scholarly journals QUASIHARMONIC BENDING WAVE, DISTRIBUTING IN THE BALK OF TIMOSHENKO, LYING ON A NONLINEAR ELASTIC BASE

2021 ◽  
Vol 83 (1) ◽  
pp. 61-75
Author(s):  
V.I. Erofeev ◽  
A.V. Leontieva
Keyword(s):  
Cross Sections ◽  
Modulation Instability ◽  
Good Description ◽  
Elastic Base ◽  
Base Change ◽  
Flexural Wave ◽  
Bending Vibrations ◽  
Technical Theory ◽  
Basic Equations ◽  
Nonlinear Elastic

In this paper, we consider the modulation instability of a quasiharmonic flexural wave propagating in a homogeneous beam fixed on a nonlinear elastic foundation. The dynamic behavior of the beam is determined by Timoshenko's theory. Timoshenko's model, refining the technical theory of rod bending, assumes that the crosssections remain flat, but not perpendicular to the deformable midline of the rod; normal stresses on sites parallel to the axis are zero; the inertial components associated with the rotation of the cross sections are taken into account. The uniqueness of the model lies in the fact that, allowing a good description of many processes occurring in real structures, it remains quite simple, accessible for analytical research. The system of equations describing the bending vibrations of the beam is reduced to one nonlinear fourthorder equation for the transverse displacements of the beam particles. The nonlinear Schrödinger equation, one of the basic equations of nonlinear wave dynamics, is obtained by the method of many scales. Regions of modulation instability are determined according to the Lighthill criterion. It is shown hot the boundaries of these areas shift when the parameters characterizing the elastic properties of the beam material and the nonlinearity of the base change. Nonlinear stationary envelope waves are considered. An equation that generalizes the Duffing equation, which contains two additional terms in negative powers (first and third), is obtained and qualitatively analyzed. Solutions of the Schr?dinger equation in the form of envelope solitons are found and the dependences of their main parameters (amplitude, width) on the parameters of the system are analyzed. The dynamics of the points of intersection of the amplitudes and widths of "light" solitons in the case of soft nonlinearity of the base is shown within the region of modulation instability.

scholarly journals ω AND η (η') MESONS FROM NN AND ND COLLISIONS AT INTERMEDIATE ENERGIES

2010 ◽  
Vol 19 (05n06) ◽  
pp. 894-902 ◽  
Author(s):  
L. P. KAPTARI ◽  
B. KÄMPFER
Keyword(s):  
Cross Sections ◽  
Good Description ◽  
Meson Production ◽  
Form Factors ◽  
Angular Distributions ◽  
Transition Form ◽  
Vector Meson Production ◽  
Intermediate Energies ◽  
Electron Production ◽  
Pseudo Scalar

The production of pseudo scalar, η, η′, and vector, ω, ρ, ϕ, mesons in NN collisions at threshold-near energies is analyzed within a covariant effective meson-nucleon theory. It is shown that a good description of cross sections and angular distributions, for vector meson production, can be accomplished by considering meson and nucleon currents only, while for pseudo scalar production an inclusion of nucleon resonances is needed. The di-electron production from subsequent Dalitz decay of the produced mesons, η′ → γγ* → γe+e- and ω → πγ* → πe+e- is also considered and numerical results are presented for intermediate energies and kinematics of possible experiments with HADES, CLAS and KEK-PS. We argue that the transition form factor ω → γ*π as well as η′ → γ*γ can be defined in a fairly model independent way and the feasibility of an experimental access to transition form factors is discussed.

Accurate prediction of the Drell-Yan φ∗ η distribution in wide dilepton mass and rapidity ranges in pp collisions through NNLO+N3LL

2021 ◽  
Author(s):  
Kadir Ocalan
Keyword(s):  
Cross Sections ◽  
Good Description ◽  
Neutral Current ◽  
Mass Range ◽  
Theoretical Description ◽  
Distribution Functions ◽  
Boson Mass ◽  
Pp Collisions ◽  
Parton Distribution Functions ◽  
Central Detector

Abstract This paper presents high-accuracy predictions for the differential cross sections as a function of the key observable φ*η of the neutral-current Drell-Yan (DY) dilepton production in proton-proton (pp) collisions. The differential distributions for the φ*η are presented by using the state-of-the-art predictions from the combined calculations of fixed-order perturbative QCD corrections at next-to-next-to-leading order (NNLO) accuracy and resummation of large logarithmic terms at next-to-next-to-leading logarithmic (NNLL) and next-to-NNLL (N3LL) accuracies, i.e., NNLO+NNLL and NNLO+N3LL, respectively. The predicted distributions are reported for a thorough set of the DY dilepton invariant mass mll ranges, spanning a wide kinematic region of 50 < mll< 1000 GeV both near and away from the Z-boson mass peak, and rapidity yll ranges in the central detector acceptance region of |yll| < 2.4. The differential φ*η distributions in the wide mll and yll ranges offer stringent tests to assess the reliability of the predictions, where the mll and yll are closely correlated with the parton distribution functions (PDFs) of the incoming partons. The merged predictions through NNLO+N3LL are observed to provide good description of the 13 TeV pp collision data for the φ*η (including the dilepton transverse momentum pll T as well) distributions in almost the entire mll and yll ranges, apart from the intermediate- to high-φ*η region in the lowest mass range 50–76 GeV which is assessed to constitute a challenge for the presented predictions. The merged predictions at NNLO+N3LL are also reported at 14 TeV for the upcoming high-luminosity running era of the LHC, in which increasing amount of data is expected to require more accurate and precise theoretical description. The most recent PDF models MSHT20 and CT18 are tested for the first time in addition to the NNPDF3.1 exploiting the merged φ*η predictions.

An analysis of stress–strain behaviour and wetting effects on quarried rock shells

2005 ◽  
Vol 42 (1) ◽  
pp. 51-60 ◽  
Author(s):  
Ignacio Escuder ◽  
Joaquin Andreu ◽  
Manuel Rechea
Keyword(s):  
Cross Sections ◽  
Research Work ◽  
Road Construction ◽  
Stress Strain ◽  
Simulation Procedure ◽  
Earth Core ◽  
Strain Behaviour ◽  
Points Of View ◽  
Nonlinear Elastic ◽  
Strain Model

The analysis of stress–strain behaviour and the effects of submergence on quarried rock shells, used mainly in dams but also in road construction, is of major importance from both economic and safety points of view. The research work presented here starts with an in-depth review of the nonlinear elastic procedure widely used in rockfill analyses since 1970, its later application to simulate wetting effects, and the latest published modifications to the so-called hyperbolic stress–strain model. An update of the existing wetting simulation procedure has been formulated, calculation routines to analyze constructional behaviour and wetting effects on rockfills have been implemented, and the methodology developed has been applied to a structure 100 m high. Calculation routines have been written to run in FLAC, a finite difference based code that incorporates a programming language. The analyzed structure is part of a road rockfill located at the Contreras Reservoir in Spain and consists specifically of two shell-shaped cross sections subjected to the influence of submergence. The results are expected to be useful in estimating collapse settlements in the upstream shells of earth-core dams.Key words: elasticity, stress–strain, rockfills, behaviour, numerical, dams.

Coupled Axial-Flexural-Torsional Vibration of Internally Damped Timoshenko Frames

2010 ◽  
Author(s):  
Adil Yucel ◽  
Alaeddin Arpaci ◽  
Ekrem Tufekci
Keyword(s):  
Cross Sections ◽  
Torsional Vibration ◽  
Complex Modulus ◽  
Linear Equations ◽  
Frame Structure ◽  
Rotational Inertia ◽  
Bending Vibrations ◽  
Element Analysis ◽  
Out Of Plane ◽  
Simultaneous Linear Equations

In this study, free in-plane and out-of-plane bending vibrations of frame structures have been analyzed together with torsional vibration. Axial extension, rotational inertia and shear effects have also been considered. The frame structure has been constructed as having two beams with doubly symmetric cross-sections and connected at any angle to each other. These types of frames frequently appear on ships as bridge wings which are probably the most problematic members experiencing severe vibration. Internal damping has been incorporated into the analyses by using a complex modulus of elasticity. Natural frequencies have been obtained analytically by solving simultaneous linear equations of complex coefficients. A finite element analysis has also been conducted to verify the analytical results. Furthermore, an experimental modal analysis has been carried out and the results have been compared with theoretical ones in tables for various connection angles and damping factors. The agreement among results has been found to be good.

scholarly journals Strangeness at high μB: Recent data from FOPI and HADES

2018 ◽  
Vol 171 ◽  
pp. 02001
Author(s):  
Yvonne Leifels
Keyword(s):  
Experimental Data ◽  
Cross Sections ◽  
Particle Production ◽  
Chemical Potential ◽  
Good Description ◽  
Branching Ratio ◽  
Heavy Ion ◽  
Nuclear Medium ◽  
Strangeness Production ◽  
Baryon Chemical Potential

Strangeness production in heavy-ion reactions at incident energies at or below the threshold in NN collisions gives access to the characteristics of bulk nuclear matter and the properties of strange particles inside the hot and dense nuclear medium, like potentials and interaction cross sections. At these energies strangeness is produced in multi-step processes potentially via excitation of intermediate heavy resonances. The amount of experimental data on strangeness production at these energies has increased substantially during the last years due to the FOPI and the HADES experiments at SIS18 at GSI. Experimental data on K+ and K0 production support the assumption that particles with an s quark feel a moderate repulsive potential in the nuclear medium. The situation is not that clear in the case of K-. Here, spectra and flow of K- mesons is influenced by the contribution of ø mesons which are decaying into K+K- pairs with a branching ratio of 48.9 %. Depending on incident energy upto 30 % of all K- mesons measured in heavyion collisions are originating from ø-decays. Strangeness production yields - except the yield of Ξ- are described by thermal hadronisation models. Experimental data not only measured for heavy-ion collisions but also in proton induced reactions are described with sets of temperature T and baryon chemical potential μb which are close to a universal freeze-out curve which is fitting also experimental data obtained at lower baryon chemical potential. Despite the good description of most particle production yields, the question how this is achieved is still not settled and should be the focus of further investigations.

scholarly journals Construction And Test Of Thermostats And Twirlers For Molecular Rotations

2003 ◽  
Vol 58 (7-8) ◽  
pp. 377-391 ◽  
Author(s):  
Siegfried Hess
Keyword(s):  
Time Reversal ◽  
Rotational Diffusion ◽  
Equations Of Motion ◽  
Dynamical Variable ◽  
Two Dimensional ◽  
Polymer Molecules ◽  
Isotropic Harmonic Oscillator ◽  
Molecular Rotations ◽  
Basic Equations ◽  
Nonlinear Elastic

The equations of motion are coupled with a dynamical variable, referred to as twirler, which randomizes the angular momentum. The equations are time-reversal invariant, just as those for the standard Gaussian, Nosé-Hoover and configurational thermostats. The derivation of the basic equations is outlined. Test calculations are performed for the two-dimensional isotropic harmonic oscillator and for a nonlinear elastic dumbbell, used as a simple model to study properties of polymer molecules. Graphs of characteristic quantities and orbits, some of which are rather intriguing, are displayed. As applications, the rotational diffusion and the influence of a shear flow on the angular velocity and the deformation of the model polymer are analyzed.

DIQUARKS AND DYNAMICS OF LARGE-P⊥ BARYON PRODUCTION

1988 ◽  
Vol 03 (09) ◽  
pp. 909-916 ◽  
Author(s):  
V.T. KIM
Keyword(s):  
Cross Sections ◽  
Good Description ◽  
Baryon Production ◽  
Pp Collisions ◽  
Diquark Model ◽  
Strong Scaling

In the framework of a diquark model of the nucleon, the strong scaling violation of the p/π+-ratio in the pp-collisions from [Formula: see text] (IHEP, Serpukhov) to [Formula: see text] (FNAL) and to [Formula: see text] (CERN ISR) is described. A fairly good description of the magnitude of cross sections for single protons and for symmetric-proton-pairs with large-p⊥ is obtained. In the model with the dominating scalar (ud)-diquark, the yield relation Λ0/p≃K+/π+ is predicted.

The Calculation of Compressible Fluid Flow by the Use of a Generalized Entropy Chart

1948 ◽  
Vol 159 (1) ◽  
pp. 313-334 ◽  
Author(s):  
J. Kestin ◽  
A. K. Oppenheim
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Generalized Entropy ◽  
Specific Heats ◽  
Simplifying Assumptions ◽  
Isentropic Flows ◽  
Basic Equations ◽  
Two Parameters ◽  
Physical Phenomena ◽  
Velocity Pressure

Calculations of the flow of gases in pipes or ducts of varying cross-sections are important in the design of turbines and compressors, nozzles for various applications, exhaust or radiator ducts, thrust augmenting devices, etc. Provided certain simplifying assumptions are made, there is no difficulty in writing down the basic equations, but when the velocities are comparable to that of sound and compressibility effects cannot therefore be neglected, the solution of the transcendental equations present difficulties which hinder a clear discussion of the physical phenomena. Here the problem is solved by the use of a generalized entropy chart, off which results may be directly read. For example, if the conditions in the reservoir from which the gas is assumed to be discharged are known, the complete conditions at any given cross-section may be read off when two parameters at the section considered are specified. The parameters may include the velocity, pressure, density, temperature, local Mach number, local velocity of sound, area of cross-section, mass flow per unit area, momentum per second, etc. The method is not confined to isentropic flows and may be applied to such problems as the flow in straight pipes or convergent and divergent nozzles including losses by either friction or condensation shocks. The co-ordinates of the chart are: dimensionless entropy σ = ( s— s0) J/R and dimensionless enthalpy ι = h/h0 = T/T0 where the meaning of the symbols is given later. All other variables are expressed in terms of these two co-ordinates and tables for several values of the ratio of specific heats are included to facilitate the drawing of such charts. The method does not aim at presenting new facts, but its usefulness lies in the provision of a comprehensive graphical means of calculating one-dimensional flow of compressible fluids. The charts lend themselves to the construction of a mechanical device for simplifying their use, such as a portable scale with sliding curves.

scholarly journals High Energy Rho Meson Leptoproduction §

2014 ◽  
Vol 1 (1) ◽  
pp. 33-35
Author(s):  
Adrien Besse ◽  
Lech Szymanowski ◽  
Samuel Wallon
Keyword(s):  
Cross Sections ◽  
Scattering Amplitude ◽  
Good Description ◽  
High Energy ◽  
Energy Limit ◽  
Rho Meson ◽  
Forward Limit ◽  
Helicity Amplitudes ◽  
Impact Parameter Space ◽  
The Impact

We investigate the longitudinal and transverse polarized cross-sections of the leptoproduction of the ρ meson in the high energy limit. Our model is based on the computation of the impact factor γ*(λγ)→ ρ (λρ) using the twist expansion in the forward limit which is expressed in the impact parameter space. This treatment involves in the final stage the twist 2 and twist 3 distribution amplitudes (DAs) of the ρ meson and the dipole scattering amplitude. Taking models that exist for the DAs and for the dipole cross-section. We get a phenomenological model for the helicity amplitudes. We compare our predictions with HERA data and get a fairly good description for large enough virtualities of the photon. PACS number(s): 13.60.Le, 12.39.St, 12.38.Bx.

scholarly journals Elastica of Non-Prismatic and Nonlinear Elastic Cantilever Beams under Combined Loading

2019 ◽  
Vol 9 (5) ◽  
pp. 877 ◽  
Author(s):  
Joon Lee ◽  
Byoung Lee
Keyword(s):  
Cross Sections ◽  
Neutral Axis ◽  
Constitutive Law ◽  
Combined Loading ◽  
Cantilever Beams ◽  
Uniform Loading ◽  
Loading System ◽  
Beam Parameters ◽  
Nonlinear Elastic ◽  
Nonlinearly Elastic

This study presents the elastica of non-prismatic cantilever beams with rectangular cross-sections that are subjected to combined loading. The considered beams are nonlinearly elastic and obey Ludwick’s constitutive law. The combined loading system used in this study provides uniform loading, tip point loading, and tip couple loading individually or in combination. This loading system can create a total of seven loading cases that have not been covered in the literature. Ordinary differential equations governing the large deformed shapes of the elastica of the beams are derived and solved numerically. The effects of beam parameters on elastica behavior, including tip responses and strains and stresses loaded onto the cross-sections, were studied. It was observed that the exponential constant of the mechanical properties is very sensitive to elastica behavior. The results also demonstrate that the stresses near the neutral axis are larger with a larger exponential constant.

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