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Merging bound states in the continuum in an open acoustic resonator

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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 perfectly 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 perfectly explained by the two-and three-level approximations of the effective 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

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

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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 formation 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

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

作者： f.Sattari e.faizabadi 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 effectively controlled by the number of barriers and this results in the structure having efficient 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

Precision bending of high-quality components for volume applications

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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 field 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 effects,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 effect of upstream parameters on dimensional variability of the formed *** results show that optimal tool design and technology may in specific cases improve the dimensional accuracy of a formed *** on the findings discussed herein,it is concluded that advances in industrial bending operations require focus 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

A comprehensive study for mass attenuation coefficients of different parts of the human body through Monte Carlo methods

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Nuclear Science and Techniques 2016年第3期27卷 31-39页

作者： e.e.ermis f.B.Pilicer e.Pilicer C.Celiktas Physics Department Faculty of ScienceEge University Physics Department Faculty of Arts and ScienceUludag University

The gamma-ray mass attenuation coefficients of blood,bone,lung,eye lens,adipose,tissue,muscle,brain and skin were calculated at different energies(60,80,150,400,500,600,1000,1250,1500,and 2000 keV) by various theoretical methods such as fLUKA,GeANT4 Monte Carlo(MC) methods and XCOM program in this *** coefficients were also compared with the National Institute of Standards and Technology(NIST) *** results were highly in accordance with each other and NIST *** results showed that fLUKA was quite convenient in comparison to GeANT4 in the calculation of the mass attenuation coefficients of the used human body samples for low-energy photons(60,80,and 150 keV) when compared with the NIST values.

关键词：质量衰减系数蒙特卡洛方法 Geant4 部位 NIST 美国国家标准能量计算眼晶状体

ASYMPTOTIC LIMITS AND STABILIZATION fOR THe 1D NONLINeAR MINDLIN-TIMOSHeNKO SYSTeM

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Journal of Systems Science & Complexity 2010年第3期23卷 414-430页

作者： f.D.ARARUNA P.BRAZ e SILVA e.ZUAZUA Departamento de Matemática Universidade federal da Paraíba Departamento Ikerbasque Research Professor Basque Center for Applied Mathematics(BCAM)

This paper shows how the so called von Karman model can be obtained as a singular limit of a modified Mindlin-Timoshenko system when the modulus of elasticity in shear κ tends to infinity, provided a regularizing term through a fourth order dispersive operator is added. Introducing damping mechanisms, the authors also show that the energy of solutions for this modified Mindlin-Timoshenko system decays exponentially, uniformly with respect to the parameter k. As κ→∞, the authors obtain the damped von Karman model with associated energy exponentially decaying to zero as well.

关键词： Mindlin-Timoshenko system singular limit uniform stabilization vibrating beams von Karman system.

Different Routes to the Pore engineering of Spherical MCM-41

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Journal of Wuhan University of Technology(Materials Science) 2003年第2期18卷 1-5页

作者：刘世权 e f Vansant University of Antwerp (Belgium)

Different routes,including the replacements of the template,addition of pore expander and hydrothermal post-synthesis treatment have been used for the pore engineering of spherical MCM-41.A comparison among the pore engineering effects of these methods has been *** results show that the hydrothermal post-synthesis treatment affords the synthesized material with a larger pore size and narrow pore size distribution without changing the spherical *** far as the pore-size expansion is concerned,the addition of DMTA is the most effective one,but this might be limited by the spherical *** the replacement of C 16TMABr with the Gemini surfactant GeM 16-8-16 with an addition of DMTA gives rise to the largest pore volume and surface area.

关键词： spherical MCM-41 pore engineering pore expander post-synthesis treatment Gemini surfactant

On Quantum Mechanics on Noncommutative Quantum Phase Space

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Communications in Theoretical Physics 2004年第6期41卷 837-844页

作者： A.e.f.DjemaI H.Smail AbdusSalamInternationalCentreforTheoreticalPhysics 34100TriesteItaly DepartementdePhysique Institutd＇HydrauliqueCentreUniversitaireMustaphaStambouliMascara29000Algeria

In this work,we develop a general framework in which Noncommutative Quantum Mechanics (NCQM), characterized by a space noncommutativity matrix parameter θ=∈_(ji)~kθ_k and a momentum noncommutativity matrix parameter β_(ij)=∈_(ij)~kβ_k,is shown to be equivalent to Quantum Mechanics (QM) on a suitable transformed Quantum Phase Space (QPS).Imposing some constraints on this particular transformation,we firstly find that the product of the two parameters θ and β possesses a lower bound in direct relation with Heisenberg incertitude relations,and secondly that the two parameters are equivalent but with opposite sign,up to a dimension factor depending on the physical system under *** means that noncommutativity is represented by a unique parameter which may play the role of a fundamental constant characterizing the whole *** our framework,we treat some physical systems on NCQPS:free particle,harmonic oscillator,system of two-charged particles,Hydrogen *** the obtained results, we discover a new phenomenon which consists of a free particle on NCQPS viewed as equivalent to a harmonic oscillator with Larmor frequency depending on β,representing the same particle in presence of a magnetic field=q~(-1).for the other examples,additional correction terms depending on β appear in the expression of the energy ***,in the two-particle system case,we emphasize the fact that for two opposite charges noncornmutativity is effectively feeled with opposite sign.

关键词： noncommutative space quantum mechanics Moyal product

elimination of Quench Cracking by Controlling Agitation Uniformity

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材料热处理学报 2004年第5期25卷 457-461页

作者： CANALe Lauralice C.f TOTTeN George e Departamento de Materials Automobilistica e Aerondutica da EESC da Universidade de Sao Paulo - USP Sao Carlos SP BrazilPortland State University USA

Uniform agitation of the quenchant is a critically important control parameter in optimizing distortion control and reducing steel cracking. Quenching with ultrasonic agitation or in the presence of electrical and magnetic fields provide uniform agitation leading to improved uniformity of the stress fields within the metal not readily achievable with more traditional agitation methods such as propeller pumps and sprays. These methods provide the additional potential advantage of varying agitation throughout the cooling cycle to achieve a wide range of cooling profiles not readily achievable with quenchants and more traditional agitation systems currently in use.

关键词：热处理淬火裂纹搅拌均匀性超声搅拌