检索结果-南通市图书馆

ON THE MOdIFIEd NONLINEAr SCHrdINGEr EQUATION IN THE SEMICLASSICAL LIMIT:SUPErSONIC,SUBSONIC,ANd TrANSSONIC BEHAVIOr

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mathematica Scientia 2011年第6期31卷 2343-2377页

作者： Jeffery C. diFranco Peter d. Miller Benson K. Muite department of Mathematics Seattle University department of Mathematics University of Michigan

The purpose of this paper is to present a comparison between the modified nonlinear SchrSdinger （MNLS） equation and the focusing and defocusing variants of the （unmodified） nonlinear SchrSdinger （NLS） equation in the semiclassical limit. We describe aspects of the limiting dynamics and discuss how the nature of the dynamics is evident theoretically through inverse-scattering and noncommutative steepest descent methods. The main message is that, depending on initial data, the MNLS equation can behave either like the defocusing NLS equation, like the focusing NLS equation （in both cases the analogy is asymptotically accurate in the semiclassical limit when the NLS equation is posed with appropriately modified initial data）, or like an interesting mixture of the two. In the latter case, we identify a feature of the dynamics analogous to a sonic line in gas dynamics, a free boundary separating subsonic flow from supersonic flow.

关键词： semiclassical limits dispersionless limits modulational instability focusing,defocusing, and modified nonlinear SchrSdinger equations

Properties of Charmonium States in a Phenomenological Approach

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2019年第2期71卷 192-202页

作者： Praveen P d’Souza Antony Prakash Monteiro K.B.Vijaya Kumar department of Physics St Philomena College department of Physics Mangalore University

We investigate the spectrum and decay rates of charmonium states within the framework of the non relativistic quark model by employing a Coulomb like potential from the perturbative one gluon exchange and the linear confining potential along with the potential derived from instanton vacuum to account for the hyperfine mass splitting of charmonium states in variational approach. We predict radiative E1, M1, two-photon, lepton and two-gluon decay rates of low lying charmonium states. An overall agreement is obtained with the experimental masses and decay *** have estimated the branching ratio of two gluons decaying into light hadrons.

关键词： non-relativistic quark model instantons charmonium radiative decay two gluon decay two photon decay leptonic decay branching ratio

Composition and Genesis of Zeolitic Claystones from the Central Indian Ocean Basin

在线全文

学校读者我要写书评

暂无评论

Acta Geologica Sinica(English Edition) 2007年第5期81卷 756-770页

作者： Sridhar d.Iyer M.Sudhakar P.das National Institute of Oceanography Dona Paula Goa 403004India National Centre for Antarctic:and Ocean research Sada HeadlandVasco-da-Gama Goa403804India

We examined more than fifty indurated sediments recovered from the Central Indian Ocean Basin （CIOB） during the course of collection for manganese nodules and crusts. The samples occur as slabs either over which ferromanganese oxides are present or over a substrate of altered oceanic basalt in conjunction with palagonite or within the nucleus of manganese nodules. Mineralogically and compositionally, the samples show a mixture of phillipsite, palagonite and montmorillonite. We suggest that the volcanogenic precursors occurring in the CIOB were subjected to varying degrees of alteration under the influence of low temperature conditions, resulting in the formation of zeolitic claystones. The CIOB samples have similarities to those reported from various sites in the world oceans.

关键词： halmyrolysis zeolites alteration authigenesis Indian Ocean

Metal dusting-Mechanisms and Preventions

在线全文

学校读者我要写书评

暂无评论

中国腐蚀与防护学报 2009年第4期29卷 262-276页

作者： J. Q. ZHANG d. J. YOUNG School of Materials Science and Engineering University of New South Wales Sydney NSW 2052 Australia

Metal dusting attacks iron,low and high alloy steels and nickel-or cobalt-base alloys by disintegrating bulk metals and alloys into metal particles in a coke *** occurs in strongly carburising gas atmospheres(carbon activity a_C>1) at elevated temperatures(400℃～1000℃).This phenomenon has been studied for decades,but the detailed mechanism is still not well *** methods of protection against metal dusting are either directed to the process conditions-temperature and gas composition-or to the development of a dense adherent oxide layer on the surface of the alloy by selective ***,metal dusting still occurs by carbon dissolving in the base metal via defects in the oxide *** research work at UNSW is aimed at determining the detailed mechanism of metal dusting of both ferritic and austenitic alloys,in particular the microprocesses of graphite deposition,nanoparticle formation and underlying metal *** work was carried out using surface observation,crosssection analysis by focused ion beam and electron microscopic examination of coke deposits at different stages of the *** was found that surface orientation affected carbon deposition and metal dusting at the initial stage of the *** dusting occurred only when graphite grew into the metal interior where the volume expansion is responsible for metal disintegration and *** was also found that the metal dusting process could be significantly changed by alterations in alloy *** was found to affect the iron dusting process by destabilising Fe_3C but increasing the rate of carbon deposition and dusting,which questions the role of cementite in ferritic alloy *** adding copper to iron did not change the carburisation kinetics,cementite formation and coke morphology,copper alloying reduced nickel and nickel-base alloy dusting rates *** of these fundamental results to the dusting behaviour of engineering al

关键词：金属腐蚀氧化防护机械装置

Evolution of a flexible rule for foraging that copes with environmental variation

在线全文

学校读者我要写书评

暂无评论

Current Zoology 2015年第2期61卷 303-312页

作者： Andrew d. HIGGINSON Tim W. FAWCETT Alasdair I. HOUSTON School of Biological Sciences Life Sciences Building University of Bristol 24 Tyndall Avenue Bristol BS8 1TQ U.K.

Models of adaptive behaviour typically assume that animals behave as though they have highly complex, detailed strategies for making decisions. In reality, selection favours the optimal balance between the costs and benefits of complexity. Here we investigate this trade-off for an animal that has to decide whether or not to forage for food - and so how much energy reserves to store - depending on the food availability in its environment. We evolve a decision rule that controls the target reserve level for different ranges of food availability, but where increasing complexity is costly in that metabolic rate increases with the sensitivity of the rule. The evolved rule tends to be much less complex than the optimal strategy but performs almost as well, while being less costly to implement. It achieves this by being highly sensitive to changing food availability at low food abun- dance - where it provides a close fit to the optimal strategy - but insensitive when food is plentiful. When food availability is high, the target reserve level that evolves is much higher than under the optimal strategy, which has implications for our under- standing of obesity. Our work highlights the important principle of generalisability of simple decision-making mechanisms, which enables animals to respond reasonably well to conditions not directly experienced by themselves or their ancestors.

关键词： Behavioural mechanisms Fat storage Fluctuating environments Generalisation Obesity rule of thumb

Failure modes of PdC cutters under different loads

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 2002年第3期12卷 504-507页

作者：李夕兵赵伏军 d.A.Summers G.rupert Institute of Mining and rock Engineering Central South University Changsha 410083 China rock Mechanics and Explosives research Center University of Missouri-Rolla MO65401 USA

The capability of several types of flat PdC cutters to withstand combined loads were tested and evaluated by the impact and cutting of single PdC cutter on granite in a linear impact cutting table. The primary failure modes of PdC cutters withstanding different combined loads were investigated and analyzed. The suggestions of enhancing PdC cutters to be suitable for drilling very hard rock have been made.

关键词：聚晶金刚石失效模式金刚石钻进复合载荷

reply to the letter to the editor

在线全文

学校读者我要写书评

暂无评论

Eye and Vision 2021年第1期8卷 462-463页

作者： Jorge L.Alio Francesco Versaci Francesco d’Oria Vissum Miranza AlicanteSpain division of Ophthalmology Universidad Miguel HernándezAlicanteSpain r&d department Costruzione Strumenti Oftalmici(CSO)FlorenceItaly Section of Ophthalmology Department of Basic Medical ScienceNeuroscience and Sense OrgansUniversity of BariBariItaly

We appreciate the interest of Miguel Faria ribeiro in our paper[1],as well as the comments made to *** interest of the topic is sound,as nowadays an enormous amount of new so-called“premium lenses”are appearing in the market,with different optical profiles which obviously lead to different light distributions and different quality of retinal *** is why our interest in this topic is longstanding and we have published extensive summaries about the outcomes and complications of multifocal lenses over the last years[2,3].

关键词： editor letter enormous

Effect of Nb on Microstructure Evolution in Cold rolled dual-Phase Steels:Interaction of recovery,recrystallization and Phase Transformations

维普期刊数据库评论

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 Iron and Steel research International 2011年第S1期18卷 228-232页

作者： Pottore N Fonstein N Bhatta Charya d Jansto S ArcelorMittal Global r and d 3001 E Columbus DrEast ChicagoIN 46312USA CBMM-reference Metals Company 1000 Old Pond RoadBridgevillePA 15017USA

The effects of Nb addition,individually and in combination with Ti,were evaluated over a range of coiling *** temperature influences the ratio of soluble and precipitated Nb in the hot rolled steel containing 0.08 % C and 2.2 % *** bearing precipitates can co-precipitate on TiN and impact the microstructure and mechanical properties of the steel after annealing *** characterization revealed that recovery and recrystallization processes preceded austenite *** effects of Nb on austenite formation in cold rolled steels during heating and isothermal holding and on austenite decomposition during subsequent cooling were investigated using *** addition of Nb retarded ferrite recrystallization starting temperature,but had no significant effect on the starting temperature of austenite formation during *** Nb addition also accelerated austenite formation once the transformation started,and was beneficial for the formation of a finer and homogeneous microstructure.

关键词： niobium dual-phase steel recovery recrystallization phase transformation

Thin liquid film morphology driven by electro-static field

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2011年第8期32卷 1039-1046页

作者： E.M.TIAN T.P.SVOBOdNY J.d.PHILLIPS department of Mathematics and Statistics Wright State University

The development of stationary patterns on a thin polymer surface subject to an electric field is studied by means of the hexagonal-planform weakly nonlinear stability analysis and numerical simulations. The time evolution of the interface between the air and the polymer film on the unbounded spatial domain is described by a thin film equation, incorporating the electric driving force and the surface *** nonlinear interfacial growth includes the amplitude equations and superposition of one-dimensional structures at regular orientations. The pattern selection is driven by the subcritical instability mechanism in which the relative thickness of the polymer film plays a critical role.

关键词： thin film pattern formation electrohydrodynamic instability