Colliding Solitons for the Nonlinear Schrödinger Equation

We study the collision of two fast solitons for the nonlinear Schrödinger equation in the presence of a slowly varying external potential. For a high initial relative speed ||v|| of the solitons, we show that, up to times of order ||v|| after the collision, the solitons preserve their shape (in L ²-norm), and the dynamics of the centers of mass of the solitons is approximately determined by the external potential, plus error terms due to radiation damping and the extended nature of the solitons. We remark on how to obtain longer time scales under stronger assumptions on the initial condition and the external potential.     

Codimension Two PL Embeddings of Spheres with Nonstandard Regular Neighborhoods

For a given polyhedron K(?)M,the notation RM(K)denotes a regular neigh- borhood of K in M.The authors study the following problem:find all pairs(m,k) such that if K is a compact k-polyhedron and M a PL m-manifold,then R_M(f(K))≌R_M(g(K))for each two homotopic PL embeddings f,g:K→M.It is proved that R_S~(k 2)(S~k)(?)S~k×D~2 for each k(?)2 and some PL sphere S~k(?)S~(k 2)(even for any PL sphere S~k(?)S~(K 2)having an isolated non-locally flat point with the singularity S~(k-1)(?) S~(k 1)such thatπ_1(S~(k 1)-S~(k-1))(?)Z).     

MgxZn1-xO薄膜的生长及其光学性能

利用金属有机化学气相沉积(MOCVD)法在蓝宝石(1120)衬底上生长高质量的Mg_xZn_1-xO合金薄膜,实验研究了各种不同Mg组分对样品光学性能的影响。通过光致发光荧光衰减特性对激子发光寿命的研究表明,激子的寿命随Mg组分的增加而增加,当Mg组分达到50%时,激子的寿命为872 ps。     

燃煤锅炉粉煤灰中痕量元素赋存形态研究

本文运用改进的Tessier法对某燃煤电厂静电除尘器收集的三个电场的粉煤灰进行分级提取(SEE)实验研究.SEE实验将粉煤灰中的重金属分为五个存在形态进行分级提取:水溶态(pH=7),酸溶态(pH=5),氧化物结合态,难还原态及残渣态.试验结果表明,残渣态在ESP除尘器所收集的飞灰中含量占据绝大部分;在容易迁移的离子可交换态和酸溶态中,所研究的痕量重金属元素均呈现出FA1相似文献   

Bi，Sb及稀土元素对AZ91镁合金高温性能影响机理研究

利用大角重位点阵概念建立了AZ91镁合金基体(α相)和镁［0001］对称倾斜晶界原子结构模型,应用实空间的连分数方法计算了体系的结构能,环境敏感镶嵌能以及相互作用能.结果发现,在镁合金基体中,Al和稀土形成团簇时比较稳定,Al,Bi或Sb与稀土形成团簇时不稳定.Bi或Sb和稀土元素同时存在于AZ91镁合金中时,一方面Bi或Sb将可与RE结合形成RE₂Bi(RE₂Sb)或RE-Bi(RE-Sb)化合物弥散分布于晶界,另一方面镁合金基体中会形成Al_{11关键词： 电子理论 晶界偏聚 合金元素 高温性能}     

Stability of a Cubically Convergent Method for Generalized Equations

In Geoffroy et al, Acceleration of convergence in Dontchev's iterative method for solving variational inclusions Serdica Math. J. 29 (2003), pp. 45–54] we showed the convergence of a cubic method for solving generalized equations of the form 0 ∈ f(x) +- G(x) where f is a function and G stands for a set-valued map. We investigate here the stability of such a method with respect to some perturbations. More precisely, we consider the perturbed equation y ∈ f(x) +- G(x) and we show that the pseudo-Lipschitzness of the map (f +- G)⁻¹ is closely tied to the uniformity of our method in the sense that the attraction region does not depend on small perturbations of the parameter y. Finally, we provide an enhanced version of the convergence theorem established by Geoffroy, et al.     

Investigation of fabrication and hetero-epitaxy relationship of CoCrPt thin films grown on CrW underlayer

This paper reports that longitudinally oriented CoCrPt thin films with Cr₈₅W₁₅ underlayer and CoCr intermediate layer for use of giant magnetoresistance heads were fabricated by magnetron sputtering. Without CoCr intermediate layer, CoCrPt layer deposited directly on Cr₈₅W₁₅ underlayer which has a dominant (200) texture exhibits unexpected (10\bar {1}1) texture. After introducing CoCr intermediate layer, the CoCrPt layer shifts into (11\bar {2}0) texture. This article studies the crystallographic hetero-epitaxy relationship between magnetic layer and underlayer in order to understand the appearance of CoCrPt (10\bar {1}1) texture on (200) textured Cr underlayer and the influence of CoCr intermediate layer on the inducement of CoCrPt (11\bar {2}0) texture. The CoCr intermediate layer plays a crucial role in controlling the microstructure and consequently the magnetic properties of the overlying magnetic layer.     

Modularity of a certain Calabi-Yau threefold and combinatorial congruences

We prove a certain Calabi-Yau threefold is modular in the sense that the number of points on its reduction modulo p is expressed in terms of the pth coefficient of a weight 4 newform in S₄(Γ₀(6)). We also give a mod p² combinatorial expression for these coefficients. 2000 Mathematics Subject Classification: 11G25, 11G40