Analytical formula for the cross section of hadron production from e^(+)e^(−) collisions around the narrow charmouinum resonances

The paper reports an analytical formula for the production cross section of e^(+)e^(−)annihilation to hadrons in the vicinity of a narrow resonance,particularly in theτ-charm region,while considering initial state radiation.Despite some approximations in its derivation,comparison between the analytical formula and direct integration of ISR shows good accuracy,indicating that the analytical formula meets current experimental requirements.Furthermore,this paper presents a comparison of the cross section between the analytical formula and calculations using the ConExc Monte Carlo generator.The efficiency of the analytical formula in significantly reducing computing time makes it a favorable choice for the regression procedure to extract the parameters of narrow charmonium resonances in experiments.

New soliton solutions of Dual mode Sawada Kotera equation using a new form of modified Kudryashov method and the finite difference method

In this article,we suggest a new form of modified Kudryashov’s method(NMK)to study the Dual-mode Sawada Kotera model.We know very well that the more the solutions depend on many constants,the easier it is to study the model better by observing the change in the constants and what their impact is on the solutions.From this point of view,we developed the modified Kudryashov method and put it in a general form that contains more than one controllable constant.We have studied the model in this way and presented figures showing the correctness of what we hoped to reach from the proposed method.In addition to the results we reached,they were not sufficient,so we presented an extensive numerical study of this model using the finite differences method.We also came up with the local truncation error for the difference scheme is h^(6) k^(2)(1+k^(2)).In addition,the analytical solutions we reached were compared with the numerical solutions,and we presented many forms that show that the results we reached are a clear contribution to this field.

Improved lateral-dynamics-intended railway vehicle model involving nonlinear wheel/rail interaction and car body flexibility

To study the vehicle hunting behavior and its coupling with car body vibrations,a simplified lateral-dynamics-intended railway vehicle model is developed.A two-truck vehicle is modeled as a 17 degrees-of-freedom rigid system,into which the car body flexural vibrations of torsion and bending modes are further integrated.The wheel/rail interaction employs a real-time calculation for the Hertzian normal contact,in which the nonlinear curvatures of wheel and rail profiles are presented as functions of wheelset lateral movement and/or yaw rotation.Then the tangential/creep forces are analytically expressed as the Hertzian contact patch geometry,and lead to a continuous and fast calculation compared to a look-up table interpolation.It is shown that the hunting frequencies of the vehicle model and a truck model differ significantly,which verifies the necessity of the whole vehicle model.In the case of low wheel/rail conicity,the hunting frequency increases linearly with vehicle speed,whereas it rises slowly at high speed for a large conicity.Comparison of hunting frequency and damping ratio between various conicities shows that first hunting(car body hunting)may occur when the vehicle is operated at a low speed in a small conicity case,while a second hunting(truck hunting)appears when the vehicle is operated at a high speed in a large conicity case.Stability analysis of linear and nonlinear vehicle models was carried out through coast down method and constant speed simulations.Results tell that the linear one overestimates the lateral vibrating.Whereas the structural vibrations of car body can be ignored in the stability analysis.Compared to existing simplified models for hunting stability study,the proposed simplified vehicle model released limitations in the nonlinear geometries of wheel/rail profiles,and it is suitable for a frequency-domain analysis by deriving the analytical expressions of the normal and tangential wheel/rail contact forces.

Exact free vibration analysis of open circular cylindrical shells by the method of reverberation-ray matrix

This paper is concerned with the free vibration analysis of open circular cylindrical shells with either the two straight edges or the two curved edges simply supported and the remaining two edges supported by arbitrary classical boundary conditions. Based on the Donnell-Mushtari-Vlasov thin shell theory, an analytical solution of the traveling wave form along the simply supported edges and the modal wave form along the remaining two edges is obtained. With such a unidirectional traveling wave form solution, the method of the reverberation-ray matrix is introduced to derive the equation of natural frequencies of the shell with different classical boundary conditions. The exact solutions for natural frequencies of the open circular cylindrical shell are obtained with the employment of a golden section search algorithm. The calculation results are compared with those obtained by the finite element method and the methods in the available literature. The influence of length, thickness, radius, included angle, and the boundary conditions of the open circular cylindrical shell on the natural frequencies is investigated. The exact calculation results can be used as benchmark values for researchers to check their numerical methods and for engineers to design structures with thin shell components.