Buckling of a Timoshenko beam on elastic foundation with uncertain input data

A monotone dependence of the critical buckling load of a simplysupported Timoshenko–Mindlin beam both on the shear correctionfactor and on the stiffness of foundation is proved. Then theworst-scenario method is employed to find the ‘most dangerous’input data.     

Diffraction of a Plane Discontinuos Wave in Layered Anisotropic Elastic Media

The problem of transformation of the front of a plane longitudinal shock wave by curvilinear interfaces of layered anisotropic elastic media with different mechanical properties is considered. To solve the nonlinear Snell equations, the approach based on a synthesis of the Newton method and the algorithm of parametric continuation of a solution is used. The cases of focusing and scattering of rays by convex and concave interfaces of layered composite media and by convex lenses are investigated. Numerical examples are given for various ratios between the parameters of the elastic media.     

Nonintegrability of a Fifth-Order Equation with Integrable Two-Body Dynamics

We consider a fifth-order partial differential equation (PDE) that is a generalization of the integrable Camassa–Holm equation. This fifth-order PDE has exact solutions in terms of an arbitrary number of superposed pulsons with a geodesic Hamiltonian dynamics that is known to be integrable in the two-body case N==2. Numerical simulations show that the pulsons are stable, dominate the initial value problem, and scatter elastically. These characteristics are reminiscent of solitons in integrable systems. But after demonstrating the nonexistence of a suitable Lagrangian or bi-Hamiltonian structure and obtaining negative results from Painlevé analysis and the Wahlquist–Estabrook method, we assert that this fifth-order PDE is not integrable.     

多段构件组成的压杆平面内稳定

分析由若干段等截面或者变截面构件组成的压杆平面内稳定问题．从由三段等截面构件组成的压杆平面内稳定问题出发，对两端为变截面、中间为等截面构件组成的压杆的平面内稳定问题进行了分析，得出和两端为等截面构件情况类似的屈曲荷载计算公式．并对两端固接的情况进行了研究分析．     

德摩根一致代数的度量化

我们给出了德摩根一致代数可伪度量化的一个充分必要条件。     

一些高Tc超导体的弹性性质

 本文用超声相比较方法测定了高T_c超导体La_1.85Sr_0.15CuO₄，La₂CuO₄和YBa₂Cu₃O₇的纵波和横波声速，进而导出了它们的纵向模量、切变模量、杨氏模量、泊松比、德拜温度及定体比热。在La_1.85Sr_0.15CuO₄样品上，还进行了压力实验，发现所有弹性模量都是随压强增加而增加。定体比热c_V和泊松比σ在高压下则略有下降。德拜温度是随压强增加而增加的。     

Elastic constants of galena down to liquid helium temperatures

The elastic constants of single crystal galena have been determined from the measured ultrasonic velocities down to liquid helium temperature. A cryostat incorporating an arrangement to inject the liquid bonding material at low temperature is described. At 5 K, the values of elastic constants are C₁₁=14.9₀, C₁₂=3.5₁ and C₄₄=2.9₂×10¹⁰ N/m².     

Pion-proton elastic scattering at 200 GeV/c

Recent measurements of differential and elastic cross-sections, slope parameters and ratios of the real and imaginary parts of the forward scattering amplitudes for pion-proton elastic scattering at 200 GeV/c have been fitted by using a simple Regge pole model with phenomenological residue functions. The computed results for total cross-sections have also been compared with the experimental data.     

理想弹塑性固体Riemann问题的解结构与初值条件

针对理想弹塑性固体材料的一维Riemann问题,在不考虑真空的情况下,讨论其所有可能存在的解结构,给出每一种解结构下对应的初值条件且证明该系列初值条件的完备性,即任意给定的物理量初值均有且只有一种解结构与之对应.基于该理论,在设计精确或近似理想弹塑性Riemann问题求解器时,可以依据初值条件对任意物理量初值直接判断其对应的解结构,从而提高求解器的精度和效率.数值试验验证了该系列初值条件的正确性和有效性.     

New measurements and reanalysis of 14N elastic scattering on 10B target

The angular distributions of elastic scattering of ¹⁴N ions on ¹⁰B targets have been measured at incident beam energies of 21.0 and 24.5 MeV. Angular distributions at higher energies 38–94.0 MeV (previously measured) were also included in the analysis. All data were analyzed within the framework of the optical model and the distorted waves Born approximation method. The observed rise in cross sections at large angles was interpreted as a possible contribution of the α-cluster exchange mechanism. Spectroscopic amplitudes SA₂ and SA₄ for the configuration ¹⁴N→ ¹⁰B +α were extracted. Their average values are 0.58±0.10 and 0.81±0.12 for SA₂ and SA₄, respectively, suggesting that the exchange mechanism is a major component of the elastic scattering for this system. The energy dependence of the depths for the real and imaginary potentials was found.