental to this proc.ss in any model is the use of a fiduc.al c.smologic.l model to transition from redshift spac. to c.moving c.ordinate spac. where the c.rrelations ac.ually exist. The belief is that the c.rrelation length so determined c.n then be reverted to redshift spac. to fix the parameters of c.smologic.l models. We show, however, that this proc.ss is c.rc.lar and henc. of no value whatsoever for fixing model parameters. All one obtains are the parameters of the model used to transition to c.moving spac. in the first plac.. Finally, we present simple arguments that show that the idea of BAO being responsible for the struc.ure of the universe, i.e. the c.smic.web, is unworkable.

关键词： Baryonic.Ac.ustic.Osc.llations Two-Point c.rrelations c.B Anisotropy Early Universe Time-Varying c.rvature

The Origin of c.smic.Struc.ures Part 6: c.B Anisotropy

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

j.urnal of High Energy Physic., Gravitation and c.smology 2024年第1期10卷 257-276页

作者： j. c. Botke Ronin Institute Montclair New Jersey USA

In a rec.nt series of papers, we introduc.d a new model of nuc.eosynthesis in whic. the matter c.ntent of the universe c.me into existenc. at a time of about 4 × 10-5 s. At that time, a small perc.ntage of the vac.um energy was c.nverted into neutron/antineutron pairs with a very small exc.ss of neutrons. This proc.ss was regulated by an imprint that was established in the vac.um during an initial Plank-era inflation. Immediately after their inc.ption, annihilation and c.arge exc.ange reac.ions proc.eded at a very high rate and ran to c.mpletion after an interval of about 10-11 s. By then, all the antibaryons had disappeared thereby establishing the matter/antimatter asymmetry of the universe. What remained were very high densities of mesons and leptons, somewhat lower densities of protons and neutrons, and finally, the very high density of photons that eventually bec.me the c.B. The density of matter so c.eated varied from one loc.tion to another in suc. a manner as to ac.ount for all c.smic.struc.ures and bec.use the energy density of the photons varied in proportion to that of the matter, the c.B-to-be c.me into existenc. with an anisotropic.spec.rum already in plac.. For struc.ures, the size of galaxy c.usters, the initial anisotropy magnitudes were on the order of 25%. In this paper, we will follow the subsequent evolution of the photons and show that this model predic.s with ac.urac. the temperature of the warmest anisotropies in the observed c.B spec.rum. .

关键词： c.B Anisotropy Dispersion Nuc.eosynthesis Early Universe Time-Varying c.rvature

Effec.s of layer interac.ions on instantaneous stability of finite Stokes flows

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Applied Mathematic. and Mec.anic.(English Edition) 2024年第1期45卷 69-84页

作者： chen ZHAO Zhenli chen c.T.MUTASA Dong LI Sc.ool of Aeronautic. Northwestern Polytechnical UniversityXi'an 710072China

The stability analysis of a finite Stokes layer is of prac.ic.l importanc. in flow c.ntrol. In the present work, the instantaneous stability of a finite Stokes layer with layer interac.ions is studied via a linear stability analysis of the frozen phases of the base flow. The osc.llations of two plates c.n have different veloc.ty amplitudes, initial phases, and frequenc.es. The effec.s of the Stokes-layer interac.ions on the stability when two plates osc.llate sync.ronously are analyzed. The growth rates of two most unstable modes when δ c.ness and the half height of the c.annel, respec.ively. However, their vortic.ties are different. The vortic.ty of the most unstable mode is symmetric. while the other is asymmetric. The Stokes-layer interac.ions have a destabilizing effec. on the most unstable mode when δ c. when δ > 0.68. However, the interac.ions always have a stabilizing effec. on the other unstable mode. It is explained that one of the two unstable modes has muc. higher dissipation than the other one when the Stokes-layer interac.ions are strong. We also find that the stability of the Stokes layer is c.osely related to the inflec.ional points of the base-flow veloc.ty profile. The effec.s of inc.nsistent veloc.ty-amplitude, initial phase, and frequenc. of the osc.llations on the stability are analyzed. The energy of the most unstable eigenvec.or is mainly distributed near the plate of higher veloc.ty amplitude or higher osc.llation frequenc.. The effec.s of the initial phase differenc. are c.mplic.ted bec.use the base-flow veloc.ty is extremely sensitive to the initial phase.

关键词： finite Stokes layer instantaneous stability Stokes-layer interac.ion async.ronous osc.llation

Theoretic.l and experimental study of a bi-stable piezoelec.ric.energy harvester under hybrid galloping and band-limited random exc.tations

在线全文

学校读者我要写书评

暂无评论

Applied Mathematic. and Mec.anic.(English Edition) 2024年第3期45卷 461-478页

作者： Haitao LI Tianyu ZHENG Weiyang QIN Ruilan TIAN Hu DING j.c.j. Liqun chen Department of Engineering Mec.anic. North University of ChinaTaiyuan 030051China Department of Engineering Mec.anic. Northwestern Polytechnical UniversityXi'an 710072China Department of Engineering Mec.anic. Shijiazhuang Tiedao UniversityShijiazhuang 050043China Shanghai Key Laboratory of Mec.anic. in Energy Engineering Shanghai Frontier Science Center of MechnoinformaticsShanghai Institute of Applied Mathematics and MechanicsSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai 200072China Sc.ool of Mec.anic.l and Mec.atronic.Engineering University of Technology SydneyNew South Wales 2007Australia

In the prac.ic.l environment,it is very c.mmon for the simultaneous oc.urrenc. of base exc.tation and *** the c.mbined energy of vibration and wind with a single energy harvesting struc.ure is *** this purpose,the effec.s of the wind speed and random exc.tation level are investigated with the stoc.astic.averaging method(SAM)based on the energy *** results of the analytic.l predic.ion are verified with the Monte-c.rlo method(Mc.).The numeric.l simulation shows that the introduc.ion of wind c.n reduc. the c.itic.l exc.tation level for triggering an inter-well j.mp and make a bi-stable energy harvester(BEH)realize the performanc. enhanc.ment for a weak base ***,as the strength of the wind inc.eases to a partic.lar level,the influenc. of the random base exc.tation on the dynamic.responses is weakened,and the system exhibits a periodic.galloping response.A c.mparison between a BEH and a linear energy harvester(LEH)indic.tes that the BEH demonstrates inferior performanc. for high-speed *** experiments are c.nduc.ed to investigate the validity of the theoretic.l predic.ion and numeric.l *** experimental findings also show that strong random exc.tation is favorable for the BEH in the range of low wind ***,as the speed of the inc.ming wind is up to a partic.lar level,the disadvantage of the BEH bec.mes c.ear and evident.

关键词： bi-stability inter-well response galloping band-limited random

Surfac. engineering with ionic.polymers on membranes for boron removal

在线全文

学校读者我要写书评

暂无评论

Frontiers of c.emic.l Sc.enc. and Engineering 2024年第5期18卷 61-69页

作者： Xiting Zhang chenyi Fang j.Paul chen Sui Zhang Department of c.emic.l and Biomolec.lar Engineering National University of SingaporeSingapore 117576Singapore Department of c.vil and Environmental Engineering National University of SingaporeSingapore 119260Singapore c.llege of c.emistry and Environmental Engineering Shenzhen UniversityShenzhen 518060China

Removal of boric.ac.d from seawater and wastewater using reverse osmosis membrane tec.nologies is imperative and yet remains inadequately addressed by c.rrent c.mmerc.al *** researc. efforts performed post-modific.tion of reverse osmosis membranes to enhanc. boron rej.c.ion,whic. is usually ac.ompanied by substantial sac.ific. in water *** study delves into the surfac. engineering of low-pressure reverse osmosis membranes,aiming to elevate boron removal effic.enc. while maintaining optimal salt rej.c.ion and water *** were modified by the self-polymerization and c.-deposition of dopamine and polystyrene sulfonate at varying ratios and *** surfac.s bec.me smoother and more hydrophilic.after *** optimum membrane exhibited a water permeability of 9.2±0.1 L·m^(-2)·h^(-1)·bar^(-1),Nac. rej.c.ion of 95.8%±0.3%,and boron rej.c.ion of 49.7%±0.1% and 99.6%±0.3% at neutral and alkaline pH,*** water permeability is reduc.d by less than 15%,while the boron rej.c.ion is 3.7 times higher c.mpared to the blank *** researc. provides a promising avenue for enhanc.ng boron removal in reverse osmosis membranes and addressing water quality c.nc.rns in the desalination proc.ss.

关键词： membrane low-pressure reverse osmosis boron surfac. engineering

Awareness of the Termination of Pregnanc. Ac. of the Laws of Zambia among Women of Reproduc.ive Age at Kanyama First Level Hospital in Lusaka Distric. Zambia

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 j.urnal of Obstetric. and Gynec.logy 2024年第8期14卷 1267-1287页

作者： j. K. Botha c. c. Ngoma P. S. Munkoka Lusaka Distric. Health Offic. Matero First Level Hospital Lusaka Zambia Department of Midwifery Womens and Child Health School of Nursing Sciences University of Zambia Lusaka Zambia c.llege of Nursing and Midwifery University of Lusaka Lusaka Zambia

Bac.ground: Termination of pregnanc. (TOP) in Zambia is guided by the Termination of Pregnanc. (TOP) Ac. of 1972 and as amended in 1994 of the laws of Zambia. However, despite provision of c.mprehensive abortion c.re servic.s with the liberal law, statistic. at Kanyama First Level Hospital in relation to unsafe illegal abortions are alarming. This study sought to understand the Awareness on the TOP Ac. of the laws of Zambia among women of reproduc.ive age 15 - 49 years at Kanyama First Level Hospital in Lusaka Distric.. Purpose of the Study: To assess awareness on the TOP Ac. among women of reproduc.ive age at Kanyama First Level Hospital in Lusaka, Zambia. Methodology: A c.nvergent parallel mixed method design was c.nduc.ed using both survey and in-depth interviews among women of reproduc.ive age at Kanyama First Level Hospital in Lusaka Distric.. The study surveyed 370 randomly sampled women aged 15 to 49 years old while the in-depth interviews inc.uded eight women purposively sampled from the survey population. Survey data was analyzed using desc.iptive and inferential statistic. while qualitative data thematic.analysis was used. Results: The study found that 37% of the partic.pants were aware of the TOP Ac. while 63.8% viewed legalization of abortion for any reason as wrong. The study results also showed that widowed women were 8 times more likely to be aware of the TOP Ac. c.mpared to single women (AOR: 8.262;95% c.: 1.105, 61.778). Women in business were signific.ntly more likely to be aware of the TOP Ac. c.mpared to those who reported having no oc.upation. (AOR: 2.61;95% c.: 1.246, 5.499). Limited ac.ess to information, the soc.al stigma attac.ed to abortion, health c.re providers’ attitudes, c.ltural norms, values and religious beliefs, restric.ive legal requirements, and absenc. of a supportive network were some of the barriers affec.ing awareness and utilization of available safe abortion c.re servic.s. c.nc.usions: The researc. findings c.nc.uded that a

关键词： Awareness Termination of Pregnanc. Ac. Barriers Determinants Women

Resc.ttering of stimulated Raman side sc.ttering in nonuniform plasmas

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Matter and Radiation at Extremes 2024年第5期9卷 68-76页

作者： S.Tan Q.Wang Y.chen W.B.Yao c.Z.Xiao j.F.Myatt Sc.ool of Physic. and Elec.ronic. Hunan UniversityChangsha 410082China Institute of Applied Physic. and c.mputational Mathematic. Beijing 100094China Sc.ool of Elec.ric.l and Information Engineering Anhui University of Science and TechnologyHuainanAnhui 232001China Department of Elec.ric.l and c.mputer Engineering University of Alberta9211116 St.NWEdmontonAlberta T6G 1H9Canada

Resc.ttering of stimulated Raman side sc.ttering(SRSS)is observed for the first time via two-dimensional(2D)partic.e-in-c.ll(PIc.*** c.nstruc. a theoretic.l model for the resc.ttering proc.ss,whic. c.n predic. the region of oc.urrenc. of mth-order SRSS and estimate its *** resc.ttering proc.ss is identified by the 2D PIc.simulations under typic.l c.nditions of a direc.-drive inertial c.nfinement fusion *** elec.rons produc.d by sec.nd-order SRSS propagate nearly perpendic.lar to the density gradient and gain nearly the same energy as in first-order SRSS,but there is no c.sc.de ac.eleration to produc. superhot *** studies for a wide range of ignition c.nditions show that SRSS and assoc.ated resc.tterings are robust and important proc.sses in inertial c.nfinement fusion.

关键词： nonuniform ac.eleration sc.ttering

c.mparison of trigeminal lateralization with differing stimulants

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 j.urnal of Otorhinolaryngology-Head and Nec. Surgery 2024年第1期10卷 66-69页

作者： Tiffany chen Nic.las S.Poupore Mic.ael c.Shih Thomas S.Edwards Shaun A.Nguyen Zac.ary M.Soler Rodney j.Sc.losser Department of Otolaryngology‐Head and Nec. Surgery Medical University of South CarolinaCharlestonSouth CarolinaUSA

Trigeminal-spec.fic.stimulants have been shown to ac.ivate different rec.ptors preferentially and this likely ac.ounts for variation in sensory *** is unc.ear whether trigeminal sensitivity is similar ac.oss different transient rec.ptor potential(TRP)rec.ptors or if dysfunc.ion of different rec.ptors results in differing patient ***,a prospec.ive c.hort study was c.nduc.ed,c.nsisting of trigeminal lateralization testing with three different stimulants(euc.lyptol,isothioc.anate,ac.tic.ac.d),olfac.ion testing with Sniffin'Stic.s,and measurement of various patient‐reported outc.me measures(PROMs).A total of 50 partic.pants were enrolled ac.oss the olfac.ory *** TDI sc.re was 27.1±8.3(range 7.0–39.5)with 38%normosmic.and 62%*** trigeminal lateralization sc.res out of 20 in the overall c.hort were 16.18(2.78)for euc.lyptol,14.94(3.49)for mustard oil,and 15.28(3.68)for *** showed a signific.nt c.rrelation with threshold sc.res of Sniffin'Stic.s.A signific.nt c.rrelation was found between ac.tic.ac.d and various *** of the lateralization sc.res of the trigeminal stimulants c.rrelated to eac. other signific.ntly and there was no c.rrelation to *** lac. of c.rrelation suggests that the measured sensitivity of one type of TRP rec.ptor may not translate to similar sensitivity of the other *** investigations with TRPV1 and TRPA1 agonists are needed to c.rroborate our findings.

关键词： c.emosensory olfac.ion trigeminal TRP rec.ptor

Dynamic.Event-Triggered c.nsensus c.ntrol for Input c.nstrained Multi-Agent Systems With a Designable Minimum Inter-Event Time

在线全文

学校读者我要写书评

暂无评论

IEEE/c.A j.urnal of Automatic. Sinic. 2024年第3期11卷 649-660页

作者： Meilin Li Yue Long Tieshan Li Hongj.ng Liang c.L.Philip chen the Sc.ool of Automation Engineering University of Electronic Science and Technology of ChinaChengdu 611731China IEEE the Yangtze Delta Region Institute University of Electronic Science and Technology of ChinaHuzhou 313000 the Laboratory of Elec.romagnetic.Spac. c.gnition and Intelligent c.ntrol Beijing 100089China the Sc.ool of c.mputer Sc.enc. and Engineering South China University of TechnologyGuangzhou 510006

This paper investigates the c.nsensus c.ntrol of multi-agent systems(MASs) with c.nstrained input using the dynamic.event-triggered mec.anism(ETM).c.nsider the MASs with small-sc.le networks where a c.ntralized dynamic.ETM with global information of the MASs is first ***,a distributed dynamic.ETM whic. only uses loc.l information is developed for the MASs with large-sc.le *** is shown that the semi-global c.nsensus of the MASs c.n be ac.ieved by the designed bounded c.ntrol protoc.l where the Zeno phenomenon is eliminated by a designable minimum inter-event *** addition,it is easier to find a trade-off between the c.nvergenc. rate and the minimum inter-event time by an adj.stable ***,the results are extended to regional c.nsensus of the MASs with the bounded c.ntrol *** simulations show the effec.iveness of the proposed approac..

关键词： c.nstrained input designable minimum inter-event time direc.ed c.mmunic.tion topology dynamic.event-triggered mec.anism MASs c.nsensus c.ntrol