Buckling of a continuous beam resting on a tensionless elastic foundation

In this paper, a solution is presented to the buckling problem of a continuous beam resting on a tensionless foundation model that was proposed by Winkler and by Reissner.     

On the dynamics of an axially moving beam

The equations of motion of a beam whose length changes with time are derived. These take the form of four nonlinear partial differential equations and one algebraic relation. By assuming that the deflection gradients of the beam are small, and that the beam is axially rigid, the equations of motion are linearized. One closed-form similarity solution and a semi-analytic solution is obtained for specific axial velocities. Also, a procedure is described for obtaining approximate solutions for various axial velocities of the beam.     

Numerical transformation procedures in continuous beam analysis

Several new types of numerical procedures are presented for the calculation of bending moments in continuous beams. Basic physical properties of the beam and its loading, which are familiar to the engineer, are employed in the procedures. These basic properties are defined and may be calculated conveniently by means of a conjugate beam. The procedures bear some resemblance to the process of moment distribution. A mathematical demonstration of the validity of the procedures is given in the Appendix.     

连续梁施工控制方法的研究

随着我国高速铁路建设的迅猛发展,大跨度桥梁建设进入了前所未有的高潮时期。文章结合新建山西中南部铁路通道师村特大桥跨临汾北环高速公路连续梁工程实例,介绍了悬臂浇筑连续梁线形控制技术,并对连续梁施工控制方法进行了研究。     

科技知识人才西藏跨越式发展的不竭动力

大力实施科教兴国战略和可持续发展战略，是贯彻十六大精神的重要体现。本文就西藏如何大力发展科技，抢占知识高地，积极培育人才，实现西藏经济社会跨越式发展提出建议。文章认为：发展是维护祖国统一、增加民族团结的重要保障。一个国家一个地区的发展，国家之间地区之间的竞争，就是科技知识人才的发展竞争。少数民族地区的发展进步，更离不开科技的支撑。科技、知识、人才永远是少数民族地区经济社会发展的三大法宝。大力发展科技事业，大量的吸收引进培养选拔和使用人才，将是西藏发展过程中的一项重大任务。     

Radiation pressure on a moving resistive sheet

The paper considers the effect of radiation pressure acting upon a moving, resistive sheet; the analysis is specifically concerned with the drag and levitation forces resulting when the sheet attains velocities approaching the velocity of a plane wave of light in vacuum. Relevant graphical results are presented.     

Wave refraction at a moving dielectric layer

The interaction between a moving dielectric sheet and the radiation field to which it is exposed is analyzed. The reflection and transmission factors are obtained, and the relevant resonance patterns are exhibited.     

Jamming and unjamming transition of oil-in-water emulsions under continuous temperature change

To analyze the jamming and unjamming transition of oil-in-water emulsions under continuous temperature change, we simulated an emulsion system whose critical volume fraction was 0.3, which was validated with experimental results under oscillatory shear stress. In addition, we calculated the elastic modulus using the phase lag between strain and stress. Through heating and cooling, the emulsion experienced unjamming and jamming. A phenomenon—which is when the elastic modulus does not reach the expected value at the isothermal system—occurred when the emulsion system was cooled. We determined that this phenomenon was caused by the frequency being faster than the relaxation of the deformed droplets. We justified the relation between the frequency and relaxation by simulating the frequency dependency of the difference between the elastic modulus when cooled and the expected value at the same temperature.     

The significance of the dielectric constant of a mixture

The above review of the experimental data on the dielectric constants of mixtures shows that the dielectric constant of a mixture cannot in general be calculated from the dielectric constants of the components.     

浅析车辆的异常振动

车辆的异常振动是乘员能够感受的,直接影响乘坐体验,同时可能导致更严重的故障。本文针对车辆异常振动故障现象,分析了车辆振动的主要来源和产生机理,总结了车辆异常振动的原因,探讨了解决异常振动故障的一般方法。     

Optimal control of eutrophication processes in a moving domain

This work deals with an environmental problem related to controlling eutrophication inside a sensitive zone, by means of a regulation of the wastewater discharges in the region. After setting a detailed mathematical formulation of the optimal control problem posed on a free-boundary moving domain, we present several theoretical results on existence-regularity of optimal solutions, and their characterization by a first order optimality system. In the second part of the work a complete numerical algorithm for the resolution of the control problem is proposed, and several numerical examples are also given.     

Convection-radiation from a continuously moving fin of variable thermal conductivity

The homotopy analysis method (HAM) is applied to generate an analytic solution for heat transfer in a moving fin of variable thermal conductivity which is losing heat by simultaneous convection and radiation to its surroundings. The accuracy of the analytic solution is validated by comparing it with the direct numerical solution of the problem. The analytic solution is found to be accurate to at least three places of decimal for a wide range of values of the parameters that are commonly encountered in thermal processing application. Graphs displaying the results are interpreted in physical terms.     

Response of a viscoelastic half-space to time dependent moving surface loads

Through the use of nonpolar viscoelasticity theory, the problem of traveling loads with time dependent magnitude variability is considered. Employing a moving Lagrangian observer, a quadratic form is developed to ascertain potential time dependent magnitude variability induced shifts, bifurcations and wavelength interdependencies in the critical speeds associated with Rayleigh, plane and transverse wave phenomena. In terms of the moving Lagrangian formulation, a solution is developed which enables the characterization of response behavior in the various sub, trans and supercritical speed ranges associated with each of the different wave types. Based on the solution, the results of several numerical experiments are presented. These demonstrate various aspects of the foregoing phenomena.