The change of the superstructure of semicrystalline polymers during deformation: results from small-angle scattering with synchrotron radiation

The change of the superstructure of different polyethylenes during uniaxial deformation is investigated. The method used is small-angle scattering with synchrotron radiation. For branched polyethylene (Lupolen 1840D) the whole deformation range is analyzed. Beginning with superstructure of the lamellar cluster type, the superstructure partly disappears on a time scale of a few minutes and the fibrillar structure is built up. The degree of destruction and rebuilding depends on the drawing temperature. For very high molecular weight polyethylene (GUR) a reversible change of the superstructure at higher deformation ratios and at different temperatures is observed. The superstructure of (ethylene—hexene) copolymers (TIPELIN) at high draw ratios depends on the drawing temperature and is almost independent of the side group content. Interfibrillar microcracks parallel to the draw direction are produced in samples with a low side group content for draw ratios λ ≥ 1.5.     

关于非线性Pochhammer-Chree方程的解

本文研究了弹性杆纵向形变方程:u_(tt)—u_(ttxx)—u_(xx)—(1/3)(u~3)xx=0的椭圆余弦波解,并用Adomian分解法,求出了其初边值问题解.     

On the phase space approach to complexity

We elaborate in some detail on a new phase space approach to complexity, due to Y.-C. Zhang. We show in particular that the connection between maximal complexity and power law noise or correlations can be derived from a simple variational principle. For a 1D signal we find 1/f noise, in accordance with Zhang.     

热辐射驱动烧蚀平面金靶的数值定标定律

利用一维辐射流体力学编码数值研究了辐射烧蚀波在平面金靶中的传播情况,并在常温边界条件下得到了辐射流、烧蚀压、质量烧蚀率和特征等离子体密度的定标定律。     

迭代的计算与估计

对高次多项式函数这类非线性映射给出了一般 n次迭代的一个计算结果 ,还讨论了一维欧氏空间中一些非多项式型映射的迭代 .在二维欧氏空间中 ,我们给出了几类特殊的非线性迭代的结果 .对于一些难以精确计算迭代表达式的映射 ,我们给出了其迭代的估计 .     

On K1 and K2 of Algebraic Surfaces

In this paper we study higher Chow groups of smooth, projective surfaces over a field k of characteristic zero, using some new Hodge theoretic methods which we develop for this purpose. In particular we investigate the subgroup of CH ^r+1 (X,r) with r = 1,2 consisting of cycles that are supported over a normal crossing divisor Z on X. In this case, the Hodge theory of the complement forms an interesting variation of mixed Hodge structures in any geometric deformation of the situation. Our main result is a structure theorem in the case where X is a very general hypersurface of degree d in projective 3-space for d sufficiently large and Z is a union of very general hypersurface sections of X. In this case we show that the subgroup of CH ^r+1 (X,r) we consider is generated by obvious cycles only arising from rational functions on X with poles along Z. This can be seen as a generalization of the Noether–Lefschetz theorem for r = 0. In the case r = 1 there is a similar generalization by Müller-Stach, but our result is more precise than it, since it is geometric and not only cohomological. The case r = 2 is entirely new and original in this paper. For small d, we construct some explicit examples for r = 1 and 2 where the corresponding higher Chow groups are indecomposable, i.e. not the image of certain products of lower order groups. In an appendix Alberto Collino constructs even more indecomposable examples in CH ³ (X,2) which move in a one-dimensional family on the surface X.Contribution to appendix.     

Level shift operators for open quantum systems

Level shift operators describe the second-order displacement of eigenvalues under perturbation. They play a central role in resonance theory and ergodic theory of open quantum systems at positive temperatures. We exhibit intrinsic properties of level shift operators, properties which stem from the structure of open quantum systems at positive temperatures and which are common to all such systems. They determine the geometry of resonances bifurcating from eigenvalues of positive temperature Hamiltonians and they relate the Gibbs state, the kernel of level shift operators, and zero energy resonances. We show that degeneracy of energy levels of the small part of the open quantum system causes the Fermi Golden Rule Condition to be violated and we analyze ergodic properties of such systems.     

Laser spectroscopy of high spin isomers – a review

This review summarizes the experimental data on charge radii differences among ground state and high spin isomeric states determined by high-resolution laser spectroscopic methods. A comparison is presented between radii changes obtained from the isomeric shifts in the atomic spectra and from the quadrupole moments of both ground and isomeric states under the assumption that the radii changes are determined by the difference of the quadrupole deformations. Special attention is paid to isomers arising from the break-up of nucleon pairs and isomers of odd–odd nuclei. The characteristic features of the radii changes for isomeric states of different origin are discussed.     

An unflexural refined model of deformation of multilayered plates on an undeformable foundation

The stress-strain state of multilayered plates on an undeformable foundation is investigated. The design diagram of a transversely loaded plate is formed by supplementing it with a symmetric one about the contact surface of the foundation. The double-thickness plate obtained becomes loaded bilaterally and symmetrically about its midsurface. In such a way, only unflexural deformations can be modeled, which reduces the number of unknowns and the general order of differentiation of the resolving system of equations. The refined continual model developed takes into account the deformations of transverse shear and transverse compression in high iterative approximations. The cases of a rigid contact between the foundation and the plate and frictionless slip of the plate over the foundation are considered. Calculations confirm the efficiency of such an approach, which allows one to obtain solutions qualitatively and quantitatively close to three-dimensional ones. __________ Translated from Mekhanika Kompozitnykh Materialov, Vol. 42, No. 5, pp. 643–654, September–October, 2006.     

LiNbO3∶Cr∶Cu晶体吸收特性及非挥发全息存储研究

研究了LiNbO3∶Cr∶Cu晶体的吸收特性,发现LiNbO3∶Cr∶Cu（含0.14 wt.% Cr2O3 和 0.011 wt.% CuO）晶体存在两个明显的吸收峰,中心波长分别位于480 nm和660 nm; 随着Cr的含量逐渐减小,Cu的含量逐渐增大,短波段不存在明显吸收峰,掺Cr的含量越大,中心波长在660 nm处的吸收越大；633 nm红光虽然位于中心波长为660 nm的吸收峰内,但它无助于光折变过程.分别采用390 nm紫外光和488 nm蓝光作为敏化光,514 nm绿光作为记录光的记录方案,实现了非挥发全息记录,掺入适量的Cr( 比如NCr=2.795×1025 m－3,NCr/ NCu=1)有助于全息记录性能的提高.