检索结果-南通市图书馆

Merging bound states in the continuum in an open acoustic resonator

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 124-131页

作者： Lujun Huang Bin Jia Artem S.Pilipchuk Sibo Huang Chen Shen Almas f.Sadreev Yong Li Andrey e.Miroshnichenko School of Physics and electronic Sciences East China Normal University Institute of Acoustics Tongji University L.V.Kirensky Institute of Physics Department of Mechanical engineering Rowan University School of engineering and Technology University of New South Wales at Canberra

Bound states in the continuum （BICs） are pe.f.ctly localized resonances despite embedding in the continuum ***,an isolated BIC is very sensitive to the structure ***,we report merging acoustic BICs in a single open resonator,robust against the structure *** find that both symmetry-protected BIC and friedrich-Wintgen BIC are sustained in a single coupled waveguide-resonator *** varying the height and length of the resonator,these two BICs move toward each other and merge into a single one at a critical *** to an individual BIC,the merged BIC is robust against fabrication error because its Q-factor is proportional to ΔL-4,whereΔL embodies the structure *** essence of this extraordinary phenomenon is pe.f.ctly explained by the two-and three-level approximations of the e.f.ctive nonHermitian ***,we present direct experimental demonstrations of the moving and merging of BICs in a coupled 3D waveguide-resonator,which are evidenced by the vanishing of the linewidth of fano resonance in the transmission *** results may find exciting applications in designing high-quality acoustic sources,sensors and filters.

关键词： acoustic resonances bound state in the continuum high-Q resonances

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

为什么动物试验事关重大?

世界社会科学 2003年第2期 111-113页

作者： e.f.保罗,新馨〔美〕

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

小说在巴西民族身份建构中的作用

外国文学 1999年第4期 45-47+51页

作者：Ｅ.Ｆ.库庭霍南京师范大学

不管文学话语和民族身份之间的关联看似多么自然和必然，这种关联还只是一种相对新近的历史建构。民族文学的观念发端于１８世纪与１９世纪的交替时期，特别来源于德国的浪漫主义民族主义者。他们认为文学附属于民族，理应体现民族特征... 详细信息

不管文学话语和民族身份之间的关联看似多么自然和必然，这种关联还只是一种相对新近的历史建构。民族文学的观念发端于１８世纪与１９世纪的交替时期，特别来源于德国的浪漫主义民族主义者。他们认为文学附属于民族，理应体现民族特征。文学民族主义者的根本前提是：人类...

关键词：身份建构魔鬼荒原小说民族权利主体文学话语印第安人文学经典反英雄巴西南美洲印第安主义

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

解惑

解惑

Nonlinear Propagation of Positron-Acoustic Periodic Travelling Waves in a Magnetoplasma with Superthermal electrons and Positrons

作者： (英)e.f. 舒马赫(e.f. Schumacher)

来源：南通市图书馆图书评论

学校读者我要写书评

暂无评论

Chinese Physics Letters 2017年第6期34卷 70-74页

作者： e.f.eL-Shamy Department of Physics College of ScienceKing Khalid University Department of Physics Faculty of ScienceDamietta University

The nonlinear propagation of positron acoustic periodic （PAP） travelling waves in a magnetoplasma composed of dynamic cold positrons, superthermal kappa distributed hot positrons and electrons, and stationary positive ions is examined. The reductive perturbation technique is employed to derive a nonlinear Zakharov Kuznetsov equation that governs the essential features of nonlinear PAP travelling waves. Moreover, the bifurcation theory is used to investigate the propagation of nonlinear PAP periodic travelling wave solutions. It is found that kappa distributed hot positrons and electrons provide only the possibility of existence of nonlinear compressive PAP travelling waves. It is observed that the superthermality of hot positrons, the concentrations of superthermal electrons and positrons, the positron cyclotron frequency, the direction cosines of wave vector k along the z-axis, and the concentration of ions play pivotal roles in the nonlinear propagation of PAP travelling waves. Tile present investigation may be used to understand the.f.rmation of PAP structures in the space and laboratory plasmas with superthermal hot positrons and electrons.

关键词： Nonlinear Propagation of Positron-Acoustic Periodic Travelling Waves in a Magnetoplasma with Superthermal electrons and Positrons

Wavevector filtering through Monolayer and Bilayer Graphene Superlattices

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2013年第9期30卷 132-135页

作者： f.Sattari e.f.izabadi School of Physics Iran University of Science and Technology16844 TehranIran

We investigate the transport properties through monolayer and bilayer graphene superlattices modulated by an in-plane homogeneous electric field based on the transfer matrix *** is found that the angular range of the transmission probability through a graphene superlattice can be e.f.ctively controlled by the number of barriers and this results in the structure having e.f.cient wavevector *** the number of barriers increases,this range *** is also shown that the conductance of the systems has an oscillatory behavior with respect to the barrier height and it decreases with the increasing number of barriers.

关键词： method. monolayer oscillatory

faddeev calculations on lambda hypertriton with potentials from Gel'fand–Levitan–Marchenko theory

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2020年第10期72卷 119-124页

作者： e.f.Meoto M L Lekala Department of Physics University of South AfricaPrivate Bag X61710 JohannesburgSouth Africa

e.f.ctive lambda-proton and lambda-neutron potentials,restored from theoretical scattering phases through Gel'fand–Levitan–Marchenko theory,are tested on a lambda hypertriton through three-body *** lambda hypertriton is treated as a three-body system consisting of lambda-proton,lambda-neutron and proton–neutron *** energy and root mean square radius are computed for the ground state of lambda hypertriton(Jp=12+).In coordinate space,the dynamics of the system is described using a set of coupled hyperradial equations obtained from the differential faddeev *** solving the eigenvalue problem derived from this set of coupled hyperradial equations,the binding energy and root mean square matter radius computed are.f.und to be-2.462 MeV and 7.00 fm,*** potentials are also shown to display a satisfactory convergence behaviour.

关键词： lambda-nucleon potential lambda-proton potential lambda-neutron potential lambda hypertriton faddeev equations hyperspherical method

Precision bending of high-quality components for volume applications

在线全文

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2010年第11期20卷 2100-2110页

作者： T.WeLO f.WIDeRe Department of engineering Design and Materials Norwegian University of Science and Technology(NTNU)

Recent new technology developments were presented in the.f.eld of industrial bending operations,including flexible stretch forming and 3D rotary stretch *** were made to give an overview of different mechanisms that influence dimensional accuracy,including local cross-sectional deformations such as suck-in and volume conservation e.f.cts,along with global deformations such as *** analytical model was developed to determine the particular influence of different material,geometry and process parameters on dimensional variability of bent *** results were discussed in terms of overall process capability(Cp) and associated process *** results show that different governing mechanisms prevail in various bending operations,meaning that attention has to be placed on controlling those process parameters that really are important to part quality in each specific *** strategies may be defined for reducing *** alternative may be to design more robust process and tool technology that reduce the e.f.ct of upstream parameters on dimensional variability of the.f.rmed *** results show that optimal tool design and technology may in specific cases improve the dimensional accuracy of a formed *** on the.f.ndings discussed herein,it is concluded that advances in industrial bending operations require.f.cus on improving the understanding of mechanical mechanisms,including models and parameter development,new technology developments,including process,tool,measurement and control capabilities,and process discipline at the shop floor,combined with a basic philosophy of controlling process parameters rather than part attributes.

关键词： bending technology tools dimensional accuracy distortions springback formability

在线全文

学校读者我要写书评

暂无评论

高分子学概论

高分子学概论